GetDSequenceScreenBuffer
The GetDSequenceScreenBuffer function enables you to determine the location of the offscreen buffer allocated by the decompressor.
pascal OSErr GetDSequenceScreenBuffer (ImageSequence seqID,
GWorldPtr *gworld);
seqID
- Contains the unique sequence identifier that was returned by the
DecompressSequenceBegin function (described on page 3-107).
gworld
- Contains a pointer to a field to receive a pointer to the graphics world structure (defined by the
GWorld data type) describing the graphics world for the screen buffer. If the decompressor has allocated an offscreen buffer, the decompressor returns an appropriate GWorldPtr in the field referred to by this parameter. If the decompressor has not allocated a buffer, the function returns an error result code.
-
- You should not dispose of this graphics world--the returned pointer refers to a buffer that the Image Compression Manager is using. It is disposed of for you when the
CDSequenceEnd function is called. For details on CDSequenceEnd, see page 3-113.
DESCRIPTION
The decompressor uses this buffer for decompressed images. During decompression the decompressor writes the decompressed image to an offscreen buffer and then copies the results to the screen. This reduces the tearing effect that can result from decompressing directly to the screen. You cause the decompressor to use a screen buffer by setting the codecFlagUseScreenBuffer flag to 1 in the flags parameter to the DecompressSequenceBegin function.
RESULT CODES
| noErr | 0 | No error |
| paramErr | -50 | Invalid parameter specified |
