prs/prs.mobile.new/PRS.Mobile/CustomControls/Expander/ExpanderView.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using Xamarin.CommunityToolkit.UI.Views;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using XF.Material.Forms;

namespace PRS.Mobile
{


    public delegate void ExpanderViewSelectionChanged(object sender, EventArgs args);
    
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class ExpanderView : ContentView
    {
        private ExpanderViewData _data;
        public ExpanderViewData Data
        {
            get => _data;
            set
            {
                _data = value;
                Load();
            }
        }
        
        public Color SelectedColor { get; set; }
        public Color UnselectedColor { get; set; }

        public event ExpanderViewSelectionChanged SelectionChanged;
        
        public ExpanderView()
        {
            InitializeComponent();
            SelectedColor = Color.Red;
            UnselectedColor = Color.Silver;
        }

        public void Load()
        {
            Stack.Children.Clear();
            if (Data == null)
                return;
            
            foreach (var group in Data.Groups)
            {
                var expander = new Expander();
                expander.HorizontalOptions = LayoutOptions.Start;
                expander.Header = CreateHeader(group,(