Color of a screen pixel: Difference between revisions
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The mouse cursor may or may not have to be active in a GUI created by your program. These functions are OS related.
<br><br>
=={{header|6502 Assembly}}==
How this is done, and whether this is even possible, depends entirely on your video hardware (some machines such as the NES cannot control color data or graphics data at the pixel level.) And good luck trying to explain how this works on the Apple II.
===easy6502/6502js===
Video memory is mapped into $0200-$05ff, and the bottom 4 bits of each byte represent the pixel's color.
<syntaxhighlight lang="6502asm">LDA $0200 ;get the color of the top-left pixel of the screen
LDA $05FF ;get the color of the bottom-right pixel of the screen.</syntaxhighlight>
===Nintendo Entertainment System===
The NES can't determine the color of a single pixel. The closest you can get is a 16 pixel by 16 pixel section of graphics. And that only tells you the palette in use at that location, not the actual color. Color cells are 2 bits per 16x16 section, in the order of top-left, top-right, bottom-left, bottom-right.
<syntaxhighlight lang="6502asm">;this code will fail to produce the desired result unless it executes during vblank or forced blank.
;address $23C0 = first color cell of nametable $2000
LDA #$23
STA $2006
LDA #$C0
STA $2006
LDA $2007
AND #%11000000 ;00------ = top-left corner uses palette 0, 01------ = top-left corner uses palette 1, etc.</syntaxhighlight>
This code assumes no scrolling has taken place, as it only reads the color cells from the top-left nametable. Generally speaking, reading VRAM in this way is not a good practice, as it's very slow and can only be done during vBlank when you have better things to do. For an actual game, it's much easier to keep a shadow of this data in normal RAM and read that instead, and pretend that VRAM is write-only.
=={{header|8086 Assembly}}==
===With Interrupts===
MS-DOS has a built-in way to calculate the color of a pixel on-screen.
<syntaxhighlight lang="asm">;input: cx = x coordinate of pixel, dx = y coordinate of pixel, bh = page number
mov ah,0Dh
int 10h</syntaxhighlight>
The color is returned in AL.
=={{header|Action!}}==
<syntaxhighlight lang="action!">PROC Main()
BYTE POINTER ptr
BYTE
w=[160],h=[160],x=[0],y=[0],c,k,update=[1],
CH=$02FC ;Internal hardware value for last key pressed
CARD size=[6400],i
Graphics(15) ;Graphics 160x160 with 4 colors with text window
ptr=PeekC(88)
; Fill screen with random colors
FOR i=1 TO size
DO
ptr^=Rand(0)
ptr==+1
OD
PrintE("Use arrow keys to change position and Esc to exit.")
DO
IF update THEN
c=Locate(x,y)
PrintF("x=%B y=%B c=%B%E",x,y,c)
FI
k=CH
CH=$FF
update=1
IF k=134 THEN
IF x=0 THEN x=w-1
ELSE x==-1 FI
ELSEIF k=135 THEN
IF x=w-1 THEN x=0
ELSE x==+1 FI
ELSEIF k=142 THEN
IF y=0 THEN y=h-1
ELSE y==-1 FI
ELSEIF k=143 THEN
IF y=h-1 THEN y=0
ELSE y==+1 FI
ELSEIF k=28 THEN
EXIT
ELSE
update=0
FI
OD
RETURN</syntaxhighlight>
{{out}}
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Color_of_a_screen_pixel.png Screenshot from Atari 8-bit computer]
=={{header|App Inventor}}==
Line 14 ⟶ 96:
In the app's display below, the purple Ball sprite was touched on the left canvas, but the pixel color (green) returned was from the area below it.
[https://lh4.googleusercontent.com/-Gw0xm7RIEck/Uute2nQSGsI/AAAAAAAAJ90/rq3UuWYE9Yw/s1600/Capture.PNG <VIEW THE BLOCKS AND ANDROID APP DISPLAY>]
=={{header|AutoHotkey}}==
<syntaxhighlight lang="autohotkey">PixelGetColor, color, %X%, %Y%</syntaxhighlight>
=={{header|
<syntaxhighlight lang="autoit">Opt('MouseCoordMode',1) ; 1 = (default) absolute screen coordinates
$pos = MouseGetPos()
$c = PixelGetColor($pos[0], $pos[1])
ConsoleWrite("Color at x=" & $pos[0] & ",y=" & $pos[1] & _
" ==> " & $c & " = 0x" & Hex($c) & @CRLF)</syntaxhighlight>
{{Out}}
<pre>
Color at x=3,y=733 ==> 3829413 = 0x003A6EA5
</pre>
=={{header|Axe}}==
<syntaxhighlight lang="axe">Disp pxl-Test(50,50)▶Dec,i</syntaxhighlight>
=={{header|BaCon}}==
BaCon can make use of the High Performance Canvas include. Outside this canvas it needs to access XLib API functions.
<syntaxhighlight lang="qbasic">INCLUDE canvas
FULLSCREEN
color = GETINK(100, 100, 4)
WAITKEY</syntaxhighlight>
=={{header|BASIC}}==
==={{header|AmigaBASIC}}===
<syntaxhighlight lang="amigabasic">MOUSE ON
WHILE 1
m=MOUSE(0)
PRINT POINT(MOUSE(1),MOUSE(2))
WEND</syntaxhighlight>
(The color index is -1 if the mouse pointer is outside the Basic window.)
==={{header|Applesoft BASIC}}===
[http://en.wikipedia.org/wiki/Apple_II_graphics#Low-Resolution_.28Lo-Res.29_graphics Low-Resolution (Lo-Res) graphics] 40x48, 16 colors, page 1
<syntaxhighlight lang="applesoft basic">X = PDL (0) * 5 / 32
Y = PDL (1) * 3 / 16
COLOR= SCRN( X,Y)</
[http://en.wikipedia.org/wiki/Apple_II_graphics#High-Resolution_.28Hi-Res.29_graphics Hi-Resolution (Hi-Res) graphics] 280x192, 6 colors
There is no HSCRN( X,Y) function in Applesoft. What follows is an elaborate subroutine that determines the hi-res color at the location given by variables X and Y on the current hi-res page. A color value in the range from 0 to 7 is returned in the variable C. The color is determined by peeking at adjacent pixels and the Most Significant Bit [http://en.wikipedia.org/wiki/Most_significant_bit MSB]. The VTAB routine is used as an aid to calculate the address of pixels. Other colors beyond the 6 hi-res colors can be displayed by positioning pixels at byte boundaries using the MSB. This routine is limited to the eight hi-res colors.
<syntaxhighlight lang="applesoft basic">
100 REM GET HCOLOR
110 REM PARAMETERS: X Y
Line 66 ⟶ 184:
X = 267 : Y = 166 : GOSUB 100
HCOLOR= C
</syntaxhighlight>
==={{header|
In [[BBC BASIC for Windows]] you can read either the 'logical colour' (palette index) or the 'true colour' (24-bit RGB value).
<syntaxhighlight lang="bbcbasic"> palette_index% = POINT(x%, y%)
RGB24b_colour% = TINT(x%, y%)</syntaxhighlight>
==={{header|
'''Example 1:''' Commodore 64
There are no graphics commands in Commodore 64 BASIC. High resolution (hires) graphics are programmed by directly manipulating the hardware registers and memory.
The Commodore 64 hires bitmap is 320×200, subdivided into 8×8 cells starting at the top left and moving right. Each cell is addressed top to bottom by 8 bytes. Each byte controls a horizontal row of 8 bits. This requires calculation on the programmer's part to translate X,Y coordinates into a specific memory address/value combination (lines 1210 through 1220).
<syntaxhighlight lang="gwbasic">5 rem commodore 64 example
10 base=2*4096:x=100:y=50:poke53280,0
20 gosub 1000:print chr$(147);
30 bg=11:fg=1:rem set foreground and background colors
40 for i=1024 to 1503:poke i,fg*16+bg:next
50 for i=base to base+7990:poke i,0:next
60 gosub 1200
70 poke byte, peek(byte) or 2^bit
80 print"{home}{crsr-down 14}";
90 px=((peek(byte) and 2^bit)>0)
100 co=peek(cb)and(15+(-225*px)):if px then co=co/16
110 print"pixel color at";x;"{crsr-left},";y;"{crsr-left}:";co;"{crsr-left} "
120 getk$:ifk$=""then 120
130 gosub 1100:end
1000 rem turn on graphics
1010 poke53272,peek(53272) or 8
1020 poke53265,peek(53265) or 32
1030 return
1100 rem turn off graphics
1110 poke53265,peek(53265) and 223
1120 poke53272,peek(53272) and 247
1130 return
1200 rem convert x-y into mem location
1210 ro=int(y/8):ch=int(x/8):li=y and 7
1220 bit=7-(x and 7):byte=base+ro*320+char*8+li:cb=1024+ro+ch
1230 return
</syntaxhighlight>
'''Example 2:''' Commodore Plus 4 and 128
On both machines, there is a split graphics-text screen that can be used, and the extended BASIC provides functions for reading pixel and color values from the bitmap.
<syntaxhighlight lang="gwbasic">10 color 0,1:color 1,3: rem set border to black and pixel color to red
15 graphic 2,1: rem enter split graphics/text mode and clear screen
20 draw 1,100,50 : rem plot pixel at 100,50
30 print "pixel color at";rdot(0);",";rdot(1);"is";rclr(rdot(2))
40 get k$:if k$="" then 40
50 graphic 0,1 : rem return to text mode</syntaxhighlight>
==={{header|FreeBASIC}}===
This is a very simple example from the FreeBASIC documentation. To obtain the color of an arbitrary screen pixel (i.e. outside
the graphics screen controlled by FB) one would need to use API functions.
<syntaxhighlight lang="freebasic">FB 1.05.0 Win64
' Set an appropriate screen mode - 320 x 240 x 8bpp indexed color
ScreenRes 320, 240, 8
' Draw a line using color 12 (light red)
Line (20,20)-(100,100), 12
' Print the color of a point on the line
Print Point(20,20) '' prints 12
' Sleep before the program closes
Sleep</syntaxhighlight>
==={{header|QuickBASIC}}===
{{works with|QuickBasic|4.5}}
In a graphics mode (for instance, <tt>SCREEN 13</tt> or <tt>SCREEN 12</tt>)
<
==={{header|
See [[#Applesoft BASIC|Applesoft BASIC]].
==={{header|Liberty BASIC}}===
<syntaxhighlight lang="lb">'This example requires the Windows API
Struct point, x As long, y As long
hDC = GetDC(0)
result = GetCursorPos()
Print GetPixel(hDC, point.x.struct, point.y.struct)
Call ReleaseDC 0, hDC
End
Sub ReleaseDC hWnd, hDC
CallDLL #user32,"ReleaseDC", hWnd As uLong, hDC As uLong, ret As Long
End Sub
Function GetDC(hWnd)
CallDLL #user32, "GetDC", hWnd As uLong, GetDC As uLong
End Function
Function GetCursorPos()
CallDLL #user32, "GetCursorPos", point As struct, GetCursorPos As uLong
End Function
Function GetPixel(hDC, x, y)
CallDLL #gdi32, "GetPixel", hDC As uLong, x As long, y As long, GetPixel As long
End Function</syntaxhighlight>
==={{header|Locomotive Basic}}===
<syntaxhighlight lang="locobasic">10 x=320:y=200
20 color=TEST(x,y)
30 PRINT "Pen color at"; x; y; "is"; color</syntaxhighlight>
==={{header|PureBasic}}===
Return the color used at the x,y position in the current output. If the current output has an alpha channel then the result will be a 32bit RGBA value, otherwise it will be a 24bit RGB value. The color can be split in their RGB and alpha values by using the Red(), Green(), Blue() and Alpha() functions.
<syntaxhighlight lang="purebasic">Color = Point(x, y)</syntaxhighlight>
To get the colour of a pixel on the screen when it is not managed by PureBasic (ie. from other programs' windows), it is necessary to use Windows API. This works only under Windows.
<syntaxhighlight lang="purebasic">
hDC = GetDC_(0)
Color = GetPixel_(hDC, x, y)
ReleaseDC_(0, hDC)</syntaxhighlight>
This work fine!!
<syntaxhighlight lang="purebasic">poz.point
If OpenWindow(0,0,0,100,45,"Get pixel color at cursor position",#PB_Window_MinimizeGadget)
TextGadget(0,0,0,50,12,"Red: ")
TextGadget(1,0,15,50,12,"Green: ")
TextGadget(2,0,30,50,12,"Blue: ")
TextGadget(3,50,0,50,12,"")
TextGadget(4,50,15,50,12,"")
TextGadget(5,50,30,50,12,"")
hDC = GetDC_(0)
Repeat
oldx=poz\x
oldy=poz\y
GetCursorPos_(@poz)
Color = GetPixel_(hDC, poz\x, poz\y)
If poz\x<>oldx Or poz\y<>oldy
SetGadgetText(3,Str(Red(color)))
SetGadgetText(4,Str(Green(color)))
SetGadgetText(5,Str(Blue(color)))
EndIf
event=WaitWindowEvent(200)
Until event=#PB_Event_CloseWindow
ReleaseDC_(0, hDC)
EndIf</syntaxhighlight>
=={{header|QBasic}}==
<syntaxhighlight lang="qbasic">
'Example: Find color of a screen pixel in QBasic (adapted from QBasic Help file).
' POINT(x%, y%) returns color of pixel at coordinates x,y.
SCREEN 7 'Choose color graphics screen (1,2,4,7,8,9,11,12,13).
LINE (0, 0)-(100, 100), 2 'Draw diagonal line in color attribute 2.
LOCATE 14, 1 'Locate below diagonal line to show output.
FOR y% = 1 TO 10
FOR x% = 1 TO 10
PRINT POINT(x%, y%); 'POINT(x%, y%) displays pixel color.
NEXT x%
PRINT
NEXT y%
END
</syntaxhighlight>
==={{header|BASIC256}}===
<syntaxhighlight lang="basic256">color rgb(0, 255, 0)
rect 50, 50, 75, 75
color rgb(255, 0, 0)
line (20,20,100,100)
x = 60 : y = 50
c = pixel(x, y)
rojo = (c & 0xff0000) \ 0x10000
verde = (c & 0xff00) \ 0x100
azul = (c & 0xff)
print rojo; " "; verde; " "; azul</syntaxhighlight>
==={{header|SmileBASIC}}===
<syntaxhighlight lang="smilebasic">DEF GETPX X,Y OUT R,G,B
PCOL=GSPOIT(X,Y)
RGBREAD PCOL OUT R,G,B
END</syntaxhighlight>
==={{header|TI-89 BASIC}}===
Only the graph screen can be read.
<syntaxhighlight lang="ti89b">pxlTest(y, x) © returns boolean</syntaxhighlight>
==={{header|Visual Basic .NET}}===
<syntaxhighlight lang="vbnet"> Private Function GetPixelColor(ByVal Location As Point) As Color
Dim b As New Bitmap(1, 1)
Dim g As Graphics = Graphics.FromImage(b)
g.CopyFromScreen(Location, Point.Empty, New Size(1, 1))
Return b.GetPixel(0, 0)
End Function</syntaxhighlight>
==={{header|VBA}}===
In "pure" Visual Basic for Application, there is no way to find the color of a screen pixel.
We have to use api's functions.
This code should be adapted for 64 bits versions...
<syntaxhighlight lang="vb">
Option Explicit
Private Type POINTAPI
x As Long
y As Long
End Type
Private Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long
Private Declare Function GetCursorPos Lib "USER32" (lpPoint As POINTAPI) As Long
Private Declare Function GetWindowDC Lib "USER32" (ByVal hWnd As Long) As Long
Sub Color_of_a_screen_pixel()
Dim myColor As Long
myColor = Get_Color_Under_Cursor
End Sub
Function Get_Color_Under_Cursor() As Long
Dim Pos As POINTAPI, lngDc As Long
lngDc = GetWindowDC(0)
GetCursorPos Pos
Get_Color_Under_Cursor = GetPixel(lngDc, Pos.x, Pos.y)
End Function
</syntaxhighlight>
==={{header|Yabasic}}===
<syntaxhighlight lang="yabasic">open window 100, 100
backcolor 255, 0, 0
clear window
color 0, 255, 0
fill rectangle 50, 50, 75, 75
x = 60 : y = 60
s$ = right$(getbit$(x, y, x, y), 6)
blue = dec(right$(s$, 2))
green = dec(mid$(s$, 3, 2))
red = dec(left$(s$, 2))
print red, " ", green, " ", blue</syntaxhighlight>
==={{header|ZX Spectrum Basic}}===
The built-in function <code>POINT (x,y)</code> returns 0 if the pixel at <tt>x,y</tt> is set to the relevant <code>PAPER</code> colour, or 1 if it is set to the <code>INK</code> colour. (Note that there can only be a maximum of two colours in each 8x8-pixel section of the screen.)
=={{header|C}}==
{{libheader|Xlib}}
<syntaxhighlight lang="c">
#include <X11/Xlib.h>
void
Line 121 ⟶ 460:
get_pixel_color (display, 30, 40, &c);
printf ("%d %d %d\n", c.red, c.green, c.blue);
</syntaxhighlight>
{{works with|Windows}}
(Linux users, see [http://www.muquit.com/muquit/software/grabc/grabc.html grabc].)
<
COLORREF getColorAtCursor(void) {
Line 150 ⟶ 489:
return color;
}</
=={{header|C sharp|C#}}==
<
using System.Drawing;
using System.Windows.Forms;
Line 195 ⟶ 514:
Console.WriteLine(GetPixel(Cursor.Position));
}
}</
Sample output:
<syntaxhighlight lang="text">Color [A=255, R=243, G=242, B=231]</
=={{header|C++/CLI}}==
<syntaxhighlight lang="cpp">using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
[STAThreadAttribute]
int main()
{
Point^ MousePoint = gcnew Point();
Control^ TempControl = gcnew Control();
MousePoint = TempControl->MousePosition;
Bitmap^ TempBitmap = gcnew Bitmap(1,1);
Graphics^ g = Graphics::FromImage(TempBitmap);
g->CopyFromScreen((Point)MousePoint, Point(0, 0), Size(1, 1));
Color color = TempBitmap->GetPixel(0,0);
Console::WriteLine("R: "+color.R.ToString());
Console::WriteLine("G: "+color.G.ToString());
Console::WriteLine("B: "+color.B.ToString());
}</syntaxhighlight>
=={{header|Clojure}}==
<
(.getPixelColor (java.awt.Robot.) x y))</
=={{header|Common Lisp}}==
Using Allegro and their Common Graphics package
<
(defun print-hex (n)
Line 222 ⟶ 561:
(get-pixel (position-x pos) (position-y pos))))
(print-hex (get-mouse-pixel))</
Sample output: (values are in RGBA order):
<
=={{header|Delphi}}==
<syntaxhighlight lang="delphi">
program ScreenPixel;
Line 300 ⟶ 640:
end.
</syntaxhighlight>
Example output:
Line 321 ⟶ 661:
Colour at cursor position X:2756 Y:59 = R(250) G(196) B(182)
</pre>
=={{header|F_Sharp|F#}}==
<
open System.Windows.Forms
Line 352 ⟶ 675:
let GetPixelAtMouse () =
let pt = Cursor.Position
GetPixel pt.X pt.Y</
=={{header|FutureBasic}}==
Tracks color information of the pixel under the current mouse x/y coordinates.
<syntaxhighlight lang="futurebasic">
_window = 1
begin enum 1
_view
_colorWell
_imageView
end enum
void local fn BuildWindow
window _window, @"ColorUnderMouse", (0,0,500,400), NSWindowStyleMaskTitled + NSWindowStyleMaskClosable
view subclass _view, (0,0,500,300)
colorwell _colorWell, YES, fn ColorWhite, ( 410, 310, 70, 70 ), NO, _window
end fn
void local fn DrawRect
CFArrayRef array = @[fn ColorRed, fn ColorOrange, fn ColorYellow, fn ColorGreen, fn ColorBlue, fn ColorWithRGB(0,0.29,0.51,1), fn ColorWithRGB(0.58,0.0,0.83,1)]
GradientRef grad = fn GradientWithColors( array )
GradientDrawInRect( grad, fn ViewFrame(_view), 0 )
end fn
void local fn DoMouse( tag as NSInteger )
CGPoint pt = fn EventLocationInView( tag )
ColorRef color = fn ViewColorAtPoint( tag, pt )
ColorWellSetColor( _colorWell, color )
cls : printf @"%.0fx, %.0fy, %@", pt.x, pt.y, color
end fn
void local fn DoDialog( ev as long, tag as long )
select ( tag )
case _view
select ( ev )
case _viewDrawRect : fn DrawRect
case _viewMouseDown : fn DoMouse( tag )
case _viewMouseDragged : fn DoMouse( tag )
end select
end select
select ( ev )
case _windowWillClose : end
end select
end fn
fn BuildWindow
on dialog fn DoDialog
HandleEvents
</syntaxhighlight>
{{output}}
[[File:Color Under Mouse.png]]
=={{header|Go}}==
{{libheader|RobotGo}}
<
import (
Line 370 ⟶ 750:
color := robotgo.GetPixelColor(x, y)
fmt.Printf("Color of pixel at (%d, %d) is 0x%s\n", x, y, color)
}</
{{out}}
Line 377 ⟶ 757:
Color of pixel at (659, 253) is 0x300a24
</pre>
=={{header|Groovy}}==
<syntaxhighlight lang="groovy">import java.awt.Robot
class GetPixelColor {
static void main(args) {
println getColorAt(args[0] as Integer, args[1] as Integer)
}
static getColorAt(x, y) {
new Robot().getPixelColor(x, y)
}
}
</syntaxhighlight>
=={{header|Icon}} and {{header|Unicon}}==
Icon and Unicon don't have direct access to the screen; however, we can read the colour of of a maximal sized window instead. The graphics procedure generates all pixels from a rectangular selection as a comma separated string with RGB values.
<
procedure main()
Line 404 ⟶ 798:
WDone(W) # q to exit
end
</syntaxhighlight>
{{libheader|Icon Programming Library}}
Line 414 ⟶ 808:
x=934,y=487 pixel=0,0,0</pre>
=={{header|
Note that the concept of "screen" has both hardware and operating system dependencies.
Assuming the OS is Windows (Windows being an operating system with fairly wide adoption, which also guarantees a specific concept of "screen"):
<syntaxhighlight lang="j">GetDC=: 'user32.dll GetDC >i i'&cd NB. hdx: GetDC hwnd
GetPixel=: 'gdi32.dll GetPixel >l i i i'&cd NB. rgb: GetPixel hdc x y
GetCursorPos=: 'user32.dll GetCursorPos i *i'&cd NB. success: point</syntaxhighlight>
Task example -- reading the color of the pixel at the mouse cursor:
<syntaxhighlight lang="j"> |.(3#256) #: GetPixel (GetDC<0),1{::GetCursorPos<0 0
121 91 213</syntaxhighlight>
Breaking this down:
<syntaxhighlight lang="j"> GetDC<0
1325469620
GetCursorPos<0 0
┌─┬───────┐
│1│101 255│
└─┴───────┘
1{::GetCursorPos<0 0
101 255
GetPixel 1325469620 101 255
13982585
|.(3#256)#:13982585
121 91 213</syntaxhighlight>
(The windows color result is packed as 0x00bbggrr. So, after splitting the integer result into bytes we need to reverse their order to get red,green,blue.)
=={{header|Java}}==
{{uses from|AWT|Robot}}
<
return new Robot().getPixelColor(x, y);
}</
=={{header|Julia}}==
<
# Windows GDI version
function getpixelcolors(x, y)
Line 437 ⟶ 859:
cols = getpixelcolors(x, y)
println("At screen point (x=$x, y=$y) the color RGB components are red: $(cols[1]), green: $(cols[2]), and blue: $(cols[3])")
</
At screen point (x=120, y=100) the color RGB components are red: 1, green: 36, and blue: 86
</pre>
=={{header|Kotlin}}==
<
fun getMouseColor(): Color {
Line 451 ⟶ 873:
fun getColorAt(x: Int, y: Int): Color {
return Robot().getPixelColor(x, y)
}</
=={{header|
{{libheader|ScrnXtra3 Xtra}}
<
sx = xtra("ScrnXtra3").new()
img = sx.ScreenToImage(rect(x, y, x+1, y+1))
return img.getPixel(0, 0)
end</
=={{header|Logo}}==
Line 499 ⟶ 889:
SHOW PIXEL
[255 255 255]
=={{header|M2000 Interpreter}}==
Colors is M2000 have a negative value for RGB, or positive for default colors (0 to 15 are the default colors). Also numbers above 0x80000000 (is a positive number), are Windows colors too. Point return a negative value so we have to make it positive to get the RGB value where Red is the least significant byte. Html color has R as the most significant byte (of three), so to display properly we have to use a mix of Right$(),Mid$() and Left$() functions on string representation on color$.
<syntaxhighlight lang="m2000 interpreter">
Module CheckColor {
\\ Print hex code for color, and html code for color
Line 513 ⟶ 904:
}
CheckColor
</syntaxhighlight>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
<
=={{header|Nim}}==
===Using GTK2===
{{libheader|GTK2}}
<
type Color = tuple[r, g, b: byte]
gtk2.nim_init()
proc getPixelColor(x, y: int32):
var p = pixbufNew(COLORSPACE_RGB, false, 8, 1, 1)
discard p.getFromDrawable(getDefaultRootWindow().Drawable,
getDefaultScreen().getSystemColormap(), x, y, 0, 0, 1, 1)
result = cast[
echo getPixelColor(0, 0)</
===Using GTK3===
{{libheader|gintro}}
<syntaxhighlight lang="nim">import gintro/[gtk, gobject, gio, gdk, gdkpixbuf]
type Color = tuple[r, g, b: byte]
proc getPixelColor(x, y: int32): Color =
var pixbuf = pixbufGetFromWindow(getDefaultRootWindow(), x, y, 1, 1)
result = cast[ptr Color](pixbuf.readPixels())[]
proc activate(app: Application) =
## Needed by GTK3.
discard
let app = newApplication("org.gtk.example")
connect(app, "activate", activate)
discard run(app)
echo getPixelColor(1500, 800)</syntaxhighlight>
=={{header|Perl}}==
This example works with MacOS, customize with the appropriate <tt>screencapture</tt> utility for other OSes.
<syntaxhighlight lang="perl">use strict;
use warnings;
use GD;
my $file = '/tmp/one-pixel-screen-capture.png';
system "screencapture -R 123,456,1,1 $file";
my $image = GD::Image->newFromPng($file);
my $index = $image->getPixel(0,0);
my($red,$green,$blue) = $image->rgb($index);
print "RGB: $red, $green, $blue\n";
unlink $file;</syntaxhighlight>
{{out}}
<pre>RGB: 20, 2, 124</pre>
=={{header|Phix}}==
{{libheader|Phix/pGUI}}
<
An example of this in use can be found in demo/pGUI/simple_paint.exw
Line 540 ⟶ 974:
{{works with|Windows}}
{{libheader|GD}}
<
$color = imagecolorat($im, 10, 50);
imagedestroy($im);</
=={{header|PicoLisp}}==
Using '[http://www.muquit.com/muquit/software/grabc/grabc.html grabc]'
as recommended in the C solution
<
(mapcar hex (cdr (line NIL 1 2 2 2))) )</
Output:
<pre>73,61,205
-> (73 61 205)</pre>
=={{header|
Access any pixel value on the sketch canvas. A color in Processing is a 32-bit int, organized in four components, alpha red green blue, as AAAAAAAARRRRRRRRGGGGGGGGBBBBBBBB. Each component is 8 bits (a number between 0 and 255), and can be accessed with alpha(), red(), green(), blue().
