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;
    }
}