Tech Tip: Converting from 4D's color palette to RGB

PRODUCT: 4D | VERSION: 11 | PLATFORM: Mac & Win

Published On: August 6, 2009

Assume that you want to store a color from 4D's color palette (1-256) for programmatic use in your code. The following code converts an indexed color from 4D's color palette (1-256) to an RGB longint value (0x00RRGGBB).

`Util_ColorIndexToRGB( Ndx_I ) -> RGB_L
C_LONGINT($0;$RGB_L)
C_LONGINT($Ndx;$1)
C_LONGINT($ChartColor_L;$Red_L;$Green_L;$Blue_L)

$Ndx:=$1

$ChartColor_L:=CT Index to color ($Ndx)

` Extract the RGB values. CT COLOR TO RGB returns values from 0..65535
` in the format of 0x00bbggrr, not in the needed encoding of 0x00rrggbb
$Red_L:=($ChartColor_L & 0x00FF) ` get the red byte, 0..255
$Green_L:=(($ChartColor_L >> 8) & 0x00FF) ` get the green byte, 0..255
$Blue_L:=(($ChartColor_L >> 16) & 0x00FF) ` get the blue byte, 0..255

` Combine the RGB values to create a 4D RGB (0x00rrggbb) value
$RGB_L:=($Red_L << 16)+($Green_L << 8)+$Blue_L

$0:=$RGB_L

Use of the above methods would look like this:

C_LONGINT($ColorNdx_L;$RGB_L)

$ColorNdx_L:=122 ` Any value from 1-256
$RGB_L:=Util_ColorIndexToRGB( $ColorNdx_L )

Commented by Charlie Vass on August 12, 2009 at 10:00 AM

The method "Util_ColorIndexToRGB" is further demonstrated in asset #75865