Draw a pixel

From Rosetta Code
Task
Draw a pixel
You are encouraged to solve this task according to the task description, using any language you may know.
Task

Create a window and draw a pixel in it, subject to the following:

  1.  the window is 320 x 240
  2.  the color of the pixel must be red (255,0,0)
  3.  the position of the pixel is x = 100, y = 100

Action![edit]

The solution of this task is tricky because of technical limitation of Atari 8-bit computer. The computer supports high resolution graphics mode of 320 pixels width, 192 pixels height and 1 bit per pixel color. The color of the pixel cannot be set independently from the background color and only different luminance can be specified. To draw a red pixel the background must be set to light-red color.

PROC Main()
  BYTE
    CH=$02FC, ;Internal hardware value for last key pressed
    PALNTSC=$D014 ;To check if PAL or NTSC system is used

  Graphics(8+16) ;Graphics 320x192 with 2 luminances
  IF PALNTSC=15 THEN
    SetColor(1,4,6) ;Red color for NTSC
    SetColor(2,4,15)
  ELSE
    SetColor(1,2,6) ;Red color for PAL
    SetColor(2,2,15)
  FI
  Color=1
  Plot(100,100)
  
  DO UNTIL CH#$FF OD
  CH=$FF
RETURN
Output:

Screenshot from Atari 8-bit computer

Ada[edit]

Library: SDLAda
with SDL.Video.Windows.Makers;
with SDL.Video.Renderers.Makers;
with SDL.Events.Events;

procedure Draw_A_Pixel is

   Width   : constant := 320;
   Height  : constant := 200;

   Window   : SDL.Video.Windows.Window;
   Renderer : SDL.Video.Renderers.Renderer;

   procedure Wait is
      use type SDL.Events.Event_Types;
      Event : SDL.Events.Events.Events;
   begin
      loop
         while SDL.Events.Events.Poll (Event) loop
            if Event.Common.Event_Type = SDL.Events.Quit then
               return;
            end if;
         end loop;
         delay 0.100;
      end loop;
   end Wait;

begin
   if not SDL.Initialise (Flags => SDL.Enable_Screen) then
      return;
   end if;

   SDL.Video.Windows.Makers.Create (Win      => Window,
                                    Title    => "Draw a pixel",
                                    Position => SDL.Natural_Coordinates'(X => 10, Y => 10),
                                    Size     => SDL.Positive_Sizes'(Width, Height),
                                    Flags    => 0);
   SDL.Video.Renderers.Makers.Create (Renderer, Window.Get_Surface);
   Renderer.Set_Draw_Colour ((0, 0, 0, 255));
   Renderer.Fill (Rectangle => (0, 0, Width, Height));
   Renderer.Set_Draw_Colour ((255, 0, 0, 255));
   Renderer.Draw (Point => (100, 100));
   Window.Update_Surface;

   Wait;
   Window.Finalize;
   SDL.Finalise;
end Draw_A_Pixel;

ARM Assembly[edit]

Works with: as version Raspberry Pi
/* ARM assembly Raspberry PI  */
/*  program dpixel.s        */

/* compile with as         */
/* link with gcc and options -lX11 -L/usr/lpp/X11/lib   */

/********************************************/
/*Constantes                                */
/********************************************/
.equ STDOUT,              1     @ Linux output console
.equ EXIT,                1     @ Linux syscall
.equ WRITE,               4     @ Linux syscall
/* constantes X11 */
.equ KeyPressed,          2
.equ ButtonPress,         4
.equ MotionNotify,        6
.equ EnterNotify,         7
.equ LeaveNotify,         8
.equ Expose,              12
.equ ClientMessage,       33
.equ KeyPressMask,        1
.equ ButtonPressMask,     4
.equ ButtonReleaseMask,   8
.equ ExposureMask,        1<<15
.equ StructureNotifyMask, 1<<17
.equ EnterWindowMask,     1<<4
.equ LeaveWindowMask,     1<<5 
.equ ConfigureNotify,     22


/*******************************************/
/* DONNEES INITIALISEES                    */
/*******************************************/ 
.data
szWindowName:            .asciz "Windows Raspberry"
szRetourligne:           .asciz  "\n"
szMessDebutPgm:          .asciz "Program start. \n"
szMessErreur:            .asciz "Server X not found.\n"
szMessErrfen:            .asciz "Can not create window.\n"
szMessErreurX11:         .asciz "Error call function X11. \n"
szMessErrGc:             .asciz "Can not create graphics context.\n"
szTitreFenRed:           .asciz "Pi"    
szTexte1:                .asciz "<- red pixel is here !!"
.equ LGTEXTE1, . - szTexte1
szTexte2:                .asciz "Press q for close window or clic X in system menu."
.equ LGTEXTE2, . - szTexte2
szLibDW: .asciz "WM_DELETE_WINDOW"    @ special label for correct close error

/*************************************************/
szMessErr: .ascii	"Error code hexa : "
sHexa: .space 9,' '
         .ascii "  decimal :  "
sDeci: .space 15,' '
         .asciz "\n"

/*******************************************/
/* DONNEES NON INITIALISEES                    */
/*******************************************/ 
.bss
.align 4
ptDisplay:          .skip 4      @ pointer display
ptEcranDef:         .skip 4      @ pointer screen default
ptFenetre:          .skip 4      @ pointer window
ptGC:               .skip 4      @ pointer graphic context
ptGC1:              .skip 4      @ pointer graphic context1
key:                .skip 4      @ key code
wmDeleteMessage:    .skip 8      @ ident close message
event:              .skip 400    @ TODO event size ??
PrpNomFenetre:      .skip 100    @ window name proprety
buffer:             .skip 500 
iWhite:             .skip 4      @ rgb code for white pixel
iBlack:             .skip 4      @ rgb code for black pixel
/**********************************************/
/* -- Code section                            */
/**********************************************/
.text
.global main

main:                               @ entry of program 
    ldr r0,iAdrszMessDebutPgm   @
    bl affichageMess            @ display start message on console linux
    /* attention r6  pointer display*/
    /* attention r8  pointer graphic context   */
    /* attention r9 ident window  */
    /*****************************/
    /*    OPEN SERVER X11        */
    /*****************************/
    mov r0,#0
    bl XOpenDisplay             @ open X server
    cmp r0,#0                   @ error ?
    beq erreurServeur
    ldr r1,iAdrptDisplay
    str r0,[r1]                 @ store display address 
    mov r6,r0                   @ and in register r6
    ldr r2,[r0,#+132]           @ load default_screen
    ldr r1,iAdrptEcranDef
    str r2,[r1]                 @ store default_screen
    mov r2,r0
    ldr r0,[r2,#+140]           @ load pointer screen list
    ldr r5,[r0,#+52]            @ load value white pixel
    ldr r4,iAdrWhite            @ and store in memory
    str r5,[r4]
    ldr r3,[r0,#+56]            @ load value black pixel
    ldr r4,iAdrBlack            @ and store in memory
    str r3,[r4]
    ldr r4,[r0,#+28]            @ load bits par pixel
    ldr r1,[r0,#+8]             @ load root windows
    /**************************/
    /* CREATE WINDOW          */
    /**************************/
    mov r0,r6                   @ address display
    mov r2,#0                   @ window position X
    mov r3,#0                   @ window position Y
    mov r8,#0                   @ for stack alignement
    push {r8}
    push {r3}                   @  background  = black pixel
    push {r5}                   @  border = white pixel
    mov r8,#2                   @  border size
    push {r8}
    mov r8,#240                 @ hauteur
    push {r8}
    mov r8,#320                 @ largeur 
    push {r8}   
    bl XCreateSimpleWindow
    add sp,#24                  @ stack alignement  6 push (4 bytes * 6)
    cmp r0,#0                   @ error ?
    beq erreurF

    ldr r1,iAdrptFenetre
    str r0,[r1]                 @ store window address in memory
    mov r9,r0                   @ and in register r9
    /*****************************/
    /* add window property       */
    /*****************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    ldr r2,iAdrszWindowName     @ window name
    ldr r3,iAdrszTitreFenRed    @ window name reduced
    mov r4,#0
    push {r4}                   @ parameters not use
    push {r4}
    push {r4}
    push {r4}
    bl XSetStandardProperties
    add sp,sp,#16               @ stack alignement for 4 push
    /**************************************/
    /* for correction window close error  */
    /**************************************/
    mov r0,r6                   @ display address
    ldr r1,iAdrszLibDW          @ atom address
    mov r2,#1                   @ False  créate atom if not exists
    bl XInternAtom
    cmp r0,#0                   @ error X11 ?
    ble erreurX11
    ldr r1,iAdrwmDeleteMessage  @ recept address
    str r0,[r1]
    mov r2,r1                   @ return address
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    mov r3,#1                   @ number of protocols
    bl XSetWMProtocols
    cmp r0,#0                   @ error X11 ?
    ble erreurX11
    /**********************************/
    /*  create graphic context        */
    /**********************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    mov r2,#0                   @ not use for simply context
    mov r3,#0
    bl XCreateGC
    cmp r0,#0                   @ error ?
    beq erreurGC
    ldr r1,iAdrptGC
    str r0,[r1]                 @ store address graphic context
    mov r8,r0                   @ and in r8
    @ create other GC
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    mov r2,#0                   @ not use for simply context
    mov r3,#0
    bl XCreateGC
    cmp r0,#0                   @ error ?
    beq erreurGC
    ldr r1,iAdrptGC1
    str r0,[r1]                 @ store address graphic context 1
    mov r1,r0
    mov r0,r6
    mov r2,#0xFF0000            @ color red
    bl XSetForeground
    cmp r0,#0
    beq erreurGC
    /****************************/
    /* modif window background  */
    /****************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    ldr r2,iGris1               @ background color
    bl XSetWindowBackground   
    cmp r0,#0                   @ error ?
    ble erreurX11
    /***************************/
    /* OUF!! window display    */
    /***************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    bl XMapWindow
    /****************************/
    /* Write text1 in the window */
    /****************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    mov r2,r8                   @ address graphic context
    mov r3,#105                 @ position x 
    sub sp,#4                   @ stack alignement
    mov r4,#LGTEXTE1  - 1       @ size string 
    push {r4}                   @ on the stack
    ldr r4,iAdrszTexte1         @ string address
    push {r4}
    mov r4,#105                 @ position y 
    push {r4}
    bl XDrawString
    add sp,sp,#16               @ stack alignement 3 push and 1 stack alignement
    cmp r0,#0                   @ error ?
    blt erreurX11
    /****************************/
    /* Write text2 in the window */
    /****************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    mov r2,r8                   @ address graphic context
    mov r3,#10                  @ position x 
    sub sp,#4                   @ stack alignement
    mov r4,#LGTEXTE2  - 1       @ size string 
    push {r4}                   @ on the stack
    ldr r4,iAdrszTexte2         @ string address
    push {r4}
    mov r4,#200                 @ position y 
    push {r4}
    bl XDrawString
    add sp,sp,#16               @ stack alignement 3 push and 1 stack alignement
    cmp r0,#0                   @ error ?
    blt erreurX11
    /****************************************/
    /* draw pixel                           */
    /****************************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    ldr r2,iAdrptGC1
    ldr r2,[r2]                 @  address graphic context 1
    mov r3,#100                 @ position x
    sub sp,sp,#4                @ stack alignement
    mov r4,#100                 @ position y
    push {r4}                   @ on the stack
    bl XDrawPoint
    add sp,sp,#8                @ stack alignement 1 push and 1 stack alignement

    cmp r0,#0                   @ error ?
    blt erreurX11
    /****************************/
    /* Autorisations            */
    /****************************/
    mov r0,r6                   @ display address
    mov r1,r9                   @ window address
    ldr r2,iFenetreMask         @ autorisation mask
    bl XSelectInput
    cmp r0,#0                   @ error ?
    ble erreurX11
    /****************************/
    /* Events loop              */
    /****************************/
1:
    mov r0,r6                   @ display address
    ldr r1,iAdrevent            @ events address
    bl XNextEvent               @ event ?
    ldr r0,iAdrevent
    ldr r0,[r0]                 @ code event
    cmp r0,#KeyPressed          @ key ?
    bne 2f
    ldr r0,iAdrevent            @ yes read key in buffer
    ldr r1,iAdrbuffer
    mov r2,#255
    ldr r3,iAdrkey
    mov r4,#0
    push {r4}                   @ stack alignement
    push {r4}
    bl XLookupString 
    add sp,#8                   @ stack alignement 2 push
    cmp r0,#1                   @ is character key ?
    bne 2f
    ldr r0,iAdrbuffer           @ yes -> load first buffer character
    ldrb r0,[r0]
    cmp r0,#0x71                @ character q for quit
    beq 5f                      @ yes -> end
    b 4f
2:
    /*                                  */
    /* for example  clic mouse button   */
    /************************************/
    cmp r0,#ButtonPress         @ clic mouse buton
    bne 3f
    ldr r0,iAdrevent
    ldr r1,[r0,#+32]            @ position X mouse clic
    ldr r2,[r0,#+36]            @ position Y
    @ etc for eventuel use
    b 4f
3:
    cmp r0,#ClientMessage       @ code for close window within error
    bne 4f
    ldr r0,iAdrevent
    ldr r1,[r0,#+28]            @ code message address 
    ldr r2,iAdrwmDeleteMessage  @ equal code window créate ???
    ldr r2,[r2]
    cmp r1,r2
    beq 5f                      @ yes -> end window 

4:  @ loop for other event
    b 1b
    /***********************************/
    /* Close window -> free ressources */
    /***********************************/
5:
    mov r0,r6                  @ display address
    ldr r1,iAdrptGC
    ldr r1,[r1]                @ load context graphic address 
    bl XFreeGC
    cmp r0,#0
    blt erreurX11
    mov r0,r6                  @ display address 
    mov r1,r9                  @ window address
    bl XDestroyWindow
    cmp r0,#0
    blt erreurX11
    mov r0,r6                  @ display address
    bl XCloseDisplay
    cmp r0,#0
    blt erreurX11
    mov r0,#0                  @ return code OK
    b 100f
erreurF:   @ create error window but possible not necessary. Display error by server
    ldr r1,iAdrszMessErrfen
    bl   displayError
    mov r0,#1                  @ return error code
    b 100f
erreurGC:                      @ error create graphic context
    ldr r1,iAdrszMessErrGc
    bl   displayError
    mov r0,#1
    b 100f
erreurX11:    @ erreur X11
    ldr r1,iAdrszMessErreurX11
    bl   displayError
    mov r0,#1
    b 100f
erreurServeur:                 @ error no found X11 server see doc putty and Xming
    ldr r1,iAdrszMessErreur
    bl   displayError
    mov r0,#1
    b 100f

100:                           @ standard end of the program 
    mov r7, #EXIT
    svc 0 
iFenetreMask:        .int  KeyPressMask|ButtonPressMask|StructureNotifyMask
iGris1:              .int 0xFFA0A0A0
iAdrWhite:           .int iWhite
iAdrBlack:           .int iBlack
iAdrptDisplay:       .int ptDisplay
iAdrptEcranDef:      .int ptEcranDef
iAdrptFenetre:       .int ptFenetre
iAdrptGC:            .int ptGC
iAdrptGC1:           .int ptGC1
iAdrevent:           .int event
iAdrbuffer:          .int buffer
iAdrkey:             .int key
iAdrszLibDW:         .int szLibDW
iAdrszMessDebutPgm:  .int szMessDebutPgm
iAdrszMessErreurX11: .int szMessErreurX11
iAdrszMessErrGc:     .int szMessErrGc
iAdrszMessErreur:    .int szMessErreur
iAdrszMessErrfen:    .int szMessErrfen
iAdrszWindowName:    .int szWindowName
iAdrszTitreFenRed:   .int szTitreFenRed
iAdrszTexte1:            .int szTexte1
iAdrszTexte2:        .int szTexte2
iAdrPrpNomFenetre:   .int PrpNomFenetre
iAdrwmDeleteMessage: .int wmDeleteMessage

/******************************************************************/
/*     display text with size calculation                         */ 
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
    push {r0,r1,r2,r7,lr}                   @ save  registres
    mov r2,#0                               @ counter length 
1:                                          @ loop length calculation 
    ldrb r1,[r0,r2]                         @ read octet start position + index 
    cmp r1,#0                               @ if 0 its over 
    addne r2,r2,#1                          @ else add 1 in the length 
    bne 1b                                  @ and loop 
                                            @ so here r2 contains the length of the message 
    mov r1,r0                               @ address message in r1 
    mov r0,#STDOUT                          @ code to write to the standard output Linux 
    mov r7, #WRITE                          @ code call system "write" 
    svc #0                                  @ call systeme 
    pop {r0,r1,r2,r7,lr}                    @ restaur registers
    bx lr                                   @ return
/***************************************************/
/*   display error message                         */
/***************************************************/
/* r0 contains error code  r1 : message address */
displayError:
    push {r0-r2,lr}                         @ save registers
    mov r2,r0                               @ save error code
    mov r0,r1
    bl affichageMess
    mov r0,r2                               @ error code
    ldr r1,iAdrsHexa
    bl conversion16                         @ conversion hexa
    mov r0,r2                               @ error code
    ldr r1,iAdrsDeci                        @ result address
    bl conversion10                         @ conversion decimale
    ldr r0,iAdrszMessErr                    @ display error message
    bl affichageMess
100:
    pop {r0-r2,lr}                          @ restaur registers
    bx lr                                   @ return 
iAdrszMessErr:                 .int szMessErr
iAdrsHexa:                     .int sHexa
iAdrsDeci:                     .int sDeci
/******************************************************************/
/*     Converting a register to hexadecimal                      */ 
/******************************************************************/
/* r0 contains value and r1 address area   */
conversion16:
    push {r1-r4,lr}                                    @ save registers
    mov r2,#28                                         @ start bit position
    mov r4,#0xF0000000                                 @ mask
    mov r3,r0                                          @ save entry value
1:                                                     @ start loop
    and r0,r3,r4                                       @value register and mask
    lsr r0,r2                                          @ move right 
    cmp r0,#10                                         @ compare value
    addlt r0,#48                                       @ <10  ->digit	
    addge r0,#55                                       @ >10  ->letter A-F
    strb r0,[r1],#1                                    @ store digit on area and + 1 in area address
    lsr r4,#4                                          @ shift mask 4 positions
    subs r2,#4                                         @  counter bits - 4 <= zero  ?
    bge 1b                                             @  no -> loop

100:
    pop {r1-r4,lr}                                     @ restaur registers 
    bx lr                                              @return
/******************************************************************/
/*     Converting a register to a decimal unsigned                */ 
/******************************************************************/
/* r0 contains value and r1 address area   */
/* r0 return size of result (no zero final in area) */
/* area size => 11 bytes          */
.equ LGZONECAL,   10
conversion10:
    push {r1-r4,lr}                                 @ save registers 
    mov r3,r1
    mov r2,#LGZONECAL
1:                                                  @ start loop
    bl divisionpar10U                               @ unsigned  r0 <- dividende. quotient ->r0 reste -> r1
    add r1,#48                                      @ digit
    strb r1,[r3,r2]                                 @ store digit on area
    cmp r0,#0                                       @ stop if quotient = 0 
    subne r2,#1                                     @ else previous position
    bne 1b                                          @ and loop
                                                    @ and move digit from left of area
    mov r4,#0
2:
    ldrb r1,[r3,r2]
    strb r1,[r3,r4]
    add r2,#1
    add r4,#1
    cmp r2,#LGZONECAL
    ble 2b
                                                      @ and move spaces in end on area
    mov r0,r4                                         @ result length 
    mov r1,#' '                                       @ space
3:
    strb r1,[r3,r4]                                   @ store space in area
    add r4,#1                                         @ next position
    cmp r4,#LGZONECAL
    ble 3b                                            @ loop if r4 <= area size
 
100:
    pop {r1-r4,lr}                                    @ restaur registres 
    bx lr                                             @return
 
/***************************************************/
/*   division par 10   unsigned                    */
/***************************************************/
/* r0 dividende   */
/* r0 quotient    */
/* r1 remainder   */
divisionpar10U:
    push {r2,r3,r4, lr}
    mov r4,r0                                          @ save value
    ldr r3,iMagicNumber                                @ r3 <- magic_number    raspberry 1 2
    umull r1, r2, r3, r0                               @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0) 
    mov r0, r2, LSR #3                                 @ r2 <- r2 >> shift 3
    add r2,r0,r0, lsl #2                               @ r2 <- r0 * 5 
    sub r1,r4,r2, lsl #1                               @ r1 <- r4 - (r2 * 2)  = r4 - (r0 * 10)
    pop {r2,r3,r4,lr}
    bx lr                                              @ leave function 
iMagicNumber:  	.int 0xCCCCCCCD
/***************************************************/
/* integer division unsigned                       */
/***************************************************/
division:
    /* r0 contains dividend */
    /* r1 contains divisor */
    /* r2 returns quotient */
    /* r3 returns remainder */
    push {r4, lr}
    mov r2, #0                                         @ init quotient
    mov r3, #0                                         @ init remainder
    mov r4, #32                                        @ init counter bits
    b 2f
1:                                                    @ loop 
    movs r0, r0, LSL #1                               @ r0 <- r0 << 1 updating cpsr (sets C if 31st bit of r0 was 1)
    adc r3, r3, r3                                     @ r3 <- r3 + r3 + C. This is equivalent to r3 ? (r3 << 1) + C 
    cmp r3, r1                                         @ compute r3 - r1 and update cpsr 
    subhs r3, r3, r1                                  @ if r3 >= r1 (C=1) then r3 <- r3 - r1 
    adc r2, r2, r2                                     @ r2 <- r2 + r2 + C. This is equivalent to r2 <- (r2 << 1) + C 
2:
    subs r4, r4, #1                                   @ r4 <- r4 - 1 
    bpl 1b                                            @ if r4 >= 0 (N=0) then loop
    pop {r4, lr}
    bx lr

AutoHotkey[edit]

From AHK Forum

Gui, Add, Picture, x100 y100 w2 h2 +0x4E +HWNDhPicture
CreatePixel("FF0000", hPicture)
Gui, Show, w320 h240, Example
return

CreatePixel(Color, Handle) {
	VarSetCapacity(BMBITS, 4, 0), Numput("0x" . Color, &BMBITS, 0, "UInt")
	hBM := DllCall("Gdi32.dll\CreateBitmap", "Int", 1, "Int", 1, "UInt", 1, "UInt", 24, "Ptr", 0, "Ptr")
	hBM := DllCall("User32.dll\CopyImage", "Ptr", hBM, "UInt", 0, "Int", 0, "Int", 0, "UInt", 0x2008, "Ptr")
	DllCall("Gdi32.dll\SetBitmapBits", "Ptr", hBM, "UInt", 3, "Ptr", &BMBITS) 
	DllCall("User32.dll\SendMessage", "Ptr", Handle, "UInt", 0x172, "Ptr", 0, "Ptr", hBM)
}

BASIC256[edit]

It seems that the program should be this. And the BASIC256 tutorial programs work on my ubuntu system. This program neither draws the pixel nor resizes the window. Can't see anything when I plot many spots. Oh well. I've tried the rgb(255,0,0) function as well as the fastgraphics/refresh statements.

rem http://rosettacode.org/wiki/Draw_a_pixel

graphsize 320, 240
color red
plot 100, 100

BBC BASIC[edit]

      VDU 23, 22, 320; 240; 8, 8, 8, 0, 18, 0, 1, 25, 69, 100; 100;

C[edit]

Requires the WinBGIm library.

#include<graphics.h>

int main()
{
	initwindow(320,240,"Red Pixel");
	
	putpixel(100,100,RED);
	
	getch();
	
	return 0;
}

Commodore BASIC[edit]

The Commodore 8-bit machines only had 200 lines of vertical resolution (and the VIC-20 rarely used more than 160 of them for bitmap graphics), so these examples do not quite fit the task's 240-line requirement.

Example 1: VIC-20 with SuperExpander Cartridge

Version 2 of Commodore BASIC, which shipped on the VIC-20 and Commodore 64, did not have any graphics support. A stock VIC didn't have enough memory for high-resolution graphics anyway, so they mostly weren't used. But Commodore shipped a "SuperExpander" cartridge for the VIC which not only included enough extra RAM to support a 160x160-pixel bitmap, but also extended BASIC to include statements for drawing on it. One oddity about the VIC's iteration of the SuperExpander is that, despite the low 160x160 resolution, it treats the screen as having 1024x1024 pixels; the below program compensates for this by asking for a dot at 640,640, which maps to the physical pixel at 100,100.

10 COLOR 0,0,2,2: REM BLACK BACKGROUND AND BORDER, RED TEXT AND EXTRA COLOR
20 GRAPHIC 2:SCNCLR:REM SELECT HI-RES GRAPHICS AND CLEAR THE SCREEN
30 POINT 2,640,640:REM DRAW A POINT AT 640/1024*160,640/1024*160
40 GET K$:IF K$="" THEN 40: REM WAIT FOR KEYPRESS
50 GRAPHIC 0:REM BACK TO TEXT MODE


Example 2: Commodore 64 with built-in BASIC

The C-64 shipped with much better graphics capabilities than the VIC-20, and was originally supposed to have an extended BASIC to take advantage of them, but Commodore ran out of time before the Christmas shopping deadline and shipped it with the same BASIC that was in the VIC. It was feasible to do graphics from the onboard BASIC, as this program demonstrates; it's just slow and awkward, so programmers usually built hi-res graphics routines using machine language.

To create graphics via manual memory manipulation, it's necessary to understand the layout of the screen. Unlike many other bitmap systems, the C64's bitmap was broken up into the 8x8-pixel cells used for text characters, even in high-resolution graphics mode. So while the first byte of video RAM unsurprisingly contains the leftmost 8 pixels on the top row of the screen, the second byte contains the 8 pixels directly below those, and so on for eight rows, before the ninth byte returns us to the top row for its 9th through 16th pixels. This requires calculation on the programmer's part to translate X,Y coordinates into a specific memory address/value combination (lines 30 through 60).

10 REM PLOT A RED PIXEL AT 100,100
20 REM INITIALIZE BITMAP MODE
21 POKE 53280,0:PRINT CHR$(147);"CLEARING BITMAP... PLEASE WAIT..."
22 BASE=8192:FOR I=BASE TO BASE+7999:POKE I,0:NEXT
23 PRINT CHR$(147);
24 POKE 53272,PEEK(53272) OR 8:REM SET BITMAP MEMORY AT 8192 ($2000)
25 POKE 53265,PEEK(53265) OR 32:REM ENTER BITMAP MODE
26 REM PLOT PIXEL
30 X=100:Y=100
40 MEM=BASE+INT(Y/8)*320+INT(X/8)*8+(Y AND 7)
50 PX=7-(X AND 7)
60 POKE MEM,PEEK(MEM) OR 2^PX
65 REM WAIT FOR KEYPRESS
70 GET K$:IF K$="" THEN 70
75 REM CLEAR PIXEL, RETURN TO TEXT MODE
80 POKE MEM,0:POKE 53265,PEEK(53265) AND 223:POKE 53272,PEEK(53272) AND 247
90 POKE 53280,14:POKE 53281,6:POKE 646,14:END

Example 3: Commodore 64 with SuperExpander Cartridge

Commodore released a version of the SuperExpander Cartridge for the C64 that was similar to the one for the VIC-20, but not identical. Besides some differences in the actual BASIC statements, it also does not have the artificial scale factor; graphics statements instead take physical pixel coordinates.

10 COLOR 0,2,,,0: REM SET BACKGROUND AND BORDER TO BLACK, FOREGROUND TO RED
20 GRAPHIC 2,1:REM SELECT HIRES GRAPHICS AND CLEAR THE SCREEN
30 DRAW 1,100,100:REM DRAW A PIXEL AT 100,100
40 GET K$:IF K$="" THEN 40:REM WAIT FOR A KEYPRESS
50 GRAPHIC 0:REM RETURN TO TEXT MODE


Example 4: Commodore Plus/4, C-16, and 128 (40-column display)

By the time the Commodore Plus/4 and C-16 were released, Commodore was ready to ship them with a version of BASIC, dubbed version 3.5, that included graphic support out of the box. The statements were again similar to but slightly different from what had come before in the SuperExpander cartridges. When the Commodore 128 was released, its version of BASIC, 7.0, included all of 3.5 essentially unchanged.

10 COLOR 0,1:COLOR 1,3: REM SET BACKGROUND TO BLACK AND PIXEL COLOR TO RED
15 GRAPHIC 1,1 : REM ENTER BITMAP GRAPHICS MODE AND CLEAR SCREEN
20 DRAW 1,100,100 : REM PLOT PIXEL AT 100,100
30 GETKEY K$: REM WAIT FOR KEYPRESS THE NEW WAY
40 GRAPHIC 0,1 : REM RETURN TO TEXT MODE

Example 5: Commodore 128 (80-column display)

While the Commodore 128's BASIC 7.0 had impressive support for graphics on the 40-column display, it had no such support for bitmap graphics on the double-resolution 80-column display provided by its VDC chip. For that, we turn to BASIC 8, which was released as a separate software package that had to be loaded (or installed as a chip on the C128's motherboard). It was developed outside of Commodore and has a syntax very different from the standard BASIC's graphic commands, but it supports 3D graphics out of the box, including viewport clipping, scaling, etc. Note that the below program specifies a Z coordinate of 0 for the dot, which places it on the surface of the viewport.

10 @MODE,0:REM SELECT SCREEN SET
20 @COLOR,0,9,0:REM BACKGROUND BLACK, FOREGROUND BRIGHT RED
30 @SCREEN,0,0:REM SELECT MONOCHROME MODE
40 @CLEAR,0:REM CLEAR THE SCREEN
50 @DRWMODA,2,0,0,0,0,0,0:REM USE @COLOR COLORS
60 @SCALE,0:REM NO SCALING
70 @DOT,100,100,0:REM DRAW DOT
80 GETKEY K$:REM WAIT FOR KEYPRESS
90 @TEXT:REM BACK TO TEXT MODE

Delphi[edit]

Library: Windows
Library: Messages
Library: SysUtils

Console version using windows api, thanks for RRUZ ([1])

program Draw_a_pixel;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  Windows,
  Messages,
  SysUtils;

var
  Msg: TMSG;
  LWndClass: TWndClass;
  hMainHandle: HWND;

procedure Paint(Handle: hWnd); forward;

procedure ReleaseResources;
begin
  PostQuitMessage(0);
end;

function WindowProc(hWnd, Msg: Longint; wParam: wParam; lParam: lParam): Longint; stdcall;
begin
  case Msg of
    WM_PAINT:
      Paint(hWnd);
    WM_DESTROY:
      ReleaseResources;
  end;
  Result := DefWindowProc(hWnd, Msg, wParam, lParam);
end;


procedure CreateWin(W, H: Integer);
begin
  LWndClass.hInstance := hInstance;
  with LWndClass do
  begin
    lpszClassName := 'OneRedPixel';
    Style := CS_PARENTDC or CS_BYTEALIGNCLIENT;
    hIcon := LoadIcon(hInstance, 'MAINICON');
    lpfnWndProc := @WindowProc;
    hbrBackground := COLOR_BTNFACE + 1;
    hCursor := LoadCursor(0, IDC_ARROW);
  end;

  RegisterClass(LWndClass);
  hMainHandle := CreateWindow(LWndClass.lpszClassName,
    'Draw a red pixel on (100,100)', WS_CAPTION or WS_MINIMIZEBOX or WS_SYSMENU
    or WS_VISIBLE, ((GetSystemMetrics(SM_CXSCREEN) - W) div 2), ((GetSystemMetrics
    (SM_CYSCREEN) - H) div 2), W, H, 0, 0, hInstance, nil);
end;

procedure ShowModal;
begin
  while GetMessage(Msg, 0, 0, 0) do
  begin
    TranslateMessage(Msg);
    DispatchMessage(Msg);
  end;
end;

procedure Paint(Handle: hWnd);
var
  ps: PAINTSTRUCT;
  Dc: HDC;
begin
  Dc := BeginPaint(Handle, ps);

  // Fill bg with white
  FillRect(Dc, ps.rcPaint, CreateSolidBrush($FFFFFF));

  // Do the magic
  SetPixel(Dc, 100, 100, $FF);

  EndPaint(Handle, ps);
end;

begin
  CreateWin(320, 240);
  ShowModal();
end.
Output:

[2]

F#[edit]

Uses Windows Forms

open System.Windows.Forms
open System.Drawing

let f = new Form()
f.Size <- new Size(320,240)
f.Paint.Add(fun e -> e.Graphics.FillRectangle(Brushes.Red, 100, 100 ,1,1))
Application.Run(f)

Factor[edit]

USING: accessors arrays images images.testing images.viewer
kernel literals math sequences ;
IN: rosetta-code.draw-pixel

: draw-pixel ( -- )
    B{ 255 0 0 } 100 100 <rgb-image> 320 240 [ 2array >>dim ]
    [ * ] 2bi [ { 0 0 0 } ] replicate B{ } concat-as >>bitmap
    [ set-pixel-at ] keep image-window ;

MAIN: draw-pixel


Forth[edit]

Translation of: lua
Works with: gforth version 0.7.3
Library: SDL2
\ Bindings to SDL2 functions
s" SDL2" add-lib
\c #include <SDL2/SDL.h>
c-function sdl-init		SDL_Init		n -- n
c-function sdl-quit		SDL_Quit		-- void
c-function sdl-createwindow	SDL_CreateWindow	a n n n n n -- a
c-function sdl-createrenderer	SDL_CreateRenderer	a n n -- a
c-function sdl-setdrawcolor	SDL_SetRenderDrawColor	a n n n n -- n
c-function sdl-drawpoint	SDL_RenderDrawPoint	a n n -- n
c-function sdl-renderpresent	SDL_RenderPresent	a -- void
c-function sdl-delay            SDL_Delay               n -- void

: pixel ( -- )
  $20 sdl-init drop
  s\" Rosetta Task : Draw a pixel\x0" drop 0 0 320 240 $0 sdl-createwindow
  ( window ) -1 $2 sdl-createrenderer

  dup ( renderer ) 255 0 0 255 sdl-setdrawcolor drop
  dup ( renderer ) 100 100 sdl-drawpoint drop
      ( renderer ) sdl-renderpresent

  5000 sdl-delay
  sdl-quit
;

pixel


FreeBASIC[edit]

' version 27-06-2018
' compile with: fbc -s console
'           or: fbc -s gui

Screen 13                  ' Screen 18: 320x200,  8bit colordepth
'ScreenRes 320, 200, 24    ' Screenres: 320x200, 24bit colordepth

If ScreenPtr = 0 Then
    Print "Error setting video mode!"
    End
End If

Dim As UInteger depth, x = 100, y = 100

' what is color depth
ScreenInfo ,,depth

If depth = 8 Then
    PSet(x, y), 40   ' palette, index 40 = RGB(255, 0, 0)
Else
    PSet(x, y), RGB(255, 0, 0) ' red
End If

' empty keyboard buffer
While Inkey <> "" : Wend
WindowTitle IIf(depth = 8, "Palette","True Color") + ", hit any key to end program"
Sleep
End


FutureBasic[edit]

void local fn BuildWindow
  CGRect r = fn CGRectMake( 0, 0, 320, 240 )
  window 1, @"Single Pixel", r, NSWindowStyleMaskTitled + NSWindowStyleMaskClosable
  oval fill fn CGRectMake( 100-0.5, 100-0.5, 1, 1 ), fn ColorRed
end fn

void local fn DoDialog( ev as long, tag as long, wnd as long )
  select ( ev )
    case _windowWillClose : end
  end select
end fn

on dialog fn DoDialog

fn BuildWindow

HandleEvents


GB BASIC[edit]

The resolution of the Game Boy's screen is only 160×144, so the window requirement is out, but the pixel is easy. Also, GB BASIC doesn't support displaying the color red, so the Game Boy's grayscale equivalent, dark gray, is used instead:

10 color 1
20 point 100,100

GML[edit]

draw_point(100, 100);

Go[edit]

package main

import (
    "fmt"
    "image"
    "image/color"
    "image/draw"
)

func main() {
    rect := image.Rect(0, 0, 320, 240)
    img := image.NewRGBA(rect)

    // Use green background, say.
    green := color.RGBA{0, 255, 0, 255}
    draw.Draw(img, rect, &image.Uniform{green}, image.ZP, draw.Src)

    // Set color of pixel at (100, 100) to red
    red := color.RGBA{255, 0, 0, 255}
    img.Set(100, 100, red)

    // Check it worked.
    cmap := map[color.Color]string{green: "green", red: "red"}
    c1 := img.At(0, 0)
    c2 := img.At(100, 100)
    fmt.Println("The color of the pixel at (  0,   0) is", cmap[c1], "\b.")
    fmt.Println("The color of the pixel at (100, 100) is", cmap[c2], "\b.")
}
Output:
The color of the pixel at (  0,   0) is green.
The color of the pixel at (100, 100) is red.

Create a PNG image?

package main

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

func main() {
	// Create a 320 x 240 image
	img := image.NewRGBA(image.Rect(0, 0, 320, 240))
	// fill img in white
	draw.Draw(img, img.Bounds(), &image.Uniform{color.RGBA{0, 0, 0, 0}}, image.ZP, draw.Src)
	// Draw a red dot at (100, 100)
	img.Set(100, 100, color.RGBA{255, 0, 0, 255})
	// Save to new.png
	w, _ := os.OpenFile("new.png", os.O_WRONLY|os.O_CREATE, 0600)
	defer w.Close()
	png.Encode(w, img)
}

GUI "window" rather than an image?

package main
// first run" go get github.com/zserge/webview" 
// simple GUI "window"
import "github.com/zserge/webview"

func main() {
	// Open wikipedia in a 320*240 resizable window
	webview.Open("Minimal webview example",
		"https://en.m.wikipedia.org/wiki/Main_Page", 320, 240, true)
}

Icon and Unicon[edit]

#
# draw-pixel.icn
#
procedure main()
   &window := open("pixel", "g", "size=320,240")
   Fg("#ff0000")
   DrawPoint(100, 100)
   Event()
end

IS-BASIC[edit]

100 SET VIDEO X 40:SET VIDEO Y 26:SET VIDEO MODE 5:SET VIDEO COLOR 0
110 OPEN #101:"video:"
120 DISPLAY #101:AT 1 FROM 1 TO 26
130 SET PALETTE BLACK,RED
140 PLOT 100,100

J[edit]

require 'gl2'
coinsert 'jgl2'
wd'pc Rosetta closeok;cc task isidraw; set task wh 320 200;pshow'
glpaint glpixel 100 100 [ glpen 1 1 [ glrgb 255 0 0 [ glclear ''

Note that this single pixel tends to be invisible or almost invisible on "modern" screens. You may wish to change this to use glpen 4 1 if this is a problem on your system (though that technically would violate the requirements of this task, since we would not longer be drawing a single red pixel).

Java[edit]

Basic Implementation via subclass of JFrame:

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;

public class DrawAPixel extends JFrame{
	public DrawAPixel() {
		super("Red Pixel");
		setSize(320, 240);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setVisible(true);
	}
	@Override
	public void paint(Graphics g) {
		g.setColor(new Color(255, 0, 0));
		g.drawRect(100, 100, 1, 1);
	}
	public static void main(String[] args) {
		new DrawAPixel();
	}
}

Advanced Implementation via subclass of JPanel (more powerful especially while repainting):

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class DrawAPixel extends JPanel{	
	private BufferedImage puffer;
	private JFrame window;
	private Graphics g;
	public DrawAPixel() {
		window = new JFrame("Red Pixel");
		window.setSize(320, 240);
		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		window.setLayout(null);
		setBounds(0, 0, 320, 240);
		window.add(this);
		window.setVisible(true);
	}
	@Override
	public void paint(Graphics gr) {
		if(g == null) {
			puffer = (BufferedImage) createImage(getWidth(), getHeight());
			g = puffer.getGraphics();
		}
		g.setColor(new Color(255, 0, 0));
		g.drawRect(100, 100, 1, 1);
		gr.drawImage(puffer, 0, 0, this);
	}
	public static void main(String[] args) {
		new DrawAPixel();
	}
}

Julia[edit]

using Gtk, Graphics
 
const can = @GtkCanvas()
const win = GtkWindow(can, "Draw a Pixel", 320, 240)

draw(can) do widget
    ctx = getgc(can)
    set_source_rgb(ctx, 255, 0, 0)
    move_to(ctx, 100, 100)
    line_to(ctx, 101,100)
    stroke(ctx)
end
 
show(can)
const cond = Condition()
endit(w) = notify(cond)
signal_connect(endit, win, :destroy)
wait(cond)

Kotlin[edit]

This task seems very similar to the Bitmap task and so therefore is the code to accomplish it.

// Version 1.2.41

import java.awt.Color
import java.awt.Graphics
import java.awt.image.BufferedImage

class BasicBitmapStorage(width: Int, height: Int) {
    val image = BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR)

    fun fill(c: Color) {
        val g = image.graphics
        g.color = c
        g.fillRect(0, 0, image.width, image.height)
    }

    fun setPixel(x: Int, y: Int, c: Color) = image.setRGB(x, y, c.getRGB())

    fun getPixel(x: Int, y: Int) = Color(image.getRGB(x, y))
}

fun main(args: Array<String>) {
    val bbs = BasicBitmapStorage(320, 240)
    with (bbs) {
        fill(Color.white) // say
        setPixel(100, 100, Color.red)
        // check it worked
        val c = getPixel(100, 100)
        print("The color of the pixel at (100, 100) is ")
        println(if (c == Color.red) "red" else "white")
    }
}
Output:
The color of the pixel at (100, 100) is red

Lambdatalk[edit]

1) html/css

{div {@ style="position:relative; 
               left:0; top:0; width:320px; height:240px;
               border:1px solid #000;"}
 {div {@ style="position:absolute; left:100px; top:100px;
                width:1px; height:1px; background:#f00; border:0;"}}}

2) svg

{svg {@ width="320" height="240"
        style="border:1px solid #000;"}
  {rect {@ x="100" y="100" width="1" height="1" 
           style="fill:#f00; stroke-width:0; stroke:#f00;"}}}

3) canvas

{canvas {@ id="canvas" width="320" height="240"
           style="border:1px solid #000;"}}

{script 
  var canvas_pixel = function(x, y, canvas) {
    var ctx = document.getElementById( canvas )
                      .getContext( "2d" );
    ctx.fillStyle = "#f00";
    ctx.fillRect(x,y,1,1);
  };

  setTimeout( canvas_pixel, 1, 100, 100, "canvas" )
}

Lua[edit]

The luasdl2 library is required.

local SDL = require "SDL"

local ret = SDL.init { SDL.flags.Video }
local window = SDL.createWindow {
	title	= "Pixel",
	height	= 320,
	width	= 240
}

local renderer = SDL.createRenderer(window, 0, 0)

renderer:clear()
renderer:setDrawColor(0xFF0000)
renderer:drawPoint({x = 100,y = 100})
renderer:present()

SDL.delay(5000)

M2000 Interpreter[edit]

Version 2

M2000 Console used for text and graphics too. So for this version we plot a pixel in console and in a form (a window above console). Form is open as modal, but console is something different, so we can show or hide it.

All forms are above console (for any kind, modal or not modal form), and we can hide console using Title statement. So in this example we hide/show console (behind form window) by clicking the form. In any state of showing console, when we close form and Interpreter need to input from console (like in prompt state), console state get visible.

There is also a PSet statement for pixel drawing (from 9.5 version). Just replace the module call to PlotPixel with Pset.

Module CheckIt {
      Module PlotPixel (a as single, b as single) {
            Move a*TwipsX, b*TwipsX
            Draw TwipsX, TwipsY
      }
      Cls 5,0  \\ clear console with Magenta (5) and set split  screen from 0 (no split screen)
      Pen #55FF77 {
            PlotPixel 1000, 200
      }
      Wait 1000
      Title "", 1
      Declare DrawPixelForm Form
      With DrawPixelForm, "Title", "Draw a Pixel at 100,100"
      Layer DrawPixelForm {
            \\ 12 for 12pt fonts
            \\ use ; to center window
            Window 12, 320*twipsx, 240*twipsy;
            Cls #333333
            Pen Color(255,0,0) {
                  PlotPixel 100, 100
            }
      }
      \\ code to show/hide console clicking form
      \\ console shown behind form
      k=0
      Function DrawPixelForm.Click {
            Title "Rosetta Code Example", abs(k)
            if k then show
            k~
      }
      Method DrawPixelForm, "Show", 1
      Declare DrawPixelForm Nothing
}
CheckIt

OutPut

Mathematica/Wolfram Language[edit]

CreateWindow[PaletteNotebook[{Graphics[{Red, Point[{100, 100}]}]}], WindowSize -> {320, 240}]

Microsoft Small Basic[edit]

GraphicsWindow.Width = 320
GraphicsWindow.Height = 240
GraphicsWindow.SetPixel(100, 100, GraphicsWindow.GetColorFromRGB(255, 0, 0))

Nim[edit]

Library: rapid
import rapid/gfx

var
  window = initRWindow()
    .size(320, 240)
    .title("Rosetta Code - draw a pixel")
    .open()
  surface = window.openGfx()

surface.loop:
  draw ctx, step:
    ctx.clear(gray(0))
    ctx.begin()
    ctx.point((100.0, 100.0, rgb(255, 0, 0)))
    ctx.draw(prPoints)
    discard step # Prevent unused variable warnings
  update step:
    discard step


Translation of: Lua
Library: SDL2

Another version using SDL2.

import sdl2

discard sdl2.init(INIT_EVERYTHING)

let window = createWindow("Pixel", 100, 100, 320, 240, SDL_WINDOW_SHOWN)
let renderer = createRenderer(window, -1, Renderer_Accelerated)

renderer.clear()
renderer.setDrawColor((255u8, 0u8, 0u8, 0u8))
renderer.drawPoint(100, 100)
renderer.present()

delay(5000)

Oberon[edit]

With basic module XYplane, the size of the drawing plane cannot be set. Tested with OBNC.

MODULE pixel;

	IMPORT XYplane;
	
BEGIN
	XYplane.Open;
	XYplane.Dot(100, 100, XYplane.draw);
	REPEAT UNTIL XYplane.Key() = "q"
END pixel.

Objeck[edit]

Library: SDL2
use Game.SDL2;
use Game.Framework;

class DrawPixel {
  @framework : GameFramework;
          
  function : Main(args : String[]) ~ Nil {
    DrawPixel->New()->Run();
  }

  New() {
    @framework := GameFramework->New(320, 240, "RGB");
    @framework->SetClearColor(Color->New(0, 0, 0));
  }

  method : Run() ~ Nil {
    if(@framework->IsOk()) {
      e := @framework->GetEvent();
      
      quit := false;
      while(<>quit) {
        @framework->FrameStart();
        @framework->Clear();

        while(e->Poll() <> 0) {
          if(e->GetType() = EventType->SDL_QUIT) {
            quit := true;
          };
        };
        
        @framework->GetRenderer()->SetDrawColor(255, 0, 0, 255);
        @framework->GetRenderer()->DrawPoint(100, 100);  

        @framework->Show();
        @framework->FrameEnd();
      };
    }
    else {
      "--- Error Initializing Game Environment ---"->ErrorLine();
      return;
    };

    leaving {
      @framework->Quit();
    };
  }
}

OCaml[edit]

Using the Graphics library provided with the standard OCaml distribution:

module G = Graphics

let () =
  G.open_graph "";
  G.resize_window 320 240;
  G.set_color G.red;
  G.plot 100 100;
  ignore (G.read_key ())

run with:

$ ocaml graphics.cma draw_a_pixel.ml
Library: OCamlSDL2
open Sdl

let () =
  let width, height = (320, 240) in
  Sdl.init [`VIDEO];
  let window, renderer =
    Render.create_window_and_renderer ~width ~height ~flags:[]
  in
  let rgb = (255, 0, 0) and a = 255 in
  Render.set_draw_color renderer ~rgb ~a;
  Render.draw_point renderer (100, 100);
  Render.render_present renderer;
  Timer.delay 3000;
  Sdl.quit ()

run with:

$ ocaml -I $(ocamlfind query sdl2) sdl2.cma draw_a_pixel.ml

Odin[edit]

package main

import "vendor:sdl2"

main :: proc() {
  using sdl2

  window: ^Window = ---
  renderer: ^Renderer = ---
  event: Event = ---

  Init(INIT_VIDEO)
  CreateWindowAndRenderer(
    640, 480,
    WINDOW_SHOWN,
    &window, &renderer
  )

  SetWindowTitle(window, "Empty window")
  SetRenderDrawColor(renderer, 50, 255, 100, 255)
  RenderDrawPoint(renderer, 100, 100)
  RenderPresent(renderer)

  for event.type != .QUIT {
    Delay(10)
    PollEvent(&event)
  }

  DestroyRenderer(renderer)
  DestroyWindow(window)
  Quit()
}

Ol[edit]

Library: OpenGL
(import (lib gl))
(import (OpenGL version-1-0))

; init
(glClearColor 0.3 0.3 0.3 1)
(glOrtho 0 320 0 240 0 1)

; draw loop
(gl:set-renderer (lambda (mouse)
   (glClear GL_COLOR_BUFFER_BIT)
   (glBegin GL_POINTS)
   (glColor3f 255 0 0)
   (glVertex2f 100 100)
   (glEnd)))

Perl[edit]

