Working With Image Description Records2

AddImageDescriptionExtension

Adds an extension to an ImageDescriptionHandle .



 
pascal OSErr AddImageDescriptionExtension(

                     ImageDescriptionHandle desc, 

                     Handle extension, 

                     long idType);

desc: The handle of the ImageDescription to add the extension to.
extension: The handle containing the extension data.
idType: A four-byte signature indentifying the type of data being added to the ImageDescription.

DISCUSSION

This function allows the application to add custom data to an ImageDescriptionHandle. This data could be specific to the compressor component referenced by the image description.

Special Considerations

The Image Compression Manager makes a copy of the data referred to by the extension parameter. Thus, your application should dispose its copy of the data when it is no longer needed.

GetNextImageDescriptionExtensionType

Adds an extension to an ImageDescriptionHandle .



 
pascal OSErr GetNextImageDescriptionExtensionType(

                     ImageDescriptionHandle desc, 

                     long *idType);

desc: The ImageDescriptionHandle .
idType: A pointer to a field that, on entry, contains the starting point for the search. On return, will contain the next extension type found in the ImageDescriptionHandle .

DISCUSSION

This function allows the application to search for all types of extensions in an ImageDescriptionHandle . The idType field should be set to 0 to start the search. When no more extension types can be found, this field will be set to 0.

CountImageDescriptionExtensionType

Counts the number of extensions of a given type in an ImageDescriptionHandle .



 
pascal OSErr CountImageDescriptionExtensionType(

                     ImageDescriptionHandle desc, 

                     long idType, 

                     long *count);

desc: The ImageDescriptionHandle .
idType: A four-byte signature indentifying the type of extension data.
count: A pointer to a field to receive the number of extensions of the specified type.

DISCUSSION

This function, when used with the "GetNextImageDescriptionExtensionType" call, allows the application to determine the total set of extensions present in the ImageDescriptionHandle .

GetImageDescriptionExtension

Returns a new handle with the data from a specified image description extension.



 
pascal OSErr GetImageDescriptionExtension(

                     ImageDescriptionHandle desc, 

                     Handle *extension, 

                     long idType, 

                     long index);

desc: The ImageDescriptionHandle .
extension: A pointer to a field to receive a new handle with the extension data.
idType: The type of extension to receive.
index: The index (from 1 to the count as returned by "CountImageDescriptionExtensionType" ) of the extension to receive.

DISCUSSION

This function allows the application to get a copy of a specified image description extension.

Special Considerations

The Image Compression Manager allocates a new handle and passes it back in the extension parameter. Your application should dispose of the handle when it is no longer needed.

RemoveImageDescriptionExtension

Removes a specified extension from an ImageDescriptionHandle .



 
pascal OSErr RemoveImageDescriptionExtension(

                     ImageDescriptionHandle desc, 

                     long idType, 

                     long index);

desc: The ImageDescriptionHandle .
idType: The type of extension to receive.
index: The index (from 1 to the count as returned by "CountImageDescriptionExtensionType" ) of the extension to receive.

DISCUSSION

This function allows the application to remove a specified extension from an ImageDescriptionHandle . Note that any extensions that are present in the ImageDescriptionHandle after the deleted extension will have their index numbers renumbered.