如何从像素字节数组创建BitmapImage(实时视频显示)

Question

我需要在WPF控件上显示实时图像.我正在寻找使用WPF执行此操作的最快方法.

我正在使用其DLL API(AVT)从相机捕获图像.

图像由dll写入,摄像机使用IntPtr将回调上升到名为tFrame的Image结构(如下所述).像素数据存储在ImageBuffer属性中,其中InPtr为字节数组.

我知道如何从像素字节数组创建一个位图,但不是BitmapImage.因此可以创建一个Bitmap,然后从中创建一个BitmapImagem. 这里有一种从内存上的位图创建BitmapImage的方法.但我想直接从数据源(tFrame)创建BitmapImage.我怎样才能做到这一点？

我知道BitmapImage有一个CopyPixels方法,但它有一个SetPixels.

public struct tFrame
{
    public IntPtr AncillaryBuffer;
    public uint AncillaryBufferSize;
    public uint AncillarySize;
    public tBayerPattern BayerPattern;
    public uint BitDepth;
    public tFrameCtx Context;
    public tImageFormat Format;
    public uint FrameCount;
    public uint Height;
    public IntPtr ImageBuffer;
    public uint ImageBufferSize;
    public uint ImageSize;
    public uint RegionX;
    public uint RegionY;
    public tErr Status;
    public uint TimestampHi;
    public uint TimestampLo;
    public uint Width;
}

这是我如何从像素字节数组创建位图.这是在WinForm版本的软件中使用的.

private void CreateBitmap(tFrame frame)
{
    //This sample is for a 8bpp captured image
    PixelFormat pxFormat = PixelFormat.Format8bppIndexed;

    //STRIDE
    //[https://stackoverflow.com/questions/1983781/why-does-bitmapsource-create-throw-an-argumentexception/1983886#1983886][3]
    //float bitsPerPixel = System.Drawing.Image.GetPixelFormatSize(format);
    int bitsPerPixel = ((int)pxFormat >> 8) & 0xFF;
    //Number of bits used to store the image data per line (only the valid data)
    int validBitsPerLine = ((int)frame.Width) * bitsPerPixel;
    //4 bytes for every int32 (32 bits)
    int stride = ((validBitsPerLine + 31) / 32) * 4;

    Bitmap bmp = new Bitmap((int)frame.Width, (int)frame.Height, stride, pxFormat, frame.ImageBuffer);
}

---

编辑1:

感谢dr.mo,现在我能够显示60个FPS 1024x1024图像,CPU使用率约为3%!我在做的是:

//@ UI Thread
public WriteableBitmap wbm = new WriteableBitmap(1024, 1024, (double)96, (double)96, System.Windows.Media.PixelFormats.Gray8, null);
this.wbBackBuffer = this.wbm.BackBuffer;

//This can be called by a timer in the UI thread or at the grab Thread for every image, the CPU usage is almost the same.
void UpdateDisplayImage()
{
wbm.Lock();
wbm.AddDirtyRect(new Int32Rect(0, 0, wbm.PixelWidth, wbm.PixelHeight));
wbm.Unlock();
}

//@ Grab Thread
//Update the backbuffer with new camera image data.
UpdateBackBuffer(...);

/// <summary>
/// [http://msdn.microsoft.com/en-us/library/system.windows.media.imaging.writeablebitmap.aspx]
/// </summary>
public void UpdateBackBuffer(IntPtr pData, int w, int h, int ch)
{
    //Can not acess wbm from outside UI thread
    //CopyMemory(wbm.BackBuffer, pData, (uint)(w * h * ch));
    //I dont know if it is safe to write to it buffer like this:
    CopyMemory(this.wbBackBuffer, pData, (uint)(w * h * ch));
}

Answer 1

这应该可以解决问题.它超级快.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

using System.Drawing;
using System.Runtime.InteropServices;
using System.IO;
using System.ComponentModel;


public class MakeBitmapSource
{
    [DllImport("kernel32.dll", EntryPoint = "RtlMoveMemory")]
    public static extern void CopyMemory(IntPtr Destination, IntPtr Source, uint Length);



    public static BitmapSource FromNativePointer(IntPtr pData, int w, int h, int ch)
    {
        PixelFormat format = PixelFormats.Default;

        if (ch == 1) format = PixelFormats.Gray8; //grey scale image 0-255
        if (ch == 3) format = PixelFormats.Bgr24; //RGB
        if (ch == 4) format = PixelFormats.Bgr32; //RGB + alpha


        WriteableBitmap wbm = new WriteableBitmap(w, h, 96, 96, format, null);
        CopyMemory(wbm.BackBuffer, pData, (uint)(w * h * ch));

        wbm.Lock();
        wbm.AddDirtyRect(new Int32Rect(0, 0, wbm.PixelWidth, wbm.PixelHeight));
        wbm.Unlock();

        return wbm;
    }

    public static BitmapSource FromArray(byte[] data, int w, int h, int ch)
    {
        PixelFormat format = PixelFormats.Default;

        if (ch == 1) format = PixelFormats.Gray8; //grey scale image 0-255
        if (ch == 3) format = PixelFormats.Bgr24; //RGB
        if (ch == 4) format = PixelFormats.Bgr32; //RGB + alpha


        WriteableBitmap wbm = new WriteableBitmap(w, h, 96, 96, format, null);
        wbm.WritePixels(new Int32Rect(0, 0, w, h), data, ch * w, 0);

        return wbm;
    }
}