UWP App: `Image.SetSource` hangs computer on `StorageFiles` outside of `KnownPlaces` - xaml

Question

This one is hard to explain, so I give you some actual and pseudo code:
try
{
// If source (a string) points towards a file that is available with
// StorageFile.GetFileFromPathAsync(), just open the file that way.
// If that is not possible, use the path to look up an Access Token
// and use the file from the StorageFolder gotten via that token.
StorageFile file = await GetFileFromAccessList(source);
if (file != null)
{
bitmap = new BitmapImage();
using (IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read))
{
await bitmap.SetSourceAsync(fileStream);
}
}
}
catch (Exception e)
{
string s = e.Message;
bitmap = null;
}
with the following method:
public async Task<StorageFile> GetFileFromAccessList(string path)
{
StorageFile result = null;
if (String.IsNullOrEmpty(path) == false)
try
{
// Try to access to file directly...
result = await StorageFile.GetFileFromPathAsync(path);
}
catch (Exception)
{
result = null;
try
{
// See if the folder this thing is in is in the access list...
StorageFolder folder = await GetFolderFromAccessList(Path.GetFullPath(path));
// If there is a folder, try that.
if (folder != null)
result = await folder.GetFileAsync(Path.GetFileName(path));
}
catch (Exception)
{
result = null;
}
}
return result;
}
The resulting bitmap is used in Image.SetSource() as an ImageSource.
Now what kills me: this call works perfectly, fast and rock solid for files stored within the apps folder or KnownFolders. So it works like a charm when I don't need an Access Token. Windows.Storage.AccessCache.StorageApplicationPermissions.FutureAccessList.GetFolderAsync(token)
However, it breaks if I have to use an access token, just not all the time
This code does not break immediately: it breaks when I try to open more than 5-7 source files at the same time.
Repeat that: this works if I display 5-7 images. If I try to open more, it freezes the PC. No such problem occurs when I open StorageFiles without tokens.
I can access such files using normal file operations. I can create bitmaps from them, process them, the work.
I just cannot make them a source of an XAML Image.
Any thoughts?

Answer 1

Ah clarity.
So it turns out that using the DataContextChanged event to refresh the bitmap through Image.SetSource() is the murder weapon.
The solution: declare a property of type BitmapSource. Bind the Image.Source to that property. Update the property with the loaded bitmap upon Image.Loaded and Image.DataContextChanged. Works stable and fast now in all conditions I was able to test.