Clipping functions create, test, and alter clipping regions. A clipping region is the portion of a window's client area where GDI creates output; any output sent to that portion of the client area which is outside the clipping region will not be visible. Clipping regions are useful in any Windows application that needs to save one part of the client area and simultaneously send output to another. The following list briefly describes each clipping function:
| Function | Description | |
| ExcludeClipRect | Excludes a rectangle from the clipping region. | |
| GetClipBox | Copies the dimensions of a bounding rectangle. | |
| IntersectClipRect | Forms the intersection of a clipping region and a rectangle. | |
| OffsetClipRgn | Moves a clipping region. | |
| PtVisible | Tests whether a point lies in a region. | |
| RectVisible | Determines whether part of a rectangle lies in a region. | |
| SelectClipRgn | Selects a clipping region. |