Question

您好我需要有关如何从C＃UWP中的SoftwareBitmap获取字节数组的帮助，以便我可以通过TCP套接字发送它。

我还可以访问＆＃34; VideoFrame previewFrame＆＃34;对象是我从SoftwareBitmap获得的对象。

我在网上看过以下内容，但是UWP不支持wb.SaveJpeg(...)。除非我遗失了什么？

MemoryStream ms = new MemoryStream();
WriteableBitmap wb = new WriteableBitmap(myimage);
wb.SaveJpeg(ms, myimage.PixelWidth, myimage.PixelHeight, 0, 100);
byte [] imageBytes = ms.ToArray();

非常感谢任何帮助或正确方向的指示。

谢谢，安迪

Answer 1

据我所知，你不能这样做。但您可以使用SoftwareBitmap。看看例子：https://msdn.microsoft.com/en-us/library/windows/apps/mt244351.aspx（SoftwareBitmap是SoftwareBitmapSource的私有字段..只需通过反思读取它......也许这是完全错误的建议）

private async void SaveSoftwareBitmapToFile(SoftwareBitmap softwareBitmap, StorageFile outputFile)
{
    using (IRandomAccessStream stream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
    {
        // Create an encoder with the desired format
        BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, stream);

        // Set the software bitmap
        encoder.SetSoftwareBitmap(softwareBitmap);

        // Set additional encoding parameters, if needed
        encoder.BitmapTransform.ScaledWidth = 320;
        encoder.BitmapTransform.ScaledHeight = 240;
        encoder.BitmapTransform.Rotation = Windows.Graphics.Imaging.BitmapRotation.Clockwise90Degrees;
        encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Fant;
        encoder.IsThumbnailGenerated = true;

        try
        {
            await encoder.FlushAsync();
        }
        catch (Exception err)
        {
            switch (err.HResult)
            {
                case unchecked((int)0x88982F81): //WINCODEC_ERR_UNSUPPORTEDOPERATION
                                                 // If the encoder does not support writing a thumbnail, then try again
                                                 // but disable thumbnail generation.
                    encoder.IsThumbnailGenerated = false;
                    break;
                default:
                    throw;
            }
        }

        if (encoder.IsThumbnailGenerated == false)
        {
            await encoder.FlushAsync();
        }


    }
}

Answer 2

从SoftwareBitmap获取字节数组，你可以使用“SoftwareBitmap.CopyToBuffer”

但是，首先你需要：

使用System.Runtime.InteropServices.WindowsRuntime;

因为方法AsBuffer（）到byte []

...

struct Size
{
    const unsigned int width;
    const unsigned int height;

    static constexpr Size big = { 480, 240 };

    static constexpr Size small = { 210, 170 };

private:

    Size( ) = default;
};

Answer 3

当想要从byte[]（例如下面的jpeg）访问编码 SoftwareBitmap数组时，以下内容将有效：

private async void PlayWithData(SoftwareBitmap softwareBitmap)
{
    var data = await EncodedBytes(softwareBitmap, BitmapEncoder.JpegEncoderId);

    // todo: save the bytes to a DB, etc
}

private async Task<byte[]> EncodedBytes(SoftwareBitmap soft, Guid encoderId)
{
    byte[] array = null;

    // First: Use an encoder to copy from SoftwareBitmap to an in-mem stream (FlushAsync)
    // Next:  Use ReadAsync on the in-mem stream to get byte[] array

    using (var ms = new InMemoryRandomAccessStream())
    {
        BitmapEncoder encoder = await BitmapEncoder.CreateAsync(encoderId, ms);
        encoder.SetSoftwareBitmap(soft);

        try
        {
            await encoder.FlushAsync();
        }
        catch ( Exception ex ){ return new byte[0]; }

        array = new byte[ms.Size];
        await ms.ReadAsync(array.AsBuffer(), (uint)ms.Size, InputStreamOptions.None);
    }
    return array;
}

Answer 4

Get Preview Frame UWP相机样本将相机帧作为SoftwareBitmap获取并通过数组操纵其上的像素（就地），然后可以将其保存为JPEG。如果我理解你的问题，你需要的所有代码都应该在那里。

基本上，这应该是大部分内容（包括一些相机代码）：

private async Task GetPreviewFrameAsSoftwareBitmapAsync()
{
    // Get information about the preview
    var previewProperties = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview) as VideoEncodingProperties;

    // Create the video frame to request a SoftwareBitmap preview frame
    var videoFrame = new VideoFrame(BitmapPixelFormat.Bgra8, (int)previewProperties.Width, (int)previewProperties.Height);

    // Capture the preview frame
    using (var currentFrame = await _mediaCapture.GetPreviewFrameAsync(videoFrame))
    {
        // Collect the resulting frame
        SoftwareBitmap previewFrame = currentFrame.SoftwareBitmap;

        // Add a simple green filter effect to the SoftwareBitmap
        EditPixels(previewFrame);
    }
}

private unsafe void EditPixels(SoftwareBitmap bitmap)
{
    // Effect is hard-coded to operate on BGRA8 format only
    if (bitmap.BitmapPixelFormat == BitmapPixelFormat.Bgra8)
    {
        // In BGRA8 format, each pixel is defined by 4 bytes
        const int BYTES_PER_PIXEL = 4;

        using (var buffer = bitmap.LockBuffer(BitmapBufferAccessMode.ReadWrite))
        using (var reference = buffer.CreateReference())
        {
            // Get a pointer to the pixel buffer
            byte* data;
            uint capacity;
            ((IMemoryBufferByteAccess)reference).GetBuffer(out data, out capacity);

            // Get information about the BitmapBuffer
            var desc = buffer.GetPlaneDescription(0);

            // Iterate over all pixels
            for (uint row = 0; row < desc.Height; row++)
            {
                for (uint col = 0; col < desc.Width; col++)
                {
                    // Index of the current pixel in the buffer (defined by the next 4 bytes, BGRA8)
                    var currPixel = desc.StartIndex + desc.Stride * row + BYTES_PER_PIXEL * col;

                    // Read the current pixel information into b,g,r channels (leave out alpha channel)
                    var b = data[currPixel + 0]; // Blue
                    var g = data[currPixel + 1]; // Green
                    var r = data[currPixel + 2]; // Red

                    // Boost the green channel, leave the other two untouched
                    data[currPixel + 0] = b;
                    data[currPixel + 1] = (byte)Math.Min(g + 80, 255);
                    data[currPixel + 2] = r;
                }
            }
        }
    }
}

并在课堂外声明这个以启用GetBuffer方法：

[ComImport]
[Guid("5b0d3235-4dba-4d44-865e-8f1d0e4fd04d")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
unsafe interface IMemoryBufferByteAccess
{
    void GetBuffer(out byte* buffer, out uint capacity);
}

当然，您的项目必须允许所有这些的不安全代码才能正常工作。

最后，您可以将SoftwareBitmap保存为JPEG文件：

private static async Task SaveSoftwareBitmapAsync(SoftwareBitmap bitmap, StorageFile file)
{
    using (var outputStream = await file.OpenAsync(FileAccessMode.ReadWrite))
    {
        var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, outputStream);

        // Grab the data from the SoftwareBitmap
        encoder.SetSoftwareBitmap(bitmap);
        await encoder.FlushAsync();
    }
}

如何从SoftwareBitmap

4 个答案: