如何用QUARTZ 2D绘制一个三角形？ [英] How to draw a triangle with QUARTZ 2D?

问题描述

我正在使用3.1.3 SDK开发一个iPhone应用程序。

I'm developing an iPhone app with 3.1.3 SDK.

我试图画一个带有透明填充1px黑色笔触的三角形，

I'm trying to draw a triangle with transparent fill an 1px black stroke with this code:

CGContextMoveToPoint(ctx, position.X, position.Y - (size.height / 2));
CGContextAddLineToPoint(ctx, position.X - (size.width / 2), position.Y + (size.height / 2));
CGContextAddLineToPoint(ctx, position.X + (size.width / 2), position.Y + (size.height / 2));
CGContextFillPath(ctx);
CGContextSetLineWidth(ctx, 1.0);
CGContextStrokePath(ctx);
CGContextSetFillColorWithColor(ctx, [[UIColor clearColor] CGColor]);

但我得到一个黑色的三角形。

But I get a black filled triangle.

我做错了什么？

推荐答案

如果你想画一个透明填充的路径 - 填充它 - 只是在绘制时敲击，所以看起来你的CGContextFillPath方法是多余的 - 删除它：

If you want to draw a path with transparent fill - then you don't need to fill it - just stroke it when draw, so it seems that your CGContextFillPath method is redundant - remove it:

CGContextMoveToPoint(ctx, position.X, position.Y - (size.height / 2));
CGContextAddLineToPoint(ctx, position.X - (size.width / 2), position.Y + (size.height / 2));
CGContextAddLineToPoint(ctx, position.X + (size.width / 2), position.Y + (size.height / 2));
CGContextSetLineWidth(ctx, 1.0);
CGContextStrokePath(ctx);

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