TColorMap

This structure is the primary storage for palette data.

Declaration

Source position: agraphics.pas line 1087

`type TColorMap = record`
`Flags: Byte;`		Colormap flags (COLORMAP_*)
`Type_: Byte;`		Colormap type, reflects version (COLORMAP_TYPE_)
`Count: Word;`		Number of palette entries
`ColorTable: PWord;`		Table of high nibbles of color values (see description above)
`cm_vpe: PViewPortExtra;`		ViewPortExtra, for faster access
`LowColorBits: PWord;`		Table of low nibbles of color values
`TransparencyPlane: Byte;`
`SpriteResolution: Byte;`
`SpriteResDefault: Byte;`
`AuxFlags: Byte;`		Additional flags (CMAF_*)
`cm_vp: PViewPort;`		Points back to a ViewPort this colormap belongs to
`NormalDisplayInfo: APTR;`
`CoerceDisplayInfo: APTR;`
`cm_batch_items: PTagItem;`
`VPModeID: ULONG;`
`PalExtra: PPaletteExtra;`		Structure controlling palette sharing
`SpriteBase_Even: Word;`		Color bank for even sprites
`SpriteBase_Odd: Word;`		The same for odd sprites
`Bp_0_base: Word;`
`Bp_1_base: Word;`
`end;`

Description

Color data itself is stored in two tables: ColorTable and LowColorBits. These fields are actually pointer to arrays of Words. Each Word corresponds to one color. Number of Words in these array is equal to Count value in this structure. ColorTable stores upper nibbles of RGB values, LowColorBits stores low nibbles.

Example:

color number 4, value: $00ABCDEF
   ColorTable[4] := $0ACE,
   LowColorBits[4] := $0BDF

SpriteBase fields keep bank number, not a color number. On m68k Amiga colors are divided into banks, 16 per each. So bank number is color number divided by 16. Base color is a number which is added to all colors of the sprite in order to look up the actual palette entry. AROS may run on different hardware where sprites may have base colors that do not divide by 16. In order to cover this bank numbers have a form: ((c and $0F) shl 8 ) or (c shr 4), where c is actual color number (i. e. remainder is stored in a high byte of Word).