Question

如何在UWP上完成/关闭BitmapEncoder？

InMemoryRandomAccessStream imras = new InMemoryRandomAccessStream();
await [...] //Fill stream
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(imras);
[...] //Do something
StorageFile sf = await ApplicationData.Current.LocalFolder.CreateFileAsync("123.jpg", CreationCollisionOption.ReplaceExisting);
BitmapEncoder bmpEncoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, await sf.OpenAsync(FileAccessMode.ReadWrite));
[...]
await bmpEncoder.FlushAsync();
imras.Dispose();

现在，当我尝试访问该文件时，我收到一个System.UnauthorizedAccessException，我必须关闭UWP应用才能访问此文件...如何关闭它？

Answer 1

您需要处理每个IDisposable对象。最简单的方法是使用using关键字。

using (var stream = await storageFile.OpenAsync()) // Or any other method that will open a stream.
{
   var bitmapDecoder = await BitmapDecoder.CreateAsync(stream);

   using (var randomAccessStream = new InMemoryRandomAccessStream())
   {
      var bitmapEncoder = await BitmapEncoder.CreateForTranscodingAsync(randomAccessStream, bitmapDecoder);

      // Do stuff.

      await bitmapEncoder.FlushAsync();

      var buffer = new byte[randomAccessStream.Size];

      await randomAccessStream.AsStream().ReadAsync(buffer, 0, buffer.Length);

      var someNewFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("SomeFileName", CreationCollisionOption.ReplaceExisting);

      await FileIO.WriteBytesAsync(someNewFile, buffer);
   }
}

UWP BitmapEncoder关闭文件？

1 个答案: