Altering the Main Application Loop

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If using modeless TWAIN processing, the application loop must be altered.  Below describes the traditional application loop, the "normal" TWAIN application loop, and the "DTWAIN" application loop.

 

Here is a normal, application message loop.

Example of Traditional Application Message Loop

 

Normally, a TWAIN enabled application would need to alter the message loop similar to this:

Example of TWAIN Application Message Loop Alterations

 

A DTWAIN application that desires to alter the application's message loop needs only to do this: Example of DTWAIN Application Message Loop Alterations

 

To specify that the application desires to alter the application loop, the DTWAIN_SetTwainMode must be called before the main application loop starts processing messages.   By default, DTWAIN assumes that the application will not alter the application loop; so calling this function is mandatory.