Re: Code and Decode a CGContextRef
Re: Code and Decode a CGContextRef
- Subject: Re: Code and Decode a CGContextRef
- From: Jean-Daniel Dupas <email@hidden>
- Date: Wed, 28 Nov 2007 18:19:03 +0100
Le 28 nov. 07 à 17:57, Jason Barker a écrit :
Actually, I knew that it was a reference and not a "container".
I've just
not done much with C-style functions and structs, and so Quartz
makes my
head swim a bit, trying to change from Objective-C style syntax to
C-style
syntax.
Anyway, I just wasn't sure if I had to code/decode each property
from the
CGContextRef (width, height, bitsPerComponent, bytesPerRow, dataSize,
colorspace, data, etc.) or if there was an Objective-C type that
could just
do it all for me.
With regards to the function CGImageDestinationCreateWithData(), I
think I
understand what to pass in for the last three parameters it takes
(namely
'type', 'count' and 'options') but I don't know how to go from a
CGImageRef
to a CFMutableDataRef. Is this what I'm supposed to do? And then
once I have
a CGImageDestinationRef, how do I code/decode that?
Thanks for your help,
Jason
The CFMutableDataRef is the destination buffer where it will store
your image data.
NSMutableData *imgData = [NSMutableData data];
CGImageDestinationRef dest = CGImageDestinationCreateWithData
(imgData, ...);
CGImageDestinationAddImage(dest, myCGImageRef, NULL);
CGImageDestinationFinalize(dest);
CFRelease(dest);
Now, imgData should contains your image data and you can encode it.
Your image can contains a lots of properties (width, height,
resolution, colorspace, etc...) so you don't have to archive
additional meta-data.
To restore the context, you probably can use CGImageSource to create
a CGImageRef, creating your context as needed, and then draw the
image on your new context.
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