将媒体库中的照片保存为windows phone 8.1

Question

我从列表视图中获取照片路径并显示详细的图像屏幕。 详细页面代码在这里。

//Imaged is my image control in Xaml. 

protected override void OnNavigatedTo(NavigationEventArgs e) 
    { 
     var imagePath = e.Parameter as string; 
     imaged.Source = new BitmapImage(new Uri(imagePath, UriKind.RelativeOrAbsolute)); 


     var imgsource = imaged.Source; 
    } 

我想通过单击保存按钮事件将此图片保存在媒体库中。

这是我的保存按钮事件代码。

private async void ApplicationBarIconButton_Click_SaveToPictures(object sender, RoutedEventArgs e) 
    { 

     FileSavePicker picker = new FileSavePicker(); 

      // picker.FileTypeChoices.Add("PNG File", new List<string>() { ".png" }); 
      picker.FileTypeChoices.Add("JPEG image", new string[] { ".jpg" }); 
      picker.FileTypeChoices.Add("PNG image", new string[] { ".png" }); 
      picker.FileTypeChoices.Add("BMP image", new string[] { ".bmp" }); 
      picker.DefaultFileExtension = ".png"; 



      picker.SuggestedFileName = "bomdiaimg"; 
      picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary; 

      StorageFile file = await picker.PickSaveFileAsync(); 
      // StorageFile file = await picker.PickSaveFileAndContinue(); 
      if (file != null) 
      { 
       RenderTargetBitmap renderTargetBitMap = new RenderTargetBitmap(); 



      await renderTargetBitMap.RenderAsync(imaged, (int)imaged.Width, (int)imaged.Height); 

      var pixels = await renderTargetBitMap.GetPixelsAsync(); 



      using (IRandomAccessStream randomAccessStream = await file.OpenAsync(FileAccessMode.ReadWrite)) 
      { 
        var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, randomAccessStream); 
        byte[] bytes = pixels.ToArray(); 
        encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)renderTargetBitMap.PixelWidth, (uint)renderTargetBitMap.PixelHeight, 96, 96, bytes); await encoder.FlushAsync(); 
      } 
      } 

    } 

我无法保存图片的错误是

在这里的错误是一个例外。这种方法“这表明，使用picksavefile并继续”但是，当我用这个方法则错误显示下

 StorageFile file = await picker.PickSaveFileAsync(); 

一些次绿线。无法理解这个问题。如何将图片保存在媒体库中

Answer 1

SaveJpeg方法是名称空间System.Windows.Media.Imaging.Extensions的扩展方法。一个使用在源文件的顶部添加：

using System.Windows.Media.Imaging.Extensions; 

而且，可能你想用System.Windows.Media.Imaging.WriteableBitmap代替Windows.UI.Xaml.Media.Imaging.WriteableBitmap？

Answer 2

您可能想使用RenderTargetBitMap来保存控制图像。请检查此示例代码。

FileSavePicker picker = new FileSavePicker(); 
picker.FileTypeChoices.Add("JPG File", new List<string>() { ".jpg" }); 
StorageFile file = await picker.PickSaveFileAsync(); if (file != null) 
{ 
    RenderTargetBitmap renderTargetBitMap = new RenderTargetBitmap(); 
//With this method we can make our XAML elements in an image. await  


renderTargetBitMap.RenderAsync(grdRender, (int)grdRender.Width, (int)grdRender.Height); 

var pixels = await renderTargetBitMap.GetPixelsAsync(); 



using (IRandomAccessStream randomAccessStream = await file.OpenAsync(FileAccessMode.ReadWrite)) 
{ 
     var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, randomAccessStream); 
     byte[] bytes = pixels.ToArray(); 
     encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)renderTargetBitMap.PixelWidth, (uint)renderTargetBitMap.PixelHeight, 96, 96, bytes); await encoder.FlushAsync(); 
} 
}