/// <summary>
/// Create new gesture event instance and decode the gesture info structure
/// </summary>
/// <param name="handler">The gesture handler</param>
/// <param name="gestureInfo">The gesture information</param>
internal GestureEventArgs(GestureHandler handler, ref GESTUREINFO gestureInfo)
{
_dwFlags = gestureInfo.dwFlags;
GestureId = gestureInfo.dwID;
GestureArguments = gestureInfo.ullArguments;
//Get the last event from the handler
LastEvent = handler.LastEvent;
//Get the last begin event from the handler
LastBeginEvent = handler.LastBeginEvent;
DecodeGesture(handler.HWndWrapper, ref gestureInfo);
//new gesture, clear last and first event fields
if (IsBegin)
{
LastBeginEvent = null;
LastEvent = null;
}
}
public static extern bool GetGestureInfo(IntPtr hGestureInfo, ref GESTUREINFO pGestureInfo);
public static extern bool GetGestureInfo(IntPtr hGestureInfo, ref GESTUREINFO pGestureInfo);
/// <summary>
/// The Windows message interception for gesture events handling
/// </summary>
/// <param name="hWnd">WndProc hWnd</param>
/// <param name="msg">WndProc msg</param>
/// <param name="wParam">WndProc wParam</param>
/// <param name="lParam">WndProc lParam</param>
/// <returns>WndProc return</returns>
public override uint WindowProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam)
{
//We care only for gesture events
if (msg != User32.WM_GESTURE)
return 0;
GESTUREINFO gestureInfo = new GESTUREINFO
{
cbSize = (uint)Marshal.SizeOf(typeof(GESTUREINFO))
};
bool result = User32.GetGestureInfo(lParam, ref gestureInfo);
if (!result)
throw new Exception("Cannot get gesture information");
//Decode the gesture info and get the message event argument
GestureEventArgs eventArgs = new GestureEventArgs(this, ref gestureInfo);
try
{
//Fire the event using the event map
_eventMap[MapWM2EventId(gestureInfo.dwID, gestureInfo.dwFlags)].Invoke(this, eventArgs);
}
catch (ArgumentOutOfRangeException) //In case future releases will introduce new event values
{
}
//Keep the last message for relative calculations
LastEvent = eventArgs;
//Keep the first message for relative calculations
if (eventArgs.IsBegin)
LastBeginEvent = eventArgs;
User32.CloseGestureInfoHandle(lParam);
return 1;
}
//Decode the gesture
private void DecodeGesture(IHwndWrapper hWndWrapper, ref GESTUREINFO gestureInfo)
{
Location = hWndWrapper.PointToClient(new Point(gestureInfo.ptsLocation.x, gestureInfo.ptsLocation.y));
Center = Location;
switch (GestureId)
{
case User32.GID_ROTATE:
ushort lastArguments = (ushort)(IsBegin ? 0 : LastEvent.GestureArguments);
RotateAngle = User32.GID_ROTATE_ANGLE_FROM_ARGUMENT((ushort)(gestureInfo.ullArguments - lastArguments));
break;
case User32.GID_ZOOM:
Point first = IsBegin ? Location : LastBeginEvent.Location;
Center = new Point((Location.X + first.X) / 2, (Location.Y + first.Y) / 2);
ZoomFactor = IsBegin ? 1 : (double)gestureInfo.ullArguments / LastEvent.GestureArguments;
//DistanceBetweenFingers = User32.LoDWord(gestureInfo.ullArguments);
break;
case User32.GID_PAN:
PanTranslation = IsBegin ? new Size(0, 0) :
new Size(Location.X - LastEvent.Location.X, Location.Y - LastEvent.Location.Y);
int panVelocity = User32.HiDWord((long)(gestureInfo.ullArguments));
PanVelocity = new Size(User32.LoWord(panVelocity), User32.HiWord(panVelocity));
//DistanceBetweenFingers = User32.LoDWord(gestureInfo.ullArguments);
break;
}
}