# Bitmap/Flood fill

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Bitmap/Flood fill
You are encouraged to solve this task according to the task description, using any language you may know.

Implement a flood fill.

A flood fill is a way of filling an area using color banks to define the contained area or a target color which "determines" the area (the valley that can be flooded; Wikipedia uses the term target color). It works almost like a water flooding from a point towards the banks (or: inside the valley): if there's a hole in the banks, the flood is not contained and all the image (or all the "connected valleys") get filled.

To accomplish the task, you need to implement just one of the possible algorithms (examples are on Wikipedia). Variations on the theme are allowed (e.g. adding a tolerance parameter or argument for color-matching of the banks or target color).

Testing: the basic algorithm is not suitable for truecolor images; a possible test image is the one shown on the right box; you can try to fill the white area, or the black inner circle.

## Action!

In the following solution a simple implementation of queue has been used.

```INCLUDE "H6:RGBCIRCL.ACT" ;from task Midpoint circle algorithm

RGB black,white,yellow,blue

DEFINE PTR="CARD"
TYPE PointB=[BYTE px,py]
TYPE Queue=[PTR qfront,qrear,qdata INT capacity]

PROC QueueInit(Queue POINTER q)
DEFINE MAXSIZE="500"
CARD ARRAY a(MAXSIZE)

q.qfront=0
q.qrear=0
q.capacity=MAXSIZE
q.qdata=a
RETURN

BYTE FUNC IsQueueEmpty(Queue POINTER q)
IF q.qfront=q.qrear THEN
RETURN (1)
FI
RETURN (0)

PROC QueuePush(Queue POINTER q PointB POINTER p)
PTR rear
PointB POINTER tmp

rear=q.qrear+1
IF rear=q.capacity THEN
rear=0
FI
IF rear=q.qfront THEN
Break()
FI
tmp=q.qdata+q.qrear*2
tmp.px=p.px
tmp.py=p.py
q.qrear=rear
RETURN

PROC QueuePop(Queue POINTER q PointB POINTER p)
PointB POINTER tmp

IF IsQueueEmpty(q) THEN
Break()
FI
tmp=q.qdata+q.qfront*2
p.px=tmp.px
p.py=tmp.py
q.qfront==+1
IF q.qfront=q.capacity THEN
q.qfront=0
FI
RETURN

PROC DrawImage(RgbImage POINTER img BYTE x,y)
RGB POINTER p
BYTE i,j

p=img.data
FOR j=0 TO img.h-1
DO
FOR i=0 TO img.w-1
DO
IF RgbEqual(p,yellow) THEN
Color=1
ELSEIF RgbEqual(p,white) THEN
Color=2
ELSEIF RgbEqual(p,blue) THEN
Color=3
ELSE
Color=0
FI
Plot(x+i,y+j)
p==+RGBSIZE
OD
OD
RETURN

PROC FloodFill(RgbImage POINTER img BYTE x0,y0 RGB POINTER col)
Queue q
RGB c,tmp
PointB p

GetRgbPixel(img,x0,y0,c)
IF RgbEqual(c,col) THEN
RETURN
FI
p.px=x0 p.py=y0
QueueInit(q)
QueuePush(q,p)
WHILE IsQueueEmpty(q)=0
DO
QueuePop(q,p)
x0=p.px y0=p.py

GetRgbPixel(img,x0,y0,tmp)
IF RgbEqual(tmp,c) THEN
SetRgbPixel(img,x0,y0,col)

IF x0>0 THEN
GetRgbPixel(img,x0-1,y0,tmp)
IF RgbEqual(tmp,c) THEN
p.px=x0-1 p.py=y0
QueuePush(q,p)
FI
FI
IF x0<img.w-1 THEN
GetRgbPixel(img,x0+1,y0,tmp)
IF RgbEqual(tmp,c) THEN
p.px=x0+1 p.py=y0
QueuePush(q,p)
FI
FI
IF y0>0 THEN
GetRgbPixel(img,x0,y0-1,tmp)
IF RgbEqual(tmp,c) THEN
p.px=x0 p.py=y0-1
QueuePush(q,p)
FI
FI
IF y0<img.h-1 THEN
GetRgbPixel(img,x0,y0+1,tmp)
IF RgbEqual(tmp,c) THEN
p.px=x0 p.py=y0+1
QueuePush(q,p)
FI
FI
FI
OD
RETURN

PROC Main()
RgbImage img
BYTE CH=\$02FC,size=[40]
BYTE ARRAY p(4800)
BYTE n
INT x,y
RGB POINTER col

Graphics(7+16)
SetColor(0,13,12) ;yellow
SetColor(1,0,14)  ;white
SetColor(2,8,6)   ;blue
SetColor(4,0,0)   ;black

RgbBlack(black)
RgbYellow(yellow)
RgbWhite(white)
RgbBlue(blue)

InitRgbImage(img,size,size,p)
FillRgbImage(img,black)

RgbCircle(img,size/2,size/2,size/2-1,white)
RgbCircle(img,2*size/5,2*size/5,size/5,white)
DrawImage(img,0,(96-size)/2)

FloodFill(img,3*size/5,3*size/5,white)
DrawImage(img,size,(96-size)/2)

FloodFill(img,2*size/5,2*size/5,blue)
DrawImage(img,2*size,(96-size)/2)

FloodFill(img,3*size/5,3*size/5,yellow)
DrawImage(img,3*size,(96-size)/2)

DO UNTIL CH#\$FF OD
CH=\$FF
RETURN```
Output:

```procedure Flood_Fill
(  Picture  : in out Image;
From     : Point;
Fill     : Pixel;
Replace  : Pixel;
Distance : Luminance := 20
)  is
function Diff (A, B : Luminance) return Luminance is
pragma Inline (Diff);
begin
if A > B then
return A - B;
else
return B - A;
end if;
end Diff;

function "-" (A, B : Pixel) return Luminance is
pragma Inline ("-");
begin
return Luminance'Max (Luminance'Max (Diff (A.R, B.R), Diff (A.G, B.G)), Diff (A.B, B.B));
end "-";
procedure Column (From : Point);
procedure Row (From : Point);

Visited : array (Picture'Range (1), Picture'Range (2)) of Boolean :=
(others => (others => False));

procedure Column (From : Point) is
X1 : Positive := From.X;
X2 : Positive := From.X;
begin
Visited (From.X, From.Y) := True;
for X in reverse Picture'First (1)..From.X - 1 loop
exit when Visited (X, From.Y);
declare
Color : Pixel renames Picture (X, From.Y);
begin
Visited (X, From.Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
X1    := X;
end;
end loop;
for X in From.X + 1..Picture'Last (1) loop
exit when Visited (X, From.Y);
declare
Color : Pixel renames Picture (X, From.Y);
begin
Visited (X, From.Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
X2    := X;
end;
end loop;
for X in X1..From.X - 1 loop
Row ((X, From.Y));
end loop;
for X in From.X + 1..X2 loop
Row ((X, From.Y));
end loop;
end Column;

procedure Row (From : Point) is
Y1 : Positive := From.Y;
Y2 : Positive := From.Y;
begin
Visited (From.X, From.Y) := True;
for Y in reverse Picture'First (2)..From.Y - 1 loop
exit when Visited (From.X, Y);
declare
Color : Pixel renames Picture (From.X, Y);
begin
Visited (From.X, Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
Y1    := Y;
end;
end loop;
for Y in From.Y + 1..Picture'Last (2) loop
exit when Visited (From.X, Y);
declare
Color : Pixel renames Picture (From.X, Y);
begin
Visited (From.X, Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
Y2    := Y;
end;
end loop;
for Y in Y1..From.Y - 1 loop
Column ((From.X, Y));
end loop;
for Y in From.Y + 1..Y2 loop
Column ((From.X, Y));
end loop;
end Row;

Color : Pixel renames Picture (From.X, From.Y);
begin
if Color - Replace <= Distance then
Visited (From.X, From.Y) := True;
Color := Fill;
Column (From);
end if;
end Flood_Fill;
```

The procedure has the following parameters. Picture is the image to change. From is the point to start at. Fill is the color to fill with. Replace is the color to replace. Distance defines the range of color around Replace to replace as well. The distance is defined as a maximum of the differences of stimuli. The following code snippet reads the test file, fills the area between two circles red, and writes the result:

```declare
File : File_Type;
begin
Open (File, In_File, "Unfilledcirc.ppm");
declare
Picture : Image := Get_PPM (File);
begin
Close (File);
Flood_Fill
(  Picture  => Picture,
From     => (122, 30),
Fill     => (255,0,0),
Replace  => White
);
Create (File, Out_File, "Filledcirc.ppm");
Put_PPM (File, Picture);
Close (File);
end;
end;
```

## Applesoft BASIC

``` 100  GR:GOSUB 330"DRAW THE DEATH STAR"
110  COLOR= 12
120  X = 20:Y = 30: GOSUB 140"FLOOD FILL"
130  END
140  C =  SCRN( X,Y)
150  X(S) = X:Y(S) = Y:S = S + 1
160  FOR S = 0 TO 0 STEP  - 1
170      X = X(S):Y = Y(S)
180      LX = X
190      IF  SCRN( LX - 1,Y) = C THEN  PLOT LX - 1,Y:LX = LX - 1: GOTO 190
200      IF  SCRN( X,Y) = C THEN  PLOT X,Y:X = X + 1: GOTO 200
210      X1 = LX:X2 = X - 1:YP = Y + 1: GOSUB 250"SCAN"
220      X1 = LX:X2 = X - 1:YP = Y - 1: GOSUB 250"SCAN"
230  NEXT S
240  RETURN
250  TRUE =  NOT FALSE
260  ADDED = FALSE
270  FOR XP = X1 TO X2:
280      INSIDE =  SCRN( XP,YP) = C
290      IF  NOT INSIDE THEN ADDED = FALSE
300      IF INSIDE AND  NOT ADDED THEN X(S) = XP:Y(S) = YP:S = S + 1:ADDED = TRUE
310  NEXT XP
320  RETURN
330  COLOR= 15: CX = 20:CY = 20:R = 18: GOSUB 350"CIRCLE"
340  COLOR= 0: CX = 15:CY = 15:R = 6
350  F = 1 - R:X = 0:Y = R:DX = 0:DY =  - 2 * R:PLOT CX,CY + R:PLOT CX,CY - R:HLIN CX - R,CX + R AT CY:  IF X >  = Y THEN  RETURN
360  FOR I = 0 TO 1:IF F >  = 0 THEN Y = Y - 1:DY = DY + 2:F = F + DY
370  X = X + 1:DX = DX + 2:F = F + DX + 1:HLIN CX - X,CX + X AT CY + Y:HLIN CX - X,CX + X AT CY - Y:HLIN CX - Y,CX + Y AT CY + X:HLIN CX - Y,CX + Y AT CY - X: I = X >  = Y : NEXT I : RETURN```

## AutoHotkey

• `x`, `y` are the initial coords (relative to screen unless the `relative` parameter is true).
• `target` is the BGR hex color code to replace.
• `replacement` is the BGR hex color code to replace `target` with.
• `mode` is 1 for a four-way fill, 2 for a five-way fill (hits each pixel doubly because each calls itself), 3 for an eight-way fill, or 4 for an eight-way fill that hits each pixel doubly because it calls itself double (default 1).
• `key` is a key to press to exit if the fill takes too long.

### Recursive

This is limited to %StackSize% pixels.

```SetBatchLines, -1
CoordMode, Mouse
CoordMode, Pixel
CapsLock::
KeyWait, CapsLock
MouseGetPos, X, Y
PixelGetColor, color, X, Y
FloodFill(x, y, color, 0x000000, 1, "CapsLock")
MsgBox Done!
Return
FloodFill(x, y, target, replacement, mode=1, key="")
{
If GetKeyState(key, "P")
Return
PixelGetColor, color, x, y
If (color <> target || color = replacement || target = replacement)
Return
VarSetCapacity(Rect, 16, 0)
NumPut(x, Rect, 0)
NumPut(y, Rect, 4)
NumPut(x+1, Rect, 8)
NumPut(y+1, Rect, 12)
hDC := DllCall("GetDC", UInt, 0)
hBrush := DllCall("CreateSolidBrush", UInt, replacement)
DllCall("FillRect", UInt, hDC, Str, Rect, UInt, hBrush)
DllCall("ReleaseDC", UInt, 0, UInt, hDC)
DllCall("DeleteObject", UInt, hBrush)
FloodFill(x+1, y, target, replacement, mode, key)
FloodFill(x-1, y, target, replacement, mode, key)
FloodFill(x, y+1, target, replacement, mode, key)
FloodFill(x, y-1, target, replacement, mode, key)
If (mode = 2 || mode = 4)
FloodFill(x, y, target, replacement, mode, key)
If (Mode = 3 || mode = 4)
{
FloodFill(x+1, y+1, target, replacement, key)
FloodFill(x-1, y+1, target, replacement, key)
FloodFill(x+1, y-1, target, replacement, key)
FloodFill(x-1, y-1, target, replacement, key)
}
}
```

### Iterative

```#NoEnv
#SingleInstance, Force

SetBatchLines, -1
CoordMode, Mouse
CoordMode, Pixel
return

CapsLock::
KeyWait, CapsLock
MouseGetPos, X, Y
PixelGetColor, color, X, Y
FloodFill(x, y, color, 0x000000, 1, "Esc")
MsgBox Done!
Return

FloodFill( 0x, 0y, target, replacement, mode=1, key="" )
{
VarSetCapacity(Rect, 16, 0)
hDC := DllCall("GetDC", UInt, 0)
hBrush := DllCall("CreateSolidBrush", UInt, replacement)

l := 0
while l >= 0
{
if getkeystate(key, "P")
return
x := %l%x, y := %l%y
%l%p++
p := %l%p
PixelGetColor, color, x, y
if (color = target)
{
NumPut(x, Rect, 0)
NumPut(y, Rect, 4)
NumPut(x+1, Rect, 8)
NumPut(y+1, Rect, 12)
DllCall("FillRect", UInt, hDC, Str, Rect, UInt, hBrush)
}
else if (p = 1)
{
%l%x := %l%y := %l%p := "", l--
continue
}
if (p < 5)
ol := l++
, %l%x := %ol%x + (p = 1 ? 1 : p = 2 ? -1 : 0)
, %l%y := %ol%y + (p = 3 ? 1 : p = 4 ? -1 : 0)
else
%l%x := %l%y := %l%p := "", l--
}

DllCall("ReleaseDC", UInt, 0, UInt, hDC)
DllCall("DeleteObject", UInt, hBrush)
}
```

## BBC BASIC

BBC BASIC has a built-in flood fill statement, but to satisfy the terms of the task it is not used in this example.

```      MODE 8
GCOL 15
CIRCLE FILL 640, 512, 500
GCOL 0
CIRCLE FILL 500, 600, 200
GCOL 3
PROCflood(600, 200, 15)
GCOL 4
PROCflood(600, 700, 0)
END

DEF PROCflood(X%, Y%, C%)
LOCAL L%, R%
IF POINT(X%,Y%) <> C% ENDPROC
L% = X%
R% = X%
WHILE POINT(L%-2,Y%) = C% : L% -= 2 : ENDWHILE
WHILE POINT(R%+2,Y%) = C% : R% += 2 : ENDWHILE
LINE L%,Y%,R%,Y%
FOR X% = L% TO R% STEP 2
PROCflood(X%, Y%+2, C%)
PROCflood(X%, Y%-2, C%)
NEXT
ENDPROC
```

## C

### Simple and complete example in C89

```/*
* RosettaCode: Bitmap/Flood fill, language C, dialects C89, C99, C11.
*
* This is an implementation of the recursive algorithm. For the sake of
* simplicity, instead of reading files as JPEG, PNG, etc., the program
* read and write Portable Bit Map (PBM) files in plain text format.
* Portable Bit Map files can also be read and written with GNU GIMP.
*
* The program is just an example, so the image size is limited to 2048x2048,
* the image can only be black and white, there is no run-time validation.
*
* Data is read from a standard input stream, the results are written to the
* standard output file.
*
* In order for this program to work properly it is necessary to allocate
* enough memory for the program stack. For example, in Microsoft Visual Studio,
* the option /stack:134217728 declares a 128MB stack instead of the default
* size of 1MB.
*/
#define _CRT_SECURE_NO_WARNINGS /* Unlock printf etc. in MSVC */
#include <stdio.h>
#include <stdlib.h>

#define MAXSIZE 2048
#define BYTE unsigned char

static int width, height;
static BYTE bitmap[MAXSIZE][MAXSIZE];
static BYTE oldColor;
static BYTE newColor;

void floodFill(int i, int j)
{
if ( 0 <= i && i < height
&&   0 <= j && j < width
&&   bitmap[i][j] == oldColor )
{
bitmap[i][j] = newColor;
floodFill(i-1,j);
floodFill(i+1,j);
floodFill(i,j-1);
floodFill(i,j+1);
}
}

/* *****************************************************************************
* Input/output routines.
*/

void skipLine(FILE* file)
{
while(!ferror(file) && !feof(file) && fgetc(file) != '\n')
;
}

void skipCommentLines(FILE* file)
{
int c;
int comment = '#';

while ((c = fgetc(file)) == comment)
skipLine(file);
ungetc(c,file);
}

{
int i,j;

skipLine(file);
skipCommentLines(file);  fscanf(file,"%d",&width);
skipCommentLines(file);  fscanf(file,"%d",&height);
skipCommentLines(file);

if ( width <= MAXSIZE && height <= MAXSIZE )
for ( i = 0; i < height; i++ )
for ( j = 0; j < width; j++ )
fscanf(file,"%1d",&(bitmap[i][j]));
else exit(EXIT_FAILURE);
}

void writePortableBitMap(FILE* file)
{
int i,j;
fprintf(file,"P1\n");
fprintf(file,"%d %d\n", width, height);
for ( i = 0; i < height; i++ )
{
for ( j = 0; j < width; j++ )
fprintf(file,"%1d", bitmap[i][j]);
fprintf(file,"\n");
}
}

/* *****************************************************************************
* The main entry point.
*/

int main(void)
{
oldColor = 1;
newColor = oldColor ? 0 : 1;
floodFill(height/2,width/2);
writePortableBitMap(stdout);
return EXIT_SUCCESS;
}
```

### Second example

```// http://commons.wikimedia.org/wiki/File:Julia_immediate_basin_1_3.png

unsigned int f(unsigned int _iX, unsigned int _iY)
/*
gives position of point (iX,iY) in 1D array  ; uses also global variables
it does not check if index is good  so memory error is possible
*/
{return (_iX + (iYmax-_iY-1)*iXmax );}

int FillContour(int iXseed, int iYseed,  unsigned char color, unsigned char _data[])
{
/*
fills contour with black border ( color = iJulia)  using seed point inside contour
and horizontal lines
it starts from seed point, saves max right( iXmaxLocal) and max left ( iXminLocal) interior points of horizontal line,
in new line ( iY+1 or iY-1) it computes new interior point  : iXmidLocal=iXminLocal + (iXmaxLocal-iXminLocal)/2;
result is stored in _data array : 1D array of 1-bit colors ( shades of gray)
it does not check if index of _data array is good  so memory error is possible
*/

int iX, /* seed integer coordinate */
iY=iYseed,
/* most interior point of line iY */
iXmidLocal=iXseed,
/* min and max of interior points of horizontal line iY */
iXminLocal,
iXmaxLocal;
int i ; /* index of _data array */;

/* ---------  move up --------------- */
do{
iX=iXmidLocal;
i =f(iX,iY); /* index of _data array */;

/* move to right */
while (_data[i]==iInterior)
{ _data[i]=color;
iX+=1;
i=f(iX,iY);
}
iXmaxLocal=iX-1;

/* move to left */
iX=iXmidLocal-1;
i=f(iX,iY);
while (_data[i]==iInterior)
{ _data[i]=color;
iX-=1;
i=f(iX,iY);
}
iXminLocal=iX+1;

iY+=1; /* move up */
iXmidLocal=iXminLocal + (iXmaxLocal-iXminLocal)/2; /* new iX inside contour */
i=f(iXmidLocal,iY); /* index of _data array */;
if ( _data[i]==iJulia)  break; /*  it should not cross the border */

} while  (iY<iYmax);

/* ------  move down ----------------- */
iXmidLocal=iXseed;
iY=iYseed-1;

do{
iX=iXmidLocal;
i =f(iX,iY); /* index of _data array */;

/* move to right */
while (_data[i]==iInterior) /*  */
{ _data[i]=color;
iX+=1;
i=f(iX,iY);
}
iXmaxLocal=iX-1;

/* move to left */
iX=iXmidLocal-1;
i=f(iX,iY);
while (_data[i]==iInterior) /*  */
{ _data[i]=color;
iX-=1; /* move to right */
i=f(iX,iY);
}
iXminLocal=iX+1;

iY-=1; /* move down */
iXmidLocal=iXminLocal + (iXmaxLocal-iXminLocal)/2; /* new iX inside contour */
i=f(iXmidLocal,iY); /* index of _data array */;
if ( _data[i]==iJulia)  break; /*  it should not cross the border */
} while  (0<iY);

/* mark seed point by big pixel */
const int iSide =iXmax/500; /* half of width or height of big pixel */
for(iY=iYseed-iSide;iY<=iYseed+iSide;++iY){
for(iX=iXseed-iSide;iX<=iXseed+iSide;++iX){
i= f(iX,iY); /* index of _data array */
_data[i]=10;}}

return 0;
}
```

### Third example

 This example is in need of improvement: Very difficult to make it work, and still doesn't work correctly after that. Needs to be replaced with something sensible.

The `sys/queue.h` is not POSIX. (See FIFO)

```/* #include <sys/queue.h> */
typedef struct {
color_component red, green, blue;
} rgb_color;
typedef rgb_color *rgb_color_p;

void floodfill(image img, int px, int py,
rgb_color_p bankscolor,
rgb_color_p rcolor);
```
```#include "imglib.h"

typedef struct _ffill_node {
int px, py;
TAILQ_ENTRY(_ffill_node) nodes;
} _ffill_node_t;
typedef struct _ffill_queue_s _ffill_queue;

inline void _ffill_removehead(_ffill_queue *q)
{
_ffill_node_t *n = q->tqh_first;
if ( n != NULL ) {
TAILQ_REMOVE(q, n, nodes);
free(n);
}
}

inline void _ffill_enqueue(_ffill_queue *q, int px, int py)
{
_ffill_node_t *node;
node = malloc(sizeof(_ffill_node_t));
if ( node != NULL ) {
node->px = px; node->py = py;
TAILQ_INSERT_TAIL(q, node, nodes);
}
}

inline double color_distance( rgb_color_p a, rgb_color_p b )
{
return sqrt( (double)(a->red - b->red)*(a->red - b->red) +
(double)(a->green - b->green)*(a->green - b->green) +
(double)(a->blue - b->blue)*(a->blue - b->blue) ) / (256.0*sqrt(3.0));
}

inline void _ffill_rgbcolor(image img, rgb_color_p tc, int px, int py)
{
tc->red = GET_PIXEL(img, px, py)[0];
tc->green = GET_PIXEL(img, px, py)[1];
tc->blue = GET_PIXEL(img, px, py)[2];
}

#define NSOE(X,Y) do {							\
if ( ((X)>=0)&&((Y)>=0) && ((X)<img->width)&&((Y)<img->height)) {	\
_ffill_rgbcolor(img, &thisnode, (X), (Y));			\
if ( color_distance(&thisnode, bankscolor) > tolerance ) {	\
if (color_distance(&thisnode, rcolor) > 0.0) { 			\
put_pixel_unsafe(img, (X), (Y), rcolor->red,			\
rcolor->green,				\
rcolor->blue);				\
_ffill_enqueue(&head, (X), (Y));				\
pixelcount++;							\
}								\
}									\
}									\
} while(0)

unsigned int floodfill(image img, int px, int py,
rgb_color_p bankscolor,
rgb_color_p rcolor)
{
rgb_color thisnode;
unsigned int pixelcount = 0;
double tolerance = 0.05;

if ( (px < 0) || (py < 0) || (px >= img->width) || (py >= img->height) )
return;

_ffill_rgbcolor(img, &thisnode, px, py);
if ( color_distance(&thisnode, bankscolor) <= tolerance ) return;

while( head.tqh_first != NULL ) {
_ffill_node_t *n = head.tqh_first;
_ffill_rgbcolor(img, &thisnode, n->px, n->py);
if ( color_distance(&thisnode, bankscolor) > tolerance ) {
put_pixel_unsafe(img, n->px, n->py, rcolor->red, rcolor->green, rcolor->blue);
pixelcount++;
}
int tx = n->px, ty = n->py;
NSOE(tx - 1, ty);
NSOE(tx + 1, ty);
NSOE(tx, ty - 1);
NSOE(tx, ty + 1);
}
return pixelcount;
}
```

The pixelcount could be used to know the area of the filled region. The internal parameter `tolerance` can be tuned to cope with antialiasing, bringing "sharper" resuts.

#### Usage example

(Comments show changes to fill the white area instead of the black circle)

```#include <stdio.h>
#include <stdlib.h>
#include "imglib.h"

int main(int argc, char **argv)
{
image animage;
rgb_color ic;
rgb_color rc;

if ( argc > 1 ) {
if ( animage != NULL ) {
ic.red = 255; /* = 0; */
ic.green = 255; /* = 0; */
ic.blue = 255; /* = 0; */
rc.red = 0;
rc.green = 255;
rc.blue = 0;
floodfill(animage, 100, 100, &ic, &rc);
/*    150, 150 */
print_jpg(animage, 90);
free(animage);
}
}
return 0;
}
```

## C#

Works with: C# version 3.0

This implementation matches exact colours only. Since the example image has grey pixels around the edges of the circles, these will remain grey after the interiors are filled.

```using System;
using System.Collections.Generic;
using System.Drawing;

namespace FloodFill
{
class Program
{
private static bool ColorMatch(Color a, Color b)
{
return (a.ToArgb() & 0xffffff) == (b.ToArgb() & 0xffffff);
}

static void FloodFill(Bitmap bmp, Point pt, Color targetColor, Color replacementColor)
{
Queue<Point> q = new Queue<Point>();
q.Enqueue(pt);
while (q.Count > 0)
{
Point n = q.Dequeue();
if (!ColorMatch(bmp.GetPixel(n.X, n.Y),targetColor))
continue;
Point w = n, e = new Point(n.X + 1, n.Y);
while ((w.X >= 0) && ColorMatch(bmp.GetPixel(w.X, w.Y),targetColor))
{
bmp.SetPixel(w.X, w.Y, replacementColor);
if ((w.Y > 0) && ColorMatch(bmp.GetPixel(w.X, w.Y - 1),targetColor))
q.Enqueue(new Point(w.X, w.Y - 1));
if ((w.Y < bmp.Height - 1) && ColorMatch(bmp.GetPixel(w.X, w.Y + 1),targetColor))
q.Enqueue(new Point(w.X, w.Y + 1));
w.X--;
}
while ((e.X <= bmp.Width - 1) && ColorMatch(bmp.GetPixel(e.X, e.Y),targetColor))
{
bmp.SetPixel(e.X, e.Y, replacementColor);
if ((e.Y > 0) && ColorMatch(bmp.GetPixel(e.X, e.Y - 1), targetColor))
q.Enqueue(new Point(e.X, e.Y - 1));
if ((e.Y < bmp.Height - 1) && ColorMatch(bmp.GetPixel(e.X, e.Y + 1), targetColor))
q.Enqueue(new Point(e.X, e.Y + 1));
e.X++;
}
}
}

static void Main(string[] args)
{
Bitmap bmp = new Bitmap("Unfilledcirc.bmp");
FloodFill(bmp, new Point(200, 200), Color.White, Color.Red);
FloodFill(bmp, new Point(100, 100), Color.Black, Color.Blue);
bmp.Save("Filledcirc.bmp");
}
}
}
```

## C++

Library: OpenCV

Input is the image, the starting node (x, y), the target color we want to fill, and the replacement color that will replace the target color. It implements a 4-way flood fill algorithm.

Interface

```#ifndef PROCESSING_FLOODFILLALGORITHM_H_
#define PROCESSING_FLOODFILLALGORITHM_H_

#include <opencv2/opencv.hpp>
#include <string.h>
#include <queue>

using namespace cv;
using namespace std;

class FloodFillAlgorithm {
public:
FloodFillAlgorithm(Mat* image) :
image(image) {
}
virtual ~FloodFillAlgorithm();

void flood(Point startPoint, Scalar tgtColor, Scalar loDiff);
void flood(Point startPoint, Mat* tgtMat);

protected:
Mat* image;
private:
bool insideImage(Point p);
};

#endif /* PROCESSING_FLOODFILLALGORITHM_H_ */
```

Implementation

```#include "FloodFillAlgorithm.h"

FloodFillAlgorithm::~FloodFillAlgorithm() {
}

void FloodFillAlgorithm::flood(Point startPoint, Scalar tgtColor, Scalar loDiff) {
floodFill(*image, startPoint, tgtColor, 0, loDiff);
}

void FloodFillAlgorithm::flood(Point startPoint, Mat* tgtMat) {
if (!insideImage(startPoint))
return;

Vec3b srcColor = image->at<Vec3b>(startPoint);

if (image->at<Vec3b>(startPoint) == srcColor) {

queue<Point> pointQueue;
pointQueue.push(startPoint);

while (!pointQueue.empty()) {
Point p = pointQueue.front();
pointQueue.pop();

if (insideImage(p)) {

if ((image->at<Vec3b>(p) == srcColor)) {
image->at<Vec3b>(p) = tgtMat->at<Vec3b>(p);

pointQueue.push(Point(p.x + 1, p.y));
pointQueue.push(Point(p.x - 1, p.y));
pointQueue.push(Point(p.x, p.y + 1));
pointQueue.push(Point(p.x, p.y - 1));
}
}

}
}
}

bool FloodFillAlgorithm::insideImage(Point p) {
return (p.x >= 0) && (p.x < image->size().width) && (p.y >= 0) && (p.y < image->size().height);
}
```

## D

This version uses the bitmap module from the Bitmap Task, matches exact colours only, and is derived from the Go version (to avoid stack overflow because unlike Go the D stack is not segmented).

```import std.array, bitmap;

void floodFill(Color)(Image!Color img, in uint x, in uint y,
in Color color)
/*pure*/ nothrow in {
assert (y < img.ny && x < img.nx);
} body {
immutable target = img[x, y];
static struct Pos { uint x, y; }
auto stack = [Pos(x, y)];

while (!stack.empty) {
immutable p = stack.back;
stack.popBack;
if (p.y < img.ny && p.x < img.nx && img[p.x, p.y] == target) {
img[p.x, p.y] = color;
stack.assumeSafeAppend;
stack ~= [Pos(p.x,     p.y + 1), Pos(p.x,     p.y - 1),
Pos(p.x + 1, p.y),     Pos(p.x - 1, p.y)];
}
}
}

void main() {
Image!RGB img;
img.floodFill(200, 200, RGB(127, 0, 0));
img.savePPM6("unfilled_circ_flooded.ppm");
}
```

See #Pascal.

## E

Using the image type from Basic bitmap storage#E.

```def floodFill(image, x, y, newColor) {
def matchColor := image[x, y]
def w := image.width()
def h := image.height()

/** For any given pixel x,y, this algorithm first fills a contiguous
horizontal line segment of pixels containing that pixel, then
recursively scans the two adjacent rows over the same horizontal
interval. Let this be invocation 0, and the immediate recursive
invocations be 1, 2, 3, ..., # be pixels of the wrong color, and
* be where each scan starts; the fill ordering is as follows:

--------------##########-------
-...1111111111*11####*33333...-
###########000*000000000000...-
-...2222222222*22222##*4444...-
--------------------##---------

Each invocation returns the x coordinate of the rightmost pixel it filled,
or x0 if none were.

Since it is recursive, this algorithm is unsuitable for large images
with small stacks.
*/
def fillScan(var x0, y) {
if (y >= 0 && y < h && x0 >= 0 && x0 < w) {
image[x0, y] := newColor
var x1 := x0

# Fill rightward
while (x1 < w - 1 && image.test(x1 + 1, y, matchColor)) {
x1 += 1
image[x1, y] := newColor # This could be replaced with a horizontal-line drawing operation
}

# Fill leftward
while (x0 > 0 && image.test(x0 - 1, y, matchColor)) {
x0 -= 1
image[x0, y] := newColor
}

if (x0 > x1) { return x0 } # Filled at most center

# x0..x1 is now a run of newly-filled pixels.

# println(`Filled \$y \$x0..\$x1`)
# println(image)

# Scan the lines above and below
for ynext in [y - 1, y + 1] {
if (ynext >= 0 && ynext < h) {
var x := x0
while (x <= x1) {
if (image.test(x, ynext, matchColor)) {
x := fillScan(x, ynext)
}
x += 1
}
}
}

return x1
} else {
return x0
}
}

fillScan(x, y)
}```

Note that this does not make any attempt to smoothly fill 'banks' or have a tolerance; it matches exact colors only. This will fill the example image with red inside green, and there will be black/white fringes:

```{
def i := readPPM(<import:java.io.makeFileInputStream>(<file:Unfilledcirc.ppm>))
println("Fill 1")
floodFill(i, 100, 100, makeColor.fromFloat(1, 0, 0))
println("Fill 2")
floodFill(i, 200, 200, makeColor.fromFloat(0, 1, 0))
println("Write")
i.writePPM(<import:java.io.makeFileOutputStream>(<file:Filledcirc.ppm>))
println("Done")
}```

## ERRE

In "PC.LIB" library there is a FILL procedure that do the job, but the example program implements the algorithm in ERRE language using an iterative method. This program is taken from the distribution disk and works in 320x200 graphics.

```PROGRAM MYFILL_DEMO

!VAR SP%

!\$INTEGER

CONST IMAGE_WIDTH=320,IMAGE_HEIGHT=200

DIM STACK[6000,1]

FUNCTION QUEUE_COUNT(X)
QUEUE_COUNT=SP
END FUNCTION

!\$INCLUDE="PC.LIB"

PROCEDURE QUEUE_INIT
SP=0
END PROCEDURE

PROCEDURE QUEUE_POP(->XX,YY)
XX=STACK[SP,0]
YY=STACK[SP,1]
SP=SP-1
END PROCEDURE

PROCEDURE QUEUE_PUSH(XX,YY)
SP=SP+1
STACK[SP,0]=XX
STACK[SP,1]=YY
END PROCEDURE

PROCEDURE FLOOD_FILL(XSTART,YSTART,COLORE_PRIMA,COLORE_RIEMP)
LOCAL XEST,XWEST,YNORD,YSUD,X,Y
QUEUE_INIT
QUEUE_PUSH(XSTART,YSTART)
WHILE (QUEUE_COUNT(0)>0) DO
QUEUE_POP(->X,Y)
XWEST=X
XEST=X

IF Y>0 THEN
YNORD=Y-1
ELSE
YNORD=-1
END IF

IF Y<IMAGE_HEIGHT-1 THEN
YSUD=Y+1
ELSE
YSUD=-1
END IF

LOOP
POINT(XEST+1,Y->ZC%)
EXIT IF NOT((XEST<IMAGE_WIDTH-1) AND (ZC%=COLORE_PRIMA))
XEST=XEST+1
END LOOP

LOOP
POINT(XWEST-1,Y->ZC%)
EXIT IF NOT((XWEST>0) AND (ZC%=COLORE_PRIMA))
XWEST=XWEST-1
END LOOP

FOR X=XWEST TO XEST DO
PSET(X,Y,COLORE_RIEMP)
POINT(X,YNORD->ZC%)
IF YNORD>=0 AND ZC%=COLORE_PRIMA THEN
QUEUE_PUSH(X,YNORD)
END IF
POINT(X,YSUD->ZC%)
IF YSUD>=0 AND ZC%=COLORE_PRIMA THEN
QUEUE_PUSH(X,YSUD)
END IF
END FOR
END WHILE
END PROCEDURE ! Flood_Fill

BEGIN
SCREEN(1)
CIRCLE(100,100,75,2)
CIRCLE(120,120,20,2)
CIRCLE(80,80,15,2)
CIRCLE(120,80,10,2)
FLOOD_FILL(100,100,0,1)
END PROGRAM```

Note: I haven't an "Upload files" item, so I can't show the resulting image!

## Euler Math Toolbox

Using an emulated stack. EMT's recursive stack space is limited. For the notebook with images see this page.

```>file="test.png";
>insrgb(A);
>function floodfill (A0,i,j,color,dist) ...
\$  A=A0;
\$  R=getred(A); G=getgreen(A); B=getblue(A);
\$  d=sqrt((R-R[i,j])^2+(G-G[i,j])^2+(B-B[i,j])^2);
\$  n=rows(A); m=cols(A);
\$  V=zeros(n,m);
\$  S=zeros(n*m,2); sn=0;
\$  A[i,j]=color; V[i,j]=1;
\$  repeat;
\$    if fill(A,i+1,j,n,m,d,dist,V,S,sn,color) then i=i+1; continue;
\$    elseif fill(A,i,j+1,n,m,d,dist,V,S,sn,color) then j=j+1; continue;
\$    elseif fill(A,i-1,j,n,m,d,dist,V,S,sn,color) then i=i-1; continue;
\$    elseif fill(A,i,j-1,n,m,d,dist,V,S,sn,color) then j=j-1; continue;
\$    endif;
\$    sn=sn-1; if sn==0 then break; endif;
\$    i=S[sn,1]; j=S[sn,2];
\$  end;
\$  return A;
\$endfunction
>function fill (A,i,j,n,m,d,dist,V,S,%sn,color) ...
\$  if i<1 or i>n or j<1 or j>n then return 0; endif;
\$  if V[i,j] || d[i,j]>dist then A[i,j]=color; return 0; endif;
\$  V[i,j]=1;
\$  A[i,j]=color;
\$  %sn=%sn+1;
\$  S[%sn]=[i,j];
\$  return 1;
\$endfunction
>B=floodfill(A,10,240,rgb(0.5,0,0),0.5);
>B=floodfill(B,10,10,rgb(0.5,0,0),0.5);
>B=floodfill(B,150,60,rgb(0,0.5,0),0.5);
>B=floodfill(B,200,200,rgb(0,0,0.5),0.5);
>insrgb(B);
```

## FBSL

Using pure FBSL's built-in graphics functions:

```#DEFINE WM_LBUTTONDOWN 513
#DEFINE WM_CLOSE 16

FBSLSETTEXT(ME, "Before Flood Fill") ' Set form caption
FBSLSETFORMCOLOR(ME, RGB(0, 255, 255)) ' Cyan: persistent background color
FBSL.GETDC(ME) ' Use volatile FBSL.GETDC below to avoid extra assignments

RESIZE(ME, 0, 0, 220, 220)
CENTER(ME)
SHOW(ME)

DIM Breadth AS INTEGER, Height AS INTEGER
FBSL.GETCLIENTRECT(ME, 0, 0, Breadth, Height)

DrawCircles() ' Initialize circles

BEGIN EVENTS
SELECT CASE CBMSG
CASE WM_LBUTTONDOWN: FillCircles() ' Flood fill circles
CASE WM_CLOSE: FBSL.RELEASEDC(ME, FBSL.GETDC) ' Clean up
END SELECT
END EVENTS

SUB FillCircles()
FILL(FBSL.GETDC, Breadth / 2, Height / 2, &HFFFF) ' Yellow: flood fill using intrinsics
FOR DIM x = 0 TO Breadth / 2 ' Red: flood fill iteratively
FOR DIM y = 0 TO Height / 2
IF NOT POINT(FBSL.GETDC, x, y) THEN PSET(FBSL.GETDC, x, y, &HFF)
NEXT
NEXT
FBSLSETTEXT(ME, "After Flood Fill") ' Reset form caption
END SUB

SUB DrawCircles() ' Concatenate function calls
CIRCLE(FBSL.GETDC, Breadth / 2, Height / 2, 85, &HFFFFFF, 0, 360, 1, TRUE) _ ' White
(FBSL.GETDC, Breadth / 3, Height / 3, 30, 0, 0, 360, 1, TRUE) ' Black
END SUB
```

Output:

## Forth

This simple recursive algorithm uses routines from Basic bitmap storage.

```: third 2 pick ;
: 3dup  third third third ;
: 4dup  2over 2over ;

: flood ( color x y bmp -- )
3dup b@ >r  ( R: color to fill )
4dup b!
third 0 > if
rot 1- -rot
3dup b@ r@ = if recurse then
rot 1+ -rot
then
third 1+ over bwidth < if
rot 1+ -rot
3dup b@ r@ = if recurse then
rot 1- -rot
then
over 0 > if
swap 1- swap
3dup b@ r@ = if recurse then
swap 1+ swap
then
over 1+ over bheight < if
swap 1+ swap
3dup b@ r@ = if recurse then
swap 1- swap
then
r> drop ;
```

## Fortran

Works with: Fortran version 90 and later

Here the target color paradigm is used. Again the `matchdistance` parameter can be tuned to ignore small differences that could come because of antialiasing.

