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POCreate CGContext for CoreText
 

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    <p>I was trying to render some CoreText in a CALayer, so that i can adjust the alpha of that layer explicitly. I tried overriding the drawRect: method but that, as far as i know, only draws on the root layer of the view, and i have two sublayers, a bg image and the CoreText. Here's the method that attempts to draw the CoreText layer: (which works in drawRect if i remove the createContext code)</p> <pre><code>-(void) drawTextLayer { //get context UIGraphicsBeginImageContextWithOptions(CGSizeMake(250.0, 137.0), YES, 1.0); CGContextRef context = UIGraphicsGetCurrentContext(); //draw text //attribute string NSMutableAttributedString *attrStr = [[NSMutableAttributedString alloc] initWithString:displayTxt]; //get font NSString *fontPath = [[NSBundle mainBundle] pathForResource:@"idolwild" ofType:@"ttf"]; CFURLRef url = CFURLCreateWithFileSystemPath(kCFAllocatorDefault, (CFStringRef)fontPath, kCFURLPOSIXPathStyle, false); CGDataProviderRef dataProvider = CGDataProviderCreateWithURL(url); CGFontRef theCGFont = CGFontCreateWithDataProvider(dataProvider); CTFontRef idolwild = CTFontCreateWithGraphicsFont(theCGFont, 16.0, &amp;CGAffineTransformIdentity, nil); CFRelease(theCGFont); CFRelease(dataProvider); CFRelease(url); [attrStr addAttribute:(id)kCTFontAttributeName value:(id)idolwild range:NSMakeRange(0, [attrStr length])]; //create paragraph style and assign text alignment to it CTTextAlignment alignment = kCTCenterTextAlignment; CTParagraphStyleSetting _settings[] = { {kCTParagraphStyleSpecifierAlignment, sizeof(alignment), &amp;alignment} }; CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(_settings, sizeof(_settings) / sizeof(_settings[0])); //set paragraph style attribute [attrStr addAttribute:(id)kCTParagraphStyleAttributeName value:(id)paragraphStyle range:NSMakeRange(0, [attrStr length])]; [attrStr addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor clearColor].CGColor range:NSMakeRange(0, [attrStr length])]; [attrStr addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor blackColor].CGColor range:NSMakeRange(0, [[wordRanges objectAtIndex:currentTextindex] intValue])]; //layout master CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrStr); //bounding eclipse CGMutablePathRef boundingEclipse = CGPathCreateMutable(); CGPathAddEllipseInRect(boundingEclipse, NULL, boundingEclipseRect); //ctframe CTFrameRef bubbleFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), boundingEclipse, NULL); // flip the coordinate system CGContextSetTextMatrix(context, CGAffineTransformIdentity); CGContextTranslateCTM(context, 0, self.bounds.size.height); CGContextScaleCTM(context, 1.0, -1.0); //fill bg to visual CGContextAddPath(context, boundingEclipse); [[UIColor greenColor] setFill]; CGContextFillPath(context); //draw CTFrameDraw(bubbleFrame, context); //add to layer UIImage *tempImage = UIGraphicsGetImageFromCurrentImageContext(); textLayer.contents = tempImage; //cleanup CGPathRelease(boundingEclipse); CFRelease(framesetter); CFRelease(bubbleFrame); CFRelease(idolwild); CGContextRelease(context); [attrStr release]; } </code></pre> <p>--any theory on CALayers and CGContexts is much appreciated </p>
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