Munching squares

Munching squares
You are encouraged to solve this task according to the task description, using any language you may know.

Render a graphical pattern where each pixel is colored by the value of 'x xor y' from an arbitrary color table.

Action!

PROC PutBigPixel(BYTE x,y,c)
  BYTE i

  Color=c
  x=x*3+16
  y=y*12
  FOR i=0 TO 11
  DO
    Plot(x,y+i)
    DrawTo(x+2,y+i)
  OD
RETURN

PROC Main()
  BYTE
    CH=$02FC, ;Internal hardware value for last key pressed
    x,y

  Graphics(9)

  FOR y=0 TO 15
  DO
    FOR x=0 TO 15
    DO
      PutBigPixel(x,y,x!y)
    OD
  OD

  DO UNTIL CH#$FF OD
  CH=$FF
RETURN

Output:

Screenshot from Atari 8-bit computer

Ada

Library: GtkAda

Uses the Cairo component of GtkAda to create and save as png

with Cairo; use Cairo;
with Cairo.Png; use Cairo.Png;
with Cairo.Image_Surface; use Cairo.Image_Surface;
procedure XorPattern is
   type xorable is mod 256;
   Surface : Cairo_Surface;
   Data : RGB24_Array_Access;
   Status : Cairo_Status;
   Num : Byte;
begin
   Data := new RGB24_Array(0..256*256-1);
   for x in Natural range 0..255 loop
      for y in Natural range 0..255 loop
         Num := Byte(xorable(x) xor xorable(y));
         Data(x+256*y) := RGB24_Data'(Num,0,Num);
      end loop;
   end loop;
   Surface := Create_For_Data_RGB24(Data, 256, 256);
   Status := Write_To_Png (Surface, "AdaXorPattern.png");
   pragma Assert (Status = Cairo_Status_Success);
end XorPattern;

Output:

Applesoft BASIC

 100  DATA 0,2, 6,10,5, 6, 7,15
 110  DATA 0,1, 3,10,5, 3,11,15
 120  DATA 0,8, 9,10,5, 9,13,15
 130  DATA 0,4,12,10,5,12,14,15
 140  LET C = 7
 150  POKE 768,169: REM LDA #
 160  POKE 770,073: REM EOR #
 170  POKE 772,133: REM STA
 180  POKE 773,235: REM   $EB
 190  POKE 774,096: REM RTS
 200  GR 
 210  FOR H = 0 TO 1
 220      FOR W = 0 TO 1
 230          FOR S = 0 TO C
 240              READ C(S)
 250          NEXT S
 260          FOR Y = 0 TO C
 270              POKE 769,Y
 280              LET Y1 = H * S * 2 + Y * 2
 290              FOR X = 0 TO C
 300                  POKE 771,X
 310                  CALL 768
 320                  COLOR= C( PEEK (235))
 330                  VLIN Y1,Y1 + 1 AT W * S + X
 340                  NEXT X,Y,W,H

AWK

Works with: gawk

This program generates a PPM image, that you can view/convert using The GIMP or ImageMagick

BEGIN {
    # square size
    s = 256
    # the PPM image header needs 3 lines:
    # P3
    # width height
    # max colors number (per channel)
    print("P3\n", s, s, "\n", s - 1)
    # and now we generate pixels as a RGB pair in a relaxed
    # form "R G B\n"
    for (x = 0; x < s; x++) { 
        for (y = 0; y < s; y++) {
            p = xor(x, y)
            print(0, p, p)
        }
    }
}

BBC BASIC

Works with: BBC BASIC for Windows

      size% = 256

      VDU 23,22,size%;size%;8,8,16,0
      OFF

      DIM coltab%(size%-1)
      FOR I% = 0 TO size%-1
        coltab%(I%) = ((I% AND &FF) * &010101) EOR &FF0000
      NEXT

      GCOL 1
      FOR I% = 0 TO size%-1
        FOR J% = 0 TO size%-1
          C% = coltab%(I% EOR J%)
          COLOUR 1, C%, C%>>8, C%>>16
          PLOT I%*2, J%*2
        NEXT
      NEXT I%

      REPEAT WAIT 1 : UNTIL FALSE

Befunge

Writes the image to stdout using the PPM format.

55+::"3P",,,28*:*::..\,:.\,:v
>2%*28*:**-2/\1-:v<:8:-1<_@ v
^\-1*2%2/*:*82::\_$0.0..:^:*<

Burlesque

blsq ) 0 25r@{0 25r@\/{$$Sh2' P[}\/+]m[}m[sp
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
 1  0  3  2  5  4  7  6  9  8 11 10 13 12 15 14 17 16 19 18 21 20 23 22 25 24
 2  3  0  1  6  7  4  5 10 11  8  9 14 15 12 13 18 19 16 17 22 23 20 21 26 27
 3  2  1  0  7  6  5  4 11 10  9  8 15 14 13 12 19 18 17 16 23 22 21 20 27 26
 4  5  6  7  0  1  2  3 12 13 14 15  8  9 10 11 20 21 22 23 16 17 18 19 28 29
 5  4  7  6  1  0  3  2 13 12 15 14  9  8 11 10 21 20 23 22 17 16 19 18 29 28
 6  7  4  5  2  3  0  1 14 15 12 13 10 11  8  9 22 23 20 21 18 19 16 17 30 31
 7  6  5  4  3  2  1  0 15 14 13 12 11 10  9  8 23 22 21 20 19 18 17 16 31 30
 8  9 10 11 12 13 14 15  0  1  2  3  4  5  6  7 24 25 26 27 28 29 30 31 16 17
 9  8 11 10 13 12 15 14  1  0  3  2  5  4  7  6 25 24 27 26 29 28 31 30 17 16
10 11  8  9 14 15 12 13  2  3  0  1  6  7  4  5 26 27 24 25 30 31 28 29 18 19
11 10  9  8 15 14 13 12  3  2  1  0  7  6  5  4 27 26 25 24 31 30 29 28 19 18
12 13 14 15  8  9 10 11  4  5  6  7  0  1  2  3 28 29 30 31 24 25 26 27 20 21
13 12 15 14  9  8 11 10  5  4  7  6  1  0  3  2 29 28 31 30 25 24 27 26 21 20
14 15 12 13 10 11  8  9  6  7  4  5  2  3  0  1 30 31 28 29 26 27 24 25 22 23
15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0 31 30 29 28 27 26 25 24 23 22
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31  0  1  2  3  4  5  6  7  8  9
17 16 19 18 21 20 23 22 25 24 27 26 29 28 31 30  1  0  3  2  5  4  7  6  9  8
18 19 16 17 22 23 20 21 26 27 24 25 30 31 28 29  2  3  0  1  6  7  4  5 10 11
19 18 17 16 23 22 21 20 27 26 25 24 31 30 29 28  3  2  1  0  7  6  5  4 11 10
20 21 22 23 16 17 18 19 28 29 30 31 24 25 26 27  4  5  6  7  0  1  2  3 12 13
21 20 23 22 17 16 19 18 29 28 31 30 25 24 27 26  5  4  7  6  1  0  3  2 13 12
22 23 20 21 18 19 16 17 30 31 28 29 26 27 24 25  6  7  4  5  2  3  0  1 14 15
23 22 21 20 19 18 17 16 31 30 29 28 27 26 25 24  7  6  5  4  3  2  1  0 15 14
24 25 26 27 28 29 30 31 16 17 18 19 20 21 22 23  8  9 10 11 12 13 14 15  0  1
25 24 27 26 29 28 31 30 17 16 19 18 21 20 23 22  9  8 11 10 13 12 15 14  1  0

Must be converted to an image with a seperate program.

C

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>

void hue_to_rgb(double hue, double sat, unsigned char *p)
{
	double x;
	int c = 255 * sat;
	hue /= 60;
	x = (1 - fabs(fmod(hue, 2) - 1)) * 255;

	switch((int)hue) {
	case 0:	p[0] = c; p[1] = x; p[2] = 0; return;
	case 1:	p[0] = x; p[1] = c; p[2] = 0; return;
	case 2:	p[0] = 0; p[1] = c; p[2] = x; return;
	case 3:	p[0] = 0; p[1] = x; p[2] = c; return;
	case 4:	p[0] = x; p[1] = 0; p[2] = c; return;
	case 5:	p[0] = c; p[1] = 0; p[2] = x; return;
	}
}

int main(void)
{
	const int size = 512;
	int i, j;
	unsigned char *colors = malloc(size * 3);
	unsigned char *pix = malloc(size * size * 3), *p;
	FILE *fp;

	for (i = 0; i < size; i++)
		hue_to_rgb(i * 240. / size, i * 1. / size, colors + 3 * i);

	for (i = 0, p = pix; i < size; i++)
		for (j = 0; j < size; j++, p += 3)
			memcpy(p, colors + (i ^ j) * 3, 3);

	fp = fopen("xor.ppm", "wb");
	fprintf(fp, "P6\n%d %d\n255\n", size, size);
	fwrite(pix, size * size * 3, 1, fp);
	fclose(fp);

	return 0;
}

Output:

C#

using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;

class XORPattern
{
    static void Main()
    {
        var size = 0x100;
        var black = Color.Black.ToArgb();
        var palette = Enumerable.Range(black, size).Select(Color.FromArgb).ToArray();
        using (var image = new Bitmap(size, size))
        {
            for (var x = 0; x < size; x++)
            {
                for (var y = 0; y < size; y++)
                {
                    image.SetPixel(x, y, palette[x ^ y]);
                }
            }
            image.Save("XORPatternCSharp.png", ImageFormat.Png);
        }
    }
}

Output:

C++

#include <windows.h>
#include <string>

//--------------------------------------------------------------------------------------------------
using namespace std;

//--------------------------------------------------------------------------------------------------
const int BMP_SIZE = 512;

//--------------------------------------------------------------------------------------------------
class myBitmap
{
public:
    myBitmap() : pen( NULL ), brush( NULL ), clr( 0 ), wid( 1 ) {}
    ~myBitmap()
    {
	DeleteObject( pen );
	DeleteObject( brush );
	DeleteDC( hdc );
	DeleteObject( bmp );
    }
 
    bool create( int w, int h )
    {
	BITMAPINFO    bi;
	ZeroMemory( &bi, sizeof( bi ) );
	bi.bmiHeader.biSize        = sizeof( bi.bmiHeader );
	bi.bmiHeader.biBitCount    = sizeof( DWORD ) * 8;
	bi.bmiHeader.biCompression = BI_RGB;
	bi.bmiHeader.biPlanes      = 1;
	bi.bmiHeader.biWidth       =  w;
	bi.bmiHeader.biHeight      = -h;
 
	HDC dc = GetDC( GetConsoleWindow() );
	bmp = CreateDIBSection( dc, &bi, DIB_RGB_COLORS, &pBits, NULL, 0 );
	if( !bmp ) return false;
 
	hdc = CreateCompatibleDC( dc );
	SelectObject( hdc, bmp );
	ReleaseDC( GetConsoleWindow(), dc );
 
	width = w; height = h;
	return true;
    }
 
    void clear( BYTE clr = 0 )
    {
	memset( pBits, clr, width * height * sizeof( DWORD ) );
    }
 
    void setBrushColor( DWORD bClr )
    {
	if( brush ) DeleteObject( brush );
	brush = CreateSolidBrush( bClr );
	SelectObject( hdc, brush );
    }
 
    void setPenColor( DWORD c ) { clr = c; createPen(); }
 
    void setPenWidth( int w )   { wid = w; createPen(); }
 
    void saveBitmap( string path )
    {
	BITMAPFILEHEADER fileheader;
	BITMAPINFO       infoheader;
	BITMAP           bitmap;
	DWORD            wb;
 
	GetObject( bmp, sizeof( bitmap ), &bitmap );
	DWORD* dwpBits = new DWORD[bitmap.bmWidth * bitmap.bmHeight];
 
