Wino-Mail/Wino.Core.UWP/Controls/EqualGridPanel.cs

using Windows.Foundation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace Wino.Core.UWP.Controls
{
    public partial class EqualGridPanel : Panel
    {
        public int Rows
        {
            get { return (int)GetValue(RowsProperty); }
            set { SetValue(RowsProperty, value); }
        }

        public static readonly DependencyProperty RowsProperty =
            DependencyProperty.Register(
                nameof(Rows),
                typeof(int),
                typeof(EqualGridPanel),
                new PropertyMetadata(1, OnLayoutPropertyChanged));

        public int Columns
        {
            get { return (int)GetValue(ColumnsProperty); }
            set { SetValue(ColumnsProperty, value); }
        }

        public static readonly DependencyProperty ColumnsProperty =
            DependencyProperty.Register(
                nameof(Columns),
                typeof(int),
                typeof(EqualGridPanel),
                new PropertyMetadata(1, OnLayoutPropertyChanged));

        private static void OnLayoutPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is EqualGridPanel panel)
            {
                panel.InvalidateMeasure();
                panel.InvalidateArrange();
            }
        }

        protected override Size MeasureOverride(Size availableSize)
        {
            if (Rows <= 0 || Columns <= 0)
            {
                return new Size(0, 0);
            }

            double cellWidth = availableSize.Width / Columns;
            double cellHeight = availableSize.Height / Rows;

            foreach (UIElement child in Children)
            {
                child.Measure(new Size(cellWidth, cellHeight));
            }

            return availableSize;
        }

        protected override Size ArrangeOverride(Size finalSize)
        {
            if (Rows <= 0 || Columns <= 0)
            {
                return new Size(0, 0);
            }

            double cellWidth = finalSize.Width / Columns;
            double cellHeight = finalSize.Height / Rows;

            for (int i = 0; i < Children.Count; i++)
            {
                int row = i / Columns;
                int column = i % Columns;

                double x = column * cellWidth;
                double y = row * cellHeight;

                Rect rect = new Rect(x, y, cellWidth, cellHeight);
                Children[i].Arrange(rect);
            }

            return finalSize;
        }
    }
}