dragform.cs

来自「Fireball.CodeEditor is an source code ed」· CS 代码 · 共 95 行

#region Fireball License
//    Copyright (C) 2005  Sebastian Faltoni sebastian{at}dotnetfireball{dot}net
//
//    This library is free software; you can redistribute it and/or
//    modify it under the terms of the GNU Lesser General Public
//    License as published by the Free Software Foundation; either
//    version 2.1 of the License, or (at your option) any later version.
//
//    This library is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//    Lesser General Public License for more details.
//
//    You should have received a copy of the GNU Lesser General Public
//    License along with this library; if not, write to the Free Software
//    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#endregion
#region Original License
// *****************************************************************************
// 
//  Copyright 2004, Weifen Luo
//  All rights reserved. The software and associated documentation 
//  supplied hereunder are the proprietary information of Weifen Luo
//  and are supplied subject to licence terms.
// 
//  WinFormsUI Library Version 1.0
// *****************************************************************************
#endregion

using System;
using System.Windows.Forms;

namespace Fireball.Docking
{
	// Inspired by Chris Sano's article:
	// http://msdn.microsoft.com/smartclient/default.aspx?pull=/library/en-us/dnwinforms/html/colorpicker.asp
	// In Sano's article, the DragForm needs to meet the following criteria:
	// (1) it was not to show up in the task bar;
	//     ShowInTaskBar = false
	// (2) it needed to be the top-most window;
	//     TopMost = true (not necessary here)
	// (3) its icon could not show up in the ALT+TAB window if the user pressed ALT+TAB during a drag-and-drop;
	//     FormBorderStyle = FormBorderStyle.None;
	//     Create with WS_EX_TOOLWINDOW window style.
	//     Compares with the solution in the artile by setting FormBorderStyle as FixedToolWindow,
	//     and then clip the window caption and border, this way is much simplier.
	// (4) it was not to steal focus from the application when displayed.
	//     User Win32 ShowWindow API with SW_SHOWNOACTIVATE
	// In addition, this form should only for display and therefore should act as transparent, otherwise
	// WindowFromPoint will return this form, instead of the control beneath. Need BOTH of the following to
	// achieve this (don't know why, spent hours to try it out :( ):
	//  1. Enabled = false;
	//  2. WM_NCHITTEST returns HTTRANSPARENT
	internal class DragForm : Form
	{
		public DragForm()
		{
			FormBorderStyle = FormBorderStyle.None;
			ShowInTaskbar = false;
			SetStyle(ControlStyles.Selectable, false);
			Enabled = false;
		}

		protected override CreateParams CreateParams
		{
			get
			{
				CreateParams createParams = base.CreateParams;
				createParams.ExStyle |= (int)Win32.WindowExStyles.WS_EX_TOOLWINDOW;
				return createParams;
			}
		}

		protected override void WndProc(ref Message m)
		{
			if (m.Msg == (int)Win32.Msgs.WM_NCHITTEST)
			{
				m.Result = (IntPtr)Win32.HitTest.HTTRANSPARENT;
				return;
			}

			base.WndProc (ref m);
		}

		public virtual void Show(bool bActivate)
		{
			if (bActivate)
				Show();
			else
				User32.ShowWindow(Handle, (int)Win32.ShowWindowStyles.SW_SHOWNOACTIVATE);
		}
	}
}