Tap and Tap-and-Hold Pointer Events

ID: Q86921

The information in this article applies to:

Microsoft Windows for Pen Computing, version 1.0

SUMMARY

In the Microsoft Windows for Pen Computing environment, the pen can exhibit either mouse or pen functionality. Generally, the pen acts similar to a mouse until the Recognize function determines that the user started a recognition session. To enable the pen to function even better as a mouse in applications developed for standard (non-pen) Microsoft Windows, the Recognize() function may abort the recognition session with a pointer event return value to indicate that the user intends to perform a standard mouse operation instead of starting a recognition session. The ProcessWriting() function also exhibits this behavior.

A pen-centric application can take advantage of this functionality by clearing the RCO_NOPOINTEREVENT flag in the lRcOptions field of the recognition context (RC) data structure. The text below describes pointer events and provides some pseudocode to demonstrate how an application might process the REC_POINTEREVENT return value.

MORE INFORMATION

Windows for Pen Computing defines two types of pointer events: "tap" (Tap) and "tap and hold" (TapNHold). A Tap is analogous to clicking the left mouse button. The user produces a Tap by clicking the tip of the pen on the tablet and removing it quickly, without otherwise moving the pen. The user produces a TapNHold by clicking the tip of the pen on the tablet and holding it there without movement for a specified amount of time.

An application can be notified of these events early in the recognition process if it calls the Recognize function with a valid RC data structure. If the RCO_NOPOINTEREVENT flag is not set in the RC structure (the default), the Recognize function looks for pointer events and returns. The following pseudocode demonstrates how an application can process both types of pointer events:


   case WM_LBUTTONDOWN:
      if (IsPenEvent(message, GetMessageExtraInfo()))
      {
         // Process pen event
         InitRC(hwnd, &rc);  // May have been done previously...
         if (Recognize(&rc) == REC_POINTEREVENT)
         {
            // Process pointer event
            if (GetAsyncKeyState(VK_LBUTTON) & 0x8000)
               // Pen is still down: TapNHold functionality
            else
               // Pen up: Tap functionality
         }
      }
      else
         // Process mouse event
      break;

Note that if the Recognize function aborts with a REC_POINTEREVENT return value, no further recognition takes place. The system recognizer will not have been called. Therefore, the application will not receive a WM_RCRESULT message.

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Version : :1.0
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