Inside Macintosh: QuickTime /

Chapter 3 - Image Compression Manager / Image Compression Manager Reference

Image Compression Manager Functions / Working With Images

CompressImage

The CompressImage function allows your application to compress a single-frame image that is currently stored as a pixel map structure.

pascal OSErr CompressImage (PixMapHandle src, 
                           const  Rect *srcRect, 
                           CodecQ quality, CodecType cType,
                           ImageDescriptionHandle desc, 
                           Ptr data);

src

Contains a handle to the image to be compressed. The image must be stored in a pixel map structure.

srcRect

Contains a pointer to a rectangle defining the portion of the image to compress.

quality

Specifies the desired compressed image quality. See "Compression Quality Constants" on page 3-52 for valid values.

cType

Specifies a compressor type. You must set this parameter to a
valid compressor type (see Table 3-3 on page 3-59 for a list of the available compressor types).

desc

Contains a handle that is to receive a formatted image description structure. The Image Compression Manager resizes this handle for the returned image description structure. Your application should store this image description with the compressed image data.

data

Points to a location to receive the compressed image data. It is your program's responsibility to make sure that this location can receive at least as much data as indicated by the GetMaxCompressionSize function (described on page 3-63). The Image Compression Manager places the actual size of the compressed image into the dataSize field of the image description structure referred to by the desc parameter. This pointer must contain a 32-bit clean address. If you use a dereferenced, locked handle, you must call the Memory Manager's StripAddress routine before you use that handle with this parameter (for details on StripAddress, see Inside Macintosh: Memory).

DESCRIPTION

The CompressImage function presents a simplified interface to your application, eliminating some parameters for the sake of convenience.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified
memFullErr	-108	Not enough memory available
noCodecErr	-8961	The Image Compression Manager could not find the specified compressor

SEE ALSO

If you need to exert greater control over the compression operation, use the FCompressImage function, described in the next section.