CPF/CPF.Toolkit/Controls/MdiHost.cs

using CPF.Controls;
using CPF.Drawing;
using CPF.Platform;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace CPF.Toolkit.Controls
{
    public class MdiHost : Grid
    {
        public MdiHost()
        {
            this.TaskBarList = new Collection<UIElement>();
            this.Size = SizeField.Fill;
            this.Background = "204,204,204";
            base.RowDefinitions.Add(new RowDefinition { Height = GridLength.Star });
            base.RowDefinitions.Add(new RowDefinition { Height = "35", MaxHeight = 35 });

            base.Children.Add(this.host);
            var taskBar = base.Children.Add(new ListBox
            {
                Size = SizeField.Fill,
                Background = "white",
                BorderFill = new SolidColorFill { Color = Color.Silver },
                BorderThickness = new Thickness(0, 1, 0, 0),
                BorderType = BorderType.BorderThickness,
                ItemsPanel = new StackPanel { Orientation = Orientation.Horizontal },
                ItemTemplate = new ListBoxItem
                {
                    Height = "100%",
                    Width = 100,
                    MarginRight = 1,
                    FontSize = 16f,
                    BorderFill = "Silver",
                    BorderThickness = new Thickness(0, 0, 1, 0),
                    BorderType = BorderType.BorderThickness,
                    [nameof(ListBoxItem.Content)] = new BindingDescribe("Title")
                },
                Items = this.TaskBarList,
                [nameof(ListBox.SelectedValue)] = new BindingDescribe(this, nameof(this.SelectWindow), BindingMode.TwoWay),
            }, row: 1);
            this.host.PropertyChanged += Host_PropertyChanged;
            this.host.UIElementAdded += Host_UIElementAdded;
            this.host.UIElementRemoved += Host_UIElementRemoved;
        }

        readonly Panel host = new Panel { Size = SizeField.Fill };
        Collection<UIElement> TaskBarList { get => GetValue<Collection<UIElement>>(); set => SetValue(value); }
        public new UIElementCollection Children => host.Children;
        UIElement SelectWindow { get => GetValue<UIElement>(); set => SetValue(value); }

        protected override void OnPropertyChanged(string propertyName, object oldValue, object newValue, PropertyMetadataAttribute propertyMetadata)
        {
            if (propertyName == nameof(this.SelectWindow))
            {
                this.Topping(this.SelectWindow);
            }
            base.OnPropertyChanged(propertyName, oldValue, newValue, propertyMetadata);
        }

        private void Host_PropertyChanged(object sender, CPFPropertyChangedEventArgs e)
        {
            if (e.PropertyName.Or(nameof(ActualSize), nameof(Size), nameof(Width), nameof(Height)))
            {
                foreach (MdiWindow mdi in this.host.Children)
                {
                    if (mdi.WindowState == WindowState.Maximized) continue;

                    if (mdi.MarginLeft.Value + mdi.ActualSize.Width > this.ActualSize.Width)
                    {
                        mdi.MarginLeft = this.ActualSize.Width - mdi.ActualSize.Width;
                    }

                    if (mdi.MarginTop.Value + mdi.ActualSize.Height > this.ActualSize.Height)
                    {
                        mdi.MarginTop = this.ActualSize.Height - mdi.ActualSize.Height;
                    }
                }
            }
        }

        private void Host_UIElementRemoved(object sender, UIElementRemovedEventArgs e)
        {
            e.Element.PropertyChanged -= Element_PropertyChanged;
            e.Element.PreviewMouseDown -= Element_PreviewMouseDown;
            this.TaskBarList.Remove(e.Element);
        }

        private void Host_UIElementAdded(object sender, UIElementAddedEventArgs e)
        {
            var view = e.Element as MdiWindow;
            view.PropertyChanged += Element_PropertyChanged;
            view.PreviewMouseDown += Element_PreviewMouseDown;
            this.TaskBarList.Add(view);
            e.Element.ZIndex = this.host.Children.Max(x => x.ZIndex) + 1;
            this.Topping(e.Element);
        }

        private void Element_PreviewMouseDown(object sender, Input.MouseButtonEventArgs e)
        {
            var ele = (UIElement)sender;
            this.Topping(ele);
        }

        private void Element_PropertyChanged(object sender, CPFPropertyChangedEventArgs e)
        {
            var view = sender as MdiWindow;
            switch (e.PropertyName)
            {
                case nameof(MdiWindow.WindowState):
                    if ((WindowState)e.NewValue == WindowState.Minimized)
                    {
                        this.SelectWindow = this.host.Children.FindLast(x => x.Visibility == Visibility.Visible);
                    }
                    break;

                case nameof(ZIndex):
                    this.SelectWindow = view;
                    this.SelectWindow.Visibility = Visibility.Visible;
                    break;
            }
        }

        void Topping(UIElement ele)
        {
            if (ele == null) return;
            var index = this.host.Children.Max(x => x.ZIndex);
            if (ele.ZIndex == index)
            {
                ele.Visibility = Visibility.Visible;
                return;
            }
            ele.ZIndex = index + 1;
        }
    }
}