Re: Editing Graphics
Re: Editing Graphics
- Subject: Re: Editing Graphics
- From: "Alastair J.Houghton" <email@hidden>
- Date: Fri, 10 Oct 2003 09:46:06 +0100
On Thursday, October 9, 2003, at 10:53 pm, Geoffrey H Wathen wrote:
Hello everyone,
I'm new to developing in Cocoa, project builder, etc. I have some
experience with C programming, but I'm having some issues.
I'm trying to be able to read and change the color of a specified
pixel of an image map. I've been unable to locate information on how
to do this. Ideally, I have an image file, and I simply specify the
x, y coordinate of the pixel I'm after, and I can read and write the
color code of the pixel. Can anyone help me with this? Thanks.
It depends exactly what you want to do. You could use NSImage to load
the file (using -initWithContentsOfFile:), then -lockFocus on the
NSImage, draw using the AppKit or even directly using Core Graphics,
then -unlockFocus again. Alternatively, if you want to directly access
the image data from your code, you might be better off using NSImageRep
to load the image, then using the -bitmapData or -getBitmapDataPlanes:
method to obtain pointers to the image planes.
(BTW, to read a pixel from the currently locked view or image, you can
use NSReadPixel()).
Take a look at chapters 13 and 14 of Cocoa Programming, if you have it;
it gives a pretty thorough explanation of this area of the AppKit.
Kind regards,
Alastair.
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