Re: Code and Decode a CGContextRef
Re: Code and Decode a CGContextRef
- Subject: Re: Code and Decode a CGContextRef
- From: Alastair Houghton <email@hidden>
- Date: Wed, 28 Nov 2007 10:43:29 +0000
On 28 Nov 2007, at 05:57, Jason Barker wrote:
Uh, could both of you type slower so that I can understand you? :)
The image data in the CGContextRef is bitmap data. If I save out the
properties of the context individually, how should I handle the data?
Can that be converted to an NSData object?
The CGContextRef isn't a container for bitmap data, it's just a
reference; a handle, if you will (if you're a Windows programmer, it's
similar to an HDC; if you're an X11 programmer, it's like a GC). As
such, encoding or decoding it doesn't make any sense (in the same way
that you wouldn't encode or decode a file handle or a socket or
anything like that).
However, if the context in question is one of the types that holds
data of some sort (e.g. a bitmap context holds image data; a PDF
context holds PDF data) then you could save the data, then in your
decode routine create a new context with similar properties and load
the data into it.
My guess is that you *probably* want to use
CGBitmapContextCreateImage() to get a CGImageRef, then
CGImageDestinationCreateWithData() or
CGImageDestinationCreateWithURL() to turn it into a bitmap file of
some sort. I wouldn't go trying to store the data manually (e.g. via
CGBitmapContextGetData()) since there are a large number of possible
bitmap formats and supporting all of them in your own code would be
tedious, not to mention hard to test.
Kind regards,
Alastair.
--
http://alastairs-place.net
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