An interactive display system with a contact geometry interface is disclosed. The interactive display system may include a multi-touch display, a touch detection system configured to detect a touch input on the multi-touch display and to generate contact geometry for a contact region of the touch input, and an application programming interface executed on a processor of the interactive display system. The application programming interface may be configured to receive the contact geometry and to send the contact geometry to a requesting application program for application-level processing. Further, the application programming interface may be configured to receive from the application program a display command based on the application level-processing. The application programming interface may be configured to send the display command to the multi-touch display to adjust a display of a graphical element on the multi-touch display.