```module RCImageArea
use RCImageBasic
use RCImagePrimitive
implicit none

real, parameter, private :: matchdistance = 0.2

private :: northsouth, eastwest

contains

subroutine northsouth(img, p0, tcolor, fcolor)
type(rgbimage), intent(inout) :: img
type(point), intent(in) :: p0
type(rgb), intent(in) :: tcolor, fcolor

integer :: npy, spy, y
type(rgb) :: pc

npy = p0%y - 1
do
if ( inside_image(img, p0%x, npy) ) then
call get_pixel(img, p0%x, npy, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
npy = npy - 1
end do
npy = npy + 1
spy = p0%y + 1
do
if ( inside_image(img, p0%x, spy) ) then
call get_pixel(img, p0%x, spy, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
spy = spy + 1
end do
spy = spy - 1
call draw_line(img, point(p0%x, spy), point(p0%x, npy), fcolor)

do y = min(spy, npy), max(spy, npy)
if ( y == p0%y ) cycle
call eastwest(img, point(p0%x, y), tcolor, fcolor)
end do

end subroutine northsouth

subroutine eastwest(img, p0, tcolor, fcolor)
type(rgbimage), intent(inout) :: img
type(point), intent(in) :: p0
type(rgb), intent(in) :: tcolor, fcolor

integer :: npx, spx, x
type(rgb) :: pc

npx = p0%x - 1
do
if ( inside_image(img, npx, p0%y) ) then
call get_pixel(img, npx, p0%y, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
npx = npx - 1
end do
npx = npx + 1
spx = p0%x + 1
do
if ( inside_image(img, spx, p0%y) ) then
call get_pixel(img, spx, p0%y, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
spx = spx + 1
end do
spx = spx - 1
call draw_line(img, point(spx, p0%y), point(npx, p0%y), fcolor)

do x = min(spx, npx), max(spx, npx)
if ( x == p0%x ) cycle
call northsouth(img, point(x, p0%y), tcolor, fcolor)
end do

end subroutine eastwest

subroutine floodfill(img, p0, tcolor, fcolor)
type(rgbimage), intent(inout) :: img
type(point), intent(in) :: p0
type(rgb), intent(in) :: tcolor, fcolor

type(rgb) :: pcolor

if ( .not. inside_image(img, p0%x, p0%y) ) return
call get_pixel(img, p0%x, p0%y, pcolor)
if ( (pcolor .dist. tcolor) > matchdistance ) return

call northsouth(img, p0, tcolor, fcolor)
call eastwest(img, p0, tcolor, fcolor)
end subroutine floodfill

end module RCImageArea
```

Usage example excerpt (which on the test image will fill with green the inner black circle):

```  call floodfill(animage, point(100,100), rgb(0,0,0), rgb(0,255,0))
```

## FreeBASIC

Translation of: BBC BASIC
```' version 04-11-2016
' compile with: fbc -s console

' the flood_fill needs to know the boundries of the window/screen
' without them the routine start to check outside the window
' this leads to crashes (out of stack)
' the Line routine has clipping it will not draw outside the window

Sub flood_fill(x As Integer, y As Integer, target As UInteger, fill_color As UInteger)

Dim As Long x_max, y_max
ScreenInfo x_max, y_max

' 0, 0 is top left corner
If Point(x,y) <> target Then Exit Sub

Dim As Long l = x, r = x

While Point(l -1, y) = target AndAlso l -1 > -1
l = l -1
Wend

While Point(r +1, y) = target AndAlso r +1 < x_max
r = r +1
Wend

Line (l,y) - (r,y), fill_color

For x = l To r
If y +1 < y_max Then flood_fill(x, y +1, target, fill_color)
If y -1 >    -1 Then flood_fill(x, y -1, target, fill_color)
Next

End Sub

' ------=< MAIN >=------

Dim As ULong i, col, x, y

ScreenRes 400, 400, 32
Randomize Timer

For i As ULong = 1 To 5
Circle(Rnd * 400 ,Rnd * 400), i * 40, Rnd * &hFFFFFF
Next

' hit a key to end or close window
Do
x = Rnd * 400
y = Rnd * 400
col = Point(x, y)
flood_fill(x, y, col, Rnd * &hFFFFFF )
Sleep 2000
If InKey <> "" OrElse InKey = Chr(255) + "k" Then End
Loop```

## Go

An addition to code from the bitmap task:

```package raster

func (b *Bitmap) Flood(x, y int, repl Pixel) {
targ, _ := b.GetPx(x, y)
var ff func(x, y int)
ff = func(x, y int) {
p, ok := b.GetPx(x, y)
if ok && p.R == targ.R && p.G == targ.G && p.B == targ.B {
b.SetPx(x, y, repl)
ff(x-1, y)
ff(x+1, y)
ff(x, y-1)
ff(x, y+1)
}
}
ff(x, y)
}
```

And a test program. Works with code from read ppm and write ppm to pipe tasks. For input, it uses a version of the test file converted by the Go solution to "Read an image through a pipe". For output it uses the trick from "PPM conversion through a pipe" to write the .png suitable for uploading to RC.

```package main

import (
"log"
"os/exec"
"raster"
)

func main() {
b, err := raster.ReadPpmFile("Unfilledcirc.ppm")
if err != nil {
log.Fatal(err)
}
b.Flood(200, 200, raster.Pixel{127, 0, 0})
c := exec.Command("convert", "ppm:-", "flood.png")
pipe, err := c.StdinPipe()
if err != nil {
log.Fatal(err)
}
if err = c.Start(); err != nil {
log.Fatal(err)
}
if err = b.WritePpmTo(pipe); err != nil {
log.Fatal(err)
}
if err = pipe.Close(); err != nil {
log.Fatal(err)
}
}
```

This code uses the Bitmap and Bitmap.RGB modules defined here.

```import Data.Array.ST
import Data.STRef
import Bitmap

-- Implementation of a stack in the ST monad
pushST :: STStack s a -> a -> ST s ()
pushST s e = do
s2 <- readSTRef s
writeSTRef s (e : s2)

popST :: STStack s a -> ST s (Stack a)
popST s = do
s2 <- readSTRef s
writeSTRef s \$ tail s2
return \$ take 1 s2

isNotEmptySTStack :: STStack s a -> ST s Bool
isNotEmptySTStack s = do
s2 <- readSTRef s
return \$ not \$ null s2

emptySTStack :: ST s (STStack s a)
emptySTStack = newSTRef []

consumeSTStack :: STStack s a -> (a -> ST s ()) -> ST s ()
consumeSTStack s f = do
check <- isNotEmptySTStack s
when check \$ do
e <- popST s
f \$ head e
consumeSTStack s f

type Spanning s = STRef s (Bool, Bool)

setSpanLeft :: Spanning s -> Bool -> ST s ()
setSpanLeft s v = do
(_, r) <- readSTRef s
writeSTRef s (v, r)

setSpanRight :: Spanning s -> Bool -> ST s ()
setSpanRight s v = do
(l, _) <- readSTRef s
writeSTRef s (l, v)

setSpanNone :: Spanning s -> ST s ()
setSpanNone s = writeSTRef s (False, False)

floodFillScanlineStack :: Color c => Image s c -> Pixel -> c -> ST s (Image s c)
floodFillScanlineStack b coords newC = do
stack <- emptySTStack -- new empty stack holding pixels to fill
spans <- newSTRef (False, False) -- keep track of spans in scanWhileX
fFSS b stack coords newC spans -- function loop
return b
where
fFSS b st c newC p = do
oldC <- getPix b c
unless (oldC == newC) \$ do
pushST st c -- store the coordinates in the stack
(w, h) <- dimensions b
consumeSTStack st (scanWhileY b p oldC >=>
scanWhileX b st p oldC newC (w, h))

-- take a buffer, the span record, the color of the Color the fill is
-- started from, a coordinate from the stack, and returns the coord
-- of the next point to be filled in the same column
scanWhileY b p oldC coords@(Pixel (x, y)) =
if y >= 0
then do
z <- getPix b coords
if z == oldC
then scanWhileY b p oldC (Pixel (x, y - 1))
else do
setSpanNone p
return (Pixel (x, y + 1))
else do
setSpanNone p
return (Pixel (x, y + 1))

-- take a buffer, a stack, a span record, the old and new color, the
-- height and width of the buffer, and a coordinate.
-- paint the point with the new color, check if the fill must expand
-- to the left or right or both, and store those coordinates in the
-- stack for subsequent filling
scanWhileX b st p oldC newC (w, h) coords@(Pixel (x, y)) =
when (y < h) \$ do
z <- getPix b coords
when (z == oldC) \$ do
setPix b coords newC
(spanLeft, spanRight) <- readSTRef p
when (not spanLeft && x > 0) \$ do
z2 <- getPix b (Pixel (x - 1, y))
when (z2 == oldC) \$ do
pushST st (Pixel (x - 1, y))
setSpanLeft p True
when (spanLeft && x > 0) \$ do
z3 <- getPix b (Pixel (x - 1, y))
when (z3 /= oldC) \$
setSpanLeft p False
when (not spanRight && x < (w - 1)) \$ do
z4 <- getPix b (Pixel (x + 1, y))
when (z4 == oldC) \$ do
pushST st (Pixel (x + 1, y))
setSpanRight p True
when (spanRight && x < (w - 1)) \$ do
z5 <- getPix b (Pixel (x + 1, y))
when (z5 /= oldC) \$
setSpanRight p False
scanWhileX b st p oldC newC (w, h) (Pixel (x, y + 1))
```

## HicEst

HicEst color fill is via the decoration option of WRITE()

```WINDOW(WINdowhandle=wh, BaCkcolor=0, TItle="Rosetta test image")

WRITE(WIN=wh, DeCoRation="EL=14, BC=14") ! color 14 == bright yellow

RGB(128, 100, 0, 25) ! define color nr 25 as 128/255 red, 100/255 green, 0 blue
WRITE(WIN=wh, DeCoRation="L=1/4, R=1/2, T=1/4, B=1/2, EL=25, BC=25")

WINDOW(Kill=wh)```

## J

Solution:
Uses `getPixels` and `setPixels` from Basic bitmap storage.

```NB. finds and labels contiguous areas with the same numbers
NB. ref: http://www.jsoftware.com/pipermail/general/2005-August/023886.html
findcontig=: (|."1@|:@:>. (* * 1&(|.!.0)))^:4^:_@(* >:@i.@\$)

NB.*getFloodpoints v Returns points to fill given starting point (x) and image (y)
getFloodpoints=: [: 4&\$.@\$. [ (] = getPixels) [: findcontig ] -:"1 getPixels

NB.*floodFill v Floods area, defined by point and color (x), of image (y)
NB. x is: 2-item list of (y x) ; (color)
floodFill=: (1&({::)@[ ;~ 0&({::)@[ getFloodpoints ]) setPixels ]
```

Example Usage:
The following draws the same image as for the Tcl example image below.
Uses definitions from Basic bitmap storage, Bresenham's line algorithm and Midpoint circle algorithm.

```'white blue yellow black orange red'=: 255 255 255,0 0 255,255 255 0,0 0 0,255 165 0,:255 0 0
myimg=: white makeRGB 50 70
lines=: _2]\^:2 ] 0 0 25 0 , 25 0 25 35 , 25 35 0 35 , 0 35 0 0
myimg=: (lines;blue) drawLines myimg
myimg=: (3 3; yellow) floodFill myimg
myimg=: ((25 35 24 ,: 25 35 10);black) drawCircles myimg
myimg=: (5 34;orange) floodFill myimg
myimg=: (5 36;red) floodFill myimg
viewRGB myimg
```

Alternative findcontig:
The following alternative version of `findcontig` is less concise but is leaner, faster, works for n-dimensions and is not restricted to numerical arrays.

```NB. ref: http://www.jsoftware.com/pipermail/general/2005-August/024174.html
eq=:[:}:"1 [:(\$\$[:([:+/\1:,}:~:}.),) ,&_"1                NB. equal numbers for atoms of y connected in first direction
eq_nd=: i.@#@\$(<"0@[([:, |:^:_1"0 _)&> [:EQ&.> <@|:"0 _)] NB. n-dimensional eq, gives an #@\$,*/@\$ shaped matrix
repl=: (i.~{.){ {:@]                                      NB. replaces x by applying replace table y
cnnct=: [: |:@({."1<.//.]) [: ; <@(,.<./)/.~

findcontig_nd=: 3 : '(\$y)\${.  ([:({.,~}:) ([ repl cnnct)/\.)^:([:+./@(~:/)2&{.)^:_ (,{.) eq_nd (i.~ ~.@,) y'
```

## Java

Input is the image, the starting node (x, y), the target color we want to fill, and the replacement color that will replace the target color. It implements a 4-way flood fill algorithm. For large images, the performance can be improved by drawing the scanlines instead of setting each pixel to the replacement color, or by working directly on the databuffer.

```import java.awt.Color;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.util.Deque;

public class FloodFill {
public void floodFill(BufferedImage image, Point node, Color targetColor, Color replacementColor) {
int width = image.getWidth();
int height = image.getHeight();
int target = targetColor.getRGB();
int replacement = replacementColor.getRGB();
if (target != replacement) {
Deque<Point> queue = new LinkedList<Point>();
do {
int x = node.x;
int y = node.y;
while (x > 0 && image.getRGB(x - 1, y) == target) {
x--;
}
boolean spanUp = false;
boolean spanDown = false;
while (x < width && image.getRGB(x, y) == target) {
image.setRGB(x, y, replacement);
if (!spanUp && y > 0 && image.getRGB(x, y - 1) == target) {
queue.add(new Point(x, y - 1));
spanUp = true;
} else if (spanUp && y > 0 && image.getRGB(x, y - 1) != target) {
spanUp = false;
}
if (!spanDown && y < height - 1 && image.getRGB(x, y + 1) == target) {
queue.add(new Point(x, y + 1));
spanDown = true;
} else if (spanDown && y < height - 1 && image.getRGB(x, y + 1) != target) {
spanDown = false;
}
x++;
}
} while ((node = queue.pollFirst()) != null);
}
}
}
```

And here is an example of how to replace the white color with red from the sample image (with starting node (50, 50)):

```import java.io.IOException;
import java.awt.Color;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

public class Test {
public Test() throws IOException {
BufferedImage image = ImageIO.read(new File("Unfilledcirc.png"));
new FloodFill().floodFill(image, new Point(50, 50), Color.WHITE, Color.RED);
ImageIO.write(image, "png", new File("output.png"));
}

public static void main(String[] args) throws IOException {
new Test();
}
}
```

## Julia

Works with: Julia version 0.6

Inspired to Python version.

