c# UpdateLayeredWindow异形窗口

#region UpdateLayeredWindow #region 重写窗体的 CreateParams 属性
protected override CreateParams CreateParams
{
get
{
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x00080000; // WS_EX_LAYERED 扩展样式
//无边框任务栏窗口最小化
const int WS_MINIMIZEBOX = 0x00020000; // Winuser.h中定义
//CreateParams cp = base.CreateParams;
cp.Style = cp.Style | WS_MINIMIZEBOX; // 允许最小化操作
return cp;
}
}
#endregion #region API调用
public void SetBits(Bitmap bitmap)//调用UpdateLayeredWindow（）方法。this.BackgroundImage为你事先准备的带透明图片。
{
//if (!haveHandle) return; if (!Bitmap.IsCanonicalPixelFormat(bitmap.PixelFormat) || !Bitmap.IsAlphaPixelFormat(bitmap.PixelFormat))
throw new ApplicationException("图片必须是32位带Alhpa通道的图片。"); IntPtr oldBits = IntPtr.Zero;
IntPtr screenDC = Win32.GetDC(IntPtr.Zero);
IntPtr hBitmap = IntPtr.Zero;
IntPtr memDc = Win32.CreateCompatibleDC(screenDC); try
{
Win32.Point topLoc = new Win32.Point(Left, Top);
Win32.Size bitMapSize = new Win32.Size(bitmap.Width, bitmap.Height);
Win32.BLENDFUNCTION blendFunc = new Win32.BLENDFUNCTION();
Win32.Point srcLoc = new Win32.Point(, ); hBitmap = bitmap.GetHbitmap(Color.FromArgb());
oldBits = Win32.SelectObject(memDc, hBitmap); blendFunc.BlendOp = Win32.AC_SRC_OVER;
blendFunc.SourceConstantAlpha = ;
blendFunc.AlphaFormat = Win32.AC_SRC_ALPHA;
blendFunc.BlendFlags = ; Win32.UpdateLayeredWindow(Handle, screenDC, ref topLoc, ref bitMapSize, memDc, ref srcLoc, , ref blendFunc, Win32.ULW_ALPHA);
}
finally
{
if (hBitmap != IntPtr.Zero)
{
Win32.SelectObject(memDc, oldBits);
Win32.DeleteObject(hBitmap);
}
Win32.ReleaseDC(IntPtr.Zero, screenDC);
Win32.DeleteDC(memDc);
}
}
#endregion #endregion

public MainForm()
{
InitializeComponent();
Bitmap bg = new Bitmap(this.Width, this.Height);
Graphics g = Graphics.FromImage(bg);
g.DrawImage(img, x, y, img.Width, img.Height);
g.Dispose();
SetBits(bg);
}