如何从Surface创建位图(SharpDX)

Question

我是DirectX的新手,并尝试使用SharpDX使用Desktop Duplication API捕获屏幕截图.

我想知道是否有任何简单的方法来创建我可以在CPU中使用的位图(即保存在文件等)

我使用以下代码获取桌面屏幕截图:

var factory = new SharpDX.DXGI.Factory1();
var adapter = factory.Adapters1[0];
var output = adapter.Outputs[0];

var device = new SharpDX.Direct3D11.Device(SharpDX.Direct3D.DriverType.Hardware,
                                                       DeviceCreationFlags.BgraSupport |
                                                       DeviceCreationFlags.Debug);

var dev1 = device.QueryInterface<SharpDX.DXGI.Device1>();

var output1 = output.QueryInterface<Output1>();
var duplication = output1.DuplicateOutput(dev1);
OutputDuplicateFrameInformation frameInfo;
SharpDX.DXGI.Resource desktopResource;
duplication.AcquireNextFrame(50, out frameInfo, out desktopResource);

var desktopSurface = desktopResource.QueryInterface<Surface>();

任何人都可以给我一些关于如何从desktopSurface(DXGI.Surface实例)创建位图对象的想法？

Answer 1

我刚刚完成了这个,虽然我不打算多说这段代码!

public byte[] GetScreenData()
    {
        // We want to copy the texture from the back buffer so 
        // we don't hog it.
        Texture2DDescription desc = BackBuffer.Description;
        desc.CpuAccessFlags = CpuAccessFlags.Read;
        desc.Usage = ResourceUsage.Staging;
        desc.OptionFlags = ResourceOptionFlags.None;
        desc.BindFlags = BindFlags.None;

        byte[] data = null;

        using (var texture = new Texture2D(DeviceDirect3D, desc))
        {
            DeviceContextDirect3D.CopyResource(BackBuffer, texture);

            using (Surface surface = texture.QueryInterface<Surface>())
            {
                DataStream dataStream;
                var map = surface.Map(SharpDX.DXGI.MapFlags.Read, out dataStream);
                int lines = (int)(dataStream.Length / map.Pitch);
                data = new byte[surface.Description.Width * surface.Description.Height * 4];

                int dataCounter = 0;
                // width of the surface - 4 bytes per pixel.
                int actualWidth = surface.Description.Width * 4;
                for (int y = 0; y < lines; y++)
                {
                    for (int x = 0; x < map.Pitch; x++)
                    {
                        if (x < actualWidth)
                        {
                            data[dataCounter++] = dataStream.Read<byte>();
                        }
                        else
                        {
                            dataStream.Read<byte>();
                        }
                    }
                }
                dataStream.Dispose();
                surface.Unmap();
            }
        }

        return data;
    }

这将获得一个byte [],然后可以用它来生成位图.

以下是我保存到png图像的方法.

 using (var stream = await file.OpenAsync( Windows.Storage.FileAccessMode.ReadWrite ))
            {
                BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, stream);
                double dpi = DisplayProperties.LogicalDpi;

                encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Straight,
                    (uint)width, (uint)height, dpi, dpi, pixelData);
                encoder.BitmapTransform.ScaledWidth = (uint)newWidth;
                encoder.BitmapTransform.ScaledHeight = (uint)newHeight;
                await encoder.FlushAsync();
                waiter.Set();
            }

我知道这已经回答了一段时间了,也许你现在已经知道了:3但是如果其他人被卡住了我希望这会有所帮助!

Answer 2

桌面复制 API 的 MSDN 页面告诉我们图像的格式：

DXGI 通过新的 IDXGIOutputDuplication::AcquireNextFrame 方法提供包含当前桌面图像的表面。无论当前显示模式是什么，桌面图像的格式始终为DXGI_FORMAT_B8G8R8A8_UNORM 。

您可以使用Surface.Map(MapFlags, out DataStream)get 方法访问 CPU 上的数据。

代码应如下所示*：

DataStream dataStream;
desktopSurface.Map(MapFlags.Read, out dataStream);
for(int y = 0; y < surface.Description.Width; y++) {
    for(int x = 0; x < surface.Description.Height; x++) {
        // read DXGI_FORMAT_B8G8R8A8_UNORM pixel:
        byte b = dataStream.Read<byte>();
        byte g = dataStream.Read<byte>();
        byte r = dataStream.Read<byte>();
        byte a = dataStream.Read<byte>();
        // color (r, g, b, a) and pixel position (x, y) are available
        // TODO: write to bitmap or process otherwise
    }
}
desktopSurface.Unmap();

*免责声明：我手头没有安装 Windows 8，我只是按照文档进行操作。我希望这有效:)