c#用png图片实现不规则窗体

c#用png图片实现不规则窗体

(2012-04-21 16:26:55)

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using System;

using System.Drawing;

using System.Drawing.Imaging;

using System.Windows.Forms;

usingSystem.Runtime.InteropServices;

 

 

namespace PngWinClass

{

    // class that exposes needed win32 gdi functions.

    class Win32

    {

        Form PngWin;

 

        public Win32( Form PngWinForm)

        {

            PngWin = PngWinForm;

        }

 

        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);

 

 

 

 

 

        /// <summary>

        /// 使用指定的图像来生成PNG窗体。

        /// </summary>

        /// <param name="bitmap"></param>

        public void SetBitmap(Bitmap bitmap)

        {

            SetBitmap(bitmap, 255);

        }

 

        /// <summary>

        /// 使用构造函数中的窗体的背景图像生成 PNG 窗体。

        /// </summary>

        public void SetBitmap()

        {

            if (PngWin.BackgroundImage != null)

                SetBitmap((Bitmap)PngWin.BackgroundImage, 255);

            else

                MessageBox.Show("窗体没有可用的背景图像！","错误：", MessageBoxButtons.OK, MessageBoxIcon.Error);

        }

 

 

        /// <para>Changes the current bitmap with a custom opacity level.  Here is where all happens!</para>

        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(PngWin.Left, PngWin.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(PngWin.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);

            }

 

            bitmap.Dispose();

 

        }

 

 

    }

 

}

 

 

//######################################################################

 

// 在调用窗口的构造函数下面添加下列代码：

        public Form1()

        {

            InitializeComponent();

        }

 

        // PNG窗口要用到的：

        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;

            }

        }