I have written a rectangular user control, which contains a large rectangle inside the control. At the four vertices of the rectangle, there are four small rectangles used to control the width and height. On the far right, there is a small circle used to control the rotation direction of the rectangle. I draw this rectangle on the Canvas with the mouse. Currently, when the angle is 0, I can change the size of the rectangle and get the correct coordinates. When the angle is not 0, I can get the correct angle and the rotated coordinates. However, I want to adjust the shape and size of the rectangle by dragging its four vertices after rotation, but I cannot correctly obtain the width, height, and center point of the rectangle.