Re: Compositing to custom view in Cocoa

FROM : I. Savant
DATE : Fri Jun 30 22:52:38 2006

George:

  Thanks for this - I hadn't considered that solution.

--
I.S.


On Jun 30, 2006, at 11:17 AM, George Orthwein wrote:

> On Jun 30, 2006, at 10:36 AM, Kenny Millar wrote:

>> Because I need to change the foreground colour too, and every 
>> location on
>> the 'screen' can have a different forground/background colour.

>
> It would take two operations. You'd composite the text with 
> transparent background with a solid fill color as source, using 
> CompositeSourceIn. That colorizes the text and leaves the 
> transparency. Then you'd draw that over the background color. At 
> least, I think that should work. :)
>
> If you can't add transparency, I just discovered -
> colorizeByMappingGray:toColor:blackMapping:whiteMapping. It kinda 
> works for me but for some reason the white areas are using the gray 
> color instead of the specified white color. But I did end up with 
> custom back/foreground colors.
>
> I'm surprised there is not an NSImage method for using a grayscale 
> image as a mask. Half the messages in the archives asking about 
> this topic reference CompositeSourceIn, but I see now that that 
> will only work if you already have some transparency. There do seem 
> to be some Quartz methods though:
> http://developer.apple.com/documentation/GraphicsImaging/Conceptual/
> drawingwithquartz2d/dq_images/chapter_12_section_6.html
>
> Looks like a good candidate for an NSBitmapImageRef category. :) 
> (though I don't actually know how difficult using the quartz calls 
> would be...)
>
> George
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