#眉標=特別報導
#副標=Windows 7 Multi Touch程式開發(2)
#大標=觸控應用程式範例實作
#作者=文／圖 蔡宗翰




==<box>===========
程式1
[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool RegisterTouchWindow(
  IntPtr hWnd, ulong ulFlags);

[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool UnregisterTouchWindow(
  IntPtr hWnd);

[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool IsTouchWindow(
  IntPtr hWnd, IntPtr pulFlags);

void OnLoadHandler(Object sender, EventArgs e)
{
  try
  {
    if (!RegisterTouchWindow(this.Handle, 0))
    {
      // 無法註冊視窗以取得 WM_TOUCH 訊息
    }
  }
  catch (Exception exception)
  {
    // RegisterTouchWindow API 不存在
  }
}
==<end>==============







==<box>===========
程式2
[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool GetTouchInputInfo(
  IntPtr hTouchInput, int cInputs,
  [In, Out] TOUCHINPUT[] pInputs, int cbSize);

[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern void CloseTouchInputHandle(
  IntPtr lParam);

override void WndProc(ref Message m)
{
  bool handled;
  switch (m.Msg)
  {
    case WM_TOUCH:
      handled = DecodeTouch(ref m);
      break;
    default:
      handled = false;
      break;
  }
  // 下略
}

bool DecodeTouch(ref Message m)
{
  int inputCount = LoWord(m.WParam.ToInt32());
  TOUCHINPUT[] inputs;
  inputs = new TOUCHINPUT[inputCount];

  if (!GetTouchInputInfo(m.LParam, inputCount,
    inputs, touchInputSize))
  {
    return false;
  }
  // 中略
  CloseTouchInputHandle(m.LParam);
  return handled;
}
==<end>==============




==<box>===========
程式3
[StructLayout(LayoutKind.Sequential)]
struct TOUCHINPUT
{
    public int x;
    public int y;
    public System.IntPtr hSource;
    public int dwID;
    public int dwFlags;
    public int dwMask;
    public int dwTime;
    public System.IntPtr dwExtraInfo;
    public int cxContact;
    public int cyContact;
}
==<end>==============





==<box>===========
表1：dwFlags對應表
Flag
Value
TOUCHEVENTF_MOVE
0x0001
TOUCHEVENTF_DOWN
0x0002
TOUCHEVENTF_UP
0x0004
TOUCHEVENTF_INRANGE
0x0008
TOUCHEVENTF_PRIMARY
0x0010
TOUCHEVENTF_NOCOALESCE
0x0020
TOUCHEVENTF_PALM
0x0080
(資料來源：http://msdn.microsoft.com/library/dd317334.aspx)==<end>==============





==<box>===========
程式4
event EventHandler<WMTouchEventArgs> Touchdown;
event EventHandler<WMTouchEventArgs> Touchup;
event EventHandler<WMTouchEventArgs> TouchMove;

bool DecodeTouch(ref Message m)
{
  // 上略
  for (int i = 0; i < inputCount; i++)
  {
    TOUCHINPUT ti = inputs[i];
    EventHandler<WMTouchEventArgs> handler=null;

    if ((ti.dwFlags & TOUCHEVENTF_DOWN)!=0)
      handler = Touchdown;
    else if ((ti.dwFlags & TOUCHEVENTF_UP)!=0)
      handler = Touchup;
    else if ((ti.dwFlags & TOUCHEVENTF_MOVE)!=0)
      handler = TouchMove;

    if (handler != null)
    {
      WMTouchEventArgs te = new WMTouchEventArgs();
      // 中略，將TOUCHINFO 轉換為 WMTouchEventArgs
      handler(this, te);
      handled = true;
    }
  }
  CloseTouchInputHandle(m.LParam);
  return handled;
}
==<end>==============






==<box>===========
程式5
void OnTouchDownHandler(object sender,
    WMTouchEventArgs e)
{ 
  Debug.Assert(ActiveStrokes.Get(e.Id)
    == null); 
  Stroke newStroke = new Stroke ();
  newStroke.Color = touchColor.GetColor(
    e.IsPrimaryContact);
  newStroke.Id = e.Id; 
  ActiveStrokes.Add(newStroke);
}
==<end>==============




==<box>===========
程式6
void OnTouchMoveHandler(object sender,
    WMTouchEventArgs e)
{ 
  Stroke stroke = ActiveStrokes.Get(e.Id);
  Debug.Assert(stroke != null); 
  stroke.Add(new Point(e.LocationX,
    e.LocationY)); 
  Graphics g = this.CreateGraphics();
  stroke.DrawLast(g);
}
==<end>==============




==<box>===========
程式7
void OnTouchUpHandler(object sender,
    WMTouchEventArgs e)
{ 
  Stroke stroke =
    ActiveStrokes.Remove(e.Id);
  Debug.Assert(stroke != null); 
  FinishedStrokes.Add(stroke); 
  Invalidate();
}
==<end>==============