Inside Macintosh: QuickTime Components /

Chapter 4 - Image Compressor Components / Image Compressor Components Reference

Functions / Direct Functions

CDTrimImage

Your component receives the CDTrimImage request whenever an application calls the TrimImage function. Your component adjusts a compressed image to the boundaries defined by a rectangle specified by your application. The resulting image data is still compressed and is in the same compression format as the source image.

Note

The CDTrimImage function is optional. If your component doesn't support it, it should return the codecUnimpError result code.

pascal ComponentResult CDTrimImage 
               (ImageDescriptionHandle desc, Ptr inData, 
                long inBufferSize, DataProcRecordPtr dataProc,
                Ptr outData, long outBufferSize, 
                FlushProcRecordPtr flushProc, Rect *trimRect,
                ProgressProcRecordPtr progressProc);

desc

Contains a handle to the image description structure that describes the compressed image. Your component updates this image description to refer to the resized image.

inData

Points to the compressed image data. If the entire compressed image cannot be stored at this location, the application may provide a data-loading function (see the description of the dataProc parameter to this function for details). This is a 32-bit clean address.

inBufferSize

Specifies the size of the buffer to be used by the data-loading
function specified by the dataProc parameter. If the application did not specify a data-loading function, this parameter is nil.

dataProc

Points to a data-loading function structure. If the data stream is not all in memory when the application calls the Image Compression Manager's GetCompressedImageSize function, your component may call an application function that loads more compressed data (see the chapter "Image Compression Manager" in Inside Macintosh: QuickTime for more information about data-loading functions). This parameter contains a pointer to a structure that identifies the data-loading function. If the application did not provide a data-loading function, this parameter is nil. In this case, the entire image must be in memory at the location specified by the inData parameter.

outData

Points to a buffer to receive the trimmed image. If there is not sufficient memory to store the compressed image, the application may choose to write the compressed data to mass storage during the compression operation. The flushProc parameter identifies the data-unloading function. This is a 32-bit clean address.

Your component should place the actual size of the resulting image into the dataSize field of the image description referred to by the desc parameter.

outBufferSize

Specifies the size of the buffer to be used by the data-unloading
function specified by the flushProc parameter. If the application did not specify a data-unloading function, this parameter is nil.

flushProc

Points to a data-unloading function structure. If there is not enough memory to store the compressed image, your component may call an application function that unloads some of the compressed data (see the chapter "Image Compression Manager" in Inside Macintosh: QuickTime for more information about data-unloading functions). This parameter contains a pointer to a structure that identifies that data-unloading function. If the application did not provide a data-unloading function, this parameter is nil. In this case, your component writes the entire compressed image into the memory location specified by the outData parameter.

trimRect

Contains a pointer to a rectangle that defines the desired image dimensions. Your component adjusts the rectangle values so that they refer to the same rectangle in the resulting image (this is necessary whenever data is removed from the beginning of the image).

progressProc

Points to a progress function structure. During the operation, your component should occasionally call an application function to report its progress (see the chapter "Image Compression Manager" in Inside Macintosh: QuickTime for more information about progress functions). This parameter contains a pointer to a structure that identifies that progress function. If the application did not provide a progress function, this parameter is nil.

DESCRIPTION

Only decompressors receive this request. If the TrimImage function has been called by an application, the resulting picture should be modified.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified
memFullErr	-108	Not enough memory available
noCodecErr	-8961	Image Compression Manager could not find the specified compressor
codecUnimpErr	-8962	Feature not implemented by this compressor
codecSpoolErr	-8966	Error loading or unloading data
codecAbortErr	-8967	Operation aborted by the progress function

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