private bool UpdateEventHandlers(bool checkEvents)
{
var needEvents = checkEvents &&
_textView.VisualElement.IsVisible &&
MarginActive;
if (needEvents != _hasEvents)
{
_hasEvents = needEvents;
if (needEvents)
{
_verticalScrollBar.Map.MappingChanged += OnMappingChanged;
return(UpdateMatches());
}
_verticalScrollBar.Map.MappingChanged -= OnMappingChanged;
if (_search != null)
{
_search.Abort();
_search = null;
}
}
return(false);
}
/// <summary>
/// Start a background search
/// </summary>
/// <returns>
/// true if a either a search has been queued or if the adornments/margin have been cleared since the highlight was
/// removed.
/// </returns>
private bool UpdateMatches(bool force = false)
{
if (_hasEvents)
{
//Do a new search if the highlight changed, there is no existing search, or the existing search was on the wrong snapshot.
if (_search == null || _search.Snapshot != _textView.TextSnapshot || force)
{
//The text of the highlight changes ... restart the search.
if (_search != null)
{
//Stop and blow away the old search (even if it didn't finish, the results are not interesting anymore).
_search.Abort();
_search = null;
}
//The underlying buffer could be very large, meaning that doing the search for all matches on the UI thread
//is a bad idea. Do the search on the background thread and use a callback to invalidate the visual when
//the entire search has completed.
_search = new BackgroundMarkerPlacement(
_textView.TextSnapshot,
_textView,
delegate {
ThreadHelper.JoinableTaskFactory.Run(async delegate {
//Force the invalidate to happen on the UI thread to satisfy WPF
await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
//Guard against the view closing before dispatcher executes this.
if (!_isDisposed)
{
InvalidateVisual();
}
});
});
return(true);
}
}
return(false);
}
