Weird Problem With CGImage
Weird Problem With CGImage
- Subject: Weird Problem With CGImage
- From: "Carter R. Harrison" <email@hidden>
- Date: Fri, 25 Apr 2008 10:51:08 -0400
This bug in my code has been driving me nuts for days, but I have
finally isolated the issue - only problem now is I don't understand
what I'm doing wrong.
I have a CGImage that I want to get the raw data bytes for. My code
is below:
CGImageRef sectionToCache = CGImageCreateWithImageInRect(backingStore,
CGRectMake(x, y, cx, cy));
NSLog(@"CGImage to cache has dimensions %d x %d and %d bytes per row",
CGImageGetWidth(sectionToCache), CGImageGetHeight(sectionToCache),
CGImageGetBytesPerRow(sectionToCache));
CFDataRef dataRef =
CGDataProviderCopyData(CGImageGetDataProvider(sectionToCache));
NSLog(@"Length of cachedImage data: %d", CFDataGetLength(dataRef));
When the code runs, the log spits out the following:
CGImage to cache has dimensions 417 x 234 and 1668 bytes per row
Length of cachedImage data: 6672
What is killing me here is that the CGImage has dimensions 417x234 and
1668 bytes per row. That to me means that the CFDataRef that I am
obtaining should be 390,312 bytes (234 x 1668). But the CFDataRef is
only 6,672 bytes which is nowhere close to what I think I should be
getting. So I must be doing something wrong in trying to get the
bitmap data, but I'm not sure what else to do and I even found some
Apple docs with an example doing the exact same thing that I am
doing. Can anybody provide some insight on this? Thanks everybody.
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