Technical Q&A QA1276
CGImageRef contents are immutable
Q: Am I allowed to change the contents of a CGImageRef after it has been created?
A: No. Quartz 2D considers the contents of a CGImageRef to be constant after creation. This allows several optimizations, including caching the contents as necessary to improve performance. In addition, this allows the printing system on Mac OS X to properly handle documents with many copies of the same image and only embed one copy in the resulting PDF spool file.
Document Revision History
| Date | Notes |
|---|---|
| 2013-08-13 | Updated formatting. |
| 2003-07-17 | New document that explains that CGImageRef contents are considered immutable once created. |
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