Draw pixel 2

Draw pixel 2 is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

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

1.  the window is 640 x 480
2.  the color of the pixel must be yellow (255,255,0)
3.  the position of the pixel is random

C

Same as the Draw a pixel task, uses the random number functions of stdlib.h to plot a random point. Requires the WinBGIm library. <lang C>

1. include<graphics.h>
2. include<stdlib.h>
3. include<time.h>

int main() { srand(time(NULL));

initwindow(640,480,"Yellow Random Pixel");

putpixel(rand()%640,rand()%480,YELLOW);

getch();

return 0; } </lang>

FreeBASIC

<lang freebasic>' version 04-07-2018 ' compile with: fbc -s console ' or: fbc -s gui

Screen 18, 24 ' Screen 18: 640x480, 24bit colordepth 'ScreenRes 640, 480, 24 ' Screenres: 640x480, 24bit colordepth

If ScreenPtr = 0 Then

   Print "Error setting video mode!"
   End

End If

Randomize Timer Dim As UInteger x = Rnd * 640, y = Rnd * 480

PSet (x, y), RGB(255,255,0) ' yellow

' empty keyboard buffer While Inkey <> "" : Wend WindowTitle "0, 0 is top left, pixel is at " & x & ", " & y & " hit any key to end program" Sleep End</lang>

Go

<lang go>package main

import (

   "fmt"
   "image"
   "image/color"
   "image/draw"
   "math/rand"
   "time"

)

func main() {

   rect := image.Rect(0, 0, 640, 480)
   img := image.NewRGBA(rect)

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

   // Set color of a random pixel to yellow
   yellow := color.RGBA{255, 255, 0, 255}
   width := img.Bounds().Dx()
   height := img.Bounds().Dy()
   rand.Seed(time.Now().UnixNano())
   x := rand.Intn(width)
   y := rand.Intn(height)
   img.Set(x, y, yellow)

   // Check there's exactly one random yellow pixel.
   cmap := map[color.Color]string{blue: "blue", yellow: "yellow"}
   for i := 0; i < width; i++ {
       for j := 0; j < height; j++ {
           c := img.At(i, j)
           if cmap[c] == "yellow" {
               fmt.Printf("The color of the pixel at (%d, %d) is yellow\n", i, j)
           }
       }
   }

}</lang>

Output:

Sample output:

The color of the pixel at (525, 163) is yellow

Kotlin

This is a variation of the Draw a pixel task and so therefore is the code to accomplish it. <lang scala>// Version 1.2.41

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

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 rand = Random()
   val bbs = BasicBitmapStorage(640, 480)
   with (bbs) {
       fill(Color.white) // say
       val x = rand.nextInt(image.width)
       val y = rand.nextInt(image.height)
       setPixel(x, y, Color.yellow)
       // check there's exactly one random yellow pixel
       for (i in 0 until image.width) {
           for (j in 0 until image.height) {
               if (getPixel(i, j) == Color.yellow) {
                   println("The color of the pixel at ($i, $j) is yellow")
               }
           }
       }
   }

}</lang>

Output:

Sample output:

The color of the pixel at (296, 15) is yellow

Perl 6

Works with: Rakudo version 2018.05

Coordinates of random pixel displayed in window title. To make the single pixel show up better I filled in the drawing area background with black to get better contrast.

<lang perl6>use GTK::Simple; use GTK::Simple::DrawingArea; use Cairo; my ($w, $h) = 640, 480; my ($x, $y) = (^$w).pick, (^$h).pick;

my $app = GTK::Simple::App.new(:title("Draw Pixel 2 @ $x,$y")); my $da = GTK::Simple::DrawingArea.new; gtk_simple_use_cairo;

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

sub rect-do( $d, $ctx ) {

   given $ctx {
       .rgb(0, 0, 0);
       .rectangle(0, 0, $w, $h);
       .fill;
       .rgb(1, 1, 0);
       .rectangle($x, $y, 1, 1);
       .fill;
   }

}

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

Phix

Resize the window to see the pixel jumping about. <lang Phix>include pGUI.e

Ihandle dlg, canvas cdCanvas cddbuffer, cdcanvas

function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)

   atom {w,h} = IupGetIntInt(canvas, "DRAWSIZE")
   cdCanvasActivate(cddbuffer)
   cdCanvasClear(cddbuffer)
   cdCanvasPixel(cddbuffer, rand(w), rand(h), CD_YELLOW)
   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_BLACK)
   return IUP_DEFAULT

end function

procedure main()

   IupOpen()

   canvas = IupCanvas(NULL)
   IupSetAttribute(canvas, "RASTERSIZE", "240x50")
   IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))
   IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))

   dlg = IupDialog(canvas)
   IupSetAttribute(dlg, "TITLE", "Draw pixel")
   IupCloseOnEscape(dlg)

   IupShow(dlg)
   IupSetAttribute(canvas, "RASTERSIZE", NULL)
   IupMainLoop()
   IupClose()

end procedure

main()</lang>

Ring

<lang ring>

1. Project  : Draw pixel 2

load "guilib.ring"

new qapp {

      nwidth = 320
      nheight= 240
      win1 = new qwidget() {
                 setwindowtitle("Draw Pixel 2")
                 setgeometry(100,100,640,480)
                 label1 = new qlabel(win1) {
                             setgeometry(10,10,640,480)
                             settext("")
                 }
                 new qpushbutton(win1) {
                        setgeometry(200,400,100,30)
                        settext("draw")
                        setclickevent("draw()")
                 }
                 new qpushbutton(win1) {
                        setgeometry(300,400,100,30)
                        settext("get pixel color")
                        setclickevent("PixelColor()")
                 }
                 show()
      }
      exec()

}

func draw()

       p1 = new qpicture()
       color = new qcolor() {
                  setrgb(255,255,0,255)
                 }
       pen = new qpen() {
                 setcolor(color)
                 setwidth(10)
                 }
       new qpainter() {
              begin(p1)
              setpen(pen)
              x = random(nwidth-1) + 1
              y = random(nheight-1) + 1
              see "x = " + x + " y = " + y + nl
              drawpoint(x,y)
              endpaint()
              }
              label1 { setpicture(p1) show() }

func PixelColor()

      oapp = new qapp(0,null)  {
                 screen = win1.windowhandle().screen()
                 pixmap = screen.grabwindow(0,0,0,-1,-1)
                 image = pixmap.toimage()
                 color = image.pixel(100,100)
                 mycolor = new qcolor()
                 mycolor.setrgb(255,255,0,255)
                 see nl+"red : " + mycolor.red() + nl
                 see "green : " + mycolor.green() + nl
                 see "blue : " + mycolor.blue() + nl
                 }

</lang> Outputimage:

Draw pixel 2