读取和写入图像到隔离存储

Question

我在一些 Windows Phone 网站上遇到了几种将图像写入隔离存储的不同方法，但是我不确定哪种方法最适合用于相机应用程序，或者是否有一些比其他方法更好：

第一个来自这篇关于基本相机应用程序的帖子：http://msdn.microsoft.com/en-us/library/hh202956(v=VS.92).aspx 它从相机中获取 jpeg 并将其直接写入隔离存储。

   void cam_CaptureImageAvailable(object sender, Microsoft.Devices.ContentReadyEventArgs e)
{
    string fileName = savedCounter + ".jpg";

    try
    {   // Write message to the UI thread.
        Deployment.Current.Dispatcher.BeginInvoke(delegate()
        {
            txtDebug.Text = "Captured image available, saving picture.";
        });

        // Save picture to the library camera roll.
        library.SavePictureToCameraRoll(fileName, e.ImageStream);

        // Write message to the UI thread.
        Deployment.Current.Dispatcher.BeginInvoke(delegate()
        {
            txtDebug.Text = "Picture has been saved to camera roll.";

        });

        // Set the position of the stream back to start
        e.ImageStream.Seek(0, SeekOrigin.Begin);

        // Save picture as JPEG to isolated storage.
        using (IsolatedStorageFile isStore = IsolatedStorageFile.GetUserStoreForApplication())
        {
            using (IsolatedStorageFileStream targetStream = isStore.OpenFile(fileName, FileMode.Create, FileAccess.Write))
            {
                // Initialize the buffer for 4KB disk pages.
                byte[] readBuffer = new byte[4096];
                int bytesRead = -1;

                // Copy the image to isolated storage. 
                while ((bytesRead = e.ImageStream.Read(readBuffer, 0, readBuffer.Length)) > 0)
                {
                    targetStream.Write(readBuffer, 0, bytesRead);
                }
            }
        }

        // Write message to the UI thread.
        Deployment.Current.Dispatcher.BeginInvoke(delegate()
        {
            txtDebug.Text = "Picture has been saved to isolated storage.";

        });
    }
    finally
    {
        // Close image stream
        e.ImageStream.Close();
    }

}

似乎使用了一个 4kb 的缓冲区，这样做有什么意义吗？似乎比这种将图像转换为位图然后使用另存为 Jpeg 方法（http://www.windowsphonegeek.com/tips/All-about-WP7-Isolated-Storage---Read-and -保存图像）：

   // Create a filename for JPEG file in isolated storage.
        String tempJPEG = "logo.jpg";

        // Create virtual store and file stream. Check for duplicate tempJPEG files.
        using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
        {
            if (myIsolatedStorage.FileExists(tempJPEG))
            {
                myIsolatedStorage.DeleteFile(tempJPEG);
            }

            IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile(tempJPEG);

            StreamResourceInfo sri = null;
            Uri uri = new Uri(tempJPEG, UriKind.Relative);
            sri = Application.GetResourceStream(uri);

            BitmapImage bitmap = new BitmapImage();
            bitmap.SetSource(sri.Stream);
            WriteableBitmap wb = new WriteableBitmap(bitmap);

            // Encode WriteableBitmap object to a JPEG stream.
            Extensions.SaveJpeg(wb, fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);

            //wb.SaveJpeg(fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
            fileStream.Close();
        }

如果您有任何替代方法，我也会感兴趣，谢谢！

Answer 1

认为您应该检查一下：

我相信我已经回答了这个问题并获得了 +50 赏金

SO Save image to Isolated Storaged using byte[]