6.5. USING COORDINATE SPACES

We've discussed in quite some length the four coordinate spaces supported by the Windows graphics system—that is, world coordinate space, page coordinate space, device coordinate space, and physical device coordinate space. A world transformation maps a world coordinate space to a page coordinate space. A window-to-viewport mapping maps a page coordinate space to device coordinate space. A device coordinate space is simply a rectangular region within the physical device coordinate space, so the mapping between them is a simple translation.

Both world coordinate space and page coordinate space are referred to as logical coordinate spaces in Win32 terminology. The mappings between these four coordinate spaces are independent from each other, in that when you change one mapping, others are not changed. Yet collectively they all contribute to the mapping from the application's geometric model to locations on a physical device surface. GDI provides functions for the application to define a world transformation and window-to-viewport mapping. The mapping from a device coordinate space and a physical device coordinate space is managed by the operating system.