	ZeroMemory( dwpBits, bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD ) );
	ZeroMemory( &infoheader, sizeof( BITMAPINFO ) );
	ZeroMemory( &fileheader, sizeof( BITMAPFILEHEADER ) );
 
	infoheader.bmiHeader.biBitCount = sizeof( DWORD ) * 8;
	infoheader.bmiHeader.biCompression = BI_RGB;
	infoheader.bmiHeader.biPlanes = 1;
	infoheader.bmiHeader.biSize = sizeof( infoheader.bmiHeader );
	infoheader.bmiHeader.biHeight = bitmap.bmHeight;
	infoheader.bmiHeader.biWidth = bitmap.bmWidth;
	infoheader.bmiHeader.biSizeImage = bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD );
 
	fileheader.bfType    = 0x4D42;
	fileheader.bfOffBits = sizeof( infoheader.bmiHeader ) + sizeof( BITMAPFILEHEADER );
	fileheader.bfSize    = fileheader.bfOffBits + infoheader.bmiHeader.biSizeImage;
 
	GetDIBits( hdc, bmp, 0, height, ( LPVOID )dwpBits, &infoheader, DIB_RGB_COLORS );
 
	HANDLE file = CreateFile( path.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL );
	WriteFile( file, &fileheader, sizeof( BITMAPFILEHEADER ), &wb, NULL );
	WriteFile( file, &infoheader.bmiHeader, sizeof( infoheader.bmiHeader ), &wb, NULL );
	WriteFile( file, dwpBits, bitmap.bmWidth * bitmap.bmHeight * 4, &wb, NULL );
	CloseHandle( file );
 
	delete [] dwpBits;
    }
 
    HDC getDC() const     { return hdc; }
    int getWidth() const  { return width; }
    int getHeight() const { return height; }
 
private:
    void createPen()
    {
	if( pen ) DeleteObject( pen );
	pen = CreatePen( PS_SOLID, wid, clr );
	SelectObject( hdc, pen );
    }
 
    HBITMAP bmp;
    HDC     hdc;
    HPEN    pen;
    HBRUSH  brush;
    void    *pBits;
    int     width, height, wid;
    DWORD   clr;
};
//--------------------------------------------------------------------------------------------------
class mSquares
{
public:
    mSquares()
    {
        bmp.create( BMP_SIZE, BMP_SIZE );
        createPallete();
    }

    void draw()
    {
	HDC dc = bmp.getDC();
	for( int y = 0; y < BMP_SIZE; y++ )
	    for( int x = 0; x < BMP_SIZE; x++ )
	    {
		int c = ( x ^ y ) % 256;
		SetPixel( dc, x, y, clrs[c] );
	    }

	BitBlt( GetDC( GetConsoleWindow() ), 30, 30, BMP_SIZE, BMP_SIZE, dc, 0, 0, SRCCOPY );
	//bmp.saveBitmap( "f:\\rc\\msquares_cpp.bmp" );
    }

private:
    void createPallete()
    {
	for( int x = 0; x < 256; x++ )
	clrs[x] = RGB( x<<1, x, x<<2 );//rand() % 180 + 50, rand() % 200 + 50, rand() % 180 + 50 );
    }

    unsigned int clrs[256];
    myBitmap bmp;
};
//--------------------------------------------------------------------------------------------------
int main( int argc, char* argv[] )
{
    ShowWindow( GetConsoleWindow(), SW_MAXIMIZE );
    srand( GetTickCount() );
    mSquares s; s.draw();
    return system( "pause" );
}
//--------------------------------------------------------------------------------------------------

Commodore BASIC

Works with: Commodore BASIC version 4.0

The TED machines (C-16, Plus/4) are the only Commodore 8-bits with a large- or structured- enough color palette to make this interesting. Here's an extremely low-res version (40x25 character-sized "pixels"):

100 FOR I=0 TO 24
110 : Y=INT(I*127/24)
120 : FOR J=0 TO 39
130 :   X=INT(J*127/39)
140 :   HL = (X OR Y) AND NOT (X AND Y)
150 :   H = INT(HL / 8)
160 :   L = HL - 8 * H
170 :   POKE 2048+I*40+J,L*16+H
180 :   POKE 3072+I*40+J,160
190 : NEXT J
210 NEXT I
220 GETKEY K$

Output:

Screenshot.

D

void main() {
    import std.stdio;

    enum width = 512, height = 512;

    auto f = File("xor_pattern.ppm", "wb");
    f.writefln("P6\n%d %d\n255", width, height);
    foreach (immutable y; 0 .. height)
        foreach (immutable x; 0 .. width) {
            immutable c = (x ^ y) & ubyte.max;
            immutable ubyte[3] u3 = [255 - c, c / 2, c];
            f.rawWrite(u3);
        }
}

EchoLisp

Use the plot library, hsv->rgb ((x xor y) modulo m) as color table, and see the nice results here : http://www.echolalie.org/echolisp/help.html#bit-map .

(lib 'types)
(lib 'plot)
(plot-size 512 512) ;; for example

;; use m = 16, 32, 44, .. to change the definition (number of losanges)
(define (plot-munch (m 256))
	(define PIX (pixels->int32-vector)) ;; get canvas image
	(define (pcolor x y) ;; color at (x,y)
		(hsv->rgb
			(// (bitwise-xor (modulo x m) (modulo y m)) m)
			0.9
			0.9))
	(pixels-map pcolor PIX)
	(vector->pixels PIX)) ;; draw canvas image

(plot-much) ;; ESC to see tge drawing

Factor

USING: accessors images images.loader kernel math sequences ;
IN: rosetta-code.munching-squares

: img-data ( -- seq ) 256 sq [ B{ 0 0 0 255 } ] replicate ;

: (munching) ( elt index -- elt' )
    256 /mod bitxor [ rest ] dip prefix ;

: munching ( -- seq )
    img-data [ (munching) ] map-index B{ } concat-as ;
    
: <munching-img> ( -- img )
    <image>
    { 256 256 }      >>dim
    BGRA             >>component-order
    ubyte-components >>component-type
    munching         >>bitmap ;
    
: main ( -- ) <munching-img> "munching.png" save-graphic-image ;

MAIN: main

Output image is identical to the Racket version.

Output:

FreeBASIC

' version 03-11-2016
' compile with: fbc -s gui

Dim As ULong x, y, r, w = 256

ScreenRes w, w, 32

For x = 0 To w -1
    For y = 0 To w -1
        r =(x Xor y) And 255
        PSet(x, y), RGB(r, r , r)         ' gray scale
        ' PSet(x, y), RGB(r, 255 - r, 0)  ' red + green
        ' PSet(x, y), RGB(r, 0, 0)        ' red
    Next
Next

' empty keyboard buffer
While Inkey <> "" : Wend
WindowTitle "Close window or hit any key to end program"
Sleep
End

Fōrmulæ

Fōrmulæ programs are not textual, visualization/edition of programs is done showing/manipulating structures but not text. Moreover, there can be multiple visual representations of the same program. Even though it is possible to have textual representation —i.e. XML, JSON— they are intended for storage and transfer purposes more than visualization and edition.

Programs in Fōrmulæ are created/edited online in its website, However they run on execution servers. By default remote servers are used, but they are limited in memory and processing power, since they are intended for demonstration and casual use. A local server can be downloaded and installed, it has no limitations (it runs in your own computer). Because of that, example programs can be fully visualized and edited, but some of them will not run if they require a moderate or heavy computation/memory resources, and no local server is being used.

In this page you can see the program(s) related to this task and their results.

GLSL

This is an example that will work directly on shadertoy.com, Example [1]

vec3 color;
float c,p;
vec2 b;

void main(void)
{
	vec2 uv = gl_FragCoord.xy / iResolution.xy;
	float scale = iResolution.x / iResolution.y;
	uv = uv-0.5;
	uv.y/=scale;
	
	b    = uv*256.0+256.0;
	c = 0.0;
	
	
	for(float i=16.0;i>=1.0;i-=1.0)
	{
		p = pow(2.0,i);

		if((p < b.x) ^^
		   (p < b.y))
		{
			c += p;
		}
		
		if(p < b.x)
		{
			b.x -= p;
		}
		
		if(p < b.y)
		{
			b.y -= p;
		}
		
	}
	
	c=mod(c/128.0,1.0);
	
	color = vec3(sin(c+uv.x*cos(uv.y*1.2)), tan(c+uv.y-0.3)*1.1, cos(c-uv.y+0.9));
	
	gl_FragColor = vec4(color,1.0);
}

Gnuplot

set pm3d map
set size square
set isosamples 255,255
splot [0:255][0:255]-(floor(x)^floor(y))

Output:

Go

package main

import (
    "image"
    "image/png"
    "os"
)

func main() {
    g := image.NewGray(image.Rect(0, 0, 256, 256))
    for i := range g.Pix {
        g.Pix[i] = uint8(i>>8 ^ i)
    }
    f, _ := os.Create("xor.png")
    png.Encode(f, g)
    f.Close()
}

Haskell

import qualified Data.ByteString as BY (writeFile, pack)

import Data.Bits (xor)

main :: IO ()
main =
  BY.writeFile
    "out.pgm"
    (BY.pack
       (fmap (fromIntegral . fromEnum) "P5\n256 256\n256\n" ++
        [ x `xor` y
        | x <- [0 .. 255] 
        , y <- [0 .. 255] ]))

Icon and Unicon

512x512 bit green and red

link printf

procedure main(A)   #: XOR graphic
   wsize := 512
   cmax  := 32768
   wparms := ["Xmas Xor Graphic","g",sprintf("size=%d,%d",wsize),"bg=black"]
   &window := open!wparms | stop("Unable to open window")
 
   every y := 0 to wsize - 1 do
      every x := 0 to wsize - 1 do {
         c := cmax/wsize * iand(wsize-1,ixor(x,y))
         Fg(sprintf("%d,%d,%d",c,cmax-c,0))
         DrawPoint(x,y)
         }
 
  until Event() == &lpress     # wait for left button to quit
  close(&window)
end

Library: Icon Programming Library

printf.icn provides formatting

J

   require 'viewmat'
   viewmat ~:"1/&.#: ~ i.256

Java

Library: Swing

This example will repeat the pattern if you expand the window.

import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class XorPattern extends JFrame{
    private JPanel xorPanel;

    public XorPattern(){
        xorPanel = new JPanel(){
            @Override
            public void paint(Graphics g) {
                for(int y = 0; y < getHeight();y++){
                    for(int x = 0; x < getWidth();x++){
                        g.setColor(new Color(0, (x ^ y) % 256, 0));
                        g.drawLine(x, y, x, y);
                    }
                }
            }
        };
        add(xorPanel);
        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    public static void main(String[] args){
        new XorPattern();
    }
}

jq

Works with: jq version 1.4

The following is an adaptation of the Ruby entry, but generates an SVG image file:

jq -n -r -f Munching_squares.jq > Munching_squares.svg

Part 1: Infrastructure

# Convert the input integer to an array of bits with lsb first
def integer_to_lsb:
  [recurse(if . > 0 then ./2|floor else empty end) | . % 2] ;

# input array of bits (with lsb first) is converted to an integer
def lsb_to_integer:
  reduce .[] as $bit
    # state: [power, ans]
    ([1,0]; (.[0] * 2) as $b | [$b, .[1] + (.[0] * $bit)])
  | .[1];

def xor(x;y):
   def lxor(a;b):  # a and/or b may be null
     if a == 1 then if b==1 then 0 else 1 end
     elif b==1 then if a==1 then 0 else 1 end
     else 0
     end;
   (x|integer_to_lsb) as $s
   | (y|integer_to_lsb) as $t
   | ([$s|length, $t|length] | max) as $length
   | reduce range(0;$length) as $i
      ([]; . + [ lxor($s[$i]; $t[$i]) ] )
   | lsb_to_integer;

Part 2: SVG

def rgb2rgb:
  def p: (. + 0.5) | floor;  # to nearest integer
  "rgb(\(.red|p),\(.green|p),\(.blue|p))";

def svg(width; height): 
  "<svg width='\(width // "100%")' height='\(height // "100%")'
           xmlns='http://www.w3.org/2000/svg'>";

def pixel(x; y; color):
  (color | if type == "string" then . else rgb2rgb end) as $c
  | "<circle r='1' cx='\(x)' cy='\(y)' fill='\($c)' />";

Part 3: xor pattern

# rgb is a JSON object: { "red": _, "green": _, "blue": _}

def xor_pattern(width; height; rgb1; rgb2):
    # create colour table
    256 as $size 
    | (reduce range(0;$size) as $i
        ([]; . + [ 
        {"red":   (rgb1.red + (rgb2.red - rgb1.red) * $i / $size), 
         "green": (rgb1.green + (rgb2.green - rgb1.green) * $i / $size), 
         "blue":  (rgb1.blue + (rgb2.blue - rgb1.blue) * $i / $size) }])
      )  as $colours
    # create the image
    | svg(width; height),
      ( (range(0;width) as $x
        | range(0;height) as $y
        |   pixel($x; $y; $colours[ xor($x; $y) % $size] ) ) ),
     "</svg>" ;

