This section describes changes you can make to an application's main window procedure to enable the user to scroll a bitmap. The example in Example of Scrolling a Bitmap includes a menu item that copies the screen content to a bitmap and displays the bitmap in the client area.
The example also processes the WM_HSCROLL and WM_VSCROLL messages generated by the scroll bars so that the user may scroll the bitmap horizontally and vertically. Unlike the example for scrolled text, the bitmap example employs the BitBlt function to draw the invalid portion of the client area.