Inside Macintosh: QuickTime /

Chapter 3 - Image Compression Manager / Image Compression Manager Reference

Image Compression Manager Functions / Making Thumbnail Pictures

MakeThumbnailFromPixMap

The MakeThumbnailFromPixMap function creates an 80-by-80 pixel thumbnail picture from a specified pixel map structure.

pascal OSErr MakeThumbnailFromPixMap (PixMapHandle src, 
                              const Rect *srcRect,
                              short colorDepth, 
                              PicHandle thumbnail,
                              ProgressProcRecordPtr progressProc);

src

Contains a handle to the image from which the thumbnail is to be extracted. The image must be stored in a pixel map structure.

srcRect

Contains a pointer to a rectangle defining the portion of the image to use for the thumbnail.

colorDepth

Specifies the depth at which the image is likely to be viewed. If you set this parameter to 0, the Image Compression Manager determines the appropriate value for the source image. Values of 1, 2, 4, 8, 16, 24, and 32 indicate the number of bits per pixel for color images. Values of 34, 36, and 40 indicate 2-bit, 4-bit, and 8-bit grayscale, respectively, for grayscale images.

thumbnail

Contains a handle to the destination picture structure for the thumbnail image. The compressor resizes this handle for the resulting data.

progressProc

Points to a progress function structure. During the operation, the Image Compression Manager will occasionally call a function you provide in order to report its progress (see "Progress Functions" beginning on page 3-146, for more information about progress functions). This parameter contains a pointer to a structure that identifies that progress function. If you have not provided a progress function, set this parameter to nil. If you pass a value of -1, you obtain a standard progress function.

DESCRIPTION

The thumbnail returned is an 80-by-80 pixel picture, but the aspect ratio is maintained.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified
memFullErr	-108	Not enough memory available
codecAbortErr	-8967	Operation aborted by the progress function