expandinglabel.cs

C#编写的网络爬虫程序 效率很高 很好用！

#region Copyright (c) 2002-2003 Charlie Poole
/************************************************************************************
'
' Copyright (c) 2002-2003 Charlie Poole
'
' Later versions may be available at http://charliepoole.org.
'
' This software is provided 'as-is', without any express or implied warranty. In no 
' event will the author be held liable for any damages arising from the use of this 
' software.
' 
' Permission is granted to anyone to use this software for any purpose, including 
' commercial applications, and to alter it and redistribute it freely, subject to the 
' following restrictions:
'
' 1. The origin of this software must not be misrepresented; you must not claim that
' you wrote the original software. If you use this software in a product, you must
' include the following notice in the product documentation and/or other materials
' provided with the distribution.
'
' Portions Copyright (c) 2002-2003 Charlie Poole
'
' 2. Altered source versions must be plainly marked as such, and must not be 
' misrepresented as being the original software.
'
' 3. This notice may not be removed from or altered in any source distribution.
'
'***********************************************************************************/
#endregion

using System;
using System.Windows.Forms;
using System.ComponentModel;
using System.Drawing;

namespace CP.Windows.Forms
{
	/// <summary>
	/// A special type of label which can display a tooltip-like
	/// window to show the full extent of any text which doesn't 
	/// fit. The window may be placed directly over the label
	/// or immediately beneath it and will expand to fit in
	/// a horizontal, vertical or both directions as needed.
	/// </summary>
	public class ExpandingLabel : System.Windows.Forms.Label
	{
		#region Instance Variables

		/// <summary>
		/// Our window for displaying expanded text
		/// </summary>
		private TipWindow tipWindow;
		
		/// <summary>
		/// Direction of expansion
		/// </summary>
		private TipWindow.ExpansionStyle expansion = TipWindow.ExpansionStyle.Horizontal;
		
		/// <summary>
		/// True if tipWindow may overlay the label
		/// </summary>
		private bool overlay = true;
		
		/// <summary>
		/// Time in milliseconds that the tip window
		/// will remain displayed.
		/// </summary>
		private int autoCloseDelay = 0;

		/// <summary>
		/// Time in milliseconds that the window stays
		/// open after the mouse leaves the control.
		/// </summary>
		private int mouseLeaveDelay = 300;

		/// <summary>
		/// If true, a context menu with Copy is displayed which
		/// allows copying contents to the clipboard.
		/// </summary>
		private bool copySupported = false;

		#endregion

		#region Properties

		[Browsable( false )]
		public bool Expanded
		{
			get { return tipWindow != null && tipWindow.Visible; }
		}

		[Category ( "Behavior"  ), DefaultValue( TipWindow.ExpansionStyle.Horizontal )]
		public TipWindow.ExpansionStyle Expansion
		{
			get { return expansion; }
			set { expansion = value; }
		}

		[Category( "Behavior" ), DefaultValue( true )]
		[Description("Indicates whether the tip window should overlay the label")]
		public bool Overlay
		{
			get { return overlay; }
			set { overlay = value; }
		}

		/// <summary>
		/// Time in milliseconds that the tip window
		/// will remain displayed.
		/// </summary>
		[Category( "Behavior" ), DefaultValue( 0 )]
		[Description("Time in milliseconds that the tip is displayed. Zero indicates no automatic timeout.")]
		public int AutoCloseDelay
		{
			get { return autoCloseDelay; }
			set { autoCloseDelay = value; }
		}

		/// <summary>
		/// Time in milliseconds that the window stays
		/// open after the mouse leaves the control.
		/// Reentering the control resets this.
		/// </summary>
		[Category( "Behavior" ), DefaultValue( 300 )]
		[Description("Time in milliseconds that the tip is displayed after the mouse levaes the control")]
		public int MouseLeaveDelay
		{
			get { return mouseLeaveDelay; }
			set { mouseLeaveDelay = value; }
		}

		[Category( "Behavior"), DefaultValue( false )]
		[Description("If true, displays a context menu with Copy")]
		public bool CopySupported
		{
			get { return copySupported; }
			set 
			{ 
				copySupported = value; 
				if ( copySupported )
					base.ContextMenu = null;
			}
		}

		/// <summary>
		/// Override Text property to set up copy menu if
		/// the value is non-empty.
		/// </summary>
		public override string Text
		{
			get { return base.Text; }
			set 
			{ 
				base.Text = value;

				if ( copySupported )
				{
					if ( value == null || value == string.Empty )
					{
						if ( this.ContextMenu != null )
						{
							this.ContextMenu.Dispose();
							this.ContextMenu = null;
						}
					}
					else
					{
						this.ContextMenu = new System.Windows.Forms.ContextMenu();
						MenuItem copyMenuItem = new MenuItem( "Copy", new EventHandler( CopyToClipboard ) );
						this.ContextMenu.MenuItems.Add( copyMenuItem );
					}
				}
			}
		}

		#endregion

		#region Public Methods

		public void Expand()
		{
			if ( !Expanded )
			{
				tipWindow = new TipWindow( this );
				tipWindow.Closed += new EventHandler( tipWindow_Closed );
				tipWindow.Expansion = this.Expansion;
				tipWindow.Overlay = this.Overlay;
				tipWindow.AutoCloseDelay = this.AutoCloseDelay;
				tipWindow.MouseLeaveDelay = this.MouseLeaveDelay;
				tipWindow.WantClicks = this.CopySupported;
				tipWindow.Show();
			}
		}

		public void Unexpand()
		{
			if ( Expanded )
			{
				tipWindow.Close();
			}
		}

		#endregion

		#region Event Handlers

		private void tipWindow_Closed( object sender, EventArgs e )
		{
			tipWindow = null;
		}

		protected override void OnMouseHover(System.EventArgs e)
		{
			Graphics g = Graphics.FromHwnd( Handle );
			SizeF sizeNeeded = g.MeasureString( Text, Font );
			bool expansionNeeded = 
				Width < (int)sizeNeeded.Width ||
				Height < (int)sizeNeeded.Height;

			if ( expansionNeeded ) Expand();
		}

		/// <summary>
		/// Copy contents to clipboard
		/// </summary>
		private void CopyToClipboard( object sender, EventArgs e )
		{
			Clipboard.SetDataObject( this.Text );
		}
	
		#endregion
	}
}