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我有一些使用CGContextAddArc在iPhone應用程序中繪製的閉合形狀,並且我想對其應用漸變,但不能找到任何好的例子。我發現所有剪輯都被綁定到某個繪製的形狀引用CGRect,但我需要將漸變邊界剪裁爲非CGRect形狀。任何想法/幫助?將漸變應用於使用AddArc繪製的非正方形形狀
我使用Xcode 4.2.1與故事板和iOS5,雖然這些形狀正在以編程方式繪製在視圖中。
我用畫我的非正方形代碼:
CGContextRef context = UIGraphicsGetCurrentContext();
//set context-based constants
double widthMiddle = self.frame.size.width/2;
double heightMiddle = self.frame.size.height/2;
double avgDimension = (widthMiddle + heightMiddle)/2;
float arcRadius = avgDimension * .9;
float innerRadius = avgDimension * .4;
double startAngle = 2 * (sectionNumber - 1) * (M_PI/3);
double endAngle = (2 * (sectionNumber * (M_PI/3))) - [sectionSpacing doubleValue];
double interfaceAngle = [sectionSpacing doubleValue] * (innerRadius/arcRadius);
double ratingRadius = innerRadius + ((arcRadius-innerRadius) * percentGood);
double percentInterfaceAngle = interfaceAngle * (1-percentGood);
//NSLog(@"InterfaceAngle and percentInterfaceAngle are: %f/%f", interfaceAngle, percentInterfaceAngle);
//draw grey background shape
CGContextBeginPath(context);
CGContextSetLineWidth(context, [lineWeight doubleValue]);
//CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextSetRGBStrokeColor(context, .65, .65, .65, 1);
CGContextSetAllowsAntialiasing(context, 1);
//outer arc
CGContextAddArc(context, //context
widthMiddle, //X-value for center point of arc
heightMiddle, //Y-value for center point of arc
arcRadius, //Radius of the arc
startAngle, //start angle in radians
endAngle, //end angle in radians (2pi = full circle)
0); //Clockwise? 1 = true
//inner arc
CGContextAddArc(context, //context
widthMiddle, //X-value for center point of arc
heightMiddle, //Y-value for center point of arc
innerRadius, //Radius of the arc
endAngle - interfaceAngle, //start angle in radians
startAngle + interfaceAngle, //end angle in radians (2pi = full circle)
1); //Clockwise? 1 = true
CGContextClosePath(context);
//CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
CGContextSetRGBFillColor(context, .65, .65, .65, 1);
//CGContextSetAlpha(context, .6);
CGContextDrawPath(context, kCGPathFillStroke);
是的!那樣做了。感謝您的幫助,並感謝(長)延遲確認。 – Amos 2012-01-21 02:55:16