核心动画还是 OpenGL ES? [英] Core Animation or OpenGL ES?

问题描述

我想做以下事情:

点击屏幕并在点击的点周围绘制 3 个 cricles.使用 Core Animation 还是 OpenGL ES 会更好吗?

Tap the screen and draw 3 cricles around the the tapped point. Is it better to do this with Core Animation or OpenGL ES?

我从哪里开始?

推荐答案

如前所述，Core Graphics 框架可能是您想要的.一个好的方法是继承 UIView，然后覆盖 drawRect: 和 touchesEnded:withEvent: 这两个方法.

As mentioned, the Core Graphics framework is probably what you want. A good way to go about it would be to subclass UIView, then override the two methods drawRect: and touchesEnded:withEvent:.

当 UIView 上的触摸事件结束时，您可以从传递给 touchesEnded:withEvent: 的事件中获取最后一次触摸的点，并将其以某种方式存储在子类 UIView 的实例中.

When a touch event ends on the UIView, you can get the point of the last touch from the event passed to touchesEnded:withEvent:, and store it somehow in the instance of your subclassed UIView.

然后，在您的 drawRect: 实现中，您将获得存储的最后一个触摸点，并使用对 CGContextAddEllipseInRect 的三个调用在其周围绘制三个圆圈，如前所述此处:Quartz 2D 编程指南:路径(需要注册为 Apple Developer).

Then, in your implementation of drawRect:, you'll get the stored last touch point, and draw three circles around it using three calls to CGContextAddEllipseInRect, as discussed here: Quartz 2D Programming Guide: Paths (registration as Apple Developer required).

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