Question

视图有一个框架（superview的坐标系中的坐标）和边界（自己的坐标系中的坐标）属性，但如果你转换视图，不应该使用或依赖于frame属性了。如果您正在使用转换，请使用边界属性，而不是框架属性，因为应用了转换到界限，但不一定在框架中准确反映

http://iphonedevelopment.blogspot.jp/2008/10/demystifying-cgaffinetransform.html

我想在上面的段落中看到他的意思并打印出“框架”和“边界” 我看到只有'框架'在捏合期间发生变化。

- (IBAction)handlePinch:(UIPinchGestureRecognizer*)recognizer
{
    NSLog(@"scale: %f, velocity: %f", recognizer.scale, recognizer.velocity);
    NSLog(@"Before, frame: %@, bounds: %@", NSStringFromCGRect(recognizer.view.frame), NSStringFromCGRect(recognizer.view.bounds));
    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
    NSLog(@"After, frame: %@, bounds: %@", NSStringFromCGRect(recognizer.view.frame), NSStringFromCGRect(recognizer.view.bounds));

    recognizer.scale = 1;
}

输出:( zomming in）

2012-07-02 14:53:51.458 GestureRec[1264:707] scale: 1.030111, velocity: 0.945660
2012-07-02 14:53:51.466 GestureRec[1264:707] Before, frame: {{0, 124}, {320, 160}}, bounds: {{0, 0}, {320, 160}}
2012-07-02 14:53:51.473 GestureRec[1264:707] After, frame: {{-4.81771, 121.591}, {329.635, 164.818}}, bounds: {{0, 0}, {320, 160}}
2012-07-02 14:53:51.480 GestureRec[1264:707] scale: 1.074539, velocity: 1.889658
2012-07-02 14:53:51.484 GestureRec[1264:707] Before, frame: {{-4.81771, 121.591}, {329.635, 164.818}}, bounds: {{0, 0}, {320, 160}}
2012-07-02 14:53:51.494 GestureRec[1264:707] After, frame: {{-17.103, 115.449}, {354.206, 177.103}}, bounds: {{0, 0}, {320, 160}}
2012-07-02 14:53:51.499 GestureRec[1264:707] scale: 1.000000, velocity: 1.889658
2012-07-02 14:53:51.506 GestureRec[1264:707] Before, frame: {{-17.103, 115.449}, {354.206, 177.103}}, bounds: {{0, 0}, {320, 160}}
2012-07-02 14:53:51.510 GestureRec[1264:707] After, frame: {{-17.103, 115.449}, {354.206, 177.103}}, bounds: {{0, 0}, {320, 160}}

我误解了某些内容或博客中的作者是错误的吗？

Answer 1

我想我已经明白了：

博客是正确的，甚至根据Apple themselves：

要翻译或缩放坐标系，可以更改视图边界矩形...

然而，边界不会改变，因为矩形本身仍然与您报告的尺寸相同，只有坐标系已经缩放。你看：

更改边界矩形设置基本坐标系由视图执行的所有绘图开始。

并且因为我们从未明确地更改边界，所以只有视图的相对于其超视图的帧会发生变化。

事实上，我可以在数学上证明界限永远不会改变！在这里，改为运行此示例：

NSLog(@"scale: %f, velocity: %f", recognizer.scale, recognizer.velocity);
    NSLog(@"Before, frame: %@, bounds: %@", NSStringFromCGRect(recognizer.view.frame), NSStringFromCGRect(recognizer.view.bounds));
    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
    NSLog(@"After, frame: %@, bounds: %@ transform:%@", NSStringFromCGRect(recognizer.view.frame), NSStringFromCGRect(recognizer.view.bounds), NSStringFromCGAffineTransform(recognizer.view.transform));

    recognizer.scale = 1;

现在，如果您注意到，NSStringFromCGAffineTransform()报告的值乘以边界等于视图的帧。但博客说的是什么呢？不必然准确是正确的。变换矩阵不仅可以应用于这个东西的x和y，如果我们真的想要，我们可以变换z值并旋转，翻转，并且每个方向，所有这些都以非线性方式改变帧属性，尤其是在黑手党中使用时。

一个有趣的难题，如果我自己这样说的话。

CGAffineTransform改变了view.bounds？

1 个答案: