/// <summary>
/// Prioritizes elements for layouting. First treat the entrypoints, starting from top-left then around.
/// Then select the ones with dependencies that are already laid out.
/// </summary>
/// <param name="cluster"></param>
/// <returns></returns>
private IFrameworkElement[] OrderClusterForLayouting(List <Sibling> cluster)
{
// Give weight to panel alignments. Weight 3 for top or left so that a left-aligned only
// element (3) has precedence over a bottom-right aligned element (1+1)
var orderedByAlignment = new List <Sibling>(cluster
.OrderByDescending(s =>
(IsAlignLeftWithPanel(s.Element) ? 3 : 0) +
(IsAlignTopWithPanel(s.Element) ? 3 : 0) +
(RelativePanel.GetAlignRightWithPanel(s.Element) ? 1 : 0) +
(RelativePanel.GetAlignBottomWithPanel(s.Element) ? 1 : 0)
)
);
var ordered = new List <Sibling>();
while (orderedByAlignment.Count != 0)
{
// Take the first item in the previous list that has no direct dependency that have not already been selected
var next = orderedByAlignment.First(s => s.Dependencies
.Where(sd => !sd.IsInferred)
.Select(sd => sd.Sibling)
.Except(ordered)
.Empty()
);
orderedByAlignment.Remove(next);
ordered.Add(next);
}
return(ordered
.SelectToArray(s => s.Element));
}
/// <summary>
/// Returns true if the child is top aligned with Panel or has no vertical alignment instructions
/// </summary>
private bool IsAlignTopWithPanel(IFrameworkElement child)
{
return(RelativePanel.GetAlignTopWithPanel(child) ||
!(
RelativePanel.GetAlignBottomWithPanel(child) ||
RelativePanel.GetAlignVerticalCenterWithPanel(child) ||
RelativePanel.GetAlignTopWith(child) != null ||
RelativePanel.GetAlignBottomWith(child) != null ||
RelativePanel.GetAbove(child) != null ||
RelativePanel.GetBelow(child) != null
));
}
/// <summary>
/// Checks if the given FrameworkElement has any dependencies that would provide a bottom boundary using the existing layout info
/// </summary>
private double ComputeChildBottomBound(
IFrameworkElement child,
Size availableSize,
Dictionary <IFrameworkElement, SiblingLayoutInfo> siblingLayoutInfos,
double childTop,
Thickness graphPadding,
bool useInferred = false
)
{
var above = GetAvailableDependencies(GetSibling(child), DependencyType.Above, useInferred, siblingLayoutInfos);
if (above.Length != 0)
{
ExecuteOnSiblingLayoutInfoIfAvailable(child, siblingLayoutInfos, sli => sli.IsBottomBound = !useInferred);
return(above.Min(d => siblingLayoutInfos[d.Sibling.Element].Area.Top));
}
var bottomAlign = GetAvailableDependencies(GetSibling(child), DependencyType.AlignBottomWith, useInferred, siblingLayoutInfos);
if (bottomAlign.Length != 0)
{
ExecuteOnSiblingLayoutInfoIfAvailable(child, siblingLayoutInfos, sli => sli.IsBottomBound = !useInferred);
return(bottomAlign.Min(d => siblingLayoutInfos[d.Sibling.Element].Area.Bottom));
}
if (RelativePanel.GetAlignBottomWithPanel(child))
{
ExecuteOnSiblingLayoutInfoIfAvailable(child, siblingLayoutInfos, sli => sli.IsBottomBound = true);
return(availableSize.Height - graphPadding.Bottom);
}
if (!useInferred)
{
ComputeChildBottomBound(child, availableSize, siblingLayoutInfos, childTop, graphPadding, true);
}
// If there is no dependency, base yourself off of the available height, margins and Height/Min/Max properties
var spacing = childTop + child.Margin.Top + child.Margin.Bottom;
return(double.IsNaN(child.Height) ?
Math.Max(
Math.Min(
availableSize.Height - graphPadding.Bottom,
child.MaxHeight + spacing
),
child.MinHeight + spacing
) :
child.Height + spacing);
}
/// <summary>
/// Makes sure dependencies in the cluster are reversed if they are based on unknown boundaries
/// </summary>
private void CleanupDependencies(List <Sibling> cluster, bool isHorizontallyInfinite, bool isVerticallyInfinite)
{
if (!isHorizontallyInfinite && !isVerticallyInfinite)
{
return;
}
foreach (var sibling in cluster)
{
if (isHorizontallyInfinite && RelativePanel.GetAlignRightWithPanel(sibling.Element))
{
ReverseDependencies(sibling, true);
}
if (isVerticallyInfinite && RelativePanel.GetAlignBottomWithPanel(sibling.Element))
{
ReverseDependencies(sibling, false);
}
}
}