A callback function that advances the current position in the data stream supplied by the provider.
- iOS 2.0+
- macOS 10.5+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Core Graphics
A generic pointer to private data shared among your callback functions. This is the same pointer you supplied to
The number of bytes to skip.
The number of bytes that were actually skipped.
When Core Graphics needs to advance forward in the provider’s data stream, your function is called.