由于windows phone不能处理gif,所以我写了一个小方法,但是好像有点错误。
下面的代码在运行到 (JPG 和 PNG 部分)bitimg.SetSource(e.Result); 时总是抛出异常;
正如它所说,这是否意味着我不能使用 e.Result 因为它已被处置?但是怎么会这样呢,方法还没有停止,编译器为什么要dispose呢?
为什么以及如何解决它?
错误信息:
{System.ObjectDisposedException:无法访问已处置的对象。对象名称:“MS.Internal.InternalMemoryStream”。在 MS.Internal.InternalMemoryStream.Seek(Int64 offset, SeekOrigin origin) at ImageTools.IO.Gif.GifDecoder.Decode(ExtendedImage image, Stream stream) at xicihutong.ViewModel.RichTextBoxBindingBehavior.<>c__DisplayClass7.b__4(Object s, OpenReadCompletedEventArgs e ) 在 System.Net.WebClient.OnOpenReadCompleted(OpenReadCompletedEventArgs e) 在 System.Net.WebClient.OpenReadOperationCompleted(Object arg)}
image.Loaded += (s1, e1) =>
{
WebClient wc = new WebClient();
wc.AllowReadStreamBuffering = true;
wc.OpenReadCompleted += (s, e) =>
{
if (e.Error == null && !e.Cancelled)
{
//Check the type of the Image
ImageTypeCheck.ImageType incomingIMGType = ImageTypeCheck.getImageType(e.Result);
BitmapImage bitimg = new BitmapImage();
bitimg.CreateOptions = BitmapCreateOptions.BackgroundCreation;
switch (incomingIMGType)
{
//handle GIF for windows phone
case ImageTypeCheck.ImageType.Gif:
Decoders.AddDecoder<GifDecoder>();
Encoders.AddEncoder<JpegEncoder>();
GifDecoder gif = new GifDecoder();
JpegEncoder jpg = new JpegEncoder();
ImageTools.ExtendedImage extImg = new ImageTools.ExtendedImage();
gif.Decode(extImg, e.Result);
using (MemoryStream stream = new MemoryStream())
{
jpg.Encode(extImg, stream);
bitimg.SetSource(stream);
image.Source = bitimg;
}
break;
case ImageTypeCheck.ImageType.Bmp:
case ImageTypeCheck.ImageType.Null:
break;
case ImageTypeCheck.ImageType.Jpg:
case ImageTypeCheck.ImageType.Png:
try
{
bitimg.SetSource(e.Result);
image.Source = bitimg;
}
catch (Exception ex)
{
App.print(ex.Message);
}
break;
}
}
};
wc.OpenReadAsync(new Uri(item, UriKind.Absolute), wc);
}
====================================
using System.IO;
namespace xicihutong.DataServiceAgent
{
class ImageTypeCheck
{
/// <summary>
/// define
/// </summary>
public enum ImageType
{
Null,Png,Jpg,Gif,Bmp
}
public static ImageType getImageType(Stream stream)
{
ImageType type = ImageType.Null;
byte[] header = new byte[8];
stream.Read(header, 0, 8);
//Check if PNG then do something;
//Check if JPG then do something;
//Check if GIF then do something;
stream.Close();
return type;
}
}
}