将二维结构数组复制到 byte[]

Question

我有类似的事情：

[StructLayout(LayoutKind.Explicit)]
public struct PixelColorRGBA
{
    [FieldOffset(0)]
    public UInt32 ColorBGRA;
    [FieldOffset(0)]
    public byte Blue;
    [FieldOffset(1)]
    public byte Green;
    [FieldOffset(2)]
    public byte Red;
    [FieldOffset(3)]
    public byte Alpha;
}

将 PixelColorRGBA[w, h] 复制到 byte[w * h * 4] 的最快方法是什么，反之亦然？

Answer 1

我最终得到以下代码：

var source = new PixelColorRGBA[1000, 1000];
var destination = new byte[4000000];
{
    var start = DateTime.Now;
    unsafe
    {
        for (var q = 0; q < 100; q++)
            fixed (PixelColorRGBA* tmpSourcePtr = &source[0, 0])
            {
                var sourcePtr = (IntPtr) tmpSourcePtr;
                Marshal.Copy(sourcePtr, destination, 0, 4000000);
            }
    }
    Console.WriteLine("MS: " + DateTime.Now.Subtract(start).TotalMilliseconds);
}

在我的计算机上需要 62 毫秒。

Answer 2

尝试以下操作

    PixelColorRGBA[,] source = ...;
    byte[] dest = source
        .Cast<PixelColorRGBA>()
        .SelectMany(x => new byte[] { x.Blue, x.Green, x.Red, x.Alpha })
        .ToArray();

Answer 3

您可以使用

System.Buffer.BlockCopy(myArray, 0, byteArray, 0, length) 

或

System.Runtime.InteropServices.Marshal.Copy(myArray, 0, destPtr, length);