DrawDib Operations

You can access the entire group of DrawDib functions by using the DrawDibOpen function. This function loads the dynamic-link library (DLL), allocates memory resources, creates a DrawDib device context (DC), and maintains a reference count of the number of DCs that are initialized. DrawDibOpen also returns a handle of the new DC that you use with the other DrawDib functions.

You can release a DrawDib DC when you finish using it by using the DrawDibClose function. DrawDibClose also decrements the reference count of the applications accessing the DLL. The call to DrawDibClose should be the last DrawDib function in your application.

You can create as many DrawDib DCs as you want. You can use multiple DrawDib DCs to draw several bitmaps simultaneously. You can also create multiple DrawDib DCs, each with unique characteristics, so your application can choose and then use the DC with the most appropriate settings. For example, you can create two DrawDib DCs in an application: one that displays an image at its normal resolution, and the other that displays an enlarged portion of the image.

To run efficiently, DrawDib functions require information about the display adapter and its driver. The display profile is obtained by running a series of tests on the display adapter the first time the DLL containing the DrawDib functions is accessed. The DrawDib functions use this information for all applications. You can repeat these tests when necessary by using the DrawDibProfileDisplay function.

Note Retrieving and storing the display profile is typically a one-time occurrence. If, however, the profile information is deleted or another display driver is installed in the system, DrawDib reruns the tests.

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