/// <summary>
/// OnChildDesiredSizeChanged
/// Called from FlowDocumentPage for IContentHost implementation
///
internal void OnChildDesiredSizeChanged(UIElement child)
{
if (_structuralCache != null && _structuralCache.IsFormattedOnce && !_structuralCache.ForceReformat)
{
// If executed during formatting process, delay invalidation.
// This may happen during formatting when text host notifies its about
// baseline changes.
if (_structuralCache.IsFormattingInProgress)
{
Dispatcher.BeginInvoke(DispatcherPriority.Normal,
new DispatcherOperationCallback(OnChildDesiredSizeChangedAsync), child);
return;
}
// Get start and end positions
int childStartIndex = TextContainerHelper.GetCPFromEmbeddedObject(child, ElementEdge.BeforeStart);
if (childStartIndex < 0)
{
return;
}
TextPointer childStart = new TextPointer(_structuralCache.TextContainer.Start);
childStart.MoveByOffset(childStartIndex);
TextPointer childEnd = new TextPointer(childStart);
childEnd.MoveByOffset(TextContainerHelper.EmbeddedObjectLength);
// Create new DTR for changing UIElement and add it to DRTList.
DirtyTextRange dtr = new DirtyTextRange(childStartIndex, TextContainerHelper.EmbeddedObjectLength, TextContainerHelper.EmbeddedObjectLength);
_structuralCache.AddDirtyTextRange(dtr);
// Notify formatter about content invalidation.
if (_formatter != null)
{
_formatter.OnContentInvalidated(true, childStart, childEnd);
}
}
}
/// <summary>
/// Returns an ICollection of bounding rectangles for the given ContentElement
/// </summary>
/// <param name="child">
/// Content element for which rectangles are required
/// </param>
/// <remarks>
/// Looks at the ContentElement e line by line and gets rectangle bounds for each line
/// </remarks>
protected virtual ReadOnlyCollection<Rect> GetRectanglesCore(ContentElement child)
{
if (child == null)
{
throw new ArgumentNullException("child");
}
// If layout data is not updated we assume that we will not be able to find the element we need and throw excception
if (!IsLayoutDataValid)
{
// return empty collection
return new ReadOnlyCollection<Rect>(new List<Rect>(0));
}
// Line props may be invalid, even if Measure/Arrange is valid - rendering only props are changing.
LineProperties lineProperties = GetLineProperties();
// Check for complex content
if (_complexContent == null || !(_complexContent.TextContainer is TextContainer))
{
// return empty collection
return new ReadOnlyCollection<Rect>(new List<Rect>(0));
}
// First find the element start and end position
TextPointer start = FindElementPosition((IInputElement)child);
if (start == null)
{
return new ReadOnlyCollection<Rect>(new List<Rect>(0));
}
TextPointer end = null;
if (child is TextElement)
{
end = new TextPointer(((TextElement)child).ElementEnd);
}
else if (child is FrameworkContentElement)
{
end = new TextPointer(start);
end.MoveByOffset(+1);
}
if (end == null)
{
return new ReadOnlyCollection<Rect>(new List<Rect>(0));
}
int startOffset = _complexContent.TextContainer.Start.GetOffsetToPosition(start);
int endOffset = _complexContent.TextContainer.Start.GetOffsetToPosition(end);
int lineIndex = 0;
int lineOffset = 0;
double lineHeightOffset = 0;
int lineCount = LineCount;
while (startOffset >= (lineOffset + GetLine(lineIndex).Length) && lineIndex < lineCount)
{
Debug.Assert(lineCount == LineCount);
lineOffset += GetLine(lineIndex).Length;
lineIndex++;
lineHeightOffset += GetLine(lineIndex).Height;
}
Debug.Assert(lineIndex < lineCount);
int lineStart = lineOffset;
List<Rect> rectangles = new List<Rect>();
double wrappingWidth = CalcWrappingWidth(RenderSize.Width);
TextRunCache textRunCache = new TextRunCache();
Vector contentOffset = CalcContentOffset(RenderSize, wrappingWidth);
do
{
Debug.Assert(lineCount == LineCount);
// Check that line index never exceeds line count
Debug.Assert(lineIndex < lineCount);
// Create lines as long as they are spanned by the element
LineMetrics lineMetrics = GetLine(lineIndex);
Line line = CreateLine(lineProperties);
using (line)
{
// Check if paragraph ellipsis are rendered
bool ellipsis = ParagraphEllipsisShownOnLine(lineIndex, lineOffset);
line.Format(lineStart, wrappingWidth, GetLineProperties(lineIndex == 0, lineProperties), lineMetrics.TextLineBreak, textRunCache, ellipsis);
// Verify consistency of line formatting
//
if (lineMetrics.Length == line.Length)
{
//MS.Internal.Invariant.Assert(lineMetrics.Length == line.Length, "Line length is out of [....]");
//Debug.Assert(DoubleUtil.AreClose(CalcLineAdvance(line.Height, lineProperties), lineMetrics.Height), "Line height is out of [....].");
int boundStart = (startOffset >= lineStart) ? startOffset : lineStart;
int boundEnd = (endOffset < lineStart + lineMetrics.Length) ? endOffset : lineStart + lineMetrics.Length;
double xOffset = contentOffset.X;
double yOffset = contentOffset.Y + lineHeightOffset;
List<Rect> lineBounds = line.GetRangeBounds(boundStart, boundEnd - boundStart, xOffset, yOffset);
Debug.Assert(lineBounds.Count > 0);
rectangles.AddRange(lineBounds);
}
}
lineStart += lineMetrics.Length;
lineHeightOffset += lineMetrics.Height;
lineIndex++;
}
while (endOffset > lineStart);
// Rectangles collection must be non-null
Invariant.Assert(rectangles != null);
return new ReadOnlyCollection<Rect>(rectangles);
}
// ------------------------------------------------------------------
// IContentHost Helpers
// ------------------------------------------------------------------
/// <summary>
/// Searches for an element in the _complexContent.TextContainer. If the element is found, returns the
/// position at which it is found. Otherwise returns null.
/// </summary>
/// <param name="e">
/// Element to be found.
/// </param>
/// <remarks>
/// We assume that this function is called from within text if the caller knows that _complexContent exists
/// and contains a TextContainer. Hence we assert for this condition within the function
/// </remarks>
private TextPointer FindElementPosition(IInputElement e)
{
// Parameter validation
Debug.Assert(e != null);
// Validate that this function is only called when a TextContainer exists as complex content
Debug.Assert(_complexContent.TextContainer is TextContainer);
TextPointer position;
// If e is a TextElement we can optimize by checking its TextContainer
if (e is TextElement)
{
if ((e as TextElement).TextContainer == _complexContent.TextContainer)
{
// Element found
position = new TextPointer((e as TextElement).ElementStart);
return position;
}
}
// Else: search for e in the complex content
position = new TextPointer((TextPointer)_complexContent.TextContainer.Start);
while (position.CompareTo((TextPointer)_complexContent.TextContainer.End) < 0)
{
// Search each position in _complexContent.TextContainer for the element
switch (position.GetPointerContext(LogicalDirection.Forward))
{
case TextPointerContext.EmbeddedElement:
DependencyObject embeddedObject = position.GetAdjacentElement(LogicalDirection.Forward);
if (embeddedObject is ContentElement || embeddedObject is UIElement)
{
if (embeddedObject == e as ContentElement || embeddedObject == e as UIElement)
{
return position;
}
}
break;
default:
break;
}
position.MoveByOffset(+1);
}
// Reached end of complex content without finding the element
return null;
}
/// <summary>
/// Returns a TextPointer at a new position by a specified symbol
/// count.
/// </summary>
/// <param name="offset">
/// Number of symbols to advance. offset may be negative, in which
/// case the TextPointer is moved backwards.
/// </param>
/// <param name="direction">
/// LogicalDirection desired for a returned TextPointer.
/// </param>
/// <returns>
/// TextPointer located at requested position in case if requested position
/// does exist, otherwize returns null. LogicalDirection of the TextPointer
/// returned is as specified by a <paramref name="direction"/>.
/// </returns>
/// <remarks>
/// <para>This method, like all other TextPointer methods, defines a symbol
/// as one of:</para>
/// <para>- 16 bit Unicode character.</para>
/// <para>- opening or closing tag of a <see cref="TextElement"/>.</para>
/// <para>- the whole <see cref="UIElement"/> as atomic embedded object.</para>
/// <para>See examples in <seealso cref="TextPointer.GetPositionAtOffset(int)"/> method with one parameter.</para>
/// </remarks>
public TextPointer GetPositionAtOffset(int offset, LogicalDirection direction)
{
TextPointer position = new TextPointer(this, direction);
int actualCount = position.MoveByOffset(offset);
if (actualCount == offset)
{
position.Freeze();
return position;
}
else
{
return null;
}
}