问题
I want to get a part of picture in a PictureBox by allowing the user to select a rectangular region (similar to how it can be done in Photoshop with selection tool).
How I can do this?
回答1:
You would have to draw a rectangle or lines based on where they clicked and dragged. Your starting point would be the mouse x, y and then you would get the last point from mouse release x, y.
回答2:
Catch the mouse events on the Picture Box to define your selection rectangle and use Graphics.DrawRectangle to draw your selection rectangle in the Paint Event of the Picture Box.
来源：https://stackoverflow.com/questions/2456074/how-to-select-a-region-in-a-windows-forms-picturebox