Handling multi-touch events on Windows

Once we have installed the MultiTouchVista driver, or if we happen to have a multi-touch-capable screen, we can initialize an event loop in the application and handle the WM_TOUCH messages.

Getting ready

The first recipe contains all the relevant information about multi-touch handling. In this recipe, we only extend our code for Microsoft Windows.

Note

This book doesn’t discuss about multi-touch input emulation for Mac.

How to do it...

1. The MinGW toolchain does not include the latest Windows SDK headers, so a number of constants should be defined to use the WM_TOUCH messages:

   #if !defined(_MSC_VER)
   #define SM_DIGITIZER            94
   #define SM_MAXIMUMTOUCHES       95
   #define TOUCHEVENTF_DOWN        0x0001
   #define TOUCHEVENTF_MOVE        0x0002
   #define TOUCHEVENTF_UP          0x0004
   #define TOUCHEVENTF_PRIMARY     0x0010
   #define WM_TOUCH                0x0240

2. The TOUCHINPUT structure encapsulates a single touch using the WinAPI data types and should also be declared...