All Databases Inside Mac - Basic Toolbox

CopyMask

Copy between bitMaps or pixMaps, using masking bitMap

#include <Quickdraw.h> Color Quickdraw

void CopyMask(srcMap, maskMap, destMap, srcRect, maskRect, destRect );

BitMap *srcMap ; address of BitMap or pixMap of source image

storage

BitMap *maskMap ; address of BitMap identifying mask

BitMap *destMap ; address of BitMap or pixMap to receive masked

image

Rect *srcRect ; position and size of source image

Rect *maskRect ; position and size of masking area

Rect *destRect ; position and size of destination area

CopyMask copies image data from one bitMap or pixMap to an other, under

control of a mask. Bits are copied from srcMap to destMap only where

maskMap is a 1. For the 256K ROMs, CopyMask accepts both bitMaps and

pixMaps as either the source or the destination. However, the maskBits have to

be in the form of a bitMap.

srcMap and . . .

maskMap and . . .

destMap are addresses of 14-byte BitMap structures. The memory

pointed to by srcMap.baseAddr contains the source image; the image

will be logically ANDed with data at maskMap.baseAddr and the

resulting bits are copied into the memory addressed by

destMap.baseAddr.

srcRect and . . .

maskRect and . . .

destRect are the addresses of 8-byte Rect structures. Each identifies the

size and position within its respective bitMap or pixMap. In Color

QuickDraw, the source and mask can be stretched to fit the size of the

destination. Remember, however, that the source and the mask still

need to be the same size.

Returns: none

Notes: This function is used, along with CalcMask, to implement the "lasso

feature of many paint programs. This is great for handling bit copies that

require a complex clipping area; it's much faster than CopyBits.

srcMap maskMap destMap

If destMap belongs to the current CGrafPort or GrafPort, then the image is

clipped to its visRgn, portRect, and bitMap.bounds rectangle as well as

being masked by the data in maskMap.

Note: In the 128K ROMs, all three rectangles should be the same size; no

scaling is performed. In the 256K ROMs, Color Quickdraw correctly

stretches or shrinks the the source and mask data to fit the destRect. Still,

the source and the mask need to be the same size.

The srcMap and destMap may be the same, but the rectangles should not

overlap (no warning is given; you have to know this beforehand). If the

source and destination GrafPorts overlap, you may need to convert srcRect

and destRect to global coordinates (see LocalToGlobal) and specify

screenBits for both bitMap parameters).

Remember to set the foreground to black and the background to white

during Color QuickDraw CopyBits operations since, otherwise unwanted

colors may be applied to the image when it is copied.

The maskMap is typically an off-screen bitMap or pixMap (see

CopyBits, SetPortPix and SetPortBits).

Referenced by (34):