_RGBA - QB64Official/qb64 GitHub Wiki

The _RGBA function returns the closest palette index (legacy SCREEN modes) OR the 32-bit LONG color value (32-bit screens).

Syntax

colorIndex~& = _RGBA(red&, green&, blue&, alpha&[, imageHandle&])

  • The value returned is either the closest color attribute number or a 32-bit _UNSIGNED LONG color value.
  • Return variable types must be LONG or the resulting color may lose the _BLUE value.
  • red& specifies the red component intensity from 0 to 255.
  • green& specifies the green component intensity from 0 to 255.
  • blue& specifies the blue component intensity from 0 to 255.
  • The _ALPHA value can be set to make the color transparent (0), opaque (255) or somewhere in between.
  • Parameter values outside of the 0 to 255 range are clipped.
  • Returns LONG 32-bit hexadecimal values from &H00000000 to &HFFFFFFFF with varying _ALPHA transparency.
  • When LONG values are PUT to file, the ARGB values become BGRA. Use LEFT$(MKL$(colorIndex~&), 3) to place 3 colors.
  • If imageHandle& is omitted, the image is assumed to be the current _DEST or SCREEN page.
  • Allows the blending of pixel colors red, green and blue to create any of 16 million colors.
  • NOTE: Default 32-bit backgrounds are clear black or _RGBA(0, 0, 0, 0). Use CLS to make the black opaque.

Example(s)

Setting a font's background color alpha to clear to overlay a second text color.


scrn& = _NEWIMAGE(400, 400, 32)
SCREEN scrn&
fnt& = _LOADFONT("C:\WINDOWS\FONTS\ARIAL.TTF", 26)
_FONT fnt&
X% = 20
Y% = 20
COLOR _RGB(255, 255, 255), _RGB(0, 0, 0) 'Foreground set to WHITE background to BLACK
_PRINTSTRING (X%, Y%), "Hello World"
COLOR _RGB(255, 0, 0), _RGBA(0, 0, 0, 0) 'Foreground set to RED background to TRANSPARENT BLACK
_PRINTSTRING (X% + 2, Y% + 2), "Hello World"
END

Explanation: _PRINTSTRING allows text or font colors to be alpha blended in 32 bit screens.

See Also