iPhone 石英曲线锯齿状且有深色边框
我对石英有一个奇怪的问题。当我第一次运行下面的代码时，该线将像图像右侧的线一样绘制。第二次（以及之后的每次）执行这些行时，该行将类似于左侧的行。为什么看起来像那样？一切都是锯齿状的，并且似乎有一个黑色的边框。如果你用不透明度绘制曲线，第一次会很亮，第二次会很暗。
CGContextSetRGBFillColor(context, 0.0,0.0,0.0,0.0);
CGContextClearRect(context, CGRectMake( 0, 0, 320, 480));
CGContextSetRGBFillColor(context, 0, 0, 0, 0);
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 4.0);
CGContextMoveToPoint(context, p1.x, p1.y);
CGContextAddCurveToPoint(context, cp1.x, cp1.y, cp2.x, cp2.y, p2.x, p2.y);
CGContextDrawPath(context, kCGPathStroke);
（来源：pici.se）
I've got a weird issue with quartz. The first time I run the piece of code below, the line will be drawn like the line to the right in the image. The second time (and every time after) these lines are executed, the line will look like the line to the left. Why does it look like that? It's all jaggy and seems to have a dark border. If you'd draw the curve with opacity, it would be rather bright the first time, and very dark the second.
CGContextSetRGBFillColor(context, 0.0,0.0,0.0,0.0);
CGContextClearRect(context, CGRectMake( 0, 0, 320, 480));
CGContextSetRGBFillColor(context, 0, 0, 0, 0);
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 4.0);
CGContextMoveToPoint(context, p1.x, p1.y);
CGContextAddCurveToPoint(context, cp1.x, cp1.y, cp2.x, cp2.y, p2.x, p2.y);
CGContextDrawPath(context, kCGPathStroke);
(source: pici.se)
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抗锯齿关闭？
另外，您可能需要确保 x 和 y 值四舍五入，因为 Quartz 框架不能很好地处理半点。
antialiasing OFF?
also, you might want to make sure the x and y values are rounded as the Quartz Framework doesn't handle well the half point.