Apple Bug Friday! 60

2007-05-25 11:00:39 -08:00

This bug is NSImageInterlaced has no effect. It was filed on 2007-05-12 at 00:50 PDT.


NSBitmapImageRep does not generate interlaced data, regardless of the value of NSImageInterlaced.

Steps to Reproduce:

  1. Obtain an NSBitmapImageRep using +imageRepWithData:.
  2. Send it the -representationUsingType:properties: message, with either NSPNGFileType (as documented) or NSGIFFileType (as expected but not documented), and a dictionary that maps NSImageInterlaced to an NSNumber representing YES.

Expected Results:

You get file data that is interlaced.

Actual Results:

You get file data that is not interlaced.


None known.


A test app is included. This is a command-line utility that aims to interlace an image. It reads an image using NSData, creates an NSBitmapImageRep as described above, prints its NSImageInterlaced property (if it has oneā€”see rdar://5198981), and writes out the same image to an output file (either PNG or GIF) with NSImageInterlaced mapped to YES. In practice, the resulting image is never interlaced (checked with file(1) in the case of PNG, and GifBuilder in the case of GIF.

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