Library: Gtk3
use Gtk3 '-init';

my $window = Gtk3::Window->new();
$window->set_default_size(320, 240);
$window->set_border_width(10);
$window->set_title("Draw a Pixel");
$window->set_app_paintable(TRUE);

my $da = Gtk3::DrawingArea->new();
$da->signal_connect('draw' => \&draw_in_drawingarea);
$window->add($da);
$window->show_all();

Gtk3->main;

sub draw_in_drawingarea
{
  my ($widget, $cr, $data) = @_;
  $cr->set_source_rgb(1, 0, 0);
  $cr->set_line_width(1);
  $cr->rectangle( 100, 100, 1, 1);
  $cr->stroke;
}

Phix[edit]

Library: Phix/pGUI
Library: Phix/online

You can run this online here.

with javascript_semantics
include pGUI.e
 
cdCanvas cdcanvas
 
function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)
    cdCanvasActivate(cdcanvas)
    cdCanvasPixel(cdcanvas, 100, 100, CD_RED) 
    cdCanvasFlush(cdcanvas)
    return IUP_DEFAULT
end function
 
function map_cb(Ihandle ih)
    cdcanvas = cdCreateCanvas(CD_IUP, ih)
    return IUP_DEFAULT
end function
 
procedure main()
    IupOpen()
    Ihandle canvas = IupCanvas(NULL)
    IupSetAttribute(canvas, "RASTERSIZE", "320x240")
    IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))
    Ihandle dlg = IupDialog(canvas)
    IupSetAttribute(dlg, "TITLE", "Draw a pixel")
    IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))
    IupShow(dlg)
    if platform()!=JS then
        IupMainLoop()
        IupClose()
    end if
end procedure
 
main()

Processing[edit]

A static-mode sketch containing setting one pixel on the canvas pixels array:

size(320, 240);
set(100, 100, color(255,0,0));

The same sketch in active mode sketch is:

void setup() {
  size(320, 240);
  set(100, 100, color(255,0,0));
}

Or a pixel can be manipulated through loading and modifying the pixels array. The formula to access a pixel is x + y * image width.

void setup() {
  size(320, 240);
  loadPixels();
  pixels[width*100 + 100] = color(255,0,0);
  updatePixels();
}

Processing can also draw a dot on the canvas using the `point()` command will also draw a dot on the canvas...

size(320, 240);
stroke(color(255,0,0));
point(100, 100);

...however, whether a point corresponds to a single pixel on the screen may depend on device-specific factors such as `pixelDensity()`, render features such as 2D / 3D mode or `smooth()`, or style settings such as `strokeWidth()` or `strokeCap()`.

PureBasic[edit]

  If OpenWindow(0, 0, 0, 320, 240, "Rosetta Code Draw A Pixel in PureBasic")
    If CreateImage(0, 320, 240) And StartDrawing(ImageOutput(0))
          Plot(100, 100,RGB(255,0,0))
      StopDrawing() 
      ImageGadget(0, 0, 0, 320, 240, ImageID(0))
    EndIf
    Repeat
      Event = WaitWindowEvent()
    Until Event = #PB_Event_CloseWindow
  EndIf

Python[edit]

Works with: Python version 2.7.14
Library: PIL
from PIL import Image

img = Image.new('RGB', (320, 240))
pixels = img.load()
pixels[100,100] = (255,0,0)
img.show()

QB64[edit]

Screen _NewImage(320, 240, 32)
PSet (100, 100), _RGB(255, 0, 0)

QBasic[edit]

' http://rosettacode.org/wiki/Draw_a_pixel
' This program can run in QBASIC, QuickBASIC, gw-BASIC (adding line numbers) and VB-DOS
SCREEN 1
COLOR , 0
PSET (100, 100), 2
END

Racket[edit]

#lang racket
(require racket/draw)
(let ((b (make-object bitmap% 320 240)))
  (send b set-argb-pixels 100 100 1 1 (bytes 255 0 0 255))
  b)

Raku[edit]

(formerly Perl 6)

Works with: Rakudo version 2018.05

Really? Draw a single pixel? Sigh.

use GTK::Simple;
use GTK::Simple::DrawingArea;
use Cairo;

my $app = GTK::Simple::App.new(:title('Draw a Pixel'));
my $da  = GTK::Simple::DrawingArea.new;
gtk_simple_use_cairo;

$app.set-content( $da );
$app.border-width = 5;
$da.size-request(320,240);

sub rect-do( $d, $ctx ) {
    given $ctx {
        .rgb(1, 0, 0);
        .rectangle(100, 100, 1, 1);
        .fill;
    }
}

my $ctx = $da.add-draw-handler( &rect-do );
$app.run;

ReScript[edit]

type document  // abstract type for a document object
type context = { mutable fillStyle: string, }

@val external doc: document = "document"

@send external getElementById: (document, string) => Dom.element = "getElementById"
@send external getContext: (Dom.element, string) => context = "getContext"

@send external fillRect: (context, int, int, int, int) => unit = "fillRect"

let canvas = getElementById(doc, "my_canvas")
let ctx = getContext(canvas, "2d")

ctx.fillStyle = "#F00"
fillRect(ctx, 100, 100, 1, 1)


<!DOCTYPE html>
<html>
<head>
<title>Draw a Pixel</title>
<style rel="stylesheet" type="text/css">
body {
  background-color:#777;
}
canvas {
  background-color:#888;
  margin:60px 120px;
  border:1px solid #555;
  box-shadow: -1px 2px 6px 1px rgba(0,0,0,0.3);
}
</style>
</head>
<body>

<canvas id="my_canvas" width="320" height="240">
  No support for HTML5 Canvas.<br />
</canvas>

<script type="text/javascript" src="draw.bs.js"></script>

<noscript>
  No support for Javascript.<br />
</noscript>

</body>
</html>

REXX[edit]

This REXX version only works for:

  •   PC/REXX
  •   Personal/REXX
/*REXX program displays (draws) a pixel at a specified screen location in the color red.*/
parse upper version !ver .
!pcrexx= 'REXX/PERSONAL'==!ver | 'REXX/PC'==!ver /*obtain the REXX interpreter version. */
parse arg x y txt CC .                           /*obtain optional arguments from the CL*/
if   x=='' |  x==","  then   x= 100              /*Not specified?  Then use the default.*/
if   y=='' |  y==","  then   y= 100              /* "       "        "   "   "     "    */
if  CC=='' |  CC=","  then  CC=   4              /* "       "        "   "   "     "    */
if txt=='' | txt=","  then tzt= '·'              /* "       "        "   "   "     "    */

if ¬!pcrexx  then do; say; say "***error***  PC/REXX[interpreter] isn't being used.";  say
                      exit 23
                  end

call scrWrite x,y,txt,,,CC                       /*stick a fork in it,  we're all done. */



Ring[edit]

# Project  : Draw a pixel

load "guilib.ring"

new qapp {
       win1 = new qwidget() {
                  setwindowtitle("Drawing Pixels")
                  setgeometry(100,100,320,240)
                  label1 = new qlabel(win1) {
                              setgeometry(10,10,300,200)
                              settext("")
                  }
                  new qpushbutton(win1) {
                         setgeometry(200,200,100,30)
                         settext("draw")
                         setclickevent("draw()")
                  }
                  show()
       }
       exec()
}

func draw()
        p1 = new qpicture()
        color = new qcolor() {
                   setrgb(255,0,0,255)
                  }
        pen = new qpen() {
                  setcolor(color)
                  setwidth(5)
                  }
        new qpainter() {
               begin(p1)
               setpen(pen)
               drawpoint(100,100)
               endpaint()
               }
               label1 { setpicture(p1) show() }

Output image: Draw a pixel

Robotic[edit]

We can technically draw a pixel through the use of Sprites.

One of the requirements (fixed screen resolution) could not be met.

. "Set the sprite's reference character located at the"
. "upper-left corner of the board (char 0)"
set "SPR0_REFX" to 0
set "SPR0_REFY" to 0

. "Offset that reference by 256, leading to the first character"
. "in the extended character set"
set "SPR0_OFFSET" to 256

. "Set the width and height of the sprite"
set "SPR0_WIDTH" to 1
set "SPR0_HEIGHT" to 1

. "Unbound the sprite, removing the grid restriction"
set "SPR0_UNBOUND" to 1

. "Mark the sprite for display on the overlay (this may not be necessary)"
set "SPR0_OVERLAY" to 1

set "xPos" to 100
set "yPos" to 100

. "Display the sprite at the given location"
put c0c Sprite p00 at "('xPos')" "('yPos')"

I highly recommend you check out this tutorial for the usage of Sprites in order to get a better understanding of all this.

Ruby[edit]

Works with: Ruby version 2.6.6
Library: gtk3
require 'gtk3'

Width, Height = 320, 240
PosX, PosY = 100, 100

window = Gtk::Window.new
window.set_default_size(Width, Height)
window.title = 'Draw a pixel'

window.signal_connect(:draw) do |widget, context|
  context.set_antialias(Cairo::Antialias::NONE)
  # paint out bg with white
  # context.set_source_rgb(1.0, 1.0, 1.0)
  # context.paint(1.0)
  # draw a rectangle
  context.set_source_rgb(1.0, 0.0, 0.0)
  context.fill do
    context.rectangle(PosX, PosY, 1, 1)
  end
end

window.signal_connect(:destroy) { Gtk.main_quit }

window.show
Gtk.main

Rust[edit]

Library: piston_window
Library: image
Output Image:
RustOut


extern crate piston_window;
extern crate image;

use piston_window::*;

fn main() {
    let (width, height) = (320, 240);
    
    let mut window: PistonWindow =
        WindowSettings::new("Red Pixel", [width, height])
        .exit_on_esc(true).build().unwrap();

    // Since we cant manipulate pixels directly, we need to manipulate the pixels on a canvas.
    // Only issue is that sub-pixels exist (which is probably why the red pixel looks like a smear on the output image)
    let mut canvas = image::ImageBuffer::new(width, height);
    canvas.put_pixel(100, 100, image::Rgba([0xff, 0, 0, 0xff]));

    // Transform into a texture so piston can use it.
    let texture: G2dTexture = Texture::from_image(
        &mut window.factory,
        &canvas,
        &TextureSettings::new()
    ).unwrap();

    // The window event loop.
    while let Some(event) = window.next() {
        window.draw_2d(&event, |context, graphics| {
            clear([1.0; 4], graphics);
            image(&texture,
            context.transform,
            graphics);
        });
    }
}

Scala[edit]

Scala idiom[edit]

A more Scalesque version could be with the use of its idiom:

Output:

Best experienced in your browser with Scastie (remote JVM).

import java.awt.image.BufferedImage
import java.awt.Color
import scala.language.reflectiveCalls

object RgbBitmap extends App {

  class RgbBitmap(val dim: (Int, Int)) {
    def width = dim._1
    def height = dim._2

    private val image = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR)

    def apply(x: Int, y: Int) = new Color(image.getRGB(x, y))

    def update(x: Int, y: Int, c: Color) = image.setRGB(x, y, c.getRGB)

    def fill(c: Color) = {
      val g = image.getGraphics
      g.setColor(c)
      g.fillRect(0, 0, width, height)
    }
  }

  object RgbBitmap {
    def apply(width: Int, height: Int) = new RgbBitmap(width, height)
  }

  /** Even Javanese style testing is still possible.
    */
  private val img0 = new RgbBitmap(50, 60) { // Wrappers to enable adhoc Javanese style
    def getPixel(x: Int, y: Int) = this(x, y)
    def setPixel(x: Int, y: Int, c: Color) = this(x, y) = c
  }

  img0.fill(Color.CYAN)
  img0.setPixel(5, 6, Color.BLUE)
  // Testing in Java style
  assert(img0.getPixel(0, 1) == Color.CYAN)
  assert(img0.getPixel(5, 6) == Color.BLUE)
  assert(img0.width == 50)
  assert(img0.height == 60)
  println("Tests successfully completed with no errors found.")

}

SmileBASIC[edit]

I almost said that the 320x240 requirement was not going to happen. Then I realised the 3DS bottom screen is exactly 320x240.

XSCREEN 3
DISPLAY 1
GPSET 100, 100, RGB(255, 0, 0)
WAIT 60

Standard ML[edit]

Works with PolyML

open XWindows ;
open Motif ;

val imgWindow = fn () =>
 
 let
  val shell  =  XtAppInitialise      ""    "demo" "top" [] [ XmNwidth 320, XmNheight 240 ] ;
  val main   =  XmCreateMainWindow   shell    "main"       [ XmNmappedWhenManaged true ]   ;
  val canvas =  XmCreateDrawingArea  main   "drawarea"     [ XmNwidth 320, XmNheight 240 ] ;
  val usegc  =  DefaultGC (XtDisplay canvas) ;
  val put    =  fn (w,s,t) => ( XSetForeground usegc 0xff0000 ;
                                XDrawPoint (XtWindow canvas) usegc ( XPoint {x=100,y=100} ) ; t);
in
 
  (
   XtSetCallbacks   canvas [ (XmNexposeCallback , put) ] XmNarmCallback ;
   XtManageChild    canvas ;
   XtManageChild    main ; 
   XtRealizeWidget  shell 
  )
 
end;

call

imgWindow () ;

Tcl[edit]

Works with: Tcl version 8.5

Library: Tk
[edit]

package require Tcl 8.5
package require Tk

pack [canvas .c -width 320 -height 240 -bg #fff] -anchor nw
.c create rectangle 100 100 100 100 -fill #f00 -outline ""

True BASIC[edit]

SET WINDOW 0, 320, 0, 240
SET COLOR 4
PLOT 100,100
END

VBA[edit]

Word

Sub draw()
    Dim sh As Shape, sl As Shape
    Set sh = ActiveDocument.Shapes.AddCanvas(100, 100, 320, 240)
    Set sl = sh.CanvasItems.AddLine(100, 100, 101, 100)
    sl.Line.ForeColor.RGB = RGB(Red:=255, Green:=0, Blue:=0)
End Sub

V (Vlang)[edit]

import gg
import gx

fn main() {
    mut context := gg.new_context(
        width: 320
        height: 240
        frame_fn: frame
    )
    context.run()
}

fn frame(mut ctx gg.Context) {
    ctx.begin()
    ctx.draw_pixel(100, 100, gx.red)
    ctx.end()
}

Wee Basic[edit]

Since the resolution of the Nintendo DS's bottom screen is only 256×192 (the same applies to the top screen), the window requirement is out, but the pixel is easy:

keyhide
plot 0 100,100,5
end

Wren[edit]

Library: DOME
import "dome" for Window
import "graphics" for Canvas, Color

class Game {
    static init() {
        Window.title = "Draw a pixel"
        Window.resize(320, 240)
        Canvas.resize(320, 240)
        var red = Color.rgb(255, 0, 0)
        Canvas.pset(100, 100, red)
        // check it worked
        var col = Canvas.pget(100, 100)
        System.print("The color of the pixel at (100, 100) is %(getRGB(col))")
    }

    static update() {}

    static draw(dt) {}

    static getRGB(col) { "{%(col.r), %(col.g), %(col.b)}" }
}
Output:
$ ./dome draw_pixel.wren
The color of the pixel at (100, 100) is {255, 0, 0}

X86 Assembly[edit]

This doesn't quite meet the requirements, but it shows how little code is needed to draw a pixel on an IBM-PC VGA screen. The executable program is a mere 32 bytes long. The "window" in this case is 320x200. Palette register 28 hex is set to bright red by the BIOS at boot-up time. About half the code is used to wait for a keystroke before returning to the OS, so the pixel can be seen. Borland's tasm and tlink /t were used to create an executable .com file.

        .model  tiny
        .code
        org     100h

start:  mov     ax, 0013h       ;set 320x200x8 graphic screen
        int     10h
        push    0A000h          ;point to graphic memory segment
        pop     es
        mov     byte ptr es:[320*100+100], 28h  ;draw bright red pixel

        mov     ah, 0           ;wait for keystroke
        int     16h
        mov     ax, 0003h       ;restore normal text mode screen
        int     10h
        ret                     ;return to OS
        end     start

XPL0[edit]

This is all that's required to plot a pixel on the Raspberry Pi version of XPL0. It can do tens of millions of them per second. (FB = Frame Buffer.)

[SetFB(320, 240, 24);  Point(100, 100, $FF0000)]

Yabasic[edit]

open window 320, 240
color 255, 0, 0
dot 100, 100

ZX Spectrum Basic[edit]

The ZX Spectrum screen is only 256x224 (unless you're running one of the games like Starion or Dark Star which used scary machine code timing tricks to draw on the border), meaning the window requirement is out, but the pixel is easy:

PLOT INK 2;100,100