旋转图像数学 (C#)

问题描述

我有一个包含两个点的图像，对齐如下:

I have an image with two points, aligned something like this:

|----------------|
|                |
|    .           |
|                |
|          .     |
|                |
|----------------|

我有两个点的 X、Y 坐标，我需要将图像旋转 X 度，所以它看起来像这样:

I have both X, Y coordinates for both points and I need to rotate the image X degrees so it looks like this instead:

|----------------|
|                |
|                |
|    .     .     |
|                |
|                |
|----------------|

基本上，它们彼此对齐，这是什么数学?(C# 中的代码示例会更好，但不是必需的)

Basically so they align next to eachother, what's the math for this? (A code example in C# would be even better but not required)

推荐答案

这取决于您想将哪个点用作旋转的中心".让我们将这个点称为左上点 A 和右下点 B.如果您想绕 A 点旋转，使 B 点与它对齐，则以弧度计算旋转角度如下:

It depends on which point you want to use as a "center" for your rotation. Let's call the point to the up and left pointA and the one to the right and below pointB. If you want to rotate around the point A so that point B aligns with it, calculating the rotation angle in radians would go like this:

double angle = Math.Atan2(pointB.Y - pointA.Y, pointB.X - pointA.X);

我不知道您如何处理您的图像，因此以下内容仅适用于您使用 System.Drawing.Graphics:

I don't how you're handling your image, so the following applies only if you're using System.Drawing.Graphics:

myImage.TranslateTransform(-pointA.X, -pointA.Y);
myImage.RotateTransform((float) angle, MatrixOrder.Append);
myImage.TranslateTransform(pointA.X, pointA.Y, MatrixOrder.Append);

希望对你有帮助.

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