Question

我正在使用此代码

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

来自Convert image to byte array on Windows Phone 7 No System.Drawing Dll any other way?，但WriteableBitmap在Windows Phone 8.1环境中不包含SaveJpeg方法。

Answer 1

在 Windows Phone 8.1 Silverlight应用程序上，您的代码运行正常，我认为myImage是BitmapImage。唯一必须做的就是等待BitmapImage加载完整：

using System.IO;
using System.Windows.Media.Imaging;
...
myImage = new BitmapImage(new Uri("http://i.stack.imgur.com/830Ke.jpg?s=128&g=1", UriKind.Absolute));
myImage.CreateOptions = BitmapCreateOptions.None;
myImage.ImageOpened += myImage_ImageOpened;
...
void myImage_ImageOpened(object sender, RoutedEventArgs e)
{
    MemoryStream ms = new MemoryStream();
    WriteableBitmap wb = new WriteableBitmap(myImage);
    wb.SaveJpeg(ms, myImage.PixelWidth, myImage.PixelHeight, 0, 100);
    byte[] imageBytes = ms.ToArray();
}

我刚刚测试了该代码，它在WP8.1上完美运行。

但是当您评论另一篇文章时，您无法引用Microsoft.Phone，您可能正在使用Windows Phone 8.1商店应用，在这种情况下，您可以使用以下代码：

using Windows.UI.Xaml.Media.Imaging;
using Windows.Storage.Streams;
using System.Runtime.InteropServices.WindowsRuntime;
...
BitmapImage bitmapImage = new BitmapImage(new Uri("http://i.stack.imgur.com/830Ke.jpg?s=128&g=1"));
RandomAccessStreamReference rasr = RandomAccessStreamReference.CreateFromUri(bitmapImage.UriSource);
var streamWithContent = await rasr.OpenReadAsync();
byte[] buffer = new byte[streamWithContent.Size];
await streamWithContent.ReadAsync(buffer.AsBuffer(), (uint)streamWithContent.Size, InputStreamOptions.None);

Answer 2

我怀疑你定位Windows Runtime Apps，因为你还没找到the namespace suggested in this answer (which will work for WP8.1 Silverlight)。

在Windows运行时应用中，您可以使用Encoder - 示例代码如下所示：

// lets assume that you have your image in WriteableBitmap yourWb
using (MemoryStream ms = new MemoryStream())
{
    var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, ms.AsRandomAccessStream());
    encoder.SetPixelData(BitmapPixelFormat.Bgra8,
        BitmapAlphaMode.Ignore,
        imageWidth,
        imageHeight,
        horizontalDPI,
        verticalDPI,
        yourWb.PixelBuffer.ToArray());

    await encoder.FlushAsync();
}

Answer 3

SaveJpeg是一种扩展方法（http://msdn.microsoft.com/en-US/library/windowsphone/develop/system.windows.media.imaging.extensions.savejpeg(v=vs.105).aspx）。您是否在项目参考中引用了Microsoft.Phone并将using System.Windows.Media.Imaging;添加到.cs文件中？

如何使用c＃将图像转换为Windows Phone 8.1中的字节数组

3 个答案: