private FrameworkElement GetPreviewElement(object previewItem)
{
if (previewItem is DifferenceViewerPreview)
{
// Contract is there should be only 1 diff viewer, otherwise we leak.
// cache the diff viewer so that we can close it when panel goes away.
// this is a bit wierd since we are mutating state here.
_differenceViewerPreview = (DifferenceViewerPreview)previewItem;
PreviewDockPanel.Background = _differenceViewerPreview.Viewer.InlineView.Background;
var previewElement = _differenceViewerPreview.Viewer.VisualElement;
return(previewElement);
}
if (previewItem is string s)
{
return(GetPreviewForString(s));
}
if (previewItem is FrameworkElement frameworkElement)
{
return(frameworkElement);
}
// preview item we don't know how to show to users
return(null);
}
void IDisposable.Dispose()
{
// VS editor will call Dispose at which point we should Close() the embedded IWpfDifferenceViewer.
_differenceViewerPreview?.Dispose();
_differenceViewerPreview = null;
}