Part 4: Example

def black: { "red": 0, "green": 0, "blue": 0};
def red: black + { "red": 255 };
def yellow: red + { "green": 255 };

xor_pattern(384; 384; red; yellow)

Julia

using Gtk, Cairo

const can = @GtkCanvas()
const win = GtkWindow(can, "Munching Squares", 512, 512)

@guarded draw(can) do widget
    ctx = getgc(can)
    for x in 0:255, y in 0:255
        set_source_rgb(ctx, abs(255 - x - y) / 255, ((255 - x) ⊻ y) / 255, (x ⊻ (255 - y)) / 255)
        circle(ctx, 2x, 2y, 2)
        fill(ctx)
    end
end

show(can)
const cond = Condition()
endit(w) = notify(cond)
signal_connect(endit, win, :destroy)
wait(cond)

Kotlin

// version 1.1.4-3

import javax.swing.JFrame
import javax.swing.JPanel
import java.awt.Graphics
import java.awt.Graphics2D
import java.awt.Color
import java.awt.Dimension
import java.awt.BorderLayout
import java.awt.RenderingHints
import javax.swing.SwingUtilities

class XorPattern : JPanel() {

    init {
        preferredSize = Dimension(256, 256)
        background = Color.white
    }

    override fun paint(gg: Graphics) {
        super.paintComponent(gg)
        val g = gg as Graphics2D
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                           RenderingHints.VALUE_ANTIALIAS_ON)
        for (y in 0 until width) {
            for (x in 0 until height) {
                g.color = Color(0, (x xor y) % 256, 255)
                g.drawLine(x, y, x, y)
            }
        }
    }
}

fun main(args: Array<String>) {
    SwingUtilities.invokeLater {
        val f = JFrame()
        with (f) {
            defaultCloseOperation = JFrame.EXIT_ON_CLOSE
            title = "Munching squares"
            isResizable = false
            add(XorPattern(), BorderLayout.CENTER)
            pack()
            setLocationRelativeTo(null)
            isVisible = true
        }
    }
}

Liberty BASIC

    nomainwin

    w =512
    '   allow for title bar and window border
    WindowWidth  =w +2
    WindowHeight =w +34

    open "XOR Pattern" for graphics_nsb_nf as #w

    #w "trapclose quit"

    #w "down"

    for x =0 to w -1
        for y =0 to w -1
            b =( x xor y) and 255
            print b
            #w "color "; 255 -b; " "; b /2; " "; b
            #w "set "; x; " "; w -y -1
            scan
        next y
    next x

    #w "flush"

    wait

    sub quit j$
    close #w
    end
    end sub

Image available at [[2]]

Lua

Works with: LÖVE version 11.0 or higher

local clr =  {}
function drawMSquares()
	local points = {}
	for y = 0, hei-1 do
		for x = 0, wid-1 do
			local idx = bit.bxor(x, y)%256
			local r, g, b = clr[idx][1], clr[idx][2], clr[idx][3]
			local point = {x+1, y+1, r/255, g/255, b/255, 1}
			table.insert (points, point)
		end
	end
	love.graphics.points(points)
end

function createPalette()
	for i = 0, 255 do
		clr[i] = {i*2.8%256, i*3.2%256, i*1.5%256}
	end
end

function love.load()
	wid, hei = 256, 256
	love.window.setMode(wid, hei)
	canvas = love.graphics.newCanvas()
	love.graphics.setCanvas(canvas)
		createPalette()
		drawMSquares()
	love.graphics.setCanvas()
end

function love.draw()
	love.graphics.setColor(1,1,1)
	love.graphics.draw(canvas)
end

Mathematica/Wolfram Language

ListDensityPlot[
 Table[Table[
   FromDigits[BitXor[IntegerDigits[x, 2, 8], IntegerDigits[y, 2, 8]], 
    2], {x, 0, 255}], {y, 0, 255}]]

Output #1:

ArrayPlot[Array[BitXor, {511, 511}]]

Output #2:

MATLAB

size = 256;
[x,y] = meshgrid([0:size-1]);

c = bitxor(x,y);

colormap bone(size);
image(c);
axis equal;

Output:

Microsoft Small Basic

' Munching squares - smallbasic  - 27/07/2018
  size=256
  GraphicsWindow.Width=size
  GraphicsWindow.Height=size
  For i=0 To size-1
    For j=0 To size-1
      BitXor() 'color=i Xor j
      GraphicsWindow.SetPixel(i,j,GraphicsWindow.GetColorFromRGB(0,color,color))
    EndFor
  EndFor

Sub BitXor '(i,j)->color
  n=i
  Int2Bit()
  ib=ret
  n=j
  Int2Bit()
  jb=ret
  color=0
  For k=1 to 8
    ki=Text.GetSubText(ib,k,1)
    kj=Text.GetSubText(jb,k,1)
    If ki="1" Or kj="1" Then
      kk="1"
    Else
      kk="0"
    EndIf
    If ki="1" And kj="1" Then
      kk="0"
    EndIf
    color=2*color+kk
  EndFor
EndSub 

Sub Int2Bit 'n->ret
  x=n
  ret=""
  For k=1 to 8
    t=Math.Floor(x/2)
    r=Math.Remainder(x,2)
    ret=Text.Append(r,ret)
    x=t
  EndFor
EndSub

Output:

Munching squares - SmallBasic

MiniScript

This version runs in Mini Micro (for the graphics). Note that because MiniScript does not currently have any bit operations (all numbers are floating-point), we have to implement an xor function the hard way.

xor = function(a, b)
	result = 0
	bit = 1
	while a > 0 or b > 0
		if (a%2 == 0) != (b%2 == 0) then result = result + bit
		bit = bit * 2
		a = floor(a/2)
		b = floor(b/2)
	end while
	return result
end function

for x in range(0,255)
	for y in range(0,255)
		gfx.setPixel x, y, color.rgb(0, xor(x,y), 0)
	end for
end for

Output:

Nim

Library: imageman

import random
import imageman

randomize()

# Build a color table.
var colors: array[256, ColorRGBU]
for color in colors.mitems:
  color = ColorRGBU [byte rand(255), byte rand(255), byte rand(255)]


var image = initImage[ColorRGBU](256, 256)

for i in 0..255:
  for j in 0..255:
    image[i, j] = colors[i xor j]

image.savePNG("munching_squares.png")

OCaml

open Graphics

let () =
  open_graph "";
  resize_window 256 256;
  for y = 0 to pred (size_y()) do
    for x = 0 to pred (size_x()) do
      let v = (x lxor y) land 0xFF in
      set_color (rgb v (255 - v) 0);
      plot x y
    done;
  done;
  ignore(read_key())

Run with:

$ ocaml graphics.cma xor_pattern.ml

Output:

Octave

size = 256;
[x,y] = meshgrid([0:size-1]);

c = bitxor(x,y);

colormap(jet(size));
image(c);
axis equal;

Output:

Perl

use GD;

my $img = new GD::Image(256, 256, 1);

for my $y(0..255) {
        for my $x(0..255) {
                my $color = $img->colorAllocate( abs(255 - $x - $y),  (255-$x) ^ $y , $x ^ (255-$y));
                $img->setPixel($x, $y, $color);
        }
}

print $img->png

Output:

Phix

Library: Phix/pGUI

Library: Phix/online

You can run this online here.

--
-- demo\rosetta\Munching_squares.exw
-- =================================
--
with javascript_semantics
include pGUI.e

Ihandle dlg, canvas
cdCanvas cddbuffer, cdcanvas

function redraw_cb(Ihandle /*ih*/, integer /*posx*/, /*posy*/)
integer {width, height} = IupGetIntInt(canvas, "DRAWSIZE")
    cdCanvasActivate(cddbuffer)
    for y=0 to height-1 do
        for x=0 to width-1 do
            cdCanvasPixel(cddbuffer, x, y, xor_bits(x,y))
        end for
    end for
    cdCanvasFlush(cddbuffer)
    return IUP_DEFAULT
end function

function map_cb(Ihandle ih)
    cdcanvas = cdCreateCanvas(CD_IUP, ih)
    cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)
    cdCanvasSetBackground(cddbuffer, CD_WHITE)
    cdCanvasSetForeground(cddbuffer, CD_RED)
    return IUP_DEFAULT
end function

procedure main()
    IupOpen()
    canvas = IupCanvas("RASTERSIZE=250x250")
    IupSetCallbacks(canvas, {"MAP_CB", Icallback("map_cb"),
                             "ACTION", Icallback("redraw_cb")})
    dlg = IupDialog(canvas, `TITLE="Munching squares",RESIZE=NO`)
    IupShow(dlg)
    if platform()!=JS then
        IupMainLoop()
        IupClose()
    end if
end procedure

main()

PHP

header("Content-Type: image/png");

$w = 256;
$h = 256;

$im = imagecreate($w, $h)
    or die("Cannot Initialize new GD image stream");

$color = array();
for($i=0;$i<256;$i++)
{
        array_push($color,imagecolorallocate($im,sin(($i)*(2*3.14/256))*128+128,$i/2,$i));
}

for($i=0;$i<$w;$i++)
{
        for($j=0;$j<$h;$j++)
        {
                imagesetpixel($im,$i,$j,$color[$i^$j]);
        }
}

imagepng($im);
imagedestroy($im);

Output:

PL/I

munch: procedure options (main); /* 21 May 2014 */

   declare screen (0:255, 0:255) bit(24) aligned;
   declare b bit(8) aligned;
   declare (x, y) unsigned fixed binary (8);

   do x = 0 upthru hbound(screen,2);
      do y = 0 upthru hbound(screen,1);
         b = unspec(x) ^ unspec(y);
         screen(x,y) = b;
      end;
   end;
   call writeppm(screen);
end munch;

Processing

Renders grayscale image, the larger the window the more the squares will repeat along the main diagonal from top left to bottom right.

//Aamrun, 26th June 2022

size(1200,720);

loadPixels();

for(int i=0;i<height;i++){
  for(int j=0;j<width;j++){
    pixels[j + i*width] = color(i^j);
  }
}

updatePixels();

Prolog

Works with SWI-Prolog and his GUI XPCE.

xor_pattern :-
	new(D, window('XOR Pattern')),
	send(D, size, size(512,512)),
	new(Img, image(@nil, width := 512, height := 512 , kind := pixmap)),

	forall(between(0,511, I),
	       (   forall(between(0,511, J),
			  (   V is I xor J,
			      R is (V * 1024) mod 65536,
			      G is (65536 - V * 1024) mod 65536,
			      (	  V mod 2 =:= 0
			      ->  B is  (V * 4096) mod 65536
			      ;	   B is  (65536 - (V * 4096)) mod 65536),
			      send(Img, pixel(I, J, colour(@default, R, G, B))))))),

	new(Bmp, bitmap(Img)),
	send(D, display, Bmp, point(0,0)),
	send(D, open).

PureBasic

#palletteSize = 128
Procedure.f XorPattern(x, y) ;compute the gradient value from the pixel values
  Protected result = x ! y
  ProcedureReturn Mod(result, #palletteSize) / #palletteSize
EndProcedure

Procedure drawPattern()
  StartDrawing(ImageOutput(0))
    DrawingMode(#PB_2DDrawing_Gradient)
    CustomGradient(@XorPattern())
    ;specify a gradient pallette from which only specific indexes will be used
    For i = 1 To #palletteSize 
      GradientColor(1 / i, i * $BACE9B) ; or alternatively use $BEEFDEAD
    Next 
    Box(0, 0, ImageWidth(0), ImageHeight(0))
  StopDrawing()
EndProcedure

If OpenWindow(0, 0, 0, 128, 128, "XOR Pattern", #PB_Window_SystemMenu)
  CreateImage(0, WindowWidth(0), WindowHeight(0))
  drawPattern()
  ImageGadget(0, 0, 0, ImageWidth(0), ImageHeight(0), ImageID(0))
  Repeat
    event = WaitWindowEvent(20)
  Until event = #PB_Event_CloseWindow
EndIf

