On Apr 8, 2010, at 5:02 AM, vincent habchi wrote:
> I've been fiddling with NSAttributedString lately, and the way to display
> them through Core Text. In the docs, I've read that NSAttributedString and
> CFAttributedStringRef were supposed to be "toll free" bridged; I assumed that
> meant that one could be used in lieu of the other with (or maybe even
> without) a simple cast.
>
> But I found this is not true. Specifically, I was getting strange errors like
> "CFSet[Stroke|Fill]ColorFromColor : invalid context 0x0" each time I printed
> my NSAttributedString by CTLineDraw(), although I had a perfectly valid
> context. The glyph were drawn, but always in black, while I was attempting to
> get another color via the NSForegroundColorAttributeName. At the end, I had
> to replace the pair (NSColor, NSForeground…) by a (CGColorRef,
> kCTForeground…), and now it works.
>
> Is that supposed to be a "normal" behavior, did I misunderstand the meaning
> of "toll free", or is it a bug?
You need to have a current NSGraphicsContext for NSColor (and possibly other)
attributes. This is pretty easy, as in the following snippet from my own code:
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:[NSGraphicsContext
graphicsContextWithGraphicsPort:ctxt flipped:NO]];
CTFrameDraw(frame, ctxt);
CGContextFlush(ctxt);
CFRelease(frame);
[NSGraphicsContext restoreGraphicsState];
If this works, you can thank David Duncan for the fix:
http://lists.apple.com/archives/quartz-dev/2008/Jun/msg00043.html
hth,
Adam
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