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BitBltLin

Copy a linear block of video memory to another location in video memory.

Declaration

void NAPI GA_2DRenderFuncs::BitBltLin(
N_int32 srcOfs,
N_int32 srcPitch,
N_int32 srcLeft,
N_int32 srcTop,
N_int32 width,
N_int32 height,
N_int32 dstLeft,
N_int32 dstTop,
N_int32 mix)

Prototype In

snap/graphics.h

Parameters

srcOfs | Offset of source bitmap in video memory
srcPitch | Pitch of source bitmap in bytes
srcLeft | Left coordinate within source bitmap to copy
srcTop | Top coordinate within source bitmap to copy
width | Width of the rectangle in pixels
height | Height of the rectangle in scanlines
dstLeft | Left coordinate of destination
dstTop | Top coordinate of destination
mix | Mix code for the copy (GA_mixCodesType)

Description

This routine will copy a linear region of video memory from srcOfs from the start of video memory to the destination rectangle (dstLeft, dstTop, dstLeft+width-1, dstTop+height-1) with the specified mix. The mix code will be used to combine the source bitmap data with the pixels in the destination bitmap. The results of this routine are undefined if the video memory regions overlap.

Note that the srcLeft and srcTop coordinates define an offset within the source bitmap to be copied, so it is possible to only copy a portion of an offscreen bitmap. This is useful for storing multiple images in a single offscreen bitmap, or for handling the case of software clipping offscreen bitmaps if the destination lies outside of the software clip rectangle for the destination buffer.

This version is different to the standard BitBlt function in that the source bitmap to be copied can be non-conforming, and can have a different logical scanline width to the destination bitmap. This allows the bitmaps to be stored contiguously in offscreen video memory, rather than requiring the offscreen video memory to be divided up into rectangular regions, resulting in more efficient use of available offscreen memory for bitmap storage.

Note: The value of srcOfs must be aligned to the boundary specified in the BitmapStartAlign member of the GA_modeInfo structure, and the srcPitch value must be padded to multiples of the BitmapStridePad member of the GA_modeInfo structure.

See Also

BitBlt, BitBltSys, BitBltBM, SrcTransBlt, DstTransBlt, BitBltFx

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