窗体样式使用WS_EX_LAYERED后，无法绘制windows控件的解决办法

根据一副png图片绘制半透明窗体时，用了WS_EX_LAYERED后当前窗体再也不会处理paint事件，所以所含的子控件是一辈子也不会画出来的，但是这个控件确实存在，而且可以响应事件 。而此时windows画制窗体是使用UpdateLayeredWindow这个api函数的。

其实这个问题，3年前就在csdn网友miky的"笨笨钟"发布后就讨论过了，后来出了一个叫桌面天气秀 的东东也采用类似的技术。那时候我有幸拿到了miky的delphi下实现gdi+半透明窗体的一段代码，因为无法画出button等控件和 几位高人讨论过，这里是当时的讨论情况

http://borland.mblogger.cn/jinjazz/posts/21093.aspx

最终并没有很好的解决办法，而是通过大概如下的方法解决的

————————————————————————————————————

对于按钮，完全可以自己画两个图片然后盖在button上面，通过处理button的enter和leave消息来切换者两个图片来表达按钮状态

对于输入框..这个可以用一个让任何人看了都生气地办法，那就是....两个窗体 ，的确别人就是这么做的

可以用一个空心窗体只显示该显示的控件，然后盖在你的半透明窗体上面，并处理半透明窗体的move事件，让另外一个窗体同步移动或者做其它事情

效果如下：

以下是一些C#代码，Delphi的就不贴了

主Form的代码

using  System;
using  System.Drawing;
using  System.Drawing.Imaging;
using  System.Collections;
using  System.ComponentModel;
using  System.Windows.Forms;
using  System.Data;
using  System.Runtime.InteropServices;

namespace  WindowsApplication7
... {

    
     public   class  Form1 : System.Windows.Forms.Form
     ... {
         private  System.ComponentModel.IContainer components;

         public  Form1()
         ... {
             //
             //  Windows 窗体设计器支持所必需的
             //
            InitializeComponent();
            FormBorderStyle  =  FormBorderStyle.None;

             
        }

         /**/ ///   <summary>
         ///  清理所有正在使用的资源。
         ///   </summary>
         protected   override   void  Dispose(  bool  disposing )
         ... {
             if ( disposing )
             ... {
                 if  (components  !=   null ) 
                 ... {
                    components.Dispose();
                }
            }
             base .Dispose( disposing );
        }

         Windows Form Designer generated code #region  Windows Form Designer generated code
         /**/ ///   <summary>
         ///  设计器支持所需的方法 - 不要使用代码编辑器修改
         ///  此方法的内容。
         ///   </summary>
         private   void  InitializeComponent()
         ... {
             this .button1  =   new  System.Windows.Forms.Button();
             this .SuspendLayout();
             //  
             //  button1
             //  
             this .button1.Cursor  =  System.Windows.Forms.Cursors.Hand;
             this .button1.Location  =   new  System.Drawing.Point( 20 ,  20 );
             this .button1.Name  =   " button1 " ;
             this .button1.Size  =   new  System.Drawing.Size( 113 ,  51 );
             this .button1.TabIndex  =   1 ;
             this .button1.Text  =   " button1 " ;
             this .button1.MouseLeave  +=   new  System.EventHandler( this .button1_MouseLeave);
             this .button1.Click  +=   new  System.EventHandler( this .button1_Click);
             this .button1.MouseEnter  +=   new  System.EventHandler( this .button1_MouseEnter);
             //  
             //  Form1
             //  
             this .AutoScaleBaseSize  =   new  System.Drawing.Size( 6 ,  14 );
             this .ClientSize  =   new  System.Drawing.Size( 184 ,  123 );
             this .Controls.Add( this .button1);
             this .Name  =   " Form1 " ;
             this .StartPosition  =  System.Windows.Forms.FormStartPosition.CenterScreen;
             this .Text  =   " Form1 " ;
             this .Load  +=   new  System.EventHandler( this .Form1_Load);
             this .VisibleChanged  +=   new  System.EventHandler( this .Form1_VisibleChanged);
             this .FormClosed  +=   new  System.Windows.Forms.FormClosedEventHandler( this .Form1_FormClosed);
             this .MouseDown  +=   new  System.Windows.Forms.MouseEventHandler( this .Form1_MouseDown);
             this .Move  +=   new  System.EventHandler( this .Form1_Move);
             this .ResumeLayout( false );

        }
         #endregion

         /**/ ///   <summary>
         ///  应用程序的主入口点。
         ///   </summary>
        [STAThread]
         static   void  Main() 
         ... {
            
            Application.Run( new  Form1());
        }


        Form2 controlFrm  =   new  Form2();
         private   void  button1_Click( object  sender, System.EventArgs e)
         ... {
            MessageBox.Show(controlFrm,controlFrm.textBox1.Text);
            
        }

         protected   override  CreateParams CreateParams
         ... {
             get
             ... {
                CreateParams cp  =   base .CreateParams;
                cp.ExStyle  |=   0x00080000 ;  //  This form has to have the WS_EX_LAYERED extended style
                 return  cp;
            }
        }

        
         private   void  SetStyle1()
         ... {
            Bitmap bm  =  Image.FromFile( @" Green.png " )  as  Bitmap;
            Bitmap bm2  =  Image.FromFile( @" btn.png " )  as  Bitmap;

            Graphics g  =  Graphics.FromImage(bm);
            g.DrawImage(bm2,  20 ,  20 ,  new  Rectangle( 0 ,  0 ,  90 ,  50 ), GraphicsUnit.Pixel);

            g.DrawString( " by jinjazz " ,  new  Font( " Ariel " ,  9 , FontStyle.Bold),  new  SolidBrush(Color.Black),  new  PointF( 40 ,  50 ));

             this .SetBitmap(bm,  255 );
        }
         private   void  SetStyle2()
         ... {
            Bitmap bm  =  Image.FromFile( @" Green.png " )  as  Bitmap;
            Bitmap bm2  =  Image.FromFile( @" btn.png " )  as  Bitmap;

            Graphics g  =  Graphics.FromImage(bm);
            g.DrawImage(bm2,  15 ,  15 ,  new  Rectangle( 7 ,  140 ,  100 ,  50 ), GraphicsUnit.Pixel);

            g.DrawString( " by jinjazz " ,  new  Font( " Ariel " ,  9 , FontStyle.Bold),  new  SolidBrush(Color.Black),  new  PointF( 40 ,  50 ));

             this .SetBitmap(bm,  255 );
        }

        
         private   void  Form1_Load( object  sender, System.EventArgs e)
         ... {
            
            controlFrm.Show();
            SetStyle1();
           
             // this.TopMost = true;
            controlFrm.TopMost  =   true ;
        }

         private   void  button1_MouseEnter( object  sender, EventArgs e)
         ... {

            SetStyle2();
        }
         private   void  button1_MouseLeave( object  sender, EventArgs e)
         ... {
            SetStyle1();
        }

         public   void  SetBitmap(Bitmap bitmap,  byte  opacity)
         ... {
             if  (bitmap.PixelFormat  !=  PixelFormat.Format32bppArgb)
                 throw   new  ApplicationException( " The bitmap must be 32ppp with alpha-channel. " );

             //  The ideia of this is very simple,
             //  1. Create a compatible DC with screen;
             //  2. Select the bitmap with 32bpp with alpha-channel in the compatible DC;
             //  3. Call the UpdateLayeredWindow.

            IntPtr screenDc  =  Win32.GetDC(IntPtr.Zero);
            IntPtr memDc  =  Win32.CreateCompatibleDC(screenDc);
            IntPtr hBitmap  =  IntPtr.Zero;
            IntPtr oldBitmap  =  IntPtr.Zero;

             try  
             ... {
                hBitmap  =  bitmap.GetHbitmap(Color.FromArgb( 0 ));   //  grab a GDI handle from this GDI+ bitmap
                oldBitmap  =  Win32.SelectObject(memDc, hBitmap);

                Win32.Size size  =   new  Win32.Size(bitmap.Width, bitmap.Height);
                Win32.Point pointSource  =   new  Win32.Point( 0 ,  0 );
                Win32.Point topPos  =   new  Win32.Point(Left, Top);
                Win32.BLENDFUNCTION blend  =   new  Win32.BLENDFUNCTION();
                blend.BlendOp              =  Win32.AC_SRC_OVER;
                blend.BlendFlags           =   0 ;
                blend.SourceConstantAlpha  =  opacity;
                blend.AlphaFormat          =  Win32.AC_SRC_ALPHA;

                Win32.UpdateLayeredWindow(Handle, screenDc,  ref  topPos,  ref  size, memDc,  ref  pointSource,  0 ,  ref  blend, Win32.ULW_ALPHA);
            }
             finally  
             ... {
                Win32.ReleaseDC(IntPtr.Zero, screenDc);
                 if  (hBitmap  !=  IntPtr.Zero) 
                 ... {
                    Win32.SelectObject(memDc, oldBitmap);
                     // Windows.DeleteObject(hBitmap);  //  The documentation says that we have to use the Windows.DeleteObject... but since there is no such method I use the normal DeleteObject from Win32 GDI and it's working fine without any resource leak.
                    Win32.DeleteObject(hBitmap);
                }
                Win32.DeleteDC(memDc);
            }
        }

         
         private  System.Windows.Forms.Button button1;
        
         private   void  Form1_MouseDown( object  sender, System.Windows.Forms.MouseEventArgs e)
         ... {
            Win32.ReleaseCapture();
            Win32.SendMessage( this .Handle.ToInt32(), Win32.WM_SysCommand, Win32.SC_MOVE,  0 );
        }

         private   void  Form1_Move( object  sender, EventArgs e)
         ... {
            controlFrm.Location  =   this .Location;
        }

         private   void  Form1_VisibleChanged( object  sender, EventArgs e)
         ... {
            controlFrm.Visible  =   this .Visible;
        }

         private   void  Form1_FormClosed( object  sender, FormClosedEventArgs e)
         ... {
            controlFrm.Close();
        }

    }
}

显示子控件的Form代码

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

namespace  WindowsApplication7
... {
     public   partial   class  Form2 : Form
     ... {
         public  Form2()
         ... {
            InitializeComponent();
        }
         private  System.ComponentModel.IContainer components  =   null ;

         /**/ ///   <summary>
         ///  清理所有正在使用的资源。
         ///   </summary>
         ///   <param name="disposing"> 如果应释放托管资源，为 true；否则为 false。 </param>
         protected   override   void  Dispose( bool  disposing)
         ... {
             if  (disposing  &&  (components  !=   null ))
             ... {
                components.Dispose();
            }
             base .Dispose(disposing);
        }

         Windows 窗体设计器生成的代码 #region  Windows 窗体设计器生成的代码

         /**/ ///   <summary>
         ///  设计器支持所需的方法 - 不要
         ///  使用代码编辑器修改此方法的内容。
         ///   </summary>
         private   void  InitializeComponent()
         ... {
             this .button1  =   new  System.Windows.Forms.Button();
             this .textBox1  =   new  System.Windows.Forms.TextBox();
             this .SuspendLayout();
             //  
             //  button1
             //  
             this .button1.BackColor  =  System.Drawing.SystemColors.Control;
             this .button1.Location  =   new  System.Drawing.Point( 118 ,  97 );
             this .button1.Name  =   " button1 " ;
             this .button1.Size  =   new  System.Drawing.Size( 55 ,  23 );
             this .button1.TabIndex  =   0 ;
             this .button1.Text  =   " ok " ;
             this .button1.UseVisualStyleBackColor  =   false ;
             this .button1.Click  +=   new  System.EventHandler( this .button1_Click);
             //  
             //  textBox1
             //  
             this .textBox1.Location  =   new  System.Drawing.Point( 12 ,  99 );
             this .textBox1.Name  =   " textBox1 " ;
             this .textBox1.Size  =   new  System.Drawing.Size( 100 ,  21 );
             this .textBox1.TabIndex  =   1 ;
             this .textBox1.Text  =   " I Love Jinjazz " ;
             //  
             //  Form2
             //  
             this .AutoScaleDimensions  =   new  System.Drawing.SizeF(6F, 12F);
             this .AutoScaleMode  =  System.Windows.Forms.AutoScaleMode.Font;
             this .BackColor  =  System.Drawing.Color.LightPink;
             this .ClientSize  =   new  System.Drawing.Size( 184 ,  123 );
             this .Controls.Add( this .textBox1);
             this .Controls.Add( this .button1);
             this .FormBorderStyle  =  System.Windows.Forms.FormBorderStyle.None;
             this .Name  =   " Form2 " ;
             this .ShowInTaskbar  =   false ;
             this .StartPosition  =  System.Windows.Forms.FormStartPosition.CenterScreen;
             this .Text  =   " Form2 " ;
             this .TransparencyKey  =  System.Drawing.Color.LightPink;
             this .ResumeLayout( false );
             this .PerformLayout();

        }

         #endregion

         private  System.Windows.Forms.Button button1;
         internal  System.Windows.Forms.TextBox textBox1;
         private   void  button1_Click( object  sender, EventArgs e)
         ... {
            MessageBox.Show( this .textBox1.Text);
            
        }

       
    }
}

调用API的代码

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Runtime.InteropServices;
namespace  WindowsApplication7
... {
     class  Win32
     ... {
         public   enum  Bool
         ... {
            False  =   0 ,
            True
        } ;


        [StructLayout(LayoutKind.Sequential)]
         public   struct  Point
         ... {
             public  Int32 x;
             public  Int32 y;

             public  Point(Int32 x, Int32 y)  ... {  this .x  =  x;  this .y  =  y; }
        }


        [StructLayout(LayoutKind.Sequential)]
         public   struct  Size
         ... {
             public  Int32 cx;
             public  Int32 cy;

             public  Size(Int32 cx, Int32 cy)  ... {  this .cx  =  cx;  this .cy  =  cy; }
        }


        [StructLayout(LayoutKind.Sequential, Pack  =   1 )]
         struct  ARGB
         ... {
             public   byte  Blue;
             public   byte  Green;
             public   byte  Red;
             public   byte  Alpha;
        }


        [StructLayout(LayoutKind.Sequential, Pack  =   1 )]
         public   struct  BLENDFUNCTION
         ... {
             public   byte  BlendOp;
             public   byte  BlendFlags;
             public   byte  SourceConstantAlpha;
             public   byte  AlphaFormat;
        }


         public   const  Int32 ULW_COLORKEY  =   0x00000001 ;
         public   const  Int32 ULW_ALPHA  =   0x00000002 ;
         public   const  Int32 ULW_OPAQUE  =   0x00000004 ;

         public   const   byte  AC_SRC_OVER  =   0x00 ;
         public   const   byte  AC_SRC_ALPHA  =   0x01 ;


        [DllImport( " user32.dll " , ExactSpelling  =   true , SetLastError  =   true )]
         public   static   extern  Bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst,  ref  Point pptDst,  ref  Size psize, IntPtr hdcSrc,  ref  Point pprSrc, Int32 crKey,  ref  BLENDFUNCTION pblend, Int32 dwFlags);

        [DllImport( " user32.dll " , ExactSpelling  =   true , SetLastError  =   true )]
         public   static   extern  IntPtr GetDC(IntPtr hWnd);

        [DllImport( " user32.dll " , ExactSpelling  =   true )]
         public   static   extern   int  ReleaseDC(IntPtr hWnd, IntPtr hDC);

        [DllImport( " gdi32.dll " , ExactSpelling  =   true , SetLastError  =   true )]
         public   static   extern  IntPtr CreateCompatibleDC(IntPtr hDC);

        [DllImport( " gdi32.dll " , ExactSpelling  =   true , SetLastError  =   true )]
         public   static   extern  Bool DeleteDC(IntPtr hdc);

        [DllImport( " gdi32.dll " , ExactSpelling  =   true )]
         public   static   extern  IntPtr SelectObject(IntPtr hDC, IntPtr hObject);

        [DllImport( " gdi32.dll " , ExactSpelling  =   true , SetLastError  =   true )]
         public   static   extern  Bool DeleteObject(IntPtr hObject);

        [DllImport( " user32.dll " , EntryPoint  =   " SendMessage " )]
         public   static   extern   int  SendMessage( int  hWnd,  int  wMsg,  int  wParam,  int  lParam);
        [DllImport( " user32.dll " , EntryPoint  =   " ReleaseCapture " )]

         public   static   extern   int  ReleaseCapture();
         public   const   int  WM_SysCommand  =   0x0112 ;
         public   const   int  SC_MOVE  =   0xF012 ;

         public   const   int  SC_MAXIMIZE  =   61488 ;
         public   const   int  SC_MINIMIZE  =   61472 ;
    }
}