C# 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。
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 /// <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 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; }}
