/// <summary>
/// Measures all of the RibbonGroups, and asks them to resize themselves appropriately
/// to fit within the available room in the GroupsContainer.
/// </summary>
/// <param name="availableSize">The available size that this element can give to child elements.</param>
/// <returns>
/// The size that the groups container determines it needs during layout, based
/// on its calculations of child element sizes.
/// </returns>
protected override Size MeasureOverride(Size availableSize)
{
RibbonTab ribbonTab = ParentRibbonTab;
double remainingSpace = 0;
Size desiredSize = BasicMeasure(availableSize, out remainingSpace);
UIElementCollection children = InternalChildren;
if (children.Count != _cachedChildCount)
{
ResetNextIncreaseGroupCache();
_cachedChildCount = children.Count;
}
if (DoubleUtil.GreaterThan(remainingSpace, 0))
{
// nudging the positive remaining space by a pixel
// protects against aggregation of double errors and
// provides a better appreance.
remainingSpace = Math.Max(0, remainingSpace - 1);
}
if ((DoubleUtil.GreaterThanOrClose(_cachedRemainingSpace, 0) && (DoubleUtil.LessThan(remainingSpace, 0) || DoubleUtil.GreaterThan(remainingSpace, _cachedRemainingSpace))) ||
(DoubleUtil.LessThan(_cachedRemainingSpace, 0) && DoubleUtil.GreaterThan(remainingSpace, 0)))
{
if (ribbonTab != null)
{
double?lastPreIncreaseRemainingSpace = null;
while (DoubleUtil.GreaterThan(remainingSpace, 0))
{
// When there is remaining space try to give it
// to stars, which qualify to increase before
// next group resize.
desiredSize = StarMeasure(availableSize,
desiredSize,
ribbonTab,
ref remainingSpace);
// When there is more remaining space, increase
// the size of the next group.
if (DoubleUtil.GreaterThan(remainingSpace, 0))
{
if (double.IsNaN(_nextGroupIncreaseWidth) ||
DoubleUtil.GreaterThanOrClose(remainingSpace, _nextGroupIncreaseWidth))
{
if (ribbonTab.IncreaseNextGroupSize())
{
ResetNextIncreaseGroupCache();
lastPreIncreaseRemainingSpace = remainingSpace;
desiredSize = BasicMeasure(availableSize, out remainingSpace);
}
else
{
break;
}
}
else
{
break;
}
}
}
double preDecreaseGroupRemainingSpace = remainingSpace;
while (DoubleUtil.LessThan(remainingSpace, 0))
{
// When the remaining space is negative decrease the
// next groups size.
if (ribbonTab.DecreaseNextGroupSize())
{
desiredSize = BasicMeasure(availableSize, out remainingSpace);
if (lastPreIncreaseRemainingSpace != null)
{
// Though in most of the cases we expect that the desired size of the
// entire subtree is up to date synchronously, there are some cases where desired
// size of subtree gets updated asynchronously(eg. where bindings
// impacting desired size resolve at a later time). To gaurd against infinite
// loops in such cases, if this decrease operation is to compensate any unnecessary
// increase operation performed above, then use the remaining space
// computed before such corresponding unnecessary increase operation, instead
// of the value computed post decrease which may be inaccurate due to some
// pending async updates. On the other hand if the group remains in
// same stage and when such async update happens at a later point of time,
// this measure would be executed again and hence fixing things.
remainingSpace = lastPreIncreaseRemainingSpace.Value;
// The remaining space needed to successfully perform the
// preceeding group increase without needing to do a compensating
// group decrease is cached to be used to optimize out the
// unsuccessful group size increases on further increase
// in remaining space.
_nextGroupIncreaseWidth = lastPreIncreaseRemainingSpace.Value - preDecreaseGroupRemainingSpace;
lastPreIncreaseRemainingSpace = null;
}
else
{
ResetNextIncreaseGroupCache();
}
if (DoubleUtil.GreaterThan(remainingSpace, 0))
{
// Now if there is remaining space, give it to the
// qualified stars.
desiredSize = StarMeasure(availableSize,
desiredSize,
ribbonTab,
ref remainingSpace);
}
}
else
{
break;
}
}
}
}
else if (DoubleUtil.GreaterThan(remainingSpace, 0))
{
desiredSize = StarMeasure(availableSize,
desiredSize,
ribbonTab,
ref remainingSpace);
}
_cachedRemainingSpace = remainingSpace;
//// Scroll if not enough space
return(desiredSize);
}
