c# - 来自隔离存储的图像

Question

我试图绑定(bind)保存在独立存储中的图像并将其显示在与相机相同的屏幕上，但我似乎无法显示图像。我不知道是不是因为我没有将它保存在手机相机胶卷上，但我没有保存它们是因为我要拍摄多张照片并将它们像胶片一样显示在相机取景器底部。谁能帮帮我？

我正在使用本教程 Here

public partial class Page1 : PhoneApplicationPage
{
private static ObservableCollection<PhotoImage> photoList = new ObservableCollection<PhotoImage>();//For the class and list
private int savedCounter = 0;



public Page1()
{
        InitializeComponent();
}


private void ShutterButton_Click(object sender, RoutedEventArgs e)
    {
        if (cam != null)
        {
            try
            {
                // Start image capture.
                cam.CaptureImage();

            }
            catch (Exception ex)
            {
                this.Dispatcher.BeginInvoke(delegate()
                {
                    txtDebug.Text = ex.Message;
                });
            }
        }
    }

    void cam_CaptureCompleted(object sender, CameraOperationCompletedEventArgs e)
    {
        // Increments the savedCounter variable used for generating JPEG file names.
        savedCounter++;
    }

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

        try
        {   

            // Save picture to the library camera roll.
            //library.SavePictureToCameraRoll(fileName, e.ImageStream);//dont want to save it to the 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);
                    }

                }

            }

            Deployment.Current.Dispatcher.BeginInvoke(delegate()
            {

                photoList.Add(new PhotoImage(fileName));//here is where I set with the file name
                listBoxSearch.ItemsSource = photoList; //here is the binding 
            });


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

    }
    public class PhotoImage
    {

        public string PhotoItem { get; set; }

        public PhotoImage(string pItem)
        {
            this.PhotoItem = pItem;

        }
    }

这是我的 XAML 代码

<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot" Background="Transparent">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="640" />
        <ColumnDefinition Width="160" />
    </Grid.ColumnDefinitions>

    <Canvas x:Name="viewfinderCanvas" Width="640" HorizontalAlignment="Left" Margin="0,0,0,143">

        <!--Camera viewfinder -->
        <Canvas.Background>
            <VideoBrush x:Name="viewfinderBrush" />
        </Canvas.Background>
        <TextBlock Height="40" Name="txtDebug" Width="626" FontSize="24" FontWeight="ExtraBold" Canvas.Left="14" Canvas.Top="297" />
    </Canvas>

    <!--Button StackPanel to the right of viewfinder>-->
    <StackPanel Grid.Column="1" >
        <Button x:Name="ShutterButton" Content="SH" Click="ShutterButton_Click" FontSize="26" FontWeight="ExtraBold" Height="75" />
    </StackPanel>
    <Grid>
        <ListBox Foreground="RoyalBlue" Height="131"  Name="listBoxSearch"  Width="438"  TabIndex="10" Margin="96,343,106,6">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal" Height="Auto" >
                        <Image Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0" Source="{Binding PhotoItem }" />
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

    </Grid>

</Grid>

Answer 1

好的 - 问题是没有知道如何获取 IsoStorage URI 并加载它的隐式转换器。

一个简单的解决方案是向您的 PhotoImage 类添加另一个属性并绑定(bind)到它 - 这是一个快速而肮脏的方法:

public ImageSource SourceItem
{
  get
  {
    BitmapImage image = new BitmapImage();
    image.SetSource(isStore.OpenFile(PhotoItem, FileMode.Open));  
    return image;
  }
}

请注意，这不是一个很好的解决方案 - 我只是向您展示了总体思路。实现您自己的时要考虑的事项:

1. 流没有被丢弃。将 Stream 设置为 image 时将其包装在 using 中。
2. 根据您尝试执行的操作，您可能希望使用 image.CreateOptions 来提高应用的响应速度(但随后您需要弄清楚如何处理需要保留的流打开)
3. 最后，要加载的图像将是全分辨率的。您可能需要查看 PictureDecoder.DecodeJpeg() 来加载图像的缩略图(或查看相机对象提供的缩略图)