旋转后 UIView 坐标被交换但 UIWindow 不是? [英] After rotation UIView coordinates are swapped but UIWindow's are not?

问题描述

使用 Xcode 4.2.1 iPad iOS 5.0.1，创建一个新的单一视图"iPad 项目.在控制器中，添加:

Using Xcode 4.2.1 iPad iOS 5.0.1, create a new "Single View" iPad project. In the controller, add:

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}

- (void) dumpView: (UIView *) view {
    CGRect frame = view.frame ;
    CGRect bounds = view.bounds ;
    CGPoint center = view.center ;

    NSLog(@"view [%@]:%d frame=%@ bounds=%@ center=%@"
          ,   NSStringFromClass(view.class)
          ,   [view hash]
          ,   NSStringFromCGRect(frame)
          ,   NSStringFromCGRect(bounds)
          ,   NSStringFromCGPoint(center)) ;
}

- (void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation) fromInterfaceOrientation {

    NSLog(@"INViewController.didRotateFromInterfaceOrientation: %d to %d", fromInterfaceOrientation, self.interfaceOrientation) ;
    [self dumpView: self.view] ;
    [self dumpView: self.view.superview] ;
}

运行它，旋转设备，你会得到:

Run it, rotate the device and you will get:

INViewController.didRotateFromInterfaceOrientation: 2 to 4
view [UIView]   bounds={{0, 0}, {1024, 748}} center={394, 512}
view [UIWindow] bounds={{0, 0}, {768, 1024}} center={384, 512}

换句话说，UIView 的坐标按预期交换为横向"，但其父 UIWindow 仍声称处于纵向模式...

In other words, the UIView has its coordinates "swapped to landscape" as expected, but its parent UIWindow still claims to be in portrait mode...

此外，UIView 的大小似乎有点错误:应该在 20 的 y 坐标在 0 ...

Also, the UIView size seems to be slightly wrong: the y coordinate which should be at 20 is at 0 ...

有人知道这是什么意思吗?

Anyone knows what this means?

推荐答案

UIWindow 的坐标系始终处于纵向.它通过设置其 rootViewController 的视图变换来应用旋转.例如，我使用单视图模板创建了一个测试应用程序并运行它.纵向:

The UIWindow's coordinate system is always in portrait orientation. It applies the rotation by setting its rootViewController's view's transform. For example, I created a test app using the single-view template and ran it. In portrait orientation:

(gdb) po [[(id)UIApp keyWindow] recursiveDescription]
<UIWindow: 0x9626a90; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x9626b80>>
   | <UIView: 0x96290e0; frame = (0 20; 768 1004); autoresize = W+H; layer = <CALayer: 0x96286a0>>

向左旋转后:

(gdb) po [[(id)UIApp keyWindow] recursiveDescription]
<UIWindow: 0x9626a90; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x9626b80>>
   | <UIView: 0x96290e0; frame = (0 0; 748 1024); transform = [0, 1, -1, 0, 0, 0]; autoresize = W+H; layer = <CALayer: 0x96286a0>>

向右旋转后:

(gdb) po [[(id)UIApp keyWindow] recursiveDescription]
<UIWindow: 0x9626a90; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x9626b80>>
   | <UIView: 0x96290e0; frame = (20 0; 748 1024); transform = [0, -1, 1, 0, 0, 0]; autoresize = W+H; layer = <CALayer: 0x96286a0>>

注意当设备旋转时如何设置变换(到 90 度旋转矩阵).

Notice how the transform is set (to a 90-degree rotation matrix) when the device is rotated.

关于您关于 UIView 大小的问题:视图的边界在其自己的坐标空间中，默认情况下，视图的边界原点位于其坐标空间的原点 (0,0).视图的框架位于其父级的坐标空间中.您可以在上面的递归描述中看到您期望的 20，或者直接打印框架:

Regarding your question about the UIView size: a view's bounds are in its own coordinate space, and by default a view's bounds' origin is at the origin (0,0) of its coordinate space. A view's frame is in its parent's coordinate space. You can see the 20 you were expecting in the recursive descriptions above, or by printing the frame directly:

(gdb) p (CGRect)[[[[(id)UIApp keyWindow] subviews] lastObject] frame]
$2 = {
  origin = {
    x = 0, 
    y = 20
  }, 
  size = {
    width = 768, 
    height = 1004
  }
}

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