```using Images, FileIO

function floodfill!(img::Matrix{<:Color}, initnode::CartesianIndex{2}, target::Color, replace::Color)
img[initnode] != target && return img
# constants
north = CartesianIndex(-1,  0)
south = CartesianIndex( 1,  0)
east  = CartesianIndex( 0,  1)
west  = CartesianIndex( 0, -1)

queue = [initnode]
while !isempty(queue)
node = pop!(queue)
if img[node] == target
wnode = node
enode = node + east
end
# Move west until color of node does not match target color
while checkbounds(Bool, img, wnode) && img[wnode] == target
img[wnode] = replace
if checkbounds(Bool, img, wnode + north) && img[wnode + north] == target
push!(queue, wnode + north)
end
if checkbounds(Bool, img, wnode + south) && img[wnode + south] == target
push!(queue, wnode + south)
end
wnode += west
end
# Move east until color of node does not match target color
while checkbounds(Bool, img, enode) && img[enode] == target
img[enode] = replace
if checkbounds(Bool, img, enode + north) && img[enode + north] == target
push!(queue, enode + north)
end
if checkbounds(Bool, img, enode + south) && img[enode + south] == target
push!(queue, enode + south)
end
enode += east
end
end
return img
end

floodfill!(img, CartesianIndex(100, 100), Gray(false), Gray(true))
save("data/filledcircle.png", img)
```

## Kotlin

Translation of: Java
```// version 1.1.4-3

import java.awt.Color
import java.awt.Point
import java.awt.image.BufferedImage
import java.io.File
import javax.imageio.ImageIO
import javax.swing.JOptionPane
import javax.swing.JLabel
import javax.swing.ImageIcon

fun floodFill(image: BufferedImage, node: Point, targetColor: Color, replColor: Color) {
val target = targetColor.getRGB()
val replacement = replColor.getRGB()
if (target == replacement) return
val width = image.width
val height = image.height
val queue = LinkedList<Point>()
var nnode: Point? = node

do {
var x = nnode!!.x
val y = nnode.y
while (x > 0 && image.getRGB(x - 1, y) == target) x--
var spanUp = false
var spanDown = false

while (x < width && image.getRGB(x, y) == target) {
image.setRGB(x, y, replacement)

if (!spanUp && y > 0 && image.getRGB(x, y - 1) == target) {
queue.add(Point(x, y - 1))
spanUp = true
}
else if (spanUp && y > 0 && image.getRGB(x, y - 1) != target) {
spanUp = false
}

if (!spanDown && y < height - 1 && image.getRGB(x, y + 1) == target) {
queue.add(Point(x, y + 1))
spanDown = true
}
else if (spanDown && y < height - 1 && image.getRGB(x, y + 1) != target) {
spanDown = false
}
x++
}
nnode = queue.pollFirst()
}
while (nnode != null)
}

fun main(args: Array<String>) {
val image = ImageIO.read(File("Unfilledcirc.png"))
floodFill(image, Point(50, 50), Color.white, Color.yellow)
val title = "Floodfilledcirc.png"
ImageIO.write(image, "png", File(title))
JOptionPane.showMessageDialog(null, JLabel(ImageIcon(image)), title, JOptionPane.PLAIN_MESSAGE)
}
```

## Liberty BASIC

```'This example requires the Windows API
NoMainWin
WindowWidth = 267.5
WindowHeight = 292.5
UpperLeftX=int((DisplayWidth-WindowWidth)/2)
UpperLeftY=int((DisplayHeight-WindowHeight)/2)

Global hDC : hDC = GetDC(0)
Struct point, x As long, y As long
Struct RGB, Red As long, Green As long, Blue As long
Struct rect, left As long, top As long, right As long, bottom As long

StyleBits #main.gbox, 0, _WS_BORDER, 0, 0
GraphicBox #main.gbox, 2.5, 2.5, 253, 252

Open "Flood Fill - Click a Color" For Window As #main
Print #main, "TrapClose quit"
Print #main.gbox, "Down; Fill Black; Place 125 125; BackColor White; " _
+ "CircleFilled 115; Place 105 105; BackColor Black; CircleFilled 50; Flush"
Print #main.gbox, "When leftButtonUp gBoxClick"
Print #main.gbox, "Size 1"
Wait

Sub quit handle\$
Call ReleaseDC 0, hDC
Close #main
End
End Sub

Sub gBoxClick handle\$, MouseX, MouseY
result = GetCursorPos()
targetRGB = GetPixel(hDC, point.x.struct, point.y.struct)
ColorDialog "", replacementColor\$
If replacementColor\$ = "" Then Exit Sub
Print #main.gbox, "Color " + Word\$(replacementColor\$, 1) + " " + Word\$(replacementColor\$, 2) + " " + Word\$(replacementColor\$, 3)
result = FloodFill(MouseX, MouseY, targetRGB)
Print #main.gbox, "DelSegment FloodFill"
Print #main.gbox, "GetBMP FloodFill 0 0 500 500; CLS; DrawBMP FloodFill 0 0; Flush FloodFill"
Notice "Complete!"
End Sub

Sub ReleaseDC hWnd, hDC
CallDLL #user32,"ReleaseDC", hWnd As uLong, hDC As uLong, ret As Long
End Sub

Function GetDC(hWnd)
CallDLL #user32, "GetDC", hWnd As uLong, GetDC As uLong
End Function

Function GetCursorPos()
CallDLL #user32, "GetCursorPos", point As struct, GetCursorPos As uLong
End Function

Function GetPixel(hDC, x, y)
CallDLL #gdi32, "GetPixel", hDC As uLong, x As long, y As long, GetPixel As long
End Function

Function getLongRGB(RGB.Blue)
getLongRGB = (RGB.Blue * (256 * 256))
End Function

Function GetWindowRect(hWnd)
'Get ClientRectangle
CallDLL #user32, "GetWindowRect", hWnd As ulong, rect As struct, GetWindowRect As ulong
End Function

Function FloodFill(mouseXX, mouseYY, targetColor)
Scan
result = GetWindowRect(Hwnd(#main.gbox))
X = Int(mouseXX + rect.left.struct)
Y = Int(mouseYY + rect.top.struct)
If (GetPixel(hDC, X, Y) <> targetColor) Then
Exit Function
Else
CLS
Print str\$(mouseXX) + "   " + str\$(mouseYY)
Print #main.gbox, "Set " + str\$(mouseXX) + " " + str\$(mouseYY)
End If
If (mouseXX > 0) And (mouseXX < 253) Then
result = FloodFill((mouseXX - 1), mouseYY, targetColor)
result = FloodFill((mouseXX + 1), mouseYY, targetColor)
End If
If (mouseYY > 0) And (mouseYY < 252) Then
result = FloodFill(mouseXX, (mouseYY + 1), targetColor)
result = FloodFill(mouseXX, (mouseYY - 1), targetColor)
End If
End Function```

## Lingo

Lingo has built-in flood fill for image objects, so a custom implementation would be pointless:

`img.floodFill(x, y, rgb(r,g,b))`

## Lua

Uses Bitmap class here, with an RGB tuple pixel representation, then extending..

```\$ magick unfilledcirc.png -depth 8 unfilledcirc.ppm
```

Some rudimentary PPM support:

```function Bitmap:loadPPM(filename)
local fp = io.open( filename, "rb" )
if fp == nil then return false end
local head, width, height, depth, tail = fp:read("*line", "*number", "*number", "*number", "*line")
self.width, self.height = width, height
self:alloc()
for y = 1, self.height do
for x = 1, self.width do
end
end
fp:close()
end

function Bitmap:savePPM(filename)
local fp = io.open( filename, "wb" )
if fp == nil then return false end
fp:write(string.format("P6\n%d %d\n%d\n", self.width, self.height, 255))
for y = 1, self.height do
for x = 1, self.width do
local pix = self.pixels[y][x]
fp:write(string.char(pix[1]), string.char(pix[2]), string.char(pix[3]))
end
end
fp:close()
end
```

```function Bitmap:floodfill(x, y, c)
local b = self:get(x, y)
if not b then return end
local function matches(a)
if not a then return false end
-- this is where a "tolerance" could be implemented:
return a[1]==b[1] and a[2]==b[2] and a[3]==b[3]
end
local function ff(x, y)
if not matches(self:get(x, y)) then return end
self:set(x, y, c)
ff(x+1, y)
ff(x, y-1)
ff(x-1, y)
ff(x, y+1)
end
ff(x, y)
end
```

Demo:

```bitmap = Bitmap(0, 0)
bitmap:floodfill( 1, 1, { 255,0,0 }) -- fill exterior (except bottom right) with red
bitmap:floodfill( 50, 50, { 0,255,0 })-- fill larger circle with green
bitmap:floodfill( 100, 100, { 0,0,255 })-- fill smaller circle with blue
bitmap:savePPM("filledcirc.ppm")
```

## Mathematica / Wolfram Language

```createMask[img_, pos_, tol_] :=
RegionBinarize[img, Image[SparseArray[pos -> 1, ImageDimensions[img]]], tol];
floodFill[img_Image, pos_List, tol_Real, color_List] :=
ImageCompose[
SetAlphaChannel[ImageSubtract[img, createMask[img, pos, tol]], 1],
SetAlphaChannel[Image[ConstantArray[color, ImageDimensions[img]]],
]
]
```
Output:

Import the test image and fill the region containing the pixel at coordinate 100,100 with red (RGB 100%,0%,0%) using a tolerance of 1%

`floodFill[Import["http://rosettacode.org/mw/images/0/0f/Unfilledcirc.png"], {100, 100}, 0.01, {1, 0, 0}]`

## MiniScript

This implementation is for use with Mini Micro. The first parameter can be either a PixelDisplay or Image object. Flooding only occurs if the color as well as the opacity matches.

```floodFill = function(bmp, x, y, targetColor, replacementColor)
// Check if pixel is outside the bounds
if not(0 < x < bmp.width) or not(0 < y < bmp.height) then return

// Check the current pixel color
currentColor = bmp.pixel(x, y)
if currentColor != targetColor then return

// Replace the color
bmp.setPixel x, y, replacementColor
// Recursively apply to adjacent pixels
floodFill(bmp, x + 1, y, targetColor, replacementColor)
floodFill(bmp, x - 1, y, targetColor, replacementColor)
floodFill(bmp, x, y + 1, targetColor, replacementColor)
floodFill(bmp, x, y - 1, targetColor, replacementColor)
end function
clear
gfx.drawImage img, 0, 0
floodFill gfx, 50, 50, "#FFFFFFFF", "#00FFFFFF"
floodFill gfx, 100, 125, "#000000FF", "#0000FFFF"
```

## Nim

Translation of: Python
```import bitmap

proc floodFill*(img: Image; initPoint: Point; targetColor, replaceColor: Color) =

var stack: seq[Point]
let width = img.w
let height = img.h

if img[initPoint.x, initPoint.y] != targetColor:
return

while stack.len > 0:
var w, e: Point
let pt = stack.pop()
if img[pt.x, pt.y] == targetColor:
w = pt
e = if pt.x + 1 < width: (pt.x + 1, pt.y) else: pt
else:
continue  # Already processed.

# Move west until color of node does not match "targetColor".
while w.x >= 0 and img[w.x, w.y] == targetColor:
img[w.x, w.y] = replaceColor
if w.y + 1 < height and img[w.x, w.y + 1] == targetColor:
stack.add((w.x, w.y + 1))
if w.y - 1 >= 0 and img[w.x, w.y - 1] == targetColor:
stack.add((w.x, w.y - 1))
dec w.x

# Move east until color of node does not match "targetColor".
while e.x < width and img[e.x, e.y] == targetColor:
img[e.x, e.y] = replaceColor
if e.y + 1 < height and img[e.x, e.y + 1] == targetColor:
stack.add((e.x, e.y + 1))
if e.y - 1 >= 0 and img[e.x, e.y - 1] == targetColor:
stack.add((e.x, e.y - 1))
inc e.x

#———————————————————————————————————————————————————————————————————————————————————————————————————

when isMainModule:

var img = readPPM("Unfilledcirc.ppm")
img.floodFill((30, 122), White, color(255, 0, 0))
img.writePPM("Unfilledcirc_red.ppm")
```

## OCaml

Translation of: C
```let floodFill ~img (i, j) newColor =
let oldColor = get_pixel ~img ~pt:(i, j) in
let width, height = get_dims ~img in

let rec aux (i, j) =
if 0 <= i && i < height
&& 0 <= j && j < width
&& (get_pixel ~img ~pt:(i, j)) = oldColor
then begin
put_pixel img newColor i j;
aux (i-1, j);
aux (i+1, j);
aux (i, j-1);
aux (i, j+1);
end;
in
aux (i, j)
```

## Pascal

Translation of: C#
```program FloodFillTest;

{\$APPTYPE CONSOLE}
{\$R *.res}

uses
Winapi.Windows,
System.SysUtils,
System.Generics.Collections,
vcl.Graphics;

procedure FloodFill(bmp: tBitmap; pt: TPoint; targetColor: TColor;
replacementColor: TColor);
var
q: TQueue<TPoint>;
n, w, e: TPoint;
begin
q := TQueue<TPoint>.Create;

q.Enqueue(pt);

while (q.Count > 0) do
begin
n := q.Dequeue;
if bmp.Canvas.Pixels[n.X, n.Y] <> targetColor then
Continue;

w := n;
e := TPoint.Create(n.X + 1, n.Y);

while ((w.X >= 0) and (bmp.Canvas.Pixels[w.X, w.Y] = targetColor)) do
begin
bmp.Canvas.Pixels[w.X, w.Y] := replacementColor;
if ((w.Y > 0) and (bmp.Canvas.Pixels[w.X, w.Y - 1] = targetColor)) then
q.Enqueue(TPoint.Create(w.X, w.Y - 1));
if ((w.Y < bmp.Height - 1) and (bmp.Canvas.Pixels[w.X, w.Y + 1] = targetColor)) then
q.Enqueue(TPoint.Create(w.X, w.Y + 1));
dec(w.X);
end;

while ((e.X <= bmp.Width - 1) and (bmp.Canvas.Pixels[e.X, e.Y] = targetColor)) do
begin
bmp.Canvas.Pixels[e.X, e.Y] := replacementColor;
if ((e.Y > 0) and (bmp.Canvas.Pixels[e.X, e.Y - 1] = targetColor)) then
q.Enqueue(TPoint.Create(e.X, e.Y - 1));

if ((e.Y < bmp.Height - 1) and (bmp.Canvas.Pixels[e.X, e.Y + 1] = targetColor)) then
q.Enqueue(TPoint.Create(e.X, e.Y + 1));
inc(e.X);
end;
end;
q.Free;
end;

var
bmp: TBitmap;

begin
bmp := TBitmap.Create;
try
FloodFill(bmp, TPoint.Create(200, 200), clWhite, clRed);
FloodFill(bmp, TPoint.Create(100, 100), clBlack, clBlue);
bmp.SaveToFile('Filledcirc.bmp');
finally
bmp.Free;
end;

end.
```

## Perl

Library: Imlib2

The fill of the Perl package Image::Imlib2 is a flood fill (so the documentatin of Image::Imlib2 says). The target colour is the one of the starting point pixel; the color set with set_color is the fill colour.

```#! /usr/bin/perl

use strict;
use Image::Imlib2;

my \$img = Image::Imlib2->load("Unfilledcirc.jpg");
\$img->set_color(0, 255, 0, 255);
\$img->fill(100,100);
\$img->save("filledcirc.jpg");
exit 0;
```

A homemade implementation can be:

```use strict;
use Image::Imlib2;

sub colordistance
{
my ( \$c1, \$c2 ) = @_;

my ( \$r1, \$g1, \$b1 ) = @\$c1;
my ( \$r2, \$g2, \$b2 ) = @\$c2;
return sqrt(( (\$r1-\$r2)**2 + (\$g1-\$g2)**2 + (\$b1-\$b2)**2 ))/(255.0*sqrt(3.0));
}

sub floodfill
{
my ( \$img, \$x, \$y, \$r, \$g, \$b ) = @_;
my \$distparameter = 0.2;

my %visited = ();
my @queue = ();

my @tcol = ( \$r, \$g, \$b );
my @col = \$img->query_pixel(\$x, \$y);
if ( colordistance(\@tcol, \@col) > \$distparameter ) { return; }
push @queue, [\$x, \$y];
while ( @queue ) {
my \$pointref = shift(@queue);
( \$x, \$y ) = @\$pointref;
if ( (\$x < 0) || (\$y < 0) || ( \$x >= \$img->width ) || ( \$y >= \$img->height ) ) { next; }
if ( ! exists(\$visited{"\$x,\$y"}) ) {
@col = \$img->query_pixel(\$x, \$y);
if ( colordistance(\@tcol, \@col) <= \$distparameter ) {
\$img->draw_point(\$x, \$y);
\$visited{"\$x,\$y"} = 1;
push @queue, [\$x+1, \$y];
push @queue, [\$x-1, \$y];
push @queue, [\$x, \$y+1];
push @queue, [\$x, \$y-1];
}
}
}
}

# usage example
my \$img = Image::Imlib2->load("Unfilledcirc.jpg");
\$img->set_color(0,255,0,255);
floodfill(\$img, 100,100, 0, 0, 0);
\$img->save("filledcirc1.jpg");
exit 0;
```

This fills better than the Image::Imlib2 fill function the inner circle, since because of JPG compression and thanks to the \$distparameter, it "sees" as black also pixel that are no more exactly black.

## Phix

Translation of: Go

Requires read_ppm() from Read a PPM file, write_ppm() from Write a PPM file.
Uses the output of Midpoint circle algorithm (Circle.ppm), results may be verified with demo\rosetta\viewppm.exw

```-- demo\rosetta\Bitmap_FloodFill.exw  (runnable version)
include ppm.e -- blue, green, read_ppm(), write_ppm() (covers above requirements)

function ff(sequence img, integer x, y, colour, target)
if  x>=1 and x<=length(img)
and y>=1 and y<=length(img[x])
and img[x][y]=target then
img[x][y] = colour
img = ff(img,x-1,y,colour,target)
img = ff(img,x+1,y,colour,target)
img = ff(img,x,y-1,colour,target)
img = ff(img,x,y+1,colour,target)
end if
return img
end function

function FloodFill(sequence img, integer x, y, colour)
integer target = img[x][y]
return ff(img,x,y,colour,target)
end function

sequence img = read_ppm("Circle.ppm")
img = FloodFill(img, 200, 100, blue)
write_ppm("FloodIn.ppm",img)
img = FloodFill(img, 10, 10, green)
write_ppm("FloodOut.ppm",img)
```

## PicoLisp

Using the format of Bitmap, a minimal recursive solution:

```(de ppmFloodFill (Ppm X Y Color)
(let Target (get Ppm Y X)
(recur (X Y)
(when (= Target (get Ppm Y X))
(set (nth Ppm Y X) Color)
(recurse (dec X) Y)
(recurse (inc X) Y)
(recurse X (dec Y))
(recurse X (inc Y)) ) ) )
Ppm )```

Test using 'ppmRead' from Bitmap/Read a PPM file#PicoLisp and 'ppmWrite' from Bitmap/Write a PPM file#PicoLisp, filling the white area with red:

```(ppmWrite
(ppmFloodFill (ppmRead "Unfilledcirc.ppm") 192 128 (255 0 0))
"Filledcirc.ppm" )```

## PL/I

```fill: procedure (x, y, fill_color) recursive; /* 12 May 2010 */
declare (x, y) fixed binary;
declare fill_color bit (24) aligned;

if x <= lbound(image, 2) | x >= hbound(image, 2) then return;
if y <= lbound(image, 1) | y >= hbound(image, 1) then return;

pixel_color = image (x,y); /* Obtain the color of the current pixel. */
if pixel_color ^= area_color then return;
/* the pixel has already been filled with fill_color, */
/* or we are not within the area to be filled.        */
image(x, y) = fill_color; /* color the desired area. */

pixel_color = image (x,y-1); /* Obtain the color of the pixel to the north. */
if pixel_color = area_color then call fill (x, y-1, fill_color);

pixel_color = image (x-1,y); /* Obtain the color of the pixel to the west. */
if pixel_color = area_color then call fill (x-1, y, fill_color);

pixel_color = image (x+1,y); /* Obtain the color of the pixel to the east. */
if pixel_color = area_color then call fill (x+1, y, fill_color);

pixel_color = image (x,y+1); /* Obtain the color of the pixel to the south. */
if pixel_color = area_color then call fill (x, y+1, fill_color);

end fill;```

The following PL/I statements change the color of the white area of the sample image to red, and the central orb to green.

```   /* Fill the white area of the suggested image with red color. */
area_color = (24)'1'b;
call fill (125, 25, '000000000000000011111111'b );

/* Fill the center orb of the suggested image with green color. */
area_color = '0'b;
call fill (125, 125, '000000001111111100000000'b );
```

## Processing

```import java.awt.Point;
import java.util.Queue;

PImage img;
int tolerance;
color fill_color;
boolean allowed;

void setup() {
size(600, 400);
fill_color = color(250, 0, 0);
fill(0, 0, 100);
tolerance = 15;
image(img, 0, 0, width, height);
textSize(18);
text("Tolerance = "+tolerance+"  (Use mouse wheel to change)", 100, height-30);
text("Right click to reset", 100, height-10);
}

void draw() {
if (allowed) {
image(img, 0, 0, width, height);
text("Tolerance = "+tolerance+"  (Use mouse wheel to change)", 100, height-30);
text("Right click to reset", 100, height-10);
allowed = false;
}
}

void mousePressed() {
if (mouseButton == RIGHT) {
} else {
flood(mouseX, mouseY);
img.updatePixels();
allowed = true;
}
}

void mouseWheel(MouseEvent event) {
float e = event.getCount();
tolerance += 2*e;
if (tolerance > 128) tolerance = 128;
if (tolerance < 0) tolerance = 0;
allowed = true;
}

void flood(int x, int y) {
color target_color = img.pixels[pixel_position(mouseX, mouseY)];
if (target_color != fill_color) {
Queue<Point> queue = new LinkedList<Point>();
while (!queue.isEmpty()) {
Point p = queue.remove();
if (check(p.x, p.y, target_color)) {
}
}
}
}

int pixel_position(int x, int y) {
return x + (y * img.width);
}

boolean check(int x, int y, color target_color) {
if (x < 0 || y < 0 || y >= img.height || x >= img.width) return false;
int pp = img.pixels[pixel_position(x, y)];
boolean test_tolerance = (abs(green(target_color)-green(pp)) < tolerance
&& abs(  red(target_color)-  red(pp)) < tolerance
&& abs( blue(target_color)- blue(pp)) < tolerance);
if (!test_tolerance) return false;
img.pixels[pixel_position(x, y)] = fill_color;
return true;
}
```

### Processing Python mode

```from collections import deque

image_file = "image.png"
fill_color = color(250, 0, 0)
tolerance = 15
allowed = False

def setup():
global img
size(600, 400)
fill(0, 0, 100)
textSize(18)
show()

def show():
image(img, 0, 0, width, height)
text("Tolerance = {}    (Use mouse wheel to change)".format(tolerance),
100, height - 30)
text("Right click to reset", 100, height - 10)

def draw():
global allowed
if allowed:
show()
allowed = False

def mousePressed():
global allowed, img
if mouseButton == RIGHT:
else:
flood(mouseX, mouseY)
img.updatePixels()
allowed = True

def mouseWheel(event):
global allowed, tolerance
e = event.getCount()
tolerance += 2 * e
if tolerance > 128:
tolerance = 128
if tolerance < 0:
tolerance = 0
allowed = True

def flood(x, y):
target_color = img.pixels[pixel_position(mouseX, mouseY)]
if target_color != fill_color:
queue = deque()
queue.append((x, y))
while len(queue) > 0:
p_x, p_y = queue.popleft()
if (check(p_x, p_y, target_color)):
queue.append((p_x, p_y - 1))
queue.append((p_x, p_y + 1))
queue.append((p_x - 1, p_y))
queue.append((p_x + 1, p_y))

def pixel_position(x, y):
return x + (y * img.width)

def check(x, y, target_color):
if x < 0 or y < 0 or y >= img.height or x >= img.width:
return False
pp = img.pixels[pixel_position(x, y)]
test_tolerance = (abs(green(target_color) - green(pp)) < tolerance
and abs(red(target_color) - red(pp)) < tolerance
and abs(blue(target_color) - blue(pp)) < tolerance)
if not test_tolerance:
return False
img.pixels[pixel_position(x, y)] = fill_color
return True
```

## PureBasic

### built-in

```FillArea(0,0,-1,\$ff)
; Fills an Area in red```

### Iterative

```  Procedure Floodfill(x,y,new_color)
old_color = Point(x,y)
NewList stack.POINT()
AddElement(stack()):stack()\x = x : stack()\y = y
While(LastElement(stack()))
x = stack()\x  : y = stack()\y
DeleteElement(stack())
If Point(x,y) = old_color
Plot(x, y, new_color)
AddElement(stack()):stack()\x = x    : stack()\y = y +1
AddElement(stack()):stack()\x = x    : stack()\y = y -1
AddElement(stack()):stack()\x = x +1 : stack()\y = y
AddElement(stack()):stack()\x = x -1 : stack()\y = y
EndIf
Wend
EndProcedure

If OpenWindow(0, 0, 0, 200, 200, "Floodfill Beispiel", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
StartDrawing(WindowOutput(0))
Box(0, 0, 200, 200, RGB(255, 255, 255))
DrawingMode(#PB_2DDrawing_Outlined )
Circle(100, 100, 90, RGB(255 ,0,0)): Circle(120, 80, 30, RGB(255 ,0,0)): Circle(200,200, 70, RGB(255 ,0,0))

Floodfill(40,40,RGB(0 ,255,0))

StopDrawing()
Repeat
Event = WaitWindowEvent()
Until Event = #PB_Event_CloseWindow
EndIf```

## Python

```import Image
def FloodFill( fileName, initNode, targetColor, replaceColor ):
img = Image.open( fileName )
xsize, ysize = img.size
Q = []
if pix[ initNode[0], initNode[1] ] != targetColor:
return img
Q.append( initNode )
while Q != []:
node = Q.pop(0)
if pix[ node[0], node[1] ] == targetColor:
W = list( node )
if node[0] + 1 < xsize:
E = list( [ node[0] + 1, node[1] ] )
else:
E = list( node )
# Move west until color of node does not match targetColor
while pix[ W[0], W[1] ] == targetColor:
pix[ W[0], W[1] ] = replaceColor
if W[1] + 1 < ysize:
if pix[ W[0], W[1] + 1 ] == targetColor:
Q.append( [ W[0], W[1] + 1 ] )
if W[1] - 1 >= 0:
if pix[ W[0], W[1] - 1 ] == targetColor:
Q.append( [ W[0], W[1] - 1 ] )
if W[0] - 1 >= 0:
W[0] = W[0] - 1
else:
break
# Move east until color of node does not match targetColor
while pix[ E[0], E[1] ] == targetColor:
pix[ E[0], E[1] ] = replaceColor
if E[1] + 1 < ysize:
if pix[ E[0], E[1] + 1 ] == targetColor:
Q.append( [ E[0], E[1] + 1 ] )
if E[1] - 1 >= 0:
if pix[ E[0], E[1] - 1 ] == targetColor:
Q.append( [ E[0], E[1] -1 ] )
if E[0] + 1 < xsize:
E[0] = E[0] + 1
else:
break
return img
```

### Usage example

```# "FloodFillClean.png" is name of input file
# [55,55] the x,y coordinate where fill starts
# (0,0,0,255) the target colour being filled( black in this example )
# (255,255,255,255) the final colour ( white in this case )
img = FloodFill( "FloodFillClean.png", [55,55], (0,0,0,255), (255,255,255,255) )
#The resulting image is saved as Filled.png
img.save( "Filled.png" )
```

## R

Stack-based recursive version

```library(png)
M <- img[ , , 1]
M <- ifelse(M < 0.5, 0, 1)
image(M, col = c(1, 0))

# https://en.wikipedia.org/wiki/Flood_fill
floodfill <- function(row, col, tcol, rcol) {
if (tcol == rcol) return()
if (M[row, col] != tcol) return()
M[row, col] <<- rcol
floodfill(row - 1, col    , tcol, rcol) # south
floodfill(row + 1, col    , tcol, rcol) # north
floodfill(row    , col - 1, tcol, rcol) # west
floodfill(row    , col + 1, tcol, rcol) # east
return("filling completed")
}

options(expressions = 10000)
startrow <- 100; startcol <- 100
floodfill(startrow, startcol, 0, 2)

image(M, col = c(1, 0, 2))
```

Queue-based version (Forest Fire algorithm)

```library(png)
M <- img[ , , 1]
M <- ifelse(M < 0.5, 0, 1)
M <- rbind(M, 0)
M <- cbind(M, 0)
image(M, col = c(1, 0))

# https://en.wikipedia.org/wiki/Flood_fill
floodfill <- function(row, col, tcol, rcol) {
if (tcol == rcol) return()
if (M[row, col] != tcol) return()
Q <- matrix(c(row, col), 1, 2)
while (dim(Q)[1] > 0) {
n <- Q[1, , drop = FALSE]
west  <- cbind(n[1]    , n[2] - 1)
east  <- cbind(n[1]    , n[2] + 1)
north <- cbind(n[1] + 1, n[2]    )
south <- cbind(n[1] - 1, n[2]    )
Q <- Q[-1, , drop = FALSE]
if (M[n] == tcol) {
M[n] <<- rcol
if (M[west] == tcol)  Q <- rbind(Q, west)
if (M[east] == tcol)  Q <- rbind(Q, east)
if (M[north] == tcol) Q <- rbind(Q, north)
if (M[south] == tcol) Q <- rbind(Q, south)
}
}
return("filling completed")
}

startrow <- 100; startcol <- 100
floodfill(startrow, startcol, 0, 2)
startrow <- 50; startcol <- 50
floodfill(startrow, startcol, 1, 3)

image(M, col = c(1, 0, 2, 3))
```

## Racket

```#lang racket

(require racket/draw)

;; flood-fill: bitmap<%> number number color color -> void
;; An example of flood filling a bitmap.
;;
;; We'll use a raw, byte-oriented interface here for demonstration
;; purposes.  Racket does provide get-pixel and set-pixel functions
;; which work on color% structures rather than bytes, but it's useful
;; to see that the byte approach works as well.
(define (flood-fill bm start-x start-y target-color replacement-color)
;; The main loop.
;; http://en.wikipedia.org/wiki/Flood_fill
(define (iter x y)
(when (and (in-bounds? x y) (target-color-at? x y))
(replace-color-at! x y)
(iter (add1 x) y)
(iter (sub1 x) y)
(iter x (add1 y))
(iter x (sub1 y))))

;; With auxillary definitions below:
(define width (send bm get-width))
(define height (send bm get-height))

(define buffer (make-bytes (* width height 4)))
(send bm get-argb-pixels 0 0 width height buffer)

(define-values (target-red target-green target-blue)
(values (send target-color red)
(send target-color green)
(send target-color blue)))

(define-values (replacement-red replacement-green replacement-blue)
(values (send replacement-color red)
(send replacement-color green)
(send replacement-color blue)))

(define (offset-at x y) (* 4 (+ (* y width) x)))

(define (target-color-at? x y)
(define offset (offset-at x y))
(and (= (bytes-ref buffer (+ offset 1)) target-red)
(= (bytes-ref buffer (+ offset 2)) target-green)
(= (bytes-ref buffer (+ offset 3)) target-blue)))

(define (replace-color-at! x y)
(define offset (offset-at x y))
(bytes-set! buffer (+ offset 1) replacement-red)
(bytes-set! buffer (+ offset 2) replacement-green)
(bytes-set! buffer (+ offset 3) replacement-blue))

(define (in-bounds? x y)
(and (<= 0 x) (< x width) (<= 0 y) (< y height)))

;; Finally, let's do the fill, and then store the
;; result back into the bitmap:
(iter start-x start-y)
(send bm set-argb-pixels 0 0 width height buffer))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Example: flood fill a hole shape.
(define bm (make-bitmap 100 100))
(define dc (send bm make-dc))

;; We intentionally set the smoothing of the dc to
;; aligned so that there are no gaps in the shape for the
;; flood to leak through.
(send dc set-smoothing 'aligned)
(send dc draw-rectangle 10 10 80 80)
(send dc draw-rounded-rectangle 20 20 50 50)
;; In DrRacket, we can print the bm to look at it graphically,
;; before the flood fill:
bm

(flood-fill bm 50 50
(send the-color-database find-color "white")
(send the-color-database find-color "DarkSeaGreen"))
;; ... and after:
bm
```

## Raku

(formerly Perl 6)

Works with: Rakudo version 2019.11

Using bits and pieces from various other bitmap tasks.

```class Pixel { has Int (\$.R, \$.G, \$.B) }
class Bitmap {
has Int (\$.width, \$.height);
has Pixel @.data;

method pixel(
\$i where ^\$!width,
\$j where ^\$!height
--> Pixel
) is rw { @!data[\$i + \$j * \$!width] }
}

role PPM {
method P6 returns Blob {
"P6\n{self.width} {self.height}\n255\n".encode('ascii')
~ Blob.new: flat map { .R, .G, .B }, self.data
}
}

sub load-ppm ( \$ppm ) {
my \$fh    = \$ppm.IO.open( :enc('ISO-8859-1') );
my \$type  = \$fh.get;
my (\$width, \$height) = \$fh.get.split: ' ';
my \$depth = \$fh.get;
Bitmap.new( width => \$width.Int, height => \$height.Int,
data => ( \$fh.slurp.ords.rotor(3).map:
{ Pixel.new(R => \$_[0], G => \$_[1], B => \$_[2]) } )
)
}

sub color-distance (Pixel \$c1, Pixel \$c2) {
sqrt( ( (\$c1.R - \$c2.R)² + (\$c1.G - \$c2.G)² + (\$c1.B - \$c2.B)² ) / ( 255 * sqrt(3) ) );
}

sub flood (\$img, \$x, \$y, \$c1) {
my \$c2 = \$img.pixel(\$x, \$y);
my \$max-distance = 10;
my @queue;
my %checked;
check(\$x, \$y);
for @queue -> [\$x, \$y] {
\$img.pixel(\$x, \$y) = \$c1.clone;
}

sub check (\$x, \$y) {
my \$c3 = \$img.pixel(\$x, \$y);

if color-distance(\$c2, \$c3) < \$max-distance {
@queue.push: [\$x,\$y];
@queue.elems;
%checked{"\$x,\$y"} = 1;
check(\$x - 1, \$y) if \$x > 0               and %checked{"{\$x - 1},\$y"}:!exists;
check(\$x + 1, \$y) if \$x < \$img.width - 1  and %checked{"{\$x + 1},\$y"}:!exists;
check(\$x, \$y - 1) if \$y > 0               and %checked{"\$x,{\$y - 1}"}:!exists;
check(\$x, \$y + 1) if \$y < \$img.height - 1 and %checked{"\$x,{\$y + 1}"}:!exists;
}
}
}

my \$infile = './Unfilled-Circle.ppm';

my Bitmap \$b = load-ppm( \$infile ) but PPM;

flood(\$b, 5,     5, Pixel.new(:255R, :0G, :0B));
flood(\$b, 5,   125, Pixel.new(:255R, :0G, :0B));
flood(\$b, 125,   5, Pixel.new(:255R, :0G, :0B));
flood(\$b, 125, 125, Pixel.new(:255R, :0G, :0B));
flood(\$b, 50,   50, Pixel.new(:0R, :0G, :255B));

my \$outfile = open('./Bitmap-flood-perl6.ppm', :w, :bin);

\$outfile.write: \$b.P6;
```

See output image Bitmap-flood-perl6 (offsite image file, converted to PNG for ease of viewing)

## REXX

Translation of: PL/I
```/*REXX program  demonstrates a  method  to  perform a  flood fill  of an area.          */
black= '000000000000000000000000'b               /*define the black color  (using bits).*/
red  = '000000000000000011111111'b               /*   "    "   red    "       "     "   */
green= '000000001111111100000000'b               /*   "    "  green   "       "     "   */
white= '111111111111111111111111'b               /*   "    "  white   "       "     "   */
/*image is defined to the test image.  */
hx= 125;          hy= 125                        /*define limits  (X,Y)  for the image. */
area= white;      call fill 125,  25, red        /*fill the white area in red.          */
area= black;      call fill 125, 125, green      /*fill the center orb in green.        */
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
fill: procedure expose image. hx hy area;  parse arg x,y,fill_color   /*obtain the args.*/
if x<1 | x>hx | y<1 | y>hy   then return   /*X or Y  are outside of the image area*/
pixel= image.x.y                           /*obtain the color of the  X,Y  pixel. */
if pixel \== area  then return             /*the pixel has already been filled    */
/*with the  fill_color,  or we are not */
/*within the area to be filled.        */
image.x.y= fill_color                      /*color desired area with fill_color.  */
pixel= @(x  , y-1);   if pixel==area  then call fill x  , y-1, fill_color  /*north*/
pixel= @(x-1, y  );   if pixel==area  then call fill x-1, y  , fill_color  /*west */
pixel= @(x+1, y  );   if pixel==area  then call fill x+1, y  , fill_color  /*east */
pixel= @(x  , y+1);   if pixel==area  then call fill x  , y+1, fill_color  /*south*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
@:    parse arg \$x,\$y;      return image.\$x.\$y   /*return with color of the  X,Y  pixel.*/
```

## Ruby

```# frozen_string_literal: true

require_relative 'raster_graphics'

class RGBColour
def ==(other)
values == other.values
end
end

class Pixmap
def flood_fill(pixel, new_colour)
current_colour = self[pixel.x, pixel.y]
queue = Queue.new
queue.enq(pixel)
until queue.empty?
p = queue.pop
next unless self[p.x, p.y] == current_colour

west = find_border(p, current_colour, :west)
east = find_border(p, current_colour, :east)
draw_line(west, east, new_colour)
q = west
while q.x <= east.x
%i[north south].each do |direction|
n = neighbour(q, direction)
queue.enq(n) if self[n.x, n.y] == current_colour
end
q = neighbour(q, :east)
end
end
end

def neighbour(pixel, direction)
case direction
when :north then Pixel[pixel.x, pixel.y - 1]
when :south then Pixel[pixel.x, pixel.y + 1]
when :east  then Pixel[pixel.x + 1, pixel.y]
when :west  then Pixel[pixel.x - 1, pixel.y]
end
end

def find_border(pixel, colour, direction)
nextp = neighbour(pixel, direction)
while self[nextp.x, nextp.y] == colour
pixel = nextp
nextp = neighbour(pixel, direction)
end
pixel
end
end

bitmap = Pixmap.new(300, 300)
bitmap.draw_circle(Pixel[149, 149], 120, RGBColour::BLACK)
bitmap.draw_circle(Pixel[200, 100], 40, RGBColour::BLACK)
bitmap.flood_fill(Pixel[140, 160], RGBColour::BLUE)
bitmap.save_as_png('flood_fill.png')
```
Library: RubyGems
Library: JRubyArt

JRubyArt is a port of Processing to the ruby language

```# holder for pixel coords
Pixel = Struct.new(:x, :y)

attr_reader :img, :fill_color, :queue, :value

def setup
sketch_title 'Flood Fill'
@fill_color = color(250, 0, 0)
end

def draw
image(img, 0, 0, width, height)
no_loop
end

def mouse_clicked
flood(mouse_x, mouse_y)
img.update_pixels
redraw
end

def flood(x, y)
@queue = Queue.new
queue.enq(Pixel.new(x, y))
until queue.empty?
pix = queue.pop
next unless check(pix, color(255))

queue.enq(Pixel.new(pix.x, pix.y - 1))
queue.enq(Pixel.new(pix.x, pix.y + 1))
queue.enq(Pixel.new(pix.x - 1, pix.y))
queue.enq(Pixel.new(pix.x + 1, pix.y))
end
end

def check(pix, target_color)
unless (1...width).include?(pix.x) && (1...height).include?(pix.y)
return false
end

value = img.pixels[pix.x + (pix.y * img.width)]
return false if target_color != value

img.pixels[pix.x + (pix.y * img.width)] = fill_color
true
end

def settings
size(256, 256)
end
```

## Rust

```/* Naive Rust implementation of RosettaCode's Bitmap/Flood fill excercise.
*
* For the sake of simplicity this code reads PPM files (format specification can be found here: http://netpbm.sourceforge.net/doc/ppm.html ).
* The program assumes that the image has been created by GIMP in PPM ASCII mode and panics at any error.
*
* Also this program expects the input file to be in the same directory as the executable and named
* "input.ppm" and outputs a file in the same directory under the name "output.ppm".
*
*/

use std::fs::File; // Used for creating/opening files.

fn read_image(filename: String) -> Vec<Vec<(u8,u8,u8)>> {
let file = File::open(filename).unwrap();
let mut lines = reader.lines();

let _ = lines.next().unwrap(); // Skip P3 signature.
let _ = lines.next().unwrap(); // Skip GIMP comment.

let dimensions: (usize, usize) = {
let line = lines.next().unwrap().unwrap();
let values = line.split_whitespace().collect::<Vec<&str>>();

// We turn the &str vector that holds the width & height of the image into an usize tuplet.
(values[0].parse::<usize>().unwrap(),values[1].parse::<usize>().unwrap())
};

let _ = lines.next().unwrap(); // Skip maximum color value (we assume 255).

let mut image_data = Vec::with_capacity(dimensions.1);

for y in 0..dimensions.1 {
image_data.push(Vec::new());
for _ in 0..dimensions.0 {
// We read the R, G and B components and put them in the image_data vector.
image_data[y].push((lines.next().unwrap().unwrap().parse::<u8>().unwrap(),
lines.next().unwrap().unwrap().parse::<u8>().unwrap(),
lines.next().unwrap().unwrap().parse::<u8>().unwrap()));
}
}

image_data
}

fn write_image(image_data: Vec<Vec<(u8,u8,u8)>>) {
let mut file = File::create(format!("./output.ppm")).unwrap();

// Signature, then width and height, then 255 as max color value.
write!(file, "P3\n{} {}\n255\n", image_data.len(), image_data[0].len()).unwrap();

for row in &image_data {
// For performance reasons, we reserve a String with the necessary length for a line and
// fill that up before writing it to the file.

let mut line = String::with_capacity(row.len()*6); // 6 = r(space)g(space)b(space)
for (r,g,b) in row {

// &* is used to turn a String into a &str as needed by push_str.
line.push_str(&*format!("{} {} {} ", r,g,b));
}

write!(file, "{}", line).unwrap();
}

}

fn flood_fill(x: usize, y: usize, target: &(u8,u8,u8), replacement: &(u8,u8,u8), image_data: &mut Vec<Vec<(u8,u8,u8)>>) {
if &image_data[y][x] == target {
image_data[y][x] = *replacement;

if y > 0 {flood_fill(x,y-1, &target, &replacement, image_data);}
if x > 0 {flood_fill(x-1,y, &target, &replacement, image_data);}
if y < image_data.len()-1 {flood_fill(x,y+1, &target, &replacement, image_data);}
if x < image_data[0].len()-1 {flood_fill(x+1,y, &target, &replacement, image_data);}
}
}

fn main() {
let mut data = read_image(String::from("./input.ppm"));

flood_fill(1,50, &(255,255,255), &(0,255,0), &mut data); // Fill the big white circle with green.
flood_fill(40,35, &(0,0,0), &(255,0,0), &mut data); // Fill the small black circle with red.

write_image(data);

}
```

## Scala

Based on Lode Vandevenne's algorithm linked to from Wikipedia, Scanline Floodfill Algorithm With Stack.

See Basic Bitmap Storage for RgbBitmap class.

```import java.awt.Color
import scala.collection.mutable

object Flood {
def floodFillStack(bm:RgbBitmap, x: Int, y: Int, targetColor: Color): Unit = {
// validate
if (bm.getPixel(x,y) == targetColor) return

// vars
val oldColor = bm.getPixel(x,y)
val pixels = new mutable.Stack[(Int,Int)]

// candy coating methods
def paint(fx: Int, fy:Int) = bm.setPixel(fx,fy,targetColor)
def old(cx: Int, cy: Int): Boolean = bm.getPixel(cx,cy) == oldColor
def push(px: Int, py: Int) = pixels.push((px,py))

// starting point
push(x,y)

// work
while (pixels.nonEmpty) {
val (x, y) = pixels.pop()
var y1 = y
while (y1 >= 0 && old(x, y1)) y1 -= 1
y1 += 1
var spanLeft = false
var spanRight = false
while (y1 < bm.height && old(x, y1)) {
paint(x,y1)
if (x > 0 && spanLeft != old(x-1,y1)) {
if (old(x - 1, y1)) push(x - 1, y1)
spanLeft = !spanLeft
}
if (x < bm.width - 1 && spanRight != old(x+1,y1)) {
if (old(x + 1, y1)) push(x + 1, y1)
spanRight = !spanRight
}
y1 += 1
}
}
}
}
```

## Standard ML

This implementation is imperative, updating the pixels of the image as it goes. Flood fill is somewhat difficult to make efficient if we were to use purely functional data structures instead.

```(* For simplicity, we're going to fill black-and-white images. Nothing
* fundamental would change if we used more colors. *)
datatype color = Black | White
(* Represent an image as a 2D mutable array of pixels, since flood-fill
* is naturally an imperative algorithm. *)
type image = color array array

(* Helper functions to construct images for testing. Map 0 -> White
* and 1 -> Black so we can write images concisely as lists. *)
fun intToColor 0 = White
| intToColor _ = Black

fun listToImage (LL : int list list) : image =
Array.tabulate(List.length LL,
fn i => Array.tabulate (List.length (hd LL),
fn j => intToColor(List.nth(List.nth(LL,i),j))))

(* Is the given pixel within the image ? *)
fun inBounds (img : image) ((x,y) : int * int) : bool =
x >= 0 andalso y >= 0 andalso y < Array.length img
andalso x < Array.length (Array.sub(img, y))

(* Return an option containing the neighbors we should explore next, if any.*)
fun neighbors (img : image) (c : color) ((x,y) : int * int) : (int * int) list option =
if inBounds img (x,y) andalso Array.sub(Array.sub(img,y),x) <> c
then SOME [(x-1,y),(x+1,y),(x,y-1),(x,y+1)]
else NONE

(* Update the given pixel of the image. *)
fun setPixel (img : image) ((x,y) : int * int) (c : color) : unit =
Array.update (Array.sub(img,y),x,c)

(* Recursive fill around the given point using the given color. *)
fun fill (img : image) (c : color) ((x,y) : int * int) : unit =
case neighbors img c (x,y) of
SOME xys => (setPixel img (x,y) c; List.app (fill img c) xys)
| NONE => ()

val test = listToImage
[[0,0,1,1,0,1,0],
[1,0,1,0,1,0,0],
[1,0,0,0,0,0,1],
[0,1,0,0,0,1,0],
[1,0,0,0,0,0,1],
[0,0,1,1,1,0,0],
[0,1,0,0,0,1,0]]

(* Fill the image with black starting at the center. *)
val () = fill test Black (3,3)
```

## Tcl

Library: Tk
Library: Tcllib (Package: struct::queue)

Using code from Basic bitmap storage, Bresenham's line algorithm and Midpoint circle algorithm

```package require Tcl 8.5
package require Tk
package require struct::queue

proc floodFill {img colour point} {
set new [colour2rgb \$colour]
set old [getPixel \$img \$point]
struct::queue Q
Q put \$point
while {[Q size] > 0} {
set p [Q get]
if {[getPixel \$img \$p] eq \$old} {
set w [findBorder \$img \$p \$old west]
set e [findBorder \$img \$p \$old east]
drawLine \$img \$new \$w \$e
set q \$w
while {[x \$q] <= [x \$e]} {
set n [neighbour \$q north]
if {[getPixel \$img \$n] eq \$old} {Q put \$n}
set s [neighbour \$q south]
if {[getPixel \$img \$s] eq \$old} {Q put \$s}
set q [neighbour \$q east]
}
}
}
Q destroy
}

proc findBorder {img p colour dir} {
set lookahead [neighbour \$p \$dir]
while {[getPixel \$img \$lookahead] eq \$colour} {
set lookahead [neighbour \$p \$dir]
}
return \$p
}

proc x p {lindex \$p 0}
proc y p {lindex \$p 1}

proc neighbour {p dir} {
lassign \$p x y
switch -exact -- \$dir {
west  {return [list [incr x -1] \$y]}
east  {return [list [incr x] \$y]}
north {return [list \$x [incr y -1]]}
south {return [list \$x [incr y]]}
}
}

proc colour2rgb {color_name} {
foreach part [winfo rgb . \$color_name] {
append colour [format %02x [expr {\$part >> 8}]]
}
return #\$colour
}

set img [newImage 70 50]
fill \$img white

drawLine \$img blue {0 0} {0 25}
drawLine \$img blue {0 25} {35 25}
drawLine \$img blue {35 25} {35 0}
drawLine \$img blue {35 0} {0 0}
floodFill \$img yellow {3 3}

drawCircle \$img black {35 25} 24
drawCircle \$img black {35 25} 10
floodFill \$img orange {34 5}
floodFill \$img red {36 5}

toplevel .flood
label .flood.l -image \$img
pack .flood.l
```

Results in:

## Wren

Library: DOME

This script uses the same 'flood fill' routine as the Go entry.

It draws 3 concentric squares on the canvas colored yellow, red and white.

When the up arrow is pressed, the red square changes to blue and when the down arrow is pressed the blue square turns back to red.

```import "graphics" for Canvas, ImageData, Color
import "dome" for Window
import "input" for Keyboard

class Bitmap {
construct new(name, size) {
Window.title = name
Window.resize(size, size)
Canvas.resize(size, size)
size = size / 2
_bmp = ImageData.create(name, size, size)
_size = size
_flooded = false
}

init() {
var s = _size
var hs = s / 2
var qs = s / 4
fill(0, 0, s, s, Color.yellow)
fill(qs, qs, 3 * qs, 3 * qs, Color.red)
fill(qs * 1.5, qs * 1.5, qs * 2.5, qs * 2.5, Color.white)
_bmp.draw(hs, hs)
}

fill(s, t, w, h, col) {
for (x in s...w) {
for (y in t...h) pset(x, y, col)
}
}

flood(x, y, repl) {
var target = pget(x, y)
var ff // recursive closure
ff = Fn.new { |x, y|
if (x >= 0 && x < _bmp.width && y >= 0 && y < _bmp.height) {
var p = pget(x, y)
if (p.r == target.r && p.g == target.g && p.b == target.b) {
pset(x, y, repl)
ff.call(x-1, y)
ff.call(x+1, y)
ff.call(x, y-1)
ff.call(x, y+1)
}
}
}
ff.call(x, y)
}

pset(x, y, col) { _bmp.pset(x, y, col) }

pget(x, y) { _bmp.pget(x, y) }

update() {
var hs = _size / 2
var qs = _size / 4
if (!_flooded && Keyboard.isKeyDown("up")) {
flood(qs, qs, Color.blue)
_bmp.draw(hs, hs)
_flooded = true
} else if (_flooded && Keyboard.isKeyDown("down")) {
flood(qs, qs, Color.red)
_bmp.draw(hs, hs)
_flooded = false
}
}

draw(alpha) {}
}

var Game = Bitmap.new("Bitmap - flood fill", 600)
```

## XPL0

```include c:\cxpl\codes;

proc    Flood(X, Y, C, C0);     \Fill an area of color C0 with color C
int     X, Y,   \seed coordinate (where to start)
C, C0;  \color to fill with and color to replace
def     S=8000; \size of queue (must be an even number)
int     Q(S),   \queue (FIFO)
F, E;   \fill and empty indexes

proc    EnQ(X, Y);      \Enqueue coordinate
int     X, Y;
[Q(F):= X;
F:= F+1;
Q(F):= Y;
F:= F+1;
if F >= S then F:= 0;
];      \EnQ

proc    DeQ;            \Dequeue coordinate
[X:= Q(E);
E:= E+1;
Y:= Q(E);
E:= E+1;
if E >= S then E:= 0;
];      \DeQ

[F:= 0;  E:= 0;
EnQ(X, Y);
while E # F do
[DeQ;
if ReadPix(X, Y) = C0 then
[Point(X, Y, C);
EnQ(X+1, Y);    \enqueue adjacent pixels
EnQ(X-1, Y);
EnQ(X, Y+1);
EnQ(X, Y-1);
];
];
];      \Flood

def     Size = 30.0;
int     X, Y;
real    Ang, Dist;
[SetVid(\$101);                  \set 640x480 graphics with 256 colors

Ang:= 0.0;                      \draw some flower petals
repeat  Dist:= Size*(Cos(Ang*3.0) - 1.0);
X:= fix(Dist*Cos(Ang));
Y:= fix(Dist*Sin(Ang));
Point(X+320, 240-Y, \$F);
Ang:= Ang + 0.001;      \draw dots close together to prevent leaks
until   Ang >= 2.0*3.14159;

Flood(330, 240, \$2A, 0);        \color the petals
Flood(310, 230, \$2C, 0);
Flood(310, 250, \$2E, 0);

if ChIn(1) then [];             \wait for keystroke
SetVid(3);                      \restore normal text mode
]```

## zkl

Translation of: D

Uses the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl

```fcn flood(pixmap, x,y, repl){  // slow!
targ,h,w:=pixmap[x,y], pixmap.h,pixmap.w;
stack:=List(T(x,y));
while(stack){
x,y:=stack.pop();
if((0<=y<h) and (0<=x<w)){
p:=pixmap[x,y];
if(p==targ){
pixmap[x,y]=repl;
stack.append( T(x-1,y), T(x+1,y), T(x, y-1), T(x, y+1) );
}
}
}
}```
```pixmap:=PPM(250,302,0xFF|FF|FF);
pixmap.circle(101,200,100,0); pixmap.circle(75,100,25,0);

flood(pixmap,200,100, 0xF0|00|00);
flood(pixmap, 75,110, 0x00|F0|00);
flood(pixmap, 75,100, 0x00|00|F0);

pixmap.writeJPGFile("flood.zkl.jpg");```