The PM has three different functions that enable you to correlate a uniquely identified retained segment.
Function
For nonretained graphics, the correlation hits are returned by the actual drawing commands. For retained graphics, the correlation hits are returned by the three correlation functions listed above.
The size of the pick aperture is set using GpiSetPickApertureSize, just as with nonretained graphics. However, the coordinate position on which the pick aperture is centered usually is obtained from operator input, for example, from a WM_BUTTON1DOWN message, instead of from GpiSetPickAperturePosition.
After the graphics orders that create pictures are stored in retained segments, the pictures can be re-created by your application with the various GpiDraw... functions. Then the user can view the pictures, if the output is directed to a screen for example. After the user selects an area of interest, a GpiCorrelate... function redraws the picture internally to determine just what intersects the pick aperture. The user does not see the re-creation. A standard order of functions within your application would be: