AllocBitMap

Allocate a bitmap and attach bitplanes to it.

Declaration

Source position: agraphics.pas line 2450

Arguments

Description

Allocates and initializes a bitmap structure. Allocates and initializes bitplane data, and sets the bitmap's planes to point to it.

BMF_CLEAR

to specify that the allocated raster should be filled with color 0.

BMF_DISPLAYABLE

to specify that this bitmap data should be allocated in such a manner that it can be displayed. Displayable data has more severe alignment restrictions than non-displayable data in some systems.

BMF_INTERLEAVED

tells graphics that you would like your bitmap to be allocated with one large chunk of display memory for all bitplanes. This minimizes color flashing on deep displays. If there is not enough contiguous RAM for an interleaved bitmap, graphics.library will fall back to a non-interleaved one.

BMF_MINPLANES

causes graphics to only allocate enough space in the bitmap structure for "depth" plane pointers. This is for system use and should not be used by applications use as it is inefficient, and may waste memory.

NOTE:

When allocating using a friend bitmap, it is not safe to assume anything about the structure of the bitmap data if that friend BitMap might not be a standard amiga bitmap (for instance, if the workbench is running on a non-amiga display device, its Screen^.RastPort^.BitMap won't be in standard amiga format. The only safe operations to perform on a non-standard BitMap are:

• blitting it to another bitmap, which must be either a standard Amiga bitmap, or a friend of this bitmap.
• blitting from this bitmap to a friend bitmap or to a standard Amiga bitmap.
• attaching it to a rastport and making rendering calls.

Good arguments to pass for the friend_bitmap are your window's RPort^.BitMap, and your screen's RastPort^.BitMap. Do not pass @(screenptr^.BitMap)!

BitMaps not allocated with BMF_DISPLAYABLE may not be used as Intuition Custom BitMaps or as RasInfo^.BitMaps. They may be blitted to a BMF_DISPLAYABLE BitMap, using one of the BltBitMap() family of functions.

See also