The _RGB function returns the closest palette attribute index (legacy SCREEN modes) OR the LONG 32-bit color value (32-bit screens).
Syntax
colorIndex~& = _RGB(red&, green&, blue&[, imageHandle&])
Description
- 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 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.
- Intensity values outside the valid range are clipped.
- Returns LONG 32-bit hexadecimal values from &HFF000000 to &HFFFFFFFF, always with full _ALPHA.
- When LONG values are PUT to file, the ARGB values become BGRA. Use LEFT$(MKL$(colorIndex~&), 3) to place 3 colors.
- If the imageHandle& is omitted the image is assumed to be the current _DEST or SCREEN page.
- Colors returned are always opaque as the transparency value is always 255. Use _ALPHA or _CLEARCOLOR to change it.
- NOTE: Default 32-bit backgrounds are clear black or _RGBA(0, 0, 0, 0). Use CLS to make the black opaque.
Example(s)
Converting the color port RGB intensity palette values 0 to 63 to 32 bit hexadecimal values.
SCREEN 12
DIM hex32$(15)
FOR attribute = 1 TO 15
OUT &H3C7, attribute 'set color attribute to read
red = INP(&H3C9) * 4 'multiply by 4 to convert intensity to 0 to 255 RGB values
grn = INP(&H3C9) * 4
blu = INP(&H3C9) * 4
hex32$(attribute) = "&H" + HEX$(_RGB32(red, grn, blu)) 'always returns the 32 bit value
COLOR attribute
PRINT "COLOR" + STR$(_RGB(red, grn, blu)) + " = " + hex32$(attribute) 'closest attribute
NEXT
COLOR 1 = &HFF0000A8
COLOR 2 = &HFF00A800
COLOR 3 = &HFF00A8A8
COLOR 4 = &HFFA80000
COLOR 5 = &HFFA800A8
COLOR 6 = &HFFA85400
COLOR 7 = &HFFA8A8A8
COLOR 8 = &HFF545454
COLOR 9 = &HFF5454FC
COLOR 10 = &HFF54FC54
COLOR 11 = &HFF54FCFC
COLOR 12 = &HFFFC5454
COLOR 13 = &HFFFC54FC
COLOR 14 = &HFFFCFC54
COLOR 15 = &HFFFCFCFC
Note: This procedure also shows how the returns from _RGB and _RGB32 differ in a non-32 bit screen mode.