Python

Library: PIL

import Image, ImageDraw

image = Image.new("RGB", (256, 256))
drawingTool = ImageDraw.Draw(image)

for x in range(256):
    for y in range(256):
        drawingTool.point((x, y), (0, x^y, 0))

del drawingTool
image.save("xorpic.png", "PNG")

QBasic

w = 254

SCREEN 13
VIEW (0, 0)-(w / 2, w / 2), , 0

FOR x = 0 TO w
    FOR y = 0 TO w
        COLOR ((x XOR y) AND 255)
        PSET (x, y)
    NEXT y
NEXT x

Racket

#lang racket
(require racket/draw)
(define palette (for/vector ([x 256]) (make-object color% 0 0 x)))
(define bm (make-object bitmap% 256 256))
(define dc (new bitmap-dc% [bitmap bm]))
(for* ([x 256] [y 256])
  (define c (vector-ref palette (bitwise-xor x y)))
  (send dc set-pixel x y c))
bm

Raku

(formerly Perl 6)

Here's one simple way:

my $ppm = open("munching0.ppm", :w) orelse .die;

$ppm.print(q :to 'EOT');
P3
256 256
255
EOT

for 0 .. 255 -> $row {
    for 0 .. 255 -> $col {
        my $color = $row +^ $col;
        $ppm.print("0 $color 0 ");
    }
    $ppm.say();
}

$ppm.close();

Another way:

my @colors = map -> $r, $g, $b { Buf.new: $r, $g, $b },
		map -> $x { floor ($x/256) ** 3 * 256 },
		    (flat (0...255) Z
		     (255...0) Z
		     flat (0,2...254),(254,252...0));


my $PPM = open "munching1.ppm", :w orelse .die;

$PPM.print: qq:to/EOH/;
    P6
    # munching.pgm
    256 256 
    255
    EOH

$PPM.write: @colors[$_] for ^256 X+^ ^256;

$PPM.close;

REXX

Translation of: Burlesque

/*REXX program renders a  graphical pattern  by  coloring  each pixel   with   x XOR y  */
/*─────────────────────────────────────────  from an arbitrary constructed color table. */
rows= 2                                          /*the number of rows in the color table*/
cols= 5                                          /* "     "    " cols  "  "    "     "  */
        do row  =0  for rows*3                   /*construct a color table, size  25x50.*/
          do col=0  for cols*3
                              $= (row+col) // 255
          @.row.col= x2b( d2x($+0, 2) )  ||,     /*ensure $ is converted──►2 hex nibbles*/
                     x2b( d2x($+1, 2) )  ||,
                     x2b( d2x($+2, 2) )
          end   /*col*/                          /* [↑]  construct a three-byte pixel.  */
        end     /*row*/

        do   x=0  for cols                       /*create a graphical pattern with XORs.*/
          do y=0  for rows
          @.x.y= bitxor(@.x, @.y)                /*renders 3 bytes (a pixel) at a time. */
          end   /*y*/
        end     /*x*/                            /*stick a fork in it,  we're all done. */

Must be converted to an image with a separate program.

Ring

# Project : Munching squares

load "guilib.ring"

paint = null

new qapp 
        {
        win1 = new qwidget() {
                  setwindowtitle("Archimedean spiral")
                  setgeometry(100,100,500,600)
                  label1 = new qlabel(win1) {
                              setgeometry(10,10,400,400)
                              settext("")
                  }
                  new qpushbutton(win1) {
                          setgeometry(150,500,100,30)
                          settext("draw")
                          setclickevent("draw()")
                  }
                  show()
        }
        exec()
        }

func draw
        p1 = new qpicture()
               color = new qcolor() {
               setrgb(0,0,255,255)
        }
        pen = new qpen() {
                 setcolor(color)
                 setwidth(1)
        }
        paint = new qpainter() {
                  begin(p1)
                  setpen(pen)

        w = 100
        for x = 0 to w
             for y = 0 to w
                   b = (x ^ y)
                   color = new qcolor()
                   color.setrgb(255 -b,b /2,b,255)
                   pen.setcolor(color) 
                   setpen(pen)    
                   drawpoint(x,w -y -1)
             next
         next

        endpaint()
        }
        label1 { setpicture(p1) show() }
        return

Output:

https://www.dropbox.com/s/wvdqyihtxralviz/Squares.jpg?dl=0

Ruby

Uses Raster graphics operations/Ruby

Sample output from Ruby program

load 'raster_graphics.rb'

class Pixmap
  def self.xor_pattern(width, height, rgb1, rgb2)
    # create colour table
    size = 256
    colours = Array.new(size) do |i|
      RGBColour.new(
        (rgb1.red + (rgb2.red - rgb1.red) * i / size), 
        (rgb1.green + (rgb2.green - rgb1.green) * i / size), 
        (rgb1.blue + (rgb2.blue - rgb1.blue) * i / size), 
      )
    end

    # create the image
    pixmap = new(width, height)
    pixmap.each_pixel do |x, y|
      pixmap[x,y] = colours[(x^y)%size]
    end
    pixmap
  end
end

img = Pixmap.xor_pattern(384, 384, RGBColour::RED, RGBColour::YELLOW)
img.save_as_png('xorpattern.png')

Run BASIC

w = 100
graphic #g, w,w
for x = 0 to w
  for y = 0 to w
    b = (x xor y) and 255
    #g color(255 -b,b /2,b)
    #g "set "; x; " "; w -y -1
  next y
next x
render #g 
#g "flush"