<syntaxhighlight lang="processing">void draw(){
color c = get(mouseX,mouseY);
println(c, red(c), green(c), blue(c));
}</syntaxhighlight>
For greater speed, pixels may be looked up by index in the pixels[] array, and color components may be retrieved by bit-shifting.
<syntaxhighlight lang="processing">void draw(){
loadPixels();
color c = pixels[mouseY * width + mouseX];
println(c, c >> 16 & 0xFF, c >> 8 & 0xFF, c >> 8 & 0xFF);
}</syntaxhighlight>
=={{header|Python}}==
{{libheader|PyWin32}}
{{works_with|Windows}}
<syntaxhighlight lang="python">def get_pixel_colour(i_x, i_y):
import win32gui
i_desktop_window_id = win32gui.GetDesktopWindow()
Line 598 ⟶ 1,012:
long_colour = win32gui.GetPixel(i_desktop_window_dc, i_x, i_y)
i_colour = int(long_colour)
win32gui.ReleaseDC(i_desktop_window_id,i_desktop_window_dc)
return (i_colour & 0xff), ((i_colour >> 8) & 0xff), ((i_colour >> 16) & 0xff)
print (get_pixel_colour(0, 0))</
{{libheader|PIL}}
{{works_with|Windows}}
<
import PIL.ImageGrab
return PIL.ImageGrab.grab().load()[i_x, i_y]
print (get_pixel_colour(0, 0))</
{{libheader|PIL}}
{{libheader|python-xlib}}
<
import PIL.Image # python-imaging
import PIL.ImageStat # python-imaging
Line 622 ⟶ 1,037:
return tuple(map(int, lf_colour))
print (get_pixel_colour(0, 0))</
{{libheader|PyGTK}}
<
import gtk # python-gtk2
o_gdk_pixbuf = gtk.gdk.Pixbuf(gtk.gdk.COLORSPACE_RGB, False, 8, 1, 1)
Line 630 ⟶ 1,045:
return tuple(o_gdk_pixbuf.get_pixels_array().tolist()[0][0])
print (get_pixel_colour(0, 0))</
{{libheader|PyQt}}
<
import PyQt4.QtGui # python-qt4
app = PyQt4.QtGui.QApplication([])
Line 640 ⟶ 1,055:
return ((i_colour >> 16) & 0xff), ((i_colour >> 8) & 0xff), (i_colour & 0xff)
print (get_pixel_colour(0, 0))</
=={{header|Racket}}==
See [https://github.com/zdhickman/rosetta-code/blob/master/get-pixel-color.rkt get-pixel-color.rkt].
=={{header|Raku}}==
(formerly Perl 6)
This example works with MacOS, customize with the appropriate <tt>screencapture</tt> utility for other OSes.
<syntaxhighlight lang="raku" line>use GD::Raw;
my $file = '/tmp/one-pixel-screen-capture.png';
qqx/screencapture -R 123,456,1,1 $file/;
my $fh = fopen($file, "rb") or die;
my $image = gdImageCreateFromPng($fh);
my $pixel = gdImageGetPixel($image, 0, 0);
my ($red,$green,$blue) =
gdImageRed( $image, $pixel),
gdImageGreen($image, $pixel),
gdImageBlue( $image, $pixel);
say "RGB: $red, $green, $blue";
fclose($fh);
unlink $file;</syntaxhighlight>
{{out}}
<pre>RGB: 20, 2, 124</pre>
Alternately, a version that should work in any X11 environment. Needs X11::xdo and MagickWand installed.
<syntaxhighlight lang="raku" line>signal(SIGINT).tap: { sleep .1; cleanup(); print "\n" xx 50, "\e[H\e[J"; exit(0) }
multi MAIN () {
use X11::libxdo;
my $xdo = Xdo.new;
my ($lx, $ly) = 0, 0;
loop {
sleep .1;
my ($x, $y, $) = $xdo.get-mouse-location;
next if $lx == $x and $ly == $y;
($lx, $ly) = $x, $y;
display $x, $y, |get-pixel($x, $y);
}
}
my %*SUB-MAIN-OPTS = :named-anywhere;
multi MAIN (
Int $x, #= Integer x coordinate to pick
Int $y, #= Integer y coordinate to pick
$q = False #= Boolean "quiet" mode, set truthy for decimal values, set to h for hex values
) {
my ($red, $green, $blue) = get-pixel($x, $y);
if $q {
$q.lc eq 'h' ??
( printf "%02X:%02X:%02X\n", $red, $green, $blue ) !!
( printf "%03d:%03d:%03d\n", $red, $green, $blue );
} else {
display($x, $y, $red, $green, $blue);
cleanup();
}
exit(0);
}
sub get-pixel ($x, $y) {
my $xcolor =
qqx/import -window root -crop 1x1+{$x-1 max 0}+{$y-2 max 0} -depth 8 txt:-/
.comb(/<?after '#'><xdigit> ** 6/);
|$xcolor.comb(2)».parse-base(16);
}
sub display ($x, $y, $r, $g, $b) {
print "\e[?25l\e[48;2;0;0;0m\e[38;2;255;255;255m\e[H\e[J";
printf " x: %4d y: $y\n", $x;
printf " RGB: %03d:%03d:%03d \n HEX: %02X:%02X:%02X\n",
$r, $g, $b, $r, $g, $b;
print "\e[38;2;{$r};{$g};{$b}m ",
('█' x 18 xx 6).join("\n "), "\n\n";
}
sub cleanup { print "\e[0m\e[?25h" }</syntaxhighlight>
=={{header|REXX}}==
Line 654 ⟶ 1,150:
The REXX program converts the hexadecimal attribute of the character at the location of the cursor to a familiar name of a color.
<
parse value cursor() with r c . /*get cursor's location in DOS screen. */
Line 674 ⟶ 1,170:
if hue=='0E'x then color= 'yellow' /*or bright yellow. */
if hue=='0F'x then color= 'white' /*or bright, brite white. */
say 'screen location ('r","c') color is:' color /*display color of char at row, column.*/</
{{out|output}}
<pre>
screen location (33,1) color is: yellow
</pre>
=={{header|Ring}}==
<
# Project : Color of a screen pixel
Line 718 ⟶ 1,212:
b = bytes2float(b)
return [r,g,b]
</syntaxhighlight>
Output:
<pre>
Line 726 ⟶ 1,220:
</pre>
=={{header|RPL}}==
RPL was designed for black-and-white LCD screens. The <code>PIX?</code> instruction returns 1 if the designated pixel is black - actually dark gray or blue, depending on the model - and 0 if it's not.
(10,10) PIX?
<code>PIX?</code> was introduced in 1990 with the HP-48. On previous machines (HP-28C/S), the only way to test a pixel was to convert the status of the 131x32 LCD matrix into a 548-character string using the <code>LCD→</code> command, and then test the appropriate bit of the appropriate character.
=={{header|Ruby}}==
This example requires ImageMagick >= 6.2.10 (works on X11, unsure about other platforms).
<
IMPORT_COMMAND = '/usr/bin/import'
Line 741 ⟶ 1,238:
end
end
end</
=={{header|Scala}}==
{{libheader|Scala}}
<
=={{header|Smalltalk}}==
{{works with|Smalltalk/X}}
<syntaxhighlight lang="smalltalk">Display rootView colorAt:(10@10).
Display rootView colorAt:(Display pointerPosition)</syntaxhighlight>
=={{header|Standard ML}}==
Works with PolyML
<syntaxhighlight lang="standard ml">open XWindows ;
val disp = XOpenDisplay "" ;
val im =
let
val pos = #4 (XQueryPointer (RootWindow disp)) ;
in
XGetImage (RootWindow disp) (MakeRect pos (AddPoint(pos,XPoint{x=1,y=1})) ) AllPlanes ZPixmap
end;
XGetPixel disp im (XPoint {x=0,y=0}) ;</syntaxhighlight>
result
val it = 6371827: int
=={{header|Tcl}}==
{{libheader|Tk}}
Works only on X11 or OSX with Xquartz.
<
package require Tk
Line 771 ⟶ 1,288:
# Demo...
puts [format "pixel at mouse: (%d,%d,%d)" \
{*}[getPixelAtPoint {*}[winfo pointerxy .]]]</
=={{header|
{{libheader|DOME}}
<syntaxhighlight lang="wren">import "dome" for Window, Process
import "graphics" for Canvas, Color
import "input" for Mouse
class Game {
static init() {
Window.title = "Color of a screen pixel"
Canvas.cls(Color.orange) // {255, 163, 0} in the default palette
}
static update() {
// report location and color of pixel at mouse cursor
// when the left button is first pressed
if (Mouse.isButtonPressed("left")) {
var x = Mouse.x
var y = Mouse.y
var col = Canvas.pget(x, y)
System.print("The color of the pixel at (%(x), %(y)) is %(getRGB(col))")
Process.exit(0)
}
}
static getRGB(col) { "{%(col.r), %(col.g), %(col.b)}" }
}</syntaxhighlight>
{{out}}
Sample output:
<pre>
$ ./dome color_of_screen_pixel.wren
The color of the pixel at (152, 115) is {255, 163, 0}
</pre>
=={{header|XPL0}}==
Line 825 ⟶ 1,331:
graphics.
<
int Color, X, Y;
Color:= ReadPix(X, Y);</
{{omit from|ACL2}}
Line 853 ⟶ 1,340:
{{omit from|Blast}}
{{omit from|Brainf***}}
{{omit from|EasyLang}}
{{omit from|GUISS}}
{{omit from|Lilypond}}
| |||