/// <summary>
/// The hook procedure for window messages generated by the FileOpenDialog
/// </summary>
/// <param name="hWnd">the handle of the window at which this message is targeted</param>
/// <param name="msg">the message identifier</param>
/// <param name="wParam">message-specific parameter data</param>
/// <param name="lParam">mess-specific parameter data</param>
/// <returns></returns>
public IntPtr MyHookProc(IntPtr hWnd, UInt16 msg, Int32 wParam, Int32 lParam)
{
// return if invalid window
if (hWnd == IntPtr.Zero)
{
return(IntPtr.Zero);
}
//the message passed by AlphaSlider control
if (msg == 0x5050)
{
//update the text box value
Trace.WriteLine(wParam);
_textAlpha.Text = wParam.ToString();
}
//this is total hack
//I could not find the message posted by ChooColor dialog when user presses OK
//this I found the last message sent and using it
//TODO: find the correct message as documented i.e. COLOROKSTRING
if (msg == 0xC072 /*==COLOROKSTRING*/)
{
//get the current ChooseColor structure
IntPtr ipNotify = new IntPtr(lParam);
ChooseColor cc = (ChooseColor)Marshal.PtrToStructure(ipNotify, typeof(ChooseColor));
IntPtr hWndParent = NativeMethods.GetParent(hWnd);
//extract the RGB values from structure
int R = (char )(cc.rgbResult);
int G = (char )(((int)(cc.rgbResult)) >> 8);
int B = (char )(cc.rgbResult >> 16);
//the typecase problem
//TODO: write the C# version of GetRValue, GetGValue, GetBValue
if (R > 256)
{
R = R / 257;
}
if (G > 256)
{
G /= 257;
}
//get the alpha value from slider control
_color = Color.FromArgb(_sliderAlpha.Value, R, G, B);
Trace.WriteLine(_color);
}
// Behaviour is dependant on the message received
switch (msg)
{
// We're not interested in every possible message; just return a NULL for those we don't care about
default:
{
return(IntPtr.Zero);
}
// WM_INITDIALOG - at this point the ChooseColorDialog exists, so we pull the user-supplied control
// into the FileOpenDialog now, using the SetParent API.
case WindowMessage.InitDialog:
{
//set the parent window of slider control to recieve change in value messages
_sliderAlpha.SetParent(hWnd);
//increase the width of the default dialog box
//place the slider and text box controls on the right most
POINT topLeft = new POINT();
POINT bottomRight = new POINT();
IntPtr ipNotify = new IntPtr(lParam);
ChooseColor cc = (ChooseColor)Marshal.PtrToStructure(ipNotify, typeof(ChooseColor));
IntPtr hWndParent = NativeMethods.GetParent(hWnd);
NativeMethods.SetParent(_panelAlpha.Handle, hWnd);
RECT rc = new RECT();
NativeMethods.GetWindowRect(hWnd, ref rc);
topLeft.X = rc.right;
topLeft.Y = rc.top;
NativeMethods.ScreenToClient(hWnd, ref topLeft);
bottomRight.X = rc.right;
bottomRight.Y = rc.bottom;
NativeMethods.ScreenToClient(hWnd, ref bottomRight);
Rectangle rcClient = _panelAlpha.ClientRectangle;
NativeMethods.MoveWindow(hWnd, rc.left, rc.top, bottomRight.X + rcClient.Width + 10, bottomRight.Y + 28, true);
return(IntPtr.Zero);
}
// WM_SIZE - the OpenFileDialog has been resized, so we'll resize the content and user-supplied
// panel to fit nicely
case WindowMessage.Size:
{
PlaceCustomControls(hWnd);
return(IntPtr.Zero);
}
}
}
internal static extern bool ChooseColor( ref ChooseColor cc );
internal static extern bool ChooseColor(ref ChooseColor cc);