矢量像可缩放的UIScrollView绘图 [英] Vector like drawing for zoomable UIScrollView

问题描述

我有一个可缩放的UIScrollView，里面有一些 CATextLayer 和简单的 CALayer 。
它们被渲染得很好，但问题是当它们被缩放时它们会变得模糊。 （即使我重绘它们）

I have a zoomable UIScrollView with some CATextLayers and simple CALayers in it. They get rendered fine but the problem is when they are zoomed they become blurry. (Even if I redraw them)

当缩放视图时，我的选项是什么让我的文字不模糊？
我应该用另一件东西吗？在 CATextLayer / CALayer 中启用某些内容？欢迎任何想法;）

What would be my options to get my text not blurry when the view is zoomed? Should I use another thing? enable something in CATextLayer/CALayer? Any idea is welcomed ;)

我使用 CALayer s因为，正如文档中所建议的， CALayer s比 UIViews 轻，我有数百个。目前它运作顺利。我尝试过 UIWebView 而我的 CALayer 版本更快;）

I am using CALayers because, as suggested in documentation, CALayers are lighter than UIViews and I have hundreds of them. Currently it works smoothly. I have tried with UIWebView and my CALayer version is faster ;)

提前致谢。

推荐答案

iOS在放大之前光栅化文本，这就是它如此模糊的原因。您只需要修复CATextLayer的一个属性contentsScale，即可在缩放后获得更高质量的渲染。实现这个UIScrollViewDelegate方法：

iOS rasterizes the text before the scale-up occurs, that's why it's so blurry. You only need to fix one property of your CATextLayer, contentsScale, to get a higher quality render after zooming. Implement this UIScrollViewDelegate method:

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView
                       withView:(UIView *)view
                        atScale:(float)scale
{
    [CATransaction begin];
    [CATransaction setValue:[NSNumber numberWithBool:YES] 
                     forKey:kCATransactionDisableActions];
    uglyBlurryTextLayer.contentsScale = scale;
    [CATransaction commit];
}

这告诉图层使用更多像素来渲染文本，并禁用进行特定更改时的核心动画。

This tells the layer to use more pixels to render the text, and it disables Core Animation when making that particular change.

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