【发布时间】：2013-03-25 01:10:37
【问题描述】：
我的 iOS 应用程序中有一个 UIToolbar，我使用 CGAffineTransform 以编程方式在 willRotateToInterfaceOrientation 函数中旋转它。变换需要缩放、旋转和平移。我知道如何计算比例和旋转参数，但似乎无法弄清楚如何计算平移参数，以便视图位于正确的位置。经过大量试验和错误后，我确定了将视图移动到 iPad 上正确位置的确切数字，但我不希望对数字进行硬编码，以免代码过于依赖设备。如何计算平移参数？
这是我当前在包含工具栏的视图控制器中的willRotateToInterfaceOrientation 函数。我想知道如何计算下面的tx 和ty，而不是对这些值进行硬编码。我尝试过使用工具栏和窗口大小的各种功能，但工具栏总是出现在一个奇怪的位置或完全在窗口之外而不是在窗口底部与窗口重叠。
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
if (UIInterfaceOrientationIsLandscape(toInterfaceOrientation))
{
// First, apply identify transformation to simplify later calculations and also because we need the toolbar's frame and Apple's docs say you cannot use a view's frame if the transform property is not the identity matrix.
self.toolbar.transform = CGAffineTransformIdentity;
// Calculate affine parameters.
// Expand width to the window's height when in landscape mode, leaving the toolbar's height unchanged.
UIWindow *window = [[UIApplication sharedApplication] keyWindow];
CGFloat sx = 1.0;
CGFloat sy = window.frame.size.height / window.frame.size.width;
// Rotate 90 degrees in either direction depending on the orientation direction change.
CGFloat rotate = M_PI_2;
if (toInterfaceOrientation == UIInterfaceOrientationLandscapeLeft)
{
rotate = -M_PI_2;
}
// Reposition the toolbar.
// TODO: Calculate values rather than hard-coding them. Why is tx not something like ((window.frame.size.width / 2) - (self.toolbar.frame.size.height / 2))?
// Note that these values work for both the original iPad and iPad Retina, presumably because the values represent points not pixels.
CGFloat tx = -365.5;
CGFloat ty = 359.5;
if (toInterfaceOrientation == UIInterfaceOrientationLandscapeLeft)
{
tx = -tx;
}
// Apply affine transformation.
CGAffineTransform transform = CGAffineTransformMakeScale(sx, sy);
transform = CGAffineTransformRotate(transform, rotate);
transform = CGAffineTransformTranslate(transform, tx, ty);
[UIView animateWithDuration:duration
animations:^{
self.toolbar.transform = transform;
}
completion:NULL
];
}
else if (toInterfaceOrientation == UIInterfaceOrientationPortrait)
{
[UIView animateWithDuration:duration
animations:^{
self.toolbar.transform = CGAffineTransformIdentity;
}completion:NULL
];
}
else if (toInterfaceOrientation == UIInterfaceOrientationPortraitUpsideDown)
{
NSLog(@"Upside-down orientation not supported");
}
}
此外，这里是我的工具栏的声明和基本初始化。请注意，我将工具栏作为子视图添加到主窗口并手动处理旋转，因为我的应用程序有一个 UITabBarController 作为根视图控制器，这是我可以让工具栏出现在选项卡栏顶部的唯一方法.
// The toolbar is strong since this controller must maintain ownership as the toolbar is removed from the parent view when this view disappears.
@property (strong, nonatomic) IBOutlet UIToolbar *toolbar;
UIWindow *window = [[UIApplication sharedApplication] keyWindow];
CGFloat height = CGRectGetHeight(self.tabBarController.tabBar.frame); // Completely cover the tab bar.
CGFloat x = window.frame.origin.x;
CGFloat y = window.frame.size.height - height;
CGFloat width = window.frame.size.width;
self.toolbar.frame = CGRectMake(x, y, width, height);
[window addSubview:self.toolbar];
最后，我使用启用了 ARC 的 Xcode 4.5.1，并在 iPad（Retina 和非 Retina）5.1 和 6.0 模拟器上进行测试。
【问题讨论】：
-
感谢您的回复。我的理解是，非 Make 函数（CGAffineTransformTranslate 而不是 CGAffineTransformMakeTranslate）通过将给定参数应用于现有仿射变换来构造新的变换矩阵。
-
@user19480 你是完全正确的，我的错误，我错过了它不是 Make 类型的事实。道歉。
标签： ios objective-c cgaffinetransform screen-rotation translate-animation