This section contains a single example that demonstrates how you can use regions to enable the user to define how a part of client area output can appear. Regions used for this purpose are called clipping regions.
The example for this section is taken from a Windows-based application that enables a user to capture the entire desktop as a bitmap and then isolate and save a part of this image as a .BMP file.
By selecting the Define Clip Region option from the application's menu, the user is able to select a clipping region by clicking the left mouse button and dragging the mouse. As the user drags the mouse, the application draws a rectangle that corresponds to the new clipping region.
By selecting the Clip option, the user is able to redraw the isolated part of the image within the boundaries of the specified rectangle.