C# - 将 WPF Image.source 转换为 System.Drawing.Bitmap

Question

我发现很多人将BitmapSource 转换为Bitmap，但是ImageSource 转换为Bitmap 呢？我正在制作一个成像程序，我需要从Image 元素中显示的图像中提取位图。有谁知道怎么做？

编辑 1：

这是一个将BitmapImage 转换为Bitmap 的函数。请记住在编译器首选项中设置“不安全”选项。

public static System.Drawing.Bitmap BitmapSourceToBitmap(BitmapSource srs)
{
    System.Drawing.Bitmap btm = null;

    int width = srs.PixelWidth;

    int height = srs.PixelHeight;

    int stride = width * ((srs.Format.BitsPerPixel + 7) / 8);

    byte[] bits = new byte[height * stride];

    srs.CopyPixels(bits, stride, 0);

    unsafe
    {
        fixed (byte* pB = bits)
        {
            IntPtr ptr = new IntPtr(pB);

            btm = new System.Drawing.Bitmap(width, height, stride, System.Drawing.Imaging.PixelFormat.Format1bppIndexed, ptr);
        }
    }
    return btm;
}

接下来是获取BitmapImage：

RenderTargetBitmap targetBitmap = new RenderTargetBitmap(
    (int)inkCanvas1.ActualWidth,
    (int)inkCanvas1.ActualHeight,
    96d, 96d,
    PixelFormats.Default);

targetBitmap.Render(inkCanvas1);

MemoryStream mse = new MemoryStream();
System.Windows.Media.Imaging.BmpBitmapEncoder mem = new BmpBitmapEncoder();
mem.Frames.Add(BitmapFrame.Create(targetBitmap));
mem.Save(mse);

mse.Position = 0;
BitmapImage bi = new BitmapImage();
bi.BeginInit();
bi.StreamSource = mse;
bi.EndInit();

接下来是转换它：

Bitmap b = new Bitmap(BitmapSourceToBitmap(bi));

Answer 1

其实你不需要使用不安全的代码。有一个接受 IntPtr 的 CopyPixels 的重载：

public static System.Drawing.Bitmap BitmapSourceToBitmap2(BitmapSource srs)
{
    int width = srs.PixelWidth;
    int height = srs.PixelHeight;
    int stride = width * ((srs.Format.BitsPerPixel + 7) / 8);
    IntPtr ptr = IntPtr.Zero;
    try
    {
        ptr = Marshal.AllocHGlobal(height * stride);
        srs.CopyPixels(new Int32Rect(0, 0, width, height), ptr, height * stride, stride);
        using (var btm = new System.Drawing.Bitmap(width, height, stride, System.Drawing.Imaging.PixelFormat.Format1bppIndexed, ptr))
        {
            // Clone the bitmap so that we can dispose it and
            // release the unmanaged memory at ptr
            return new System.Drawing.Bitmap(btm);
        }
    }
    finally
    {
        if (ptr != IntPtr.Zero)
            Marshal.FreeHGlobal(ptr);
    }
}

Answer 2

这个例子对我有用：

    public static Bitmap ConvertToBitmap(BitmapSource bitmapSource)
    {
        var width = bitmapSource.PixelWidth;
        var height = bitmapSource.PixelHeight;
        var stride = width * ((bitmapSource.Format.BitsPerPixel + 7) / 8);
        var memoryBlockPointer = Marshal.AllocHGlobal(height * stride);
        bitmapSource.CopyPixels(new Int32Rect(0, 0, width, height), memoryBlockPointer, height * stride, stride);
        var bitmap = new Bitmap(width, height, stride, PixelFormat.Format32bppPArgb, memoryBlockPointer);
        return bitmap;
    }

Answer 3

您根本不需要BitmapSourceToBitmap 方法。创建内存流后，只需执行以下操作：

mem.Position = 0;  
Bitmap b = new Bitmap(mem);

Answer 4

你的 ImageSource 不是 BitmapSource 吗？如果您从文件中加载图像，它们应该是。

回复您的评论：

听起来应该是BitmapSource，BitmapSource是ImageSource的子类型。将 ImageSource 转换为 BitmapSource 并关注其中一篇博文。