使用CGAffineTransform倾斜UIImageView [英] skewing a UIImageView using CGAffineTransform

问题描述

我正在尝试倾斜一个矩形，以便使两个垂直边倾斜但平行，并且顶部和底部是水平的.

I am trying to skew a rectangle so the two vertical sides are slanted but parallel and the top and bottom are horizontal.

我正在尝试使用CGAffineTransform并找到了这段代码，但是我没有弄清楚要放在各个部分中的内容.

I am trying to use CGAffineTransform and have found this code but I am not figuring out what to put in the various parts.

imageView.layer.somethingMagic.imageRightTop = (CGPoint){ 230, 30 };
                imageView.layer.somethingMagic.imageRightBottom = (CGPoint){ 300, 150 };

#define CGAffineTransformDistort(t, x, y) (CGAffineTransformConcat(t, CGAffineTransformMake(1, y, x, 1, 0, 0)))
#define CGAffineTransformMakeDistort(x, y) (CGAffineTransformDistort(CGAffineTransformIdentity, x, y))

尽管据说这很容易，但我不知道在不同地方放什么.

although this is said to be easy I don't know what to put in the different places.

我假设图像视图将是我要更改的图像，但是它变成了magicMagic.和imageRightTop和imageRightBottom.

I assume image view would be my image that I want to change however what goes into somethingMagic. and imageRightTop and imageRightBottom.

我该怎么定义t.

如果有更详尽的解释，我将不胜感激，因为在大多数情况下，我仅将其作为倾斜矩形的解释.

If there is a more thorough explanation I would appreciate it since in most cases I found only this as the explanation of what to do to skew a rectangle.

谢谢

推荐答案

让我们假设您有一个名为imageView的变量，其中包含对UIImageView的引用.
我写了一些样本来演示如何实现此行为.该代码的作用是创建一个新的CGAffineTransform矩阵.该矩阵具有与恒等变换矩阵相同的值，但有一个例外:位置[2,1]处的值.该值由CGAffineTransformMake函数的c参数控制，并控制沿x轴的剪切.您可以通过设置shearValue来更改剪切量.

Let's assume you have a variable named imageView holding a reference to your UIImageView.
I wrote a little sample to demonstrate how you could get this behavior. What this code does is creating a new CGAffineTransform matrix. This matrix has the same values as the identity transform matrix with one exception: the value at location [2,1]. This value is controlled by the c-parameter of the CGAffineTransformMake-function and controls the shearing along the x-axis. You can change the amount of shearing by setting shearValue.

代码:

CGFloat shearValue = 0.3f; // You can change this to anything you want
CGAffineTransform shearTransform = CGAffineTransformMake(1.f, 0.f, shearValue, 1.f, 0.f, 0.f);
[imageView setTransform:shearTransform];

雨燕5

let shearValue = CGFloat(0.3) // You can change this to anything you want
let shearTransform = CGAffineTransform(a: 1, b: 0, c: shearValue, d: 1, tx: 0, ty: 0)
imageView.transform = shearTransform

这是shearTransform-矩阵的样子:

[1     0     0]  
[0.3   1     0]  
[0     0     1]   

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