CopyDeepMask

void CopyDeepMask(srcBits, maskBits, dstBits, srcRect, maskRect,

dstRect, mode, maskRgn);

const BitMap *srcBits ; source bitmap or pixel map

const BitMap *maskBits; bitmap or pixel map mask

const BitMap *dstBits; destination bitmap or pixel map

const Rect * srcRect; source rectangle

const Rect *maskRect; mask rectangle

const Rect *dstRect; destination boundary rectangle

short mode; mode setting

RgnHandle maskRgn; handle to mask region

returns none.

The CopyDeepMask procedure copies the source bitmap or pixel map to a

destination bitmap or pixel map, using a bitmap or pixel map as a mask. The

transfer can be performed in any of the copy modes described in QuickDraw,

with or without ditherCopy set.

The result is clipped to the mask region and the boundary rectangle of the

destination. The source and mask rectangles should be the same size. The mask

rectangle selects the portion of the mask pixel map to use as the mask. If you

don't want to clip to a mask region, pass NULL for the maskRgn parameter. The

dstRect and maskRgn coordinates are in the destination coordinate system; the

srcRect coordinates are in the source coordinate system; the maskRect

coordinates are in the mask coordinate system.

All three pixel maps may range from 1 to 32 in pixel depth. The pixel values

of the mask pixel map are applied as a filter between the source and destination

pixel maps. A black mask pixel value means that the copy operation is to take

the source pixel; a white value means that the copy operation is to take the

destination pixel. Intermediate values specify a weighted average, which is

calculated on a color component basis. For each pixel's color component the

calculation is

(1 - mask) * source + (mask) * destination

Thus high mask values for a pixel's color component reduce that component's

contribution from the source pixel map.

As with the CopyMask procedure, CopyDeepMask calls are not recorded in

pictures, and do not print. The mask pixel map cannot come from the screen.

Referenced by (10):