codeproject上一个外国人写的透明TextBox控件类

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

using System.Drawing.Imaging;

namespace ZBobb
{
 /// <summary>
 /// AlphaBlendTextBox: A .Net textbox that can be translucent to the background.
 /// (C) 2003 Bob Bradley / ZBobb@hotmail.com
 /// </summary>
 ///

 

 public class AlphaBlendTextBox : System.Windows.Forms.TextBox
 {
  #region private variables

  private uPictureBox myPictureBox;
  private  bool   myUpToDate = false;
  private  bool   myCaretUpToDate = false;
  private  Bitmap myBitmap;
  private  Bitmap myAlphaBitmap;

  private int myFontHeight = 10;

  private System.Windows.Forms.Timer myTimer1;

  private bool myCaretState = true;

  private bool myPaintedFirstTime = false;

  private Color myBackColor = Color.White;
  private int myBackAlpha = 10;  
  
  /// <summary>
  /// Required designer variable.
  /// </summary>
  private System.ComponentModel.Container components = null;

  #endregion // end private variables

  #region public methods and overrides

  public AlphaBlendTextBox()
  {
   // This call is required by the Windows.Forms Form Designer.
   InitializeComponent();
   // TODO: Add any initialization after the InitializeComponent call

   this.BackColor = myBackColor;

   this.SetStyle(ControlStyles.UserPaint,false);
   this.SetStyle(ControlStyles.AllPaintingInWmPaint,true);
   this.SetStyle(ControlStyles.DoubleBuffer,true);

   myPictureBox = new uPictureBox();
   this.Controls.Add(myPictureBox);
   myPictureBox.Dock = DockStyle.Fill;
  }

  protected override void OnResize(EventArgs e)
  {
   
   base.OnResize (e);
   this.myBitmap = new Bitmap(this.ClientRectangle.Width,this.ClientRectangle.Height);//(this.Width,this.Height);
   this.myAlphaBitmap = new Bitmap(this.ClientRectangle.Width,this.ClientRectangle.Height);//(this.Width,this.Height);
   myUpToDate = false;
   this.Invalidate();
  }

  //Some of these should be moved to the WndProc later

  protected override void OnKeyDown(KeyEventArgs e)
  {
   base.OnKeyDown (e);
   myUpToDate = false;
   this.Invalidate();
  }

  protected override void OnKeyUp(KeyEventArgs e)
  {
   base.OnKeyUp (e);
   myUpToDate = false;
   this.Invalidate();

  }

  protected override void OnKeyPress(KeyPressEventArgs e)
  {
   base.OnKeyPress (e);
   myUpToDate = false;
   this.Invalidate();
  }

  protected override void OnMouseUp(MouseEventArgs e)
  {
   base.OnMouseUp (e);
   this.Invalidate();
  }

  protected override void OnGiveFeedback(GiveFeedbackEventArgs gfbevent)
  {
   base.OnGiveFeedback (gfbevent);
   myUpToDate = false;
   this.Invalidate();
  }

  protected override void OnMouseLeave(EventArgs e)
  {
   //found this code to find the current cursor location
   //at http://www.syncfusion.com/FAQ/WinForms/FAQ_c50c.asp#q597q

   Point ptCursor = Cursor.Position;
   
   Form f = this.FindForm();
   ptCursor = f.PointToClient(ptCursor);
   if( !this.Bounds.Contains(ptCursor) ) 
    base.OnMouseLeave (e);
  }  
  
     
  protected override void OnChangeUICues(UICuesEventArgs e)
  {
   base.OnChangeUICues (e);
   myUpToDate = false;
   this.Invalidate();
  }
  
  
//--
  protected override void OnGotFocus(EventArgs e)
  {
   base.OnGotFocus (e);
   myCaretUpToDate = false;
   myUpToDate = false;
   this.Invalidate();
   

   myTimer1 = new System.Windows.Forms.Timer(this.components);
   myTimer1.Interval = (int) win32.GetCaretBlinkTime(); //  usually around 500;
   
   myTimer1.Tick +=new EventHandler(myTimer1_Tick);
   myTimer1.Enabled = true;
    
  }

  protected override void OnLostFocus(EventArgs e)
  {
   base.OnLostFocus (e);
   myCaretUpToDate = false;
   myUpToDate = false;
   this.Invalidate();

   myTimer1.Dispose();
  }

//--  

  protected override void OnFontChanged(EventArgs e)
  {
   if (this.myPaintedFirstTime)
    this.SetStyle(ControlStyles.UserPaint,false);

   base.OnFontChanged (e);

   if (this.myPaintedFirstTime)
    this.SetStyle(ControlStyles.UserPaint,true);

    
   myFontHeight = GetFontHeight();

   myUpToDate = false;
   this.Invalidate();
  }

  protected override void OnTextChanged(EventArgs e)
  {
   base.OnTextChanged (e);
   myUpToDate = false;
   this.Invalidate();
  }

  
  protected override void WndProc(ref Message m)
  {

   base.WndProc (ref m);

   // need to rewrite as a big switch

   if (m.Msg == win32.WM_PAINT)
   {
    myPaintedFirstTime = true;

    if (!myUpToDate || !myCaretUpToDate)
     GetBitmaps();
    myUpToDate = true;
    myCaretUpToDate = true;

    if (myPictureBox.Image != null) myPictureBox.Image.Dispose();
    myPictureBox.Image = (Image)myAlphaBitmap.Clone();

   }

   else if (m.Msg ==  win32.WM_HSCROLL || m.Msg == win32.WM_VSCROLL)
   {
    myUpToDate = false;
    this.Invalidate();   
   }

   else if (m.Msg == win32.WM_LBUTTONDOWN
    || m.Msg == win32.WM_RBUTTONDOWN
    || m.Msg == win32.WM_LBUTTONDBLCLK
    //  || m.Msg == win32.WM_MOUSELEAVE  ///****
    )
   {
    myUpToDate = false;
    this.Invalidate();   
   }

   else if (m.Msg == win32.WM_MOUSEMOVE )
   {
    if (m.WParam.ToInt32() != 0)  //shift key or other buttons
    {
     myUpToDate = false;
     this.Invalidate();   
    }
   }

  
   //System.Diagnostics.Debug.WriteLine("Pro: " + m.Msg.ToString("X"));

  }

  /// <summary>
  /// Clean up any resources being used.
  /// </summary>
  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    //this.BackColor = Color.Pink;
    if(components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  #endregion  //end public method and overrides

  #region public property overrides

  public new BorderStyle BorderStyle
  {
   get {return base.BorderStyle;}
   set
   {
    if (this.myPaintedFirstTime)
     this.SetStyle(ControlStyles.UserPaint,false);

    base.BorderStyle = value;
    
    if (this.myPaintedFirstTime)
     this.SetStyle(ControlStyles.UserPaint,true);

    this.myBitmap = null;
    this.myAlphaBitmap = null;
    myUpToDate = false;
    this.Invalidate();
   }
  }

  public  new Color BackColor
  {
   get
   {
    return Color.FromArgb(base.BackColor.R, base.BackColor.G, base.BackColor.B);
   }
   set
   {
    myBackColor = value;
    base.BackColor = value;
    myUpToDate = false;
   }
  }
  public override bool Multiline
  {
   get{return base.Multiline;}
   set
   {
    if (this.myPaintedFirstTime)
     this.SetStyle(ControlStyles.UserPaint,false);
    
    base.Multiline = value;

    if (this.myPaintedFirstTime)
     this.SetStyle(ControlStyles.UserPaint,true);

    this.myBitmap = null;
    this.myAlphaBitmap = null;
    myUpToDate = false;
    this.Invalidate();
   }
  }

  
  #endregion    //end public property overrides

  #region private functions and classes

  private int GetFontHeight()
  {
   Graphics g = this.CreateGraphics();
   SizeF sf_font = g.MeasureString("X",this.Font);
   g.Dispose();
   return  (int) sf_font.Height;
  }
  
  
  private void GetBitmaps()
  {

   if (myBitmap == null
    || myAlphaBitmap == null
    || myBitmap.Width != Width
    || myBitmap.Height != Height  
    || myAlphaBitmap.Width != Width
    || myAlphaBitmap.Height != Height)
   {
    myBitmap = null;
    myAlphaBitmap = null;
   }

 

  if (myBitmap == null)
   {
    myBitmap = new Bitmap(this.ClientRectangle.Width,this.ClientRectangle.Height);//(Width,Height);
    myUpToDate = false;
   }

   if (!myUpToDate)
   {
    //Capture the TextBox control window

    this.SetStyle(ControlStyles.UserPaint,false);
    
    win32.CaptureWindow(this,ref myBitmap);

    this.SetStyle(ControlStyles.UserPaint,true);
    this.SetStyle(ControlStyles.SupportsTransparentBackColor,true);
    this.BackColor = Color.FromArgb(myBackAlpha,myBackColor);

   }
   //--
   

  
   Rectangle r2 = new Rectangle(0,0,this.ClientRectangle.Width,this.ClientRectangle.Height);
   ImageAttributes tempImageAttr = new ImageAttributes();
      

   //Found the color map code in the MS Help

   ColorMap[] tempColorMap = new ColorMap[1];
   tempColorMap[0] = new ColorMap();
   tempColorMap[0].OldColor = Color.FromArgb(255,myBackColor);
   tempColorMap[0].NewColor = Color.FromArgb(myBackAlpha,myBackColor);

   tempImageAttr.SetRemapTable(tempColorMap);

   if (myAlphaBitmap != null)
    myAlphaBitmap.Dispose();
     
     
   myAlphaBitmap = new Bitmap(this.ClientRectangle.Width,this.ClientRectangle.Height);//(Width,Height);

   Graphics tempGraphics1 = Graphics.FromImage(myAlphaBitmap);

   tempGraphics1.DrawImage(myBitmap,r2,0,0,this.ClientRectangle.Width,this.ClientRectangle.Height,GraphicsUnit.Pixel,tempImageAttr);

   tempGraphics1.Dispose();
   
//----

   if (this.Focused && (this.SelectionLength == 0))
   {
    Graphics tempGraphics2 = Graphics.FromImage(myAlphaBitmap);
    if (myCaretState)
    {
     //Draw the caret
     Point caret = this.findCaret();
     Pen p = new Pen(this.ForeColor,3);
     tempGraphics2.DrawLine(p,caret.X,caret.Y + 0,caret.X,caret.Y + myFontHeight);
     tempGraphics2.Dispose();
    }
      
   }

 

  }

 

  private Point findCaret()
  {
   /*  Find the caret translated from code at
    * http://www.vb-helper.com/howto_track_textbox_caret.html
    *
    * and
    *
    * http://www.microbion.co.uk/developers/csharp/textpos2.htm
    *
    * Changed to EM_POSFROMCHAR
    *
    * This code still needs to be cleaned up and debugged
    * */

   Point pointCaret = new Point(0);
   int i_char_loc = this.SelectionStart;
   IntPtr pi_char_loc = new IntPtr(i_char_loc);

   int i_point = win32.SendMessage(this.Handle,win32.EM_POSFROMCHAR,pi_char_loc,IntPtr.Zero);
   pointCaret = new Point(i_point);

   if (i_char_loc == 0)
   {
    pointCaret = new Point(0);
   }
   else if (i_char_loc >= this.Text.Length)
   {
    pi_char_loc = new IntPtr(i_char_loc - 1);
    i_point = win32.SendMessage(this.Handle,win32.EM_POSFROMCHAR,pi_char_loc,IntPtr.Zero);
    pointCaret = new Point(i_point);

    Graphics g = this.CreateGraphics();
    String t1 = this.Text.Substring(this.Text.Length-1,1) + "X";
    SizeF sizet1 = g.MeasureString(t1,this.Font);
    SizeF sizex  = g.MeasureString("X",this.Font);
    g.Dispose();
    int xoffset = (int)(sizet1.Width - sizex.Width);
    pointCaret.X = pointCaret.X + xoffset;

    if (i_char_loc == this.Text.Length)
    {
     String slast = this.Text.Substring(Text.Length-1,1);
     if (slast == "/n")
     {
      pointCaret.X = 1;
      pointCaret.Y = pointCaret.Y + myFontHeight;
     }
    }

   }

 

   return pointCaret;
  }

  private void myTimer1_Tick(object sender, EventArgs e)
  {
   //Timer used to turn caret on and off for focused control

   myCaretState = !myCaretState;
   myCaretUpToDate = false;
   this.Invalidate();
  }

  private class uPictureBox : PictureBox
  {
   public uPictureBox()
   {
    this.SetStyle(ControlStyles.Selectable,false);
    this.SetStyle(ControlStyles.UserPaint,true);
    this.SetStyle(ControlStyles.AllPaintingInWmPaint,true);
    this.SetStyle(ControlStyles.DoubleBuffer,true);

    this.Cursor = null;
    this.Enabled = true;
    this.SizeMode = PictureBoxSizeMode.Normal;
    
   }

 

   //uPictureBox
   protected override void WndProc(ref Message m)
   {
    if (m.Msg == win32.WM_LBUTTONDOWN
     || m.Msg == win32.WM_RBUTTONDOWN
     || m.Msg == win32.WM_LBUTTONDBLCLK
     || m.Msg == win32.WM_MOUSELEAVE
     || m.Msg == win32.WM_MOUSEMOVE )
    {
     //Send the above messages back to the parent control
     win32.PostMessage(this.Parent.Handle,(uint) m.Msg,m.WParam,m.LParam);
    }

    else if (m.Msg == win32.WM_LBUTTONUP)
    {
     //??  for selects and such
     this.Parent.Invalidate();
    }

    base.WndProc (ref m);
   }

  }   // End uPictureBox Class

  #endregion  // end private functions and classes

  #region Component Designer generated code
  /// <summary>
  /// Required method for Designer support - do not modify
  /// the contents of this method with the code editor.
  /// </summary>
  private void InitializeComponent()
  {
   components = new System.ComponentModel.Container();
  }
  #endregion

  #region New Public Properties

  [
  Category("Appearance"),
  Description("The alpha value used to blend the control's background. Valid values are 0 through 255."),
  Browsable(true),
  DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)

  ]
  public int BackAlpha
  {
   get { return myBackAlpha; }
   set
   {
    int v = value;
    if (v > 255)
     v = 255;
    myBackAlpha = v;
    myUpToDate = false;
    Invalidate();
   }
  }

  #endregion

 

 }  // End AlphaTextBox Class

}  // End namespace ZBobb

//----

 

 

 

 

 

//*******************************************

 

using System;
using System.Runtime.InteropServices;

using System.Drawing;

namespace ZBobb
{
 /// <summary>
 /// Win32 support code.
 /// (C) 2003 Bob Bradley / ZBobb@hotmail.com
 /// </summary>
 public class win32
 {
  
  public const int  WM_MOUSEMOVE      =              0x0200;
  public const int  WM_LBUTTONDOWN     =             0x0201;
  public const int  WM_LBUTTONUP       =             0x0202;
  public const int  WM_RBUTTONDOWN     =             0x0204;
  public const int  WM_LBUTTONDBLCLK   =             0x0203;

  public const int  WM_MOUSELEAVE      =             0x02A3;

  
  public const int WM_PAINT     =                   0x000F;
  public const int WM_ERASEBKGND   =                0x0014;
  
  public const int WM_PRINT         =               0x0317;

  //const int EN_HSCROLL       =   0x0601;
  //const int EN_VSCROLL       =   0x0602;

  public const int WM_HSCROLL       =              0x0114;
  public const int WM_VSCROLL       =              0x0115;

  public const int EM_GETSEL              = 0x00B0;
  public const int EM_LINEINDEX           = 0x00BB;
  public const int EM_LINEFROMCHAR        = 0x00C9;

  public const int EM_POSFROMCHAR         = 0x00D6;

 

  [DllImport("USER32.DLL", EntryPoint= "PostMessage")]
  public static extern bool PostMessage(IntPtr hwnd, uint msg,
   IntPtr wParam, IntPtr lParam);

  /*
   BOOL PostMessage(          HWND hWnd,
    UINT Msg,
    WPARAM wParam,
    LPARAM lParam
    );
  */

  // Put this declaration in your class   //IntPtr
  [DllImport("USER32.DLL", EntryPoint= "SendMessage")]
  public static extern int SendMessage(IntPtr hwnd, int msg, IntPtr wParam,
   IntPtr lParam);

 

  
  [DllImport("USER32.DLL", EntryPoint= "GetCaretBlinkTime")]
  public static extern uint GetCaretBlinkTime();

 

  const int WM_PRINTCLIENT = 0x0318;

  const long PRF_CHECKVISIBLE=0x00000001L;
  const long PRF_NONCLIENT = 0x00000002L;
  const long PRF_CLIENT  = 0x00000004L;
  const long PRF_ERASEBKGND = 0x00000008L;
  const long PRF_CHILDREN = 0x00000010L;
  const long PRF_OWNED  = 0x00000020L;

  /*  Will clean this up later doing something like this
  enum  CaptureOptions : long
  {
   PRF_CHECKVISIBLE= 0x00000001L,
   PRF_NONCLIENT = 0x00000002L,
   PRF_CLIENT  = 0x00000004L,
   PRF_ERASEBKGND = 0x00000008L,
   PRF_CHILDREN = 0x00000010L,
   PRF_OWNED  = 0x00000020L
  }
  */

  public static bool CaptureWindow(System.Windows.Forms.Control control,
        ref System.Drawing.Bitmap bitmap)
  {
   //This function captures the contents of a window or control

   Graphics g2 = Graphics.FromImage(bitmap);

   //PRF_CHILDREN // PRF_NONCLIENT
   int meint = (int)(PRF_CLIENT | PRF_ERASEBKGND); //| PRF_OWNED ); //  );
   System.IntPtr meptr = new System.IntPtr(meint);

   System.IntPtr hdc = g2.GetHdc();
   win32.SendMessage(control.Handle,win32.WM_PRINT,hdc,meptr);

   g2.ReleaseHdc(hdc);
   g2.Dispose();

   return true;
   
  }

 

 }
}