Allows developer to register touch event handlers if supported by HDK and firmware.
Some LinkIt HDK comes with touch screen configuration. The system framework provides a simple way for developers to register a touch event handler. Key events such as tap(VM_TOUCH_EVENT_TAP) or move(VM_TOUCH_EVENT_MOVE) are passed to the handler callback with corresponding screen coordinates. The actual value of key code depends on the design of HDK, and can be found in the HDK document.