private Size StarMeasurePass(Size availableSize)
{
Size originalDesiredSize = DesiredSize;
UIElementCollection children = InternalChildren;
int childCount = children.Count;
int starLayoutCombinationCount = _starLayoutCombinations.Count;
for (int i = 0; i < childCount; i++)
{
UIElement child = children[i];
if (IsStarChild(child))
{
if (_childIndexToStarLayoutIndexMap.ContainsKey(i))
{
int starLayoutIndex = _childIndexToStarLayoutIndexMap[i];
if (starLayoutIndex < starLayoutCombinationCount)
{
StarLayoutInfo starLayoutInfo = _starLayoutCombinations[starLayoutIndex];
child.Measure(new Size(starLayoutInfo.AllocatedStarWidth, availableSize.Height));
}
}
}
}
double desiredWidth = originalDesiredSize.Width;
AdjustDesiredWidthForStars(children, ref desiredWidth);
return(new Size(desiredWidth, originalDesiredSize.Height));
}
private void CreateStarLayoutCombination(Size constraint,
double starWeight,
double starMinWidth,
double starMaxWidth,
List <int> starChildIndices)
{
if (starChildIndices.Count > 0)
{
StarLayoutInfo starLayoutInfo = new StarLayoutInfo()
{
RequestedStarMinWidth = starMinWidth,
RequestedStarMaxWidth = starMaxWidth,
RequestedStarWeight = starWeight
};
_starLayoutCombinations.Add(starLayoutInfo);
UIElementCollection children = InternalChildren;
int starLayoutIndex = _starLayoutCombinations.Count - 1;
foreach (int starChildIndex in starChildIndices)
{
_childIndexToStarLayoutIndexMap[starChildIndex] = starLayoutIndex;
children[starChildIndex].Measure(new Size(starLayoutInfo.RequestedStarMinWidth, constraint.Height));
}
starChildIndices.Clear();
}
}
/// <summary>
/// Distributes the remaining space after step 1 equally among all the
/// qualified member, such that they are constrained by their min/max constraints
/// maintaining (but not necessarily attaining) the goal of making perstarvalue of
/// all the elements as equal as possible.
/// </summary>
private static void DistributeRemainingSpace(List <StarLayoutInfo> starInfoList,
int distributionCount,
ref double remainingSpace)
{
Debug.Assert(distributionCount > 0 && distributionCount <= starInfoList.Count);
Debug.Assert(DoubleUtil.GreaterThan(remainingSpace, 0));
double remainingStarWeight = 0;
for (int i = 0; i < distributionCount; i++)
{
remainingStarWeight += starInfoList[i].RequestedStarWeight;
}
double impactPerStar = 0;
for (int i = 0; i < distributionCount; i++)
{
StarLayoutInfo starInfo = starInfoList[i];
if (DoubleUtil.GreaterThan(remainingSpace, 0))
{
double currentContribution = starInfo.RequestedStarMaxWidth - starInfo.AllocatedStarWidth;
currentContribution -= (impactPerStar * starInfo.RequestedStarWeight);
currentContribution /= starInfo.RequestedStarWeight;
if (DoubleUtil.GreaterThan(currentContribution * remainingStarWeight, remainingSpace))
{
currentContribution = remainingSpace / remainingStarWeight;
}
impactPerStar += currentContribution;
remainingSpace -= (currentContribution * remainingStarWeight);
}
starInfo.AllocatedStarWidth += (impactPerStar * starInfo.RequestedStarWeight);
remainingStarWeight -= starInfo.RequestedStarWeight;
}
}
protected override Size ArrangeOverride(Size finalSize)
{
UIElementCollection children = InternalChildren;
int childCount = children.Count;
double remainingHeightInColumn = finalSize.Height;
double columnWidth = 0;
double currentX = 0;
double starLayoutCombinationCount = _starLayoutCombinations.Count;
for (int i = 0; i < childCount; i++)
{
UIElement child = children[i];
Size childDesiredSize = child.DesiredSize;
if (DoubleUtil.GreaterThan(childDesiredSize.Height, remainingHeightInColumn))
{
currentX += columnWidth;
columnWidth = childDesiredSize.Width;
if (IsStarChild(child))
{
if (_childIndexToStarLayoutIndexMap.ContainsKey(i))
{
int starLayoutIndex = _childIndexToStarLayoutIndexMap[i];
if (starLayoutIndex < starLayoutCombinationCount)
{
StarLayoutInfo starLayoutInfo = _starLayoutCombinations[starLayoutIndex];
columnWidth = starLayoutInfo.AllocatedStarWidth;
}
}
}
child.Arrange(new Rect(currentX, 0, columnWidth, childDesiredSize.Height));
remainingHeightInColumn = Math.Max(0, finalSize.Height - childDesiredSize.Height);
}
else
{
double arrangeWidth = child.DesiredSize.Width;
if (IsStarChild(child))
{
if (_childIndexToStarLayoutIndexMap.ContainsKey(i))
{
int starLayoutIndex = _childIndexToStarLayoutIndexMap[i];
if (starLayoutIndex < starLayoutCombinationCount)
{
if (CanChildStretch(child))
{
// If the child's HorizontalAlignment is Left/Right, then
// use its desired width as arrange width.
StarLayoutInfo starLayoutInfo = _starLayoutCombinations[starLayoutIndex];
arrangeWidth = starLayoutInfo.AllocatedStarWidth;
}
}
}
}
columnWidth = Math.Max(columnWidth, arrangeWidth);
child.Arrange(new Rect(currentX, (finalSize.Height - remainingHeightInColumn), arrangeWidth, childDesiredSize.Height));
remainingHeightInColumn -= childDesiredSize.Height;
}
}
return(finalSize);
}
private static object OnCoerceAllocatedStarWidth(DependencyObject d, object baseValue)
{
double allocatedWidth = (double)baseValue;
StarLayoutInfo layoutInfo = (StarLayoutInfo)d;
if (DoubleUtil.LessThan(allocatedWidth, layoutInfo.RequestedStarMinWidth))
{
return(layoutInfo.RequestedStarMinWidth);
}
return(baseValue);
}
private static object OnCoerceRequestedStarMaxWidth(DependencyObject d, object baseValue)
{
double maxWidth = (double)baseValue;
StarLayoutInfo starLayoutInfo = (StarLayoutInfo)d;
double minWidth = starLayoutInfo.RequestedStarMinWidth;
if (DoubleUtil.LessThan(maxWidth, minWidth))
{
return(minWidth);
}
return(baseValue);
}
private static double EqualizeLeftOf(List <StarLayoutInfo> starInfoList, int index, bool isChecking)
{
Debug.Assert(index >= 0 && index < starInfoList.Count);
double spaceNeeded = 0;
StarLayoutInfo baseStarInfo = starInfoList[index];
double basePerStar = baseStarInfo.AllocatedStarWidth / baseStarInfo.RequestedStarWeight;
for (int i = 0; i < index; i++)
{
StarLayoutInfo starInfo = starInfoList[i];
double targetValue = Math.Min(basePerStar * starInfo.RequestedStarWeight, starInfo.RequestedStarMaxWidth);
spaceNeeded += (targetValue - starInfo.AllocatedStarWidth);
if (!isChecking)
{
starInfo.AllocatedStarWidth = targetValue;
}
}
return(spaceNeeded);
}
/// <summary>
/// Adjust the desired width for all the star
/// based children in a column based upon their
/// allocated/desired width.
/// </summary>
private void AdjustDesiredWidthForStarColumn(UIElementCollection children, List <int> columnStarChildren, int starLayoutIndex, ref double desiredWidth)
{
if (columnStarChildren != null && columnStarChildren.Count > 0 && starLayoutIndex >= 0)
{
bool foundStretchableStar = false;
double columnDesiredWidth = 0;
foreach (int columnChildIndex in columnStarChildren)
{
UIElement child = children[columnChildIndex];
if (CanChildStretch(child))
{
foundStretchableStar = true;
break;
}
else
{
columnDesiredWidth = Math.Max(columnDesiredWidth, child.DesiredSize.Width);
}
}
if (foundStretchableStar)
{
// if there are any non-item based star children
// then desired width should be equal to that of
// allocated width.
StarLayoutInfo starLayoutInfo = _starLayoutCombinations[starLayoutIndex];
desiredWidth += (starLayoutInfo.AllocatedStarWidth - starLayoutInfo.RequestedStarMinWidth);
}
else
{
// if there are no non-item based star children
// then desired width should be equal to that of
// computed desired width.
StarLayoutInfo starLayoutInfo = _starLayoutCombinations[starLayoutIndex];
desiredWidth += Math.Max((columnDesiredWidth - starLayoutInfo.RequestedStarMinWidth), 0);
}
columnStarChildren.Clear();
}
}