如何将Base64字符串转换为图像，然后将其绑定到Metro风格应用程序中的GridView？

Question

我收集了来自Web服务的产品，我在网格视图中预览了这个产品，但是我将产品的图像作为Base64字符串。 如何将其转换为图像并将其绑定到网格视图中的图像？

任何能帮助我解决这个问题的代码。

Answer 1

这似乎对我有用：

    public static BitmapImage Base64StringToBitmap(string source)
    {
        var ims = new InMemoryRandomAccessStream();
        var bytes = Convert.FromBase64String(source);
        var dataWriter = new DataWriter(ims);
        dataWriter.WriteBytes(bytes);
        dataWriter.StoreAsync();
        ims.Seek(0);
        var img = new BitmapImage();
        img.SetSource(ims);
        return img;
    }

注意我没有等待任何东西，img.SetSource应该负责延迟加载。

Answer 2

下面是将Base64String绑定到Image控件的方法

1. 将字符串转换为byte []，如下所示

    byte[] bytes = System.Convert.FromBase64String(thebase64string); 

2. 传递要将Image绑定到的byte []和Image控件。

    public async void SetImageFromByteArray(byte[] data, Windows.UI.Xaml.Controls.Image image) { InMemoryRandomAccessStream raStream = new InMemoryRandomAccessStream(); DataWriter writer = new DataWriter(raStream); // Write the bytes to the stream writer.WriteBytes(data); // Store the bytes to the MemoryStream await writer.StoreAsync(); await writer.FlushAsync(); // Detach from the Memory stream so we don't close it writer.DetachStream(); raStream.Seek(0); BitmapImage bitMapImage = new BitmapImage(); bitMapImage.SetSource(raStream); image.Source = bitMapImage; } 

Answer 3

在WPF / Metro / Silverlight中，Image是一个UI控件。 它的源设置为BitmapSource。 BitmapSource是一种用于保存图像数据的数据结构。

以下是从字节数组中检索BitmapImage的代码。

public BitmapImage ImageFromBuffer(Byte[] bytes)
    {
        MemoryStream stream = new MemoryStream(bytes);
        BitmapImage image = new BitmapImage();
        image.SetSource ( stream.AsRandomAccessStream());
        return image;
    }

请注意，stream.AsRandomAccessStream在API中不可用它是一种扩展方法。 我从IDWMaster的回答中发现了这个问题

以下是扩展方法的代码

 public static class MicrosoftStreamExtensions
    {
        public static IRandomAccessStream AsRandomAccessStream(this Stream stream)
        {
            return new RandomStream(stream);
        }
    }
    class RandomStream : IRandomAccessStream
    {
        Stream internstream;
        public RandomStream(Stream underlyingstream)
        {
            internstream = underlyingstream;
        }
        public IInputStream GetInputStreamAt(ulong position)
        {
            internstream.Position = (long)position;
            return internstream.AsInputStream();
        }

        public IOutputStream GetOutputStreamAt(ulong position)
        {
            internstream.Position = (long)position;
            return internstream.AsOutputStream();
        }

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

        public bool CanRead
        {
            get { return internstream.CanRead; }
        }

        public bool CanWrite
        {
            get { return internstream.CanWrite; }
        }

        public IRandomAccessStream CloneStream()
        {
            //HACK, this is not clone, proper implementation is required, returned object will share same internal stream
            return new RandomStream(this.internstream);
        }

        public ulong Position
        {
            get { return (ulong)internstream.Position; }
        }

        public void Seek(ulong position)
        {
            internstream.Seek((long)position, SeekOrigin.Current);
        }

        public void Dispose()
        {
            internstream.Dispose();
        }

        public Windows.Foundation.IAsyncOperationWithProgress<IBuffer, uint> ReadAsync(IBuffer buffer, uint count, InputStreamOptions options)
        {
            throw new NotImplementedException();
        }

        public Windows.Foundation.IAsyncOperation<bool> FlushAsync()
        {
            throw new NotImplementedException();
        }

        public Windows.Foundation.IAsyncOperationWithProgress<uint, uint> WriteAsync(IBuffer buffer)
        {
            throw new NotImplementedException();
        }
    }

最后3种方法未实施

我没有测试，但上面应该在校长工作（可能是经过一些改进）。

Answer 4

尝试这样的事情：

byte[] encodedDataAsBytes = System.Convert.FromBase64String(encodedData);
MemoryStream stream = new MemoryStream(encodedDataAsBytes.Length);
stream.Write(encodedDataAsBytes, 0, encodedDataAsBytes.Length);
Image img = Image.FromStream(stream);

我没有使用过地铁，所以我无法帮助绑定到网格..最好的问候。