PilePanel.cs

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using Octgn.DataNew.Entities;

namespace Octgn.Play.Gui
{
    public class PilePanel : Panel
    {
        // this derived panel handles the resizing of the expanded (hand) piles so they fill up the entire width of the screen.
        // it is copied from the DockPanel base code, so there may be redundant sections.
        protected override Size MeasureOverride(Size constraint)
        {
            UIElementCollection children = InternalChildren;

            double parentWidth = 0.0;
            double accumulatedWidth = 0.0;

            foreach (UIElement child in children)
            {
                Size childConstraint;
                Size childDesiredSize;
                if (child == null) continue;

                childConstraint = new Size(Math.Max(0.0, constraint.Width - accumulatedWidth), constraint.Height);

                child.Measure(childConstraint);
                childDesiredSize = child.DesiredSize;

                accumulatedWidth += childDesiredSize.Width;

            }

            parentWidth = Math.Max(parentWidth, accumulatedWidth);

            return new Size(parentWidth, constraint.Height);
        }
        

        protected override Size ArrangeOverride(Size arrangeSize)
        {
            UIElementCollection children = InternalChildren;

            double accumulatedWidth = 0.0;
            double pileTotalWidth = 0.0;
            double expandedPileMinimumWidth = 0.0;

            foreach (ContentPresenter child in children)
            {
                if (child == null) continue;
                Size childDesiredSize = child.DesiredSize;

                if (child.Content is Pile pile && pile.ViewState == GroupViewState.Pile)
                {
                    pileTotalWidth += childDesiredSize.Width;
                }
                else
                {
                    expandedPileMinimumWidth += childDesiredSize.Width;
                }
            }

                foreach (ContentPresenter child in children)
                {
                    if (child == null) continue;
                    Size childDesiredSize = child.DesiredSize;
                    Rect rcChild = new Rect(
                        accumulatedWidth, 
                        0.0, 
                        Math.Max(0.0, arrangeSize.Width - accumulatedWidth),
                        Math.Max(0.0, arrangeSize.Height)
                        );
                    if (child.Content is Pile pile && pile.ViewState == GroupViewState.Pile)
                    {
                        accumulatedWidth += childDesiredSize.Width;
                        rcChild.Width = childDesiredSize.Width;
                    }
                    else
                    {
                        double adjustedExpandedPileWith = childDesiredSize.Width / expandedPileMinimumWidth * (arrangeSize.Width - pileTotalWidth);
                        accumulatedWidth += adjustedExpandedPileWith;
                        rcChild.Width = adjustedExpandedPileWith;
                    }
                    child.Arrange(rcChild);
                }

            return arrangeSize;
        }
    }
}