UIImageView子类需要处理调整大小 [英] UIImageView subclass needs to handle resize

问题描述

我正在创建UIImageView子类以显示音频波形。方法是加载文件，进行数学运算，保存PNG文件，然后 self.image = thePNG 。这样做的好处是，在调整大小或重新绘制UIImageView时，它将拉伸PNG并迅速拉伸。

I am creating a UIImageView subclass to display an audio waveform. The approach is to load the file, do math, save a PNG file and then self.image = thePNG. The nice part about this is that on a resize or repaint the UIImageView will stretch the PNG and stretch quickly.

现在，如果图像扩展得太多，则需要重新计算波形以避免可见像素化。由于我们知道 UIImageView不会调用 drawRect ，在调整大小期间是否有一种方法可以调用，以便我可以确定是否需要重绘？

Now if the image is expanded too much then I need to recalculate the waveform to avoid visible pixelation. Since we know that UIImageView does not call drawRect, is there a method that is called during resize so that I can decide if redrawing is necessary?

PS重新计算时，在计算完新图像后，我会淡入新图像。希望这对象Google Earth这样的用户将是无缝的。

P.S. When recalculating I will be fading in the new image after it is calculated. Hopefully this will be seamless to the user like Google Earth.

推荐答案

这是一个解决方案：

- (void)layoutSubviews
{
    [super layoutSubviews];
    NSLog(@"%@", NSStringFromCGRect(self.frame));
}

与此取舍的是，不会为动画，正如David Jeske在>是否有UIView调整大小事件中指出的那样？

The trade off with this is that it is not called for each frame of an animation, as pointed out by David Jeske in Is there a UIView resize event?

其他无效的想法：

• 覆盖 setFrame：（CGRect）frame 在

• Override setFrame:(CGRect)frame discussed at Is there a UIView resize event?

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