Graphics Subroutine: Returns the Red-Green-Blue (RGB) color values of multiple pixels.
Module
USE IFQWIN
CALL GETPIXELSRGB (n,x,y,color)
n |
(Input) INTEGER(4). Number of pixels to get. Sets the number of elements in the other argument arrays. |
x, y |
(Input) INTEGER(2). Parallel arrays containing viewport coordinates of pixels. |
color |
(Output) INTEGER(4). Array to be filled with RGB color values of the pixels at x and y. |
GETPIXELS fills in the array color with the RGB color values of the pixels specified by the two input arrays x and y. These arrays are parallel: the first element in each of the three arrays refers to a single pixel, the second element refers to the next pixel, and so on.
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 values you retrieve with GETPIXELSRGB, 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 11111111 (hex Z'FF') the maximum for each of the three components. For example, Z'0000FF' yields full-intensity red, Z'00FF00' full-intensity green, Z'FF0000' full-intensity blue, and Z'FFFFFF' full-intensity for all three, resulting in bright white.
GETPIXELSRGB is a much faster way to acquire multiple pixel RGB colors than individual calls to GETPIXELRGB. GETPIXELSRGB returns an array of true color values of multiple pixels, set with SETPIXELSRGB, SETCOLORRGB, SETBKCOLORRGB, or SETTEXTCOLORRGB, depending on the pixels' positions and the current configuration of the screen.
SETPIXELSRGB (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 RGB value with an RGB color function, rather than a palette index with a non-RGB color function.
Example
! Build as QuickWin or Standard Graphics
USE IFQWIN
INTEGER(4) color(50), result
INTEGER(2) x(50), y(50), status
TYPE (xycoord) pos
result = SETCOLORRGB(Z'FF')
CALL MOVETO(INT2(0), INT2(0), pos)
status = LINETO(INT2(100), INT2(200))
! Get 50 pixels at line 30 in viewport
DO i = 1, 50
x(i) = i-1
y(i) = 30
END DO
CALL GETPIXELSRGB(300, x, y, color)
! Move down 30 pixels and redisplay pixels
DO i = 1, 50
y(i) = y(i) + 30
END DO
CALL SETPIXELSRGB (50, x, y, color)
END