将uint8字节数组转换为任何WPF呈现对象

时间:2015-08-01 09:41:00

标签: c# c++ bitmap clr wrapper

目前我已经使用C ++ CLR为c#构建了包装器。 C ++ clr类从视频摄像机获取帧作为uint8 []并返回到c ++类中的OnVideoFrame事件。我有这样的初始化器:

ZeroMemory(&bmi_, sizeof(bmi_));
bmi_.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi_.bmiHeader.biPlanes = 1;
bmi_.bmiHeader.biBitCount = 32;
bmi_.bmiHeader.biCompression = BI_RGB;
bmi_.bmiHeader.biWidth = width;
bmi_.bmiHeader.biHeight = -height;
bmi_.bmiHeader.biSizeImage = width * height * (bmi_.bmiHeader.biBitCount >> 3);
image_.reset(new uint8[bmi_.bmiHeader.biSizeImage]);

所以问题是:

我已经在image_中有数据,但是如何将该数据发送到c#并将其转换为任何WPF位图对象以播放我的本地视频流?我正在寻找有关性能和我使用WPF的问题的最佳方法。我已经有了基本的win32 app的解决方案:

RECT rcClient;
GetClientRect(VideoRendererInternal->WindowHandle, &rcClient);
PAINTSTRUCT ps;
HDC hdc = BeginPaint(VideoRendererInternal->WindowHandle, &ps);
StretchDIBits(hdc,
    0, 0, rcClient.right, rcClient.bottom,  // destination rect
    0, 0, VideoRendererInternal->bmi_.bmiHeader.biWidth, -VideoRendererInternal->bmi_.bmiHeader.biHeight,  // source rect
    VideoRendererInternal->image_.get(), &VideoRendererInternal->bmi_, DIB_RGB_COLORS, SRCCOPY);
EndPaint(VideoRendererInternal->WindowHandle, &ps);

但找不到WPF的任何解决方案。谢谢!

2 个答案:

答案 0 :(得分:1)

有很多方法可以做到这一点,我建议你看看https://channel9.msdn.com/Events/Build/2015/3-82他们在哪里做到这一点。这是使用WPF从c ++显示图像的另一种解决方案。

使用MVVM,您需要XAML中的Image,您可以使用任何位图源进行设置。这样做WPF会重绘图像。这是在引擎盖下高度优化(在4k @ 60fps下测试)。

<Image x:Name="MainFrameBitmap" 
Height="{Binding ImageProcessingModel.MainFrameBitmap.Height}" 
Width="{Binding ImageProcessingModel.MainFrameBitmap.Width}" 
Source="{Binding ImageProcessingModel.MainFrameBitmap, UpdateSourceTrigger=PropertyChanged}" Cursor="Cross" >

在ImageProcessingModel中,您可能希望使用pinvoke或管道从c ++域获取字节。这里的计时器非常有用,因为您不希望阻止UI执行其操作。 WPF能够以120fps的速度进行本机渲染,因此如果帧源不是周期性的或以低帧速率运行,这将非常有用。

public class ImageProcessingModel : INotifyPropertyChanged
{
    public BitmapSource MainFrameBitmap
    {
        get
        {
            return _mainFrameBitmap;
        }
        private set
        {
            _mainFrameBitmap = value;
            OnPropertyChanged("MainFrameBitmap");
        }
    }

    public ImageProcessingModel(int updatePeriodInMilliseconds)
    {
        dispatcherTimer = new DispatcherTimer();
        dispatcherTimer.Tick += ServiceUiDispatcherTimerTick;
        dispatcherTimer.Interval = new TimeSpan(0, 0, 0, 0, updatePeriodInMilliseconds);
    }


    private void ServiceUiDispatcherTimerTick(object sender, EventArgs e)
    {
        try
        {
            MainFrameBitmap = ReadBitmap(FrameWidth, FrameHeight, Stride);
        }
        catch (Exception ex)
        {
            Console.WriteLine(@"UI Runtime Exception:" + ex.Message);
        }
    }

}

您可能希望有另一个类来跟踪这些原始图像字节

byte[] _imageData
public BitmapSource ReadBitmap(int w, int h, int s )
{
    int size = w*h*3 + 54;

    _imageData = new byte[size];

    // Read from pipe Read(_temp, 0, size);
    // Or use PInvoke to get a reference and manage that

    return BitmapSource.Create(w, h, 96, 96, PixelFormats.Rgb24, null, _imageData, s);
}

在c ++中,您需要为任何给定的帧构造字节,这取决于您使用的框架。下面的示例使用OpenCV,但如果使用RGBQUAD或某些此类字节缓冲区来存储图像,则代码将类似。此处选择的图像格式(和内存对齐)需要与WPF应用程序中的BitmapSource.Create函数匹配。

std::vector<uchar> buffer
DWORD UIConnection::writeToPipe(cv::Mat inputFrame){

    int buffSize = (inputFrame.rows * inputFrame.cols * 3) + 54;

    cv::Mat serviceImage;
    inputFrame.copyTo(serviceImage);

    flip(serviceImage, serviceImage, 1);
    imencode(".bmp", serviceImage, buffer);
    reverse(buffer.begin(), buffer.end());

    WriteFile(hPipe, &buffer[0], buffSize * sizeof(uchar), bytesWritten, NULL);

    return *bytesWritten;
}

答案 1 :(得分:1)

感谢您的快速回复!通过使用你的一半答案解决。不喜欢计时器,所以只是从c ++派代表发送IntPtr:

public delegate void OnNewFrame(IntPtr bitmapBuffer, int bitmapBufferLength);
...
public:
event OnNewFrame ^OnNewFrameEvent;`

然后:

System::IntPtr buffer = System::IntPtr(VideoRendererInternal->image_.get());    
OnNewFrameEvent(buffer, bufferSize);

在C#方面:

...
renderer.OnNewFrameEvent += new OnNewFrame(OnNewVideoFrame);
}

private void OnNewVideoFrame(IntPtr bitmapBuffer, int bitmapBufferLength)
{
    FrameDispatcher.Instance.DispatchFrame("LocalVideo", bitmapBuffer, bitmapBufferLength);
}

帧调度员类:

class FrameDispatcher
{

    private static FrameDispatcher StaticInstance;
    private Dictionary<String, FrameRenderer> Renderers = new Dictionary<string, FrameRenderer>();

    public static FrameDispatcher Instance {

        get {

            if (StaticInstance == null)
            {
                StaticInstance = new FrameDispatcher();
            }

            return StaticInstance;

        }

    }

    public void DispatchFrame(String id, IntPtr bitmapBuffer, int bitmapBufferLength)
    {

        if (Renderers.ContainsKey(id))
        {

            BitmapSource bitmap = BitmapSource.Create(640, 480, 96, 96, PixelFormats.Pbgra32, null, bitmapBuffer, bitmapBufferLength, 640 * 8);                
            Renderers[id].SetBitmap(bitmap);                

        }

    }

    public void RegisterFrameRenderer(FrameRenderer renderer, String id)
    {
        Renderers.Add(id, renderer);
    }

    public void UnregisterFrameRenderer(String id)
    {
        Renderers.Remove(id);
    }

}

帧渲染器类:

   class FrameRenderer : INotifyPropertyChanged
{

    private BitmapSource _Bitmap;

    public BitmapSource Bitmap
    {
        get
        {
            return _Bitmap;
        }

        private set
        {
            _Bitmap = value; 
            OnPropertyChanged("Bitmap");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;       

    private void OnPropertyChanged(String info)
    {

        PropertyChangedEventHandler handler = PropertyChanged;

        if (handler != null)
        {               
            try
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));

            }
            catch (Exception ex)
            {
                Console.WriteLine(@"UI Runtime Exception:" + ex.Message);
            }

        }
    }

    public void SetBitmap(BitmapSource bitmap) {

        bitmap.Freeze();
        Bitmap = bitmap;
        GC.Collect();

    }

}

在MainWindow控制器中注册FrameRenderer:

Renderer = new FrameRenderer();
FrameDispatcher.Instance.RegisterFrameRenderer(Renderer, "LocalVideo");

DataContext = Renderer;

现在它有效,再次感谢:)