GETPIXELRGB, GETPIXELRGB_W

Graphics Function: Returns the Red-Green-Blue (RGB) color value of the pixel at a specified location.

Module: USE DFLIB

Syntax

result = GETPIXELRGB (x, y)
result = GETPIXELRGB_W (wx, wy)

x, y
(Input) INTEGER(2). Viewport coordinates for pixel position.

wx, wy
(Input) REAL(8). Window coordinates for pixel position.

Results:

The result is of type INTEGER(4). The result is the pixel's current RGB color value.

In each RGB color value, each of the three colors, red, green, and blue, is represented by an eight-bit value (2 hex digits). In the value you retrieve with GETPIXELRGB, red is the rightmost byte, followed by green and blue. The RGB value's internal structure is as follows:

Larger numbers correspond to stronger color intensity with binary 1111111 (hex FF) the maximum for each of the three components. For example, #0000FF yields full-intensity red, #00FF00 full-intensity green, #FF0000 full-intensity blue, and #FFFFFF full-intensity for all three, resulting in bright white.

GETPIXELRGB returns the true color value of the pixel, set with SETPIXELRGB, SETCOLORRGB, SETBKCOLORRGB, or SETTEXTCOLORRGB, depending on the pixel's position and the current configuration of the screen.

SETPIXELRGB (and the other RGB color selection functions SETCOLORRGB, SETBKCOLORRGB, and SETTEXTCOLORRGB) sets colors to a color value chosen from the entire available range. The non-RGB color functions (SETPIXELS, SETCOLOR, SETBKCOLOR, and SETTEXTCOLOR) use color indexes rather than true color values. If you use color indexes, you are restricted to the colors available in the palette, at most 256. Some display adapters (SVGA and true color) are capable of creating 262,144 (256K) colors or more. To access any available color, you need to specify an explicit Red-Green-Blue (RGB) value with an RGB color function, rather than a palette index with a non-RGB color function.

Compatibility

STANDARD GRAPHICS QUICKWIN GRAPHICS LIB

See Also: SETPIXELRGB, GETPIXELSRGB, SETPIXELSRGB, GETPIXEL, GETPIXEL_W

Example

!  Build as QuickWin or Standard Graphics
USE DFLIB
INTEGER(4) pixcolor, rseed
INTEGER(2) status
REAL rnd1, rnd2
LOGICAL(4) winstat
TYPE (windowconfig) wc
CALL GETTIM (status, status, status, INT2(rseed))
CALL SEED (rseed)
CALL RANDOM (rnd1)
CALL RANDOM (rnd2)
!  Get the color index of a random pixel, normalized to
!  be in the window. Then set current color to that
!  pixel color.
winstat = GETWINDOWCONFIG(wc)
xnum = wc%numxpixels
ynum = wc%numypixels
pixcolor = GETPIXELRGB( INT2( rnd1*xnum ), INT2( rnd2*ynum ))
status = SETCOLORRGB (pixcolor)
END