Rust

extern crate image;

use image::{ImageBuffer, Pixel, Rgb};

fn main() {
    let mut img = ImageBuffer::new(256, 256);

    for x in 0..256 {
        for y in 0..256 {
            let pixel = Rgb::from_channels(0, x as u8 ^ y as u8, 0, 0);
            img.put_pixel(x, y, pixel);
        }
    }

    let _ = img.save("output.png");
}

Scala

Scala Swing

Library: org.scala-lang.modules scala-swing

import scala.swing.Swing.pair2Dimension
import scala.swing.{Color, Graphics2D, MainFrame, Panel, SimpleSwingApplication}

object XorPattern extends SimpleSwingApplication {

  def top = new MainFrame {
    preferredSize = (300, 300)
    title = "Rosetta Code >>> Task: Munching squares | Language: Scala"
    contents = new Panel {

      protected override def paintComponent(g: Graphics2D) = {
        super.paintComponent(g)
        for {
          y <- 0 until size.getHeight.toInt
          x <- 0 until size.getWidth.toInt
        } {
          g.setColor(new Color(0, (x ^ y) % 256, 0))
          g.drawLine(x, y, x, y)
        }
      }
    }

    centerOnScreen()
  }
}

Sidef

Translation of: Perl

require('Imager')

var img = %O<Imager>.new(xsize => 256, ysize => 256)

for y=(^256), x=(^256) {
    var rgb = [(255 - x - y).abs, (255-x)^y, x^(255-y)]
    img.setpixel(x => x, y => y, color => rgb)
}

img.write(file => 'xor.png')

Output image: Munching squares

Tcl

Library: Tk

package require Tk

proc xorImage {img table} {
    set data {}
    set h [image height $img]
    set w [image width $img]
    for {set y 0} {$y < $h} {incr y} {
	set row {}
	for {set x 0} {$x < $w} {incr x} {
	    lappend row [lindex $table [expr {($x^$y) % [llength $table]}]]
	}
	lappend data $row
    }
    $img put $data
}
proc inRange {i f t} {expr {$f + ($t-$f)*$i/255}}
proc mkTable {rf rt gf gt bf bt} {
    for {set i 0} {$i < 256} {incr i} {
	lappend tbl [format "#%02x%02x%02x" \
	    [inRange $i $rf $rt] [inRange $i $gf $gt] [inRange $i $bf $bt]]
    }
    return $tbl
}

set img [image create photo -width 512 -height 512]
xorImage $img [mkTable 0 255 64 192 255 0]
pack [label .l -image $img]

TI-83 BASIC

Due to the TI-83's 1 bit black and white display, this program uses the home screen and a gradient of characters. Since the TI-83 does not use a standard encoding, the first Sto→ to Str1 may be subjectively interpreted.

PROGRAM:XORPATT
" •.-,+-°-1+o*:πOX"→Str1

ClrHome

{0,0,0,0}→L1
{0,0,0,0)→L2

For(I,1,8,1)
For(J,1,16,1)
J→A
I→B

If A>8
Then
A-8→A
1→L1(1)
Else
0→L1(1)
End

If A>4
Then
A-4→A
1→L1(2)
Else
0→L1(2)
End

If A>2
Then
A-2→A
1→L1(3)
Else
0→L1(3)
End

If A>1
Then
1→L1(4)
Else
0→L1(4)
End

0→L2(1)

If B>4
Then
B-4→B
1→L2(2)
Else
0→L2(2)
End

If B>2
Then
B-2→B
1→L2(3)
Else
0→L2(3)
End

If B>1
Then
1→L2(4)
Else
0→L2(4)
End

L1≠L2→L3
8L3(1)+4L3(2)+2L3(3)+L3(4)→C
Output(I,J,sub(Str1,C+1,1))

End
End
Pause

Visual Basic .NET

Works with: Visual Basic .NET version 2011

' Munching squares - 27/07/2018
Public Class MunchingSquares
    Const xsize = 256
    Dim BMP As New Drawing.Bitmap(xsize, xsize)
    Dim GFX As Graphics = Graphics.FromImage(BMP)

    Private Sub MunchingSquares_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint
        'draw
        Dim MyGraph As Graphics = Me.CreateGraphics
        Dim nColor As Color
        Dim i, j, cp As Integer
        xPictureBox.Image = BMP
        For i = 0 To xsize - 1
            For j = 0 To xsize - 1
                cp = i Xor j
                nColor = Color.FromArgb(cp, 0, cp)
                BMP.SetPixel(i, j, nColor)
            Next j
        Next i
    End Sub 'Paint

End Class

Output:

Munching squares - vbnet

Wren

Translation of: D

Library: DOME

import "graphics" for Canvas, Color
import "dome" for Window

class Game {
    static init() {
        Window.title = "Munching squares"
        var w = 512
        var h = 512
        Window.resize(w, h)
        Canvas.resize(w, h)
        for (x in 0...w) {
            for (y in 0...h) {
                var c = (x ^ y) & 255
                Canvas.pset(x, y, Color.rgb(255-c, (c/2).floor, c))
            }
        }
    }

    static update() {}

    static draw(alpha) {}
}

XPL0

include c:\cxpl\codes;          \intrinsic 'code' declarations
int X, Y;
[SetVid($101);                  \set 640x480 graphics with 8-bit color
port($3C8):= 0;                 \set color registers with beautiful shades
for X:= 0 to 256-1 do
        [port($3C9):= X>>1;     \red
         port($3C9):= X>>3;     \green
         port($3C9):= X;        \blue
         ];
for Y:= 0 to 256-1 do           \"color table" is array of 256 registers
    for X:= 0 to 256-1 do
        Point(X, Y, X|Y);       \"|" = XOR, not OR which is "!"
X:= ChIn(1);                    \wait for keystroke
SetVid(3);                      \restore normal text mode
]

Output:

Yabasic

Translation of: FreeBASIC

w = 256
 
open window w, w
 
For x = 0 To w-1
    For y = 0 To w-1
        r =and(xor(x, y), 255)
        color r, and(r*2, 255), and(r*3, 255)
        dot x, y
    Next
Next

zkl

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

Translation of: XPL0

For a kaleidoscopic image, play with coolness.

fcn muncher{
   bitmap:=PPM(256,256);
   coolness:=(1).random(0x10000);  // 55379, 18180, 40, 51950, 57619, 43514, 65465
   foreach y,x in ([0 .. 255],[0 .. 255]){
      b:=x.bitXor(y);	// shades of blue
//      rgb:=b*coolness;                 // kaleidoscopic image
//      rgb:=(b*coolness + b)*coolness + b;  // more coolness
      rgb:=(b*0x10000 + b)*0x10000 + b;  // copy ADA image
      bitmap[x,y]=rgb;
   }
   bitmap.write(File("foo.ppm","wb"));
}();

For a cheap slide show (on Linux):

while(1){ muncher(); Atomic.sleep(3); }

run ImageViewer on foo.ppm and watch it [auto] update as the image changes.

Output:

Same as the ADA image: