修改TreeView背景TreeViewWithPaint

using System; 
using System.Drawing; 
using System.Drawing.Drawing2D; 
using System.Windows.Forms; 
using System.ComponentModel; 
 
namespace NewControls { 
 
    ///  
    /// Displays a hierarchical collection of labeled items, each represented by a System.Windows.Forms.TreeNode. 
    ///  
    [ 
    //Use the same attibutes as TreeView 
    DesignerAttribute("System.Windows.Forms.Design.TreeViewDesigner, System.Design, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"), 
    DefaultPropertyAttribute("Nodes"), 
    DefaultEventAttribute("AfterSelect") 
    ] 
    public class TreeViewWithPaint :TreeView { 
 
        Bitmap   internalBitmap = null; 
        Graphics internalGraphics = null; 
Image image = null; 
 
        private void DisposeInternal() { 
            if( internalGraphics != null ) 
                internalGraphics.Dispose(); 
            if( internalBitmap != null ) 
                internalBitmap.Dispose(); 
 
        } 
        /// Releases resources. 
        /// true = Both managed and unmanaged, false = Unmanaged only. 
        protected override void Dispose(bool disposing) { 
            if( disposing ) 
                DisposeInternal(); 
            base.Dispose (disposing); 
        } 
 
        /// Occurs when window is resized. 
        /// A System.EventArgs.Empty. 
        /// Recreates internal Graphics object.  
        protected override void OnResize( System.EventArgs e ) { 
            if( internalBitmap == null  || 
                internalBitmap.Width != Width || internalBitmap.Height != Height ) { 
 
                if( Width != 0 && Height != 0 ) { 
                    DisposeInternal(); 
                    internalBitmap = new Bitmap( Width, Height ); 
                    internalGraphics = Graphics.FromImage( internalBitmap ); 
                } 
            } 
        } 
 
/// Occurs when a Windows message is dispatched. 
/// Message to process. 
/// Overrides WM_PAINT, WM_ERASEBKGND. 
public void setBackGround(Image bk) 
{ 
image = bk; 
} 
 
        /// Occurs when a Windows message is dispatched. 
        /// Message to process. 
        /// Overrides WM_PAINT, WM_ERASEBKGND. 
        protected override void WndProc(ref Message message)  
{ 
            const int WM_PAINT = 0x000F; 
            const int WM_PRINTCLIENT = 0x0318; 
            const int WM_ERASEBKGND = 0x0014; 
 
            switch( message.Msg ) { 
 
                case WM_ERASEBKGND: 
                    return; 
 
                case WM_PAINT: 
                    // The designer host does not call OnResize()                     
                    if( internalGraphics == null ) 
                        OnResize( EventArgs.Empty ); 
 
                    //Set up  
                    Win32.RECT updateRect = new Win32.RECT(); 
                    if( Win32.GetUpdateRect( message.HWnd, ref updateRect, false) == 0 ) 
                        break; 
 
//Draw Internal Graphics 
IntPtr hdc = internalGraphics.GetHdc(); 
Message printClientMessage = Message.Create( Handle, WM_PRINTCLIENT, hdc, IntPtr.Zero );   
DefWndProc( ref printClientMessage ); 
internalGraphics.ReleaseHdc( hdc ); 
 
//Add the missing OnPaint() call 
OnPaint( new PaintEventArgs( internalGraphics, Rectangle.FromLTRB(  
updateRect.left, 
updateRect.top, 
updateRect.right, 
updateRect.bottom ) ) ); 
 
 
                    Win32.PAINTSTRUCT paintStruct = new Win32.PAINTSTRUCT(); 
                    //IntPtr screenHdc1 = Win32.BeginPaint(message.HWnd, ref paintStruct); 
IntPtr screenHdc = Win32.GetDC(message.HWnd); 
                    using( Graphics screenGraphics = Graphics.FromHdc( screenHdc ) )  
{ 
                        //Draw Screen Graphics 
 
Bitmap temp = new Bitmap(internalBitmap, internalBitmap.Size); 
temp.MakeTransparent(Color.White); 
internalGraphics.FillRectangle(Brushes.White, 0, 0, this.Bounds.Width, this.Bounds.Height); 
if (image != null) 
internalGraphics.DrawImage (image, 0, 0, image.Width, image.Height); 
internalGraphics.DrawImage(temp, 0, 0, temp.Width, temp.Height); 
 
screenGraphics.DrawImage( internalBitmap, 0, 0 ); 
                    } 
 
                    //Tear down 
int ret = Win32.ReleaseDC(message.HWnd, screenHdc); 
Win32.ValidateRect(message.HWnd, ref updateRect); 
//Win32.EndPaint( message.HWnd, ref paintStruct ); 
                    return; 
            } 
            base.WndProc(ref message); 
        } 
 
        /// Occurs when the control is redrawn. 
        /// Re enable browsing attributes for the Paint Event. 
        [ 
        EditorBrowsableAttribute( EditorBrowsableState.Always ), 
        BrowsableAttribute(true) 
        ] 
        public new event PaintEventHandler Paint { 
            add   { base.Paint += value; } 
            remove{ base.Paint -= value; } 
        } 
    } 
}