/// <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 left aligned with Panel or has no horizontal alignment instructions
/// </summary>
private bool IsAlignLeftWithPanel(IFrameworkElement child)
{
return(RelativePanel.GetAlignLeftWithPanel(child) ||
!(
RelativePanel.GetAlignRightWithPanel(child) ||
RelativePanel.GetAlignHorizontalCenterWithPanel(child) ||
RelativePanel.GetAlignLeftWith(child) != null ||
RelativePanel.GetAlignRightWith(child) != null ||
RelativePanel.GetRightOf(child) != null ||
RelativePanel.GetLeftOf(child) != null
));
}
/// <summary>
/// Checks if the given FrameworkElement has any dependencies that would provide a right boundary using the existing layout info
/// </summary>
private double ComputeChildRightBound(
IFrameworkElement child,
Size availableSize,
Dictionary <IFrameworkElement, SiblingLayoutInfo> siblingLayoutInfos,
double childLeft,
Thickness graphPadding,
bool useInferred = false
)
{
var leftOf = GetAvailableDependencies(GetSibling(child), DependencyType.LeftOf, useInferred, siblingLayoutInfos);
if (leftOf.Length != 0)
{
ExecuteOnSiblingLayoutInfoIfAvailable(child, siblingLayoutInfos, sli => sli.IsRightBound = !useInferred);
return(leftOf.Min(d => siblingLayoutInfos[d.Sibling.Element].Area.Left));
}
var rightAlign = GetAvailableDependencies(GetSibling(child), DependencyType.AlignRightWith, useInferred, siblingLayoutInfos);
if (rightAlign.Length != 0)
{
ExecuteOnSiblingLayoutInfoIfAvailable(child, siblingLayoutInfos, sli => sli.IsRightBound = !useInferred);
return(rightAlign.Min(d => siblingLayoutInfos[d.Sibling.Element].Area.Right));
}
if (RelativePanel.GetAlignRightWithPanel(child))
{
ExecuteOnSiblingLayoutInfoIfAvailable(child, siblingLayoutInfos, sli => sli.IsRightBound = true);
return(availableSize.Width - graphPadding.Right);
}
if (!useInferred)
{
return(ComputeChildRightBound(child, availableSize, siblingLayoutInfos, childLeft, graphPadding, true));
}
// If there is no dependency, base yourself off of the available width, margins and Width/Min/Max properties
var spacing = childLeft + child.Margin.Left + child.Margin.Right;
return(double.IsNaN(child.Width) ?
Math.Max(
Math.Min(
availableSize.Width - graphPadding.Right,
child.MaxWidth + spacing
),
child.MinWidth + spacing
) :
child.Width + 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);
}
}
}