Question

我正在尝试将字节数组转换为XAML中的图像。我知道我的服务中有一个字节数组。我不确定为什么我的代码失败了：

 public async void GetImage()
    {
        var serviceClient = new MyServiceClient();
        var prod = await serviceClient.GetProductImageAsync(pr.ProductID);
        if (prod != null)
        {
            var ras = new InMemoryRandomAccessStream();
            BitmapImage bi = new BitmapImage();

            using (MemoryStream ms = new MemoryStream(prod.LargeImage, 0,
              prod.LargeImage.Length))
            {
                BitmapImage im = new BitmapImage();
                await ms.CopyToAsync(ras.AsStreamForWrite());
                im.SetSource(ras);
                this.image1.Source = im;
            }
        }
        else
        {
            MessageDialog messageDialog = new MessageDialog("There is no picture available for " + pr.Name, "No Image");
            messageDialog.ShowAsync();
        }
        myBar.Visibility = Windows.UI.Xaml.Visibility.Collapsed;            
    }

Answer 1

不知道为什么会失败，有没有理由不将来源设为byte[]？

im.SetSource(new MemoryStream(prod.GetBytes()));

Answer 2

这是我使用的最终代码：

namespace MenuFinderWin8.Pages
{
/// <summary>
/// A basic page that provides characteristics common to most applications.
/// </summary>
public sealed partial class ImagePage : MenuFinderWin8.Common.LayoutAwarePage
{
    Product pr;

    public ImagePage()
    {
        this.InitializeComponent();
        pr = App.CurrentProduct;
        GetImage();
    }


    public async void GetImage()
    {
        MenuFinderAppServiceClient serviceClient = new MenuFinderAppServiceClient();
        var prod = await serviceClient.GetProductImageAsync(pr.ProductID);
        if (prod != null)
        {
            var randomAccessStream = new MemoryRandomAccessStream(prod.LargeImage);
            BitmapImage bi = new BitmapImage();
            await bi.SetSourceAsync(randomAccessStream);
            image1.Source = bi;
        }
        else
        {
            MessageDialog messageDialog = new MessageDialog("There is no picture available for " + pr.Name, "No Image");
            messageDialog.ShowAsync();
        }
        myBar.Visibility = Windows.UI.Xaml.Visibility.Collapsed;            
    }

    /// <summary>
    /// Populates the page with content passed during navigation.  Any saved state is also
    /// provided when recreating a page from a prior session.
    /// </summary>
    /// <param name="navigationParameter">The parameter value passed to
    /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
    /// </param>
    /// <param name="pageState">A dictionary of state preserved by this page during an earlier
    /// session.  This will be null the first time a page is visited.</param>
    protected override void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
    {
    }

    /// <summary>
    /// Preserves state associated with this page in case the application is suspended or the
    /// page is discarded from the navigation cache.  Values must conform to the serialization
    /// requirements of <see cref="SuspensionManager.SessionState"/>.
    /// </summary>
    /// <param name="pageState">An empty dictionary to be populated with serializable state.</param>
    protected override void SaveState(Dictionary<String, Object> pageState)
    {
    }
}

class MemoryRandomAccessStream : IRandomAccessStream
{
    private Stream m_InternalStream;

    public MemoryRandomAccessStream(Stream stream)
    {
        this.m_InternalStream = stream;
    }



    public MemoryRandomAccessStream(byte[] bytes)
    {
        this.m_InternalStream = new MemoryStream(bytes);
    }

    public IInputStream GetInputStreamAt(ulong position)
    {
        this.m_InternalStream.Seek((long)position, SeekOrigin.Begin);


        return this.m_InternalStream.AsInputStream();
    }

    public IOutputStream GetOutputStreamAt(ulong position)
    {
        this.m_InternalStream.Seek((long)position, SeekOrigin.Begin);


        return this.m_InternalStream.AsOutputStream();
    }

    public ulong Size
    {
        get { return (ulong)this.m_InternalStream.Length; }
        set { this.m_InternalStream.SetLength((long)value); }
    }

    public bool CanRead
    {
        get { return true; }
    }

    public bool CanWrite
    {
        get { return true; }
    }

    public IRandomAccessStream CloneStream()
    {
        throw new NotSupportedException();
    }

    public ulong Position
    {
        get { return (ulong)this.m_InternalStream.Position; }
    }

    public void Seek(ulong position)
    {
        this.m_InternalStream.Seek((long)position, 0);
    }

    public void Dispose()
    {
        this.m_InternalStream.Dispose();
    }

    public Windows.Foundation.IAsyncOperationWithProgress<IBuffer, uint> ReadAsync(IBuffer buffer, uint count, InputStreamOptions options)
    {
        var inputStream = this.GetInputStreamAt(0);
        return inputStream.ReadAsync(buffer, count, options);
    }

    public Windows.Foundation.IAsyncOperation<bool>


FlushAsync()
    {
        var outputStream = this.GetOutputStreamAt(0);
        return outputStream.FlushAsync();
    }

    public Windows.Foundation.IAsyncOperationWithProgress<uint, uint>


 WriteAsync(IBuffer buffer)
    {
        var outputStream = this.GetOutputStreamAt(0);
        return outputStream.WriteAsync(buffer);
    }
}

}

Metro Image字节数组

2 个答案: