What Are Color Controls?
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4/8/2010
Through the color control interface, DirectDrawSurface objects enable you to change how the system displays the contents of the surface, without affecting the contents of the surface itself.
You can think of these controls as very simple filters that DirectDraw applies to the data as it leaves a surface before being rendered on the screen.
Surface objects implement the IDirectDrawColorControl interface which expose methods to adjust how the surface's contents are filtered. You can retrieve a pointer to this interface by using the IUnknown::QueryInterface method of the target surface, specifying the IID_IDirectDrawColorControl reference identifier.
The IDirectDrawColorControl interface allows you to control color in a surface much like the color controls you might find on a television.
The similarity between IDirectDrawColorControl and the actual controls on a TV is no mistake — this interface is most appropriate for adjusting how broadcast video looks in an overlay surface, so it makes sense that it should provide similar control over colors.
You can use color controls to allow a user to change video characteristics such as hue, saturation, contrast, and several others. For more information, see Using Color Controls.