/// <summary>
/// Determines whether additional overflow columns are needed and if existing columns can
/// be removed.
/// </summary>
/// <param name="availableSize">The size of the space available, used to constrain the
/// number of additional columns that can be created.</param>
/// <returns>The resulting size of the original content plus any extra columns.</returns>
protected override Size MeasureOverride(Size availableSize)
{
if (RichTextContent == null)
{
return(new Size(0, 0));
}
// Make sure the RichTextBlock is a child, using the lack of
// a list of additional columns as a sign that this hasn't been
// done yet
if (_overflowColumns == null)
{
Children.Add(RichTextContent);
_overflowColumns = new List <RichTextBlockOverflow>();
}
// Start by measuring the original RichTextBlock content
RichTextContent.Measure(availableSize);
var maxWidth = RichTextContent.DesiredSize.Width;
var maxHeight = RichTextContent.DesiredSize.Height;
var hasOverflow = RichTextContent.HasOverflowContent;
// Make sure there are enough overflow columns
int overflowIndex = 0;
while (hasOverflow && maxWidth < availableSize.Width && ColumnTemplate != null)
{
// Use existing overflow columns until we run out, then create
// more from the supplied template
RichTextBlockOverflow overflow;
if (_overflowColumns.Count > overflowIndex)
{
overflow = _overflowColumns[overflowIndex];
}
else
{
overflow = (RichTextBlockOverflow)ColumnTemplate.LoadContent();
_overflowColumns.Add(overflow);
Children.Add(overflow);
if (overflowIndex == 0)
{
RichTextContent.OverflowContentTarget = overflow;
}
else
{
_overflowColumns[overflowIndex - 1].OverflowContentTarget = overflow;
}
}
// Measure the new column and prepare to repeat as necessary
overflow.Measure(new Size(availableSize.Width - maxWidth, availableSize.Height));
maxWidth += overflow.DesiredSize.Width;
maxHeight = Math.Max(maxHeight, overflow.DesiredSize.Height);
hasOverflow = overflow.HasOverflowContent;
overflowIndex++;
}
// Disconnect extra columns from the overflow chain, remove them from our private list
// of columns, and remove them as children
if (_overflowColumns.Count > overflowIndex)
{
if (overflowIndex == 0)
{
RichTextContent.OverflowContentTarget = null;
}
else
{
_overflowColumns[overflowIndex - 1].OverflowContentTarget = null;
}
while (_overflowColumns.Count > overflowIndex)
{
_overflowColumns.RemoveAt(overflowIndex);
Children.RemoveAt(overflowIndex + 1);
}
}
// Report final determined size
return(new Size(maxWidth, maxHeight));
}
protected override Size MeasureOverride(Size availableSize)
{
if (RichTextContent == null)
{
return(new Size(0, 0));
}
if (_overflowColumns == null)
{
Children.Add(RichTextContent);
_overflowColumns = new List <RichTextBlockOverflow>();
}
RichTextContent.Measure(availableSize);
var maxWidth = RichTextContent.DesiredSize.Width;
var maxHeight = RichTextContent.DesiredSize.Height;
var hasOverflow = RichTextContent.HasOverflowContent;
var overflowIndex = 0;
while (hasOverflow && maxWidth < availableSize.Width && ColumnTemplate != null)
{
RichTextBlockOverflow overflow;
if (_overflowColumns.Count > overflowIndex)
{
overflow = _overflowColumns[overflowIndex];
}
else
{
overflow = (RichTextBlockOverflow)ColumnTemplate.LoadContent();
_overflowColumns.Add(overflow);
Children.Add(overflow);
if (overflowIndex == 0)
{
RichTextContent.OverflowContentTarget = overflow;
}
else
{
_overflowColumns[overflowIndex - 1].OverflowContentTarget = overflow;
}
}
overflow.Measure(new Size(availableSize.Width - maxWidth, availableSize.Height));
maxWidth += overflow.DesiredSize.Width;
maxHeight = Math.Max(maxHeight, overflow.DesiredSize.Height);
hasOverflow = overflow.HasOverflowContent;
overflowIndex++;
}
if (_overflowColumns.Count > overflowIndex)
{
if (overflowIndex == 0)
{
RichTextContent.OverflowContentTarget = null;
}
else
{
_overflowColumns[overflowIndex - 1].OverflowContentTarget = null;
}
while (_overflowColumns.Count > overflowIndex)
{
_overflowColumns.RemoveAt(overflowIndex);
Children.RemoveAt(overflowIndex + 1);
}
}
return(new Size(maxWidth, maxHeight));
}