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Chapter 3 - Image Compression Manager / Image Compression Manager Reference

Application-Defined Functions / Progress Functions

MyProgressProc

Your progress function should have the following form:

pascal OSErr MyProgressProc (short message, Fixed completeness, 
                              long refcon);

message

Indicates why the Image Compression Manager called your function. The following values are valid:

codecProgressOpen

Indicates the start of a long operation. This is always the first message sent to your function. Your function can use this message to trigger the display of your progress window.

codecProgressUpdatePercent

Passes completion information to your function. The Image Compression Manager repeatedly sends this message to your function. The completeness parameter indicates the relative completion of the operation. You can use this value to update your progress window.

codecProgressClose

Indicates the end of a long operation. This is always the
last message sent to your function. Your function can use this message as an indication to remove its progress window.

completeness

Contains a fixed-point value indicating how far the operation has progressed. Its value is always between 0.0 and 1.0. This parameter is valid only when the message field is set to codecProgressUpdatePercent.

refcon

Contains a reference constant value for use by your progress function. Your application specifies the value of this reference constant in the progress function structure you pass to the Image Compression Manager.

DESCRIPTION

The following functions have parameters that allow you to provide application-defined progress functions: FCompressImage, FDecompressImage, TrimImage, FCompressPicture, FCompressPictureFile,
DrawPictureFile, DrawTrimmedPicture,
DrawTrimmedPictureFile, MakeThumbNailFromPicture, MakeThumbnailFromPictureFile, MakeThumbnailFromPixMap, SetCompressedPixMapInfo, and GetCompressedPixMapInfo. If you pass a value of -1 in the progressProc parameter of any of these functions, you obtain a standard progress function.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified
codecAbortErr	-8967	Operation aborted by the progress function