将System.Drawing.Bitmap转换为Direct2D.D2DBitmap

最近在尝试Direct2D编程，挺好玩的。

但是有时候还是会用到GDI+来生成图片，但D2D绘图需要用到自己的D2DBitmap类。

因此需要转换，查阅了下网上的资料，写了这么一个方法：

 using System;
 using System.Windows.Forms;
 using System.Linq;
 using System.Text;
 using System.Diagnostics;
 using DX = SharpDX;
 using D2D = SharpDX.Direct2D1;
 using WIC = SharpDX.WIC;
 using DDW = SharpDX.DirectWrite;
 using DXGI = SharpDX.DXGI;
 using SharpDX;

         public D2D.Bitmap ConvertFromSystemBitmap(System.Drawing.Bitmap bmp)
         {
             System.Drawing.Bitmap desBitmap;//预定义要是使用的bitmap
             //如果原始的图像像素格式不是32位带alpha通道
             //需要转换为32位带alpha通道的格式
             //否则无法和Direct2D的格式对应
             if (bmp.PixelFormat != System.Drawing.Imaging.PixelFormat.Format32bppPArgb)
             {
                 desBitmap = new System.Drawing.Bitmap(bmp.Width, bmp.Height, System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
                 using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(desBitmap))
                 {
                     g.DrawImage(bmp, , );
                 }
             }
             else
             {
                 desBitmap = bmp;
             }

             //直接内存copy会非常快
             //如果使用循环逐点转换会非常慢
             System.Drawing.Imaging.BitmapData bmpData = desBitmap.LockBits(
                         new System.Drawing.Rectangle(, , desBitmap.Width, desBitmap.Height),
                         System.Drawing.Imaging.ImageLockMode.ReadOnly,
                         desBitmap.PixelFormat
                     );
             int numBytes = bmpData.Stride * desBitmap.Height;
             byte[] byteData = new byte[numBytes];
             IntPtr ptr = bmpData.Scan0;
             System.Runtime.InteropServices.Marshal.Copy(ptr, byteData, , numBytes);
             desBitmap.UnlockBits(bmpData);

             D2D.BitmapProperties bp;
             D2D.PixelFormat pixelFormat = new D2D.PixelFormat(DXGI.Format.B8G8R8A8_UNorm, D2D.AlphaMode.Premultiplied);

             bp = new D2D.BitmapProperties(
                       pixelFormat,
                       desBitmap.HorizontalResolution,
                       desBitmap.VerticalResolution
                     );
             D2D.Bitmap tempBitmap = new D2D.Bitmap(_renderTarget, new Size2(desBitmap.Width, desBitmap.Height), bp);
             tempBitmap.CopyFromMemory(byteData, bmpData.Stride);

             return tempBitmap;
         }

PS.这里我用的是SharpDX组件，因为微软的Windows API Code Pack，只更新到1.1,2010年后就不维护了