/// <summary>
/// When overridden in a derived class, participates in rendering operations that are directed by the layout system.
/// The rendering instructions for this element are not used directly when this method is invoked,
/// and are instead preserved for later asynchronous use by layout and drawing.
/// </summary>
/// <param name="drawingContext">The drawing instructions for a specific element. This context is provided to the layout system.</param>
protected override void OnRender([NotNull] DrawingContext drawingContext)
{
Assert.ArgumentNotNull(drawingContext, "drawingContext");
try
{
if (Visibility != Visibility.Visible)
{
return;
}
drawingContext.DrawRectangle(Themes.ThemeManager.Instance.ActiveTheme.GetBrushByTextColor(Themes.TextColor.None, true), new Pen(Themes.ThemeManager.Instance.ActiveTheme.GetBrushByTextColor(Themes.TextColor.None, true), 0), new Rect(0, 0, ActualWidth, ActualHeight));
var renderedLines = 0;
if (_selectionSettings.NeedUpdate)
{
_tempSelectionSettings.SelectedMessages.Clear();
}
if (_messages.Count > 0)
{
var currentHeight = ActualHeight;
var lineNumber = _currentLineNumber;
while (currentHeight > 0 && lineNumber > 0)
{
_textSource.Message = _messages[lineNumber - 1];
var textStorePosition = 0;
_linesToRenderStack.Clear();
do
{
var line = _formatter.FormatLine(_textSource, textStorePosition, ActualWidth, _customTextParagraphProperties, null, _textRunCache);
_linesToRenderStack.Push(line);
textStorePosition += line.Length;
}while (textStorePosition < _messages[lineNumber - 1].InnerText.Length);
var drawnChars = 0;
bool messageSelected = false;
while (_linesToRenderStack.Count > 0)
{
var line = _linesToRenderStack.Pop();
line.Draw(drawingContext, new Point(0, currentHeight - line.Height), InvertAxes.None);
_lineHeight = line.Height;
drawnChars += line.Length;
if (_selectionSettings.NeedUpdate)
{
messageSelected = ProcessLineForSelection(line, _messages[lineNumber - 1], currentHeight, drawnChars, messageSelected);
}
currentHeight -= line.Height;
line.Dispose();
}
renderedLines++;
lineNumber--;
_textRunCache.Invalidate();
}
}
_currentNumberOfLinesInView = renderedLines;
if (_selectionSettings.NeedUpdate)
{
_selectionSettings.SelectionEndCharacterNumber = _tempSelectionSettings.SelectionEndCharacterNumber;
_selectionSettings.SelectionStartCharacterNumber = _tempSelectionSettings.SelectionStartCharacterNumber;
_selectionSettings.SelectedMessages.Clear();
_selectionSettings.SelectedMessages.AddRange(_tempSelectionSettings.SelectedMessages);
_selectionSettings.NeedUpdate = false;
InvalidateVisual();
}
}
catch (Exception ex)
{
_selectionSettings.NeedUpdate = false;
_textRunCache.Invalidate();
ClearTextSelection();
ErrorLogger.Instance.Write(string.Format("Error rendering text {0}", ex));
}
}
public void Clear()
{
textBuilder.Clear();
spans.Clear();
cache.Invalidate();
}