用 Windows Graphics Capture 记录一个区域 API

Question

I am building a screen recording app in C# using Windows Graphics Capture API. I am using this script . I can select monitor and can record it to mp4 file. I can also select a Window and record it too. But how can we record a region with this? Ideally I need to give x,y coordinates along with width and height to record that specific region.

Here are the functions which return GraphicsCaptureItem for Window or Monitor hwnd , which can be used to record.

public static GraphicsCaptureItem CreateItemForWindow(IntPtr hwnd)
{
    var factory = WindowsRuntimeMarshal.GetActivationFactory(typeof(GraphicsCaptureItem));
    var interop = (IGraphicsCaptureItemInterop)factory;
    var temp = typeof(GraphicsCaptureItem);           
    var itemPointer = interop.CreateForWindow(hwnd, GraphicsCaptureItemGuid);
    var item = Marshal.GetObjectForIUnknown(itemPointer) as GraphicsCaptureItem;
    Marshal.Release(itemPointer);

    return item;
}

public static GraphicsCaptureItem CreateItemForMonitor(IntPtr hmon)
{
    var factory = WindowsRuntimeMarshal.GetActivationFactory(typeof(GraphicsCaptureItem));
    var interop = (IGraphicsCaptureItemInterop)factory;
    var temp = typeof(GraphicsCaptureItem);         
    var itemPointer = interop.CreateForMonitor(hmon, GraphicsCaptureItemGuid);
    var item = Marshal.GetObjectForIUnknown(itemPointer) as GraphicsCaptureItem;
    Marshal.Release(itemPointer);

    return item;
}

And this is Recording function

private async void RecordScreen(GraphicsCaptureItem item)
{
    _device = Direct3D11Helpers.CreateDevice();

    // Get our encoder properties
    uint frameRate = 30;
    uint bitrate = 3 * 1000000; 
    var width = (uint)item.Size.Width;
    var height = (uint)item.Size.Height;

    // Kick off the encoding
    try
    {
        newFile = GetTempFile();
        using (var stream = new FileStream(newFile, FileMode.CreateNew).AsRandomAccessStream())
        using (_encoder = new Encoder(_device, item))
        {
            await _encoder.EncodeAsync(
                stream,
                width, height, bitrate,
                frameRate);
        }
    }
    catch (Exception ex)
    {}
}

Answer 1

I achieved this by passing a custom region to CopySubresourceRegion in WaitForNewFrame method.

public SurfaceWithInfo WaitForNewFrame()
{
    .....
    using (var multithreadLock = new MultithreadLock(_multithread))
    using (var sourceTexture = Direct3D11Helpers.CreateSharpDXTexture2D(_currentFrame.Surface))
    {
        .....

        using (var copyTexture = new SharpDX.Direct3D11.Texture2D(_d3dDevice, description))
        {
            .....
            var region = new SharpDX.Direct3D11.ResourceRegion(
                _region.Left,
                _region.Top,
                0,
                _region.Left + _region.Width,
                _region.Top + _region.Height,
                1
            );

            _d3dDevice.ImmediateContext.CopyResource(_blankTexture, copyTexture);
            _d3dDevice.ImmediateContext.CopySubresourceRegion(sourceTexture, 0, region, copyTexture, 0);
            result.Surface = Direct3D11Helpers.CreateDirect3DSurfaceFromSharpDXTexture(copyTexture);
        }
    }
    ....
}