private Size Measure(Size constraint, ILayout layout)
{
Layout.CheckBreakOnMeasure(this);
double vMax = 0;
var uTotalSpacing = Math.Max(0, Spacing * (InternalChildren.Count - 1));
var uAvailable = Math.Max(0, layout.GetU(constraint) - uTotalSpacing);
var vAvailable = layout.GetV(constraint);
var availableSize = layout.ToSize(uAvailable, vAvailable);
double sumWeight = 0;
double uSum = 0;
foreach (UIElement child in InternalChildren)
{
var growth = GetGrowth(child);
sumWeight += Math.Abs(growth);
if (growth <= 0)
{
child.Measure(availableSize);
var desiredSize = child.DesiredSize;
vMax = Math.Max(vMax, layout.GetV(desiredSize));
uSum += layout.GetU(desiredSize);
}
}
var uRemaining = Math.Max(0, uAvailable - uSum);
foreach (UIElement child in InternalChildren)
{
var growth = GetGrowth(child);
if (growth > 0)
{
var uSize = Math.Abs(growth) * uRemaining / sumWeight;
child.Measure(layout.ToSize(uSize, vAvailable));
var desiredSize = child.DesiredSize;
vMax = Math.Max(vMax, layout.GetV(desiredSize));
uSum += double.IsInfinity(uSize) ? layout.GetU(desiredSize) : uSize;
}
}
return(layout.ToSize(uSum + uTotalSpacing, vMax));
}
private Size Arrange(Size arrangeBounds, ILayout layout)
{
Layout.CheckBreakOnArrange(this);
double uSpacing = 0;
double spacing = Spacing;
double uDesired = 0;
double totalFlexWeight = 0;
foreach (UIElement child in InternalChildren)
{
var growth = GetGrowth(child);
uDesired += (growth <= 0 ? layout.GetU(child.DesiredSize) : 0) + uSpacing;
totalFlexWeight += Math.Abs(growth);
uSpacing = spacing;
}
var uRemaining = Math.Max(0, layout.GetU(arrangeBounds) - uDesired);
double cursor = 0;
uSpacing = 0;
foreach (UIElement child in InternalChildren)
{
cursor += uSpacing;
var growth = GetGrowth(child);
var stretch = totalFlexWeight <= 0 ? 0 : uRemaining *Math.Abs(growth) / totalFlexWeight;
var uBase = growth <= 0 ? layout.GetU(child.DesiredSize) : 0;
double uSize = Math.Max(0, uBase + stretch);
child.Arrange(layout.ToRect(cursor, 0, uSize, layout.GetV(arrangeBounds)));
cursor += uSize;
uSpacing = spacing;
}
return(arrangeBounds);
//return new Size(cursor, arrangeBounds.Height);
}