Question

我正在设计一个支持透明度的Compact Framework Control，对于控件的运行时版本，一切正常，只需在此API上执行平台调用：

[DllImport("coredll.dll")]
    extern public static Int32 AlphaBlend(IntPtr hdcDest, Int32 xDest, Int32 yDest, Int32 cxDest, Int32 cyDest, IntPtr hdcSrc, Int32 xSrc, Int32 ySrc, Int32 cxSrc, Int32 cySrc, BlendFunction blendFunction);

显然，对“coredll.dll”的调用不适用于桌面设计时间体验，而且现在，当绘画发生时，我只是检测到控件正在设计并且绘制它而没有任何透明度。我希望能够提供更好的设计时体验，并在Visual Studio Designer中显示相同的透明度。

我尝试过这个平台电话：

[DllImport("gdi32.dll", EntryPoint = "GdiAlphaBlend")]
    public static extern bool AlphaBlendDesktop(IntPtr hdcDest, int nXOriginDest, int nYOriginDest,
        int nWidthDest, int nHeightDest,
        IntPtr hdcSrc, int nXOriginSrc, int nYOriginSrc, int nWidthSrc, int nHeightSrc,
        BlendFunction blendFunction);

但是当它返回true时，结果是什么都没有画到设计时间视图。

有什么想法吗？

Answer 1

这让我欺骗设计师执行AlphaBlend操作。

// PixelFormatIndexed = 0x00010000, // Indexes into a palette
// PixelFormatGDI = 0x00020000, // Is a GDI-supported format
// PixelFormatAlpha = 0x00040000, // Has an alpha component
// PixelFormatPAlpha = 0x00080000, // Pre-multiplied alpha
// PixelFormatExtended = 0x00100000, // Extended color 16 bits/channel
// PixelFormatCanonical = 0x00200000,
// PixelFormat32bppARGB = (10 | (32 << 8) | PixelFormatAlpha | PixelFormatGDI | PixelFormatCanonical),

// cheat the design time to create a bitmap with an alpha channel
using (Bitmap bmp = new Bitmap(image.Width, image.Height, (PixelFormat) 
                                           PixelFormat32bppARGB))
{
  // copy the original image
  using(Graphics g = Graphics.FromImage(bmp))
  {
    g.DrawImage(image,0,0);
  }

  // Lock the bitmap's bits.  
  Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
  System.Drawing.Imaging.BitmapData bmpData =
  bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite,
                            (PixelFormat)PixelFormat32bppARGB);

  // Get the address of the first line.
  IntPtr ptr = bmpData.Scan0;

  // Declare an array to hold the bytes of the bitmap.
  // This code is specific to a bitmap with 32 bits per pixels.
  int bytes = bmp.Width * bmp.Height * 4;
  byte[] argbValues = new byte[bytes];

  // Copy the ARGB values into the array.
  System.Runtime.InteropServices.Marshal.Copy(ptr, argbValues, 0, bytes);

  // Set every alpha value to the given transparency.  
  for (int counter = 3; counter < argbValues.Length; counter += 4)
                           argbValues[counter] = transparency;

  // Copy the ARGB values back to the bitmap
  System.Runtime.InteropServices.Marshal.Copy(argbValues, 0, ptr, bytes);

  // Unlock the bits.
  bmp.UnlockBits(bmpData);

  gx.DrawImage(bmp, x, y);
}

Answer 2

很抱歉，这并不能完全回答你的问题...但你应该查看.Net Compact Framework的UI框架，它已经进行了alpha混合。

http://code.msdn.microsoft.com/uiframework

如何在设计时为Alpha框架控件进行Alpha混合

2 个答案: