Re: Custom text via Core Text in a layer.

FROM : John Harper
DATE : Mon Nov 19 19:45:44 2007

We saw something like this when implementing CATextLayer – if your 
string has NSColor attributes, you need an NSGraphicsContext pointing 
at the current CGContext you're drawing into, e.g. something like this:

[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:[NSGraphicsContext 
graphicsContextWithGraphicsPort:ctx flipped:NO]];

... draw text ...

[NSGraphicsContext restoreGraphicsState];

   John


On Nov 19, 2007, at 9:39 AM, John Clayton wrote:

> Hi All,
>
> I'm using the following code to draw an attributed string into a 
> layer (my own CATextLayer), but the text *always* draws black - is 
> there something simple that I'm doing wrong? I am of course assuming 
> that the colour into in the attributed string would determine how 
> that content is being drawn.
>
> Please note: most code is taken directly from the core-text API 
> docs :-)
>
> // HEADER
>
> @interface TextLayerCustom : EffectorBaseLayer
> {
>     NSAttributedString* _string;
> }
>
> @property(readwrite, retain) NSAttributedString* string;
>
> @end
>
> // IMPL
>
> @implementation TextLayerCustom
>
> - (void) drawInContext:(CGContextRef)context
> {
>     // core-text, here we come
>     
>     CGContextSetTextMatrix(context, CGAffineTransformIdentity);
>     
>     CGMutablePathRef path = CGPathCreateMutable();
>     if(path)
>     {
>         CGPathAddRect(path, NULL, self.bounds);
>         
>         CTFramesetterRef framesetter = 
> CTFramesetterCreateWithAttributedString(
>             (CFAttributedStringRef)_string
>         );
>         
>         // Create the frame and draw it into the graphics context
>         CTFrameRef frame = CTFramesetterCreateFrame(framesetter,
>             CFRangeMake(0, 0), path, NULL);
>         
>         if(frame)
>             CTFrameDraw(frame, context);
>         
>         if(framesetter)
>             CFRelease(framesetter);
>         
>         if(frame)
>             CFRelease(frame);
>     }
>     
>     if(path)
>         CFRelease(path);
> }
>
> - (id) init
> {
>     self = [super init];
>     _string = 0;
>     
>     // in order to redraw so that justification and line wrapping take 
> effect
>     [self setNeedsDisplayOnBoundsChange:YES];
>     
>     return self;
> }
>
> - (void) dealloc
> {
>     [_string release];
>     [super dealloc];
> }
>
> - (NSAttributedString*) string
> {
>     return [[_string retain] autorelease];
> }
>
> - (void) setString:(NSAttributedString *)str
> {
>     [_string release];
>     _string = [[NSMutableAttributedString alloc] 
> initWithAttributedString:str];
>     [self setNeedsDisplay];
> }
>
> @end
>
> thanks!!
>
>
> --
> John Clayton
> http://www.coderage-software.com/
>
>
>
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