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, 0, 0);
                }
            }
            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(0, 0, 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, 0, 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