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核心函数是:CGContextAddArc(CGContextRef c, CGFloat x, CGFloat y, CGFloat radius, CGFloat startAngle, CGFloat endAngle, int clockwise) * CGContextRef: 图形上下文 * x,y: 开始画的坐标 * radius: 半径 * startAngle, endAngle: 开始的弧度,结束的弧度 * clockwise: 画的方向(顺时针,逆时针) 有了这个函数可以画出任意扇形,所以饼图也不再话下. #define PI 3.14159265358979323846 #define radius 100 static inline float radians(double degrees) { return degrees * PI / 180; } static inline void drawArc(CGContextRef ctx, CGPoint point, float angle_start, float angle_end, UIColor* color) { CGContextMoveToPoint(ctx, point.x, point.y); CGContextSetFillColor(ctx, CGColorGetComponents( [color CGColor])); CGContextAddArc(ctx, point.x, point.y, radius, angle_start, angle_end, 0); //CGContextClosePath(ctx); CGContextFillPath(ctx); } - (void)drawRect:(CGRect)rect { CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextClearRect(ctx, rect); float angle_start = radians(0.0); float angle_end = radians(121.0); drawArc(ctx, self.center, angle_start, angle_end, [UIColor yellowColor]); angle_start = angle_end; angle_end = radians(228.0); drawArc(ctx, self.center, angle_start, angle_end, [UIColor greenColor]); angle_start = angle_end; angle_end = radians(260); drawArc(ctx, self.center, angle_start, angle_end, [UIColor orangeColor]); angle_start = angle_end; angle_end = radians(360); drawArc(ctx, self.center, angle_start, angle_end, [UIColor purpleColor]); }iPhone 利用CG API画一个饼图(Pie chart)
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原文地址：http://www.cnblogs.com/QQ765286788/p/4766396.html
