Question

In my application, I need to grab the thumbnail image from files picked using File Picker. The following line throws COM exception when File Picker returns a file that does not have a thumbnail image such as an empty *.bmp file. How do I avoid this?

 StorageItemThumbnail t = await f.GetThumbnailAsync(Windows.Storage.FileProperties.ThumbnailMode.DocumentsView);

EDIT: additional details and I meant .bmp not .png sorry…

To reproduce:

1. Right click in any directory in Metro desktop mode, in the context menu click New->Bitmap Image
2. In a test program, launch File Picker, then call GetThumbnailAsync on that file returned; you get the exception below.

Exception Details:

System.Runtime.InteropServices.COMException was unhandled by user code

HResult=-2147467259
Message=Error HRESULT E_FAIL has been returned
from a call to a COM component.
Source=mscorlib
ErrorCode=-2147467259 StackTrace:
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
—some stuff ommitted—
InnerException: null

Code to launch the File Picker:

public static async Task<IReadOnlyList<StorageFile>> PickMulipleFilesAsync()
    {
        FileOpenPicker picker = new FileOpenPicker();
        picker.SuggestedStartLocation = PickerLocationId.Desktop;
        picker.FileTypeFilter.Add("*");
        var files = await picker.PickMultipleFilesAsync();

        return files;
    }

Answer 1

As mentioned in above comments and also by someone on MSDN forums. A workaround is simply the call to GetThumbnailAsync in a in a try-catch block and put a placeholder image when there is no thumbnail.

StorageItemThumbnail t=null;
BitmapImage thumbnailImage= new BitmapImage();//image used for display
try{    
    t = await f.GetThumbnailAsync(Windows.Storage.FileProperties.ThumbnailMode.DocumentsView);
}
catch(Exception e){
    t = null;
}
if (null == t)
    thumbnailImage = placeholder;//no thumbnail then use the placeholder image
else 
    thumbnailImage.SetSource(t);