void SetDecorations(swd.TextRange range, sw.TextDecorationCollection decorations, bool value)
{
using (Control.DeclareChangeBlock())
{
// set the property to each element in the range so it keeps all other decorations
foreach (var element in range.GetElements().OfType <swd.Inline>().Distinct())
{
var existingDecorations = element.GetValue(swd.Inline.TextDecorationsProperty) as sw.TextDecorationCollection;
// need to keep the range before changing otherwise the range changes
var elementRange = new swd.TextRange(element.ElementStart, element.ElementEnd);
sw.TextDecorationCollection newDecorations = null;
// remove decorations from the element
element.SetValue(swd.Inline.TextDecorationsProperty, null);
if (existingDecorations != null && existingDecorations.Count > 0)
{
// merge desired decorations with existing decorations.
if (value)
{
newDecorations = new sw.TextDecorationCollection(existingDecorations.Union(decorations));
}
else
{
newDecorations = new sw.TextDecorationCollection(existingDecorations.Except(decorations));
}
// split up existing decorations to the parts of the element that don't fall within the range
existingDecorations = new sw.TextDecorationCollection(existingDecorations); // copy so we don't update existing elements
if (elementRange.Start.CompareTo(range.Start) < 0)
{
new swd.TextRange(elementRange.Start, range.Start).ApplyPropertyValue(swd.Inline.TextDecorationsProperty, existingDecorations);
}
if (elementRange.End.CompareTo(range.End) > 0)
{
new swd.TextRange(range.End, elementRange.End).ApplyPropertyValue(swd.Inline.TextDecorationsProperty, existingDecorations);
}
}
else
{
// no existing decorations, just set the new value
newDecorations = value ? decorations : null;
}
if (newDecorations != null && newDecorations.Count > 0)
{
// apply new decorations to the desired range, which may be a combination of existing decorations
swd.TextPointer start = elementRange.Start.CompareTo(range.Start) < 0 ? range.Start : elementRange.Start;
swd.TextPointer end = elementRange.End.CompareTo(range.End) > 0 ? range.End : elementRange.End;
new swd.TextRange(start, end).ApplyPropertyValue(swd.Inline.TextDecorationsProperty, newDecorations);
}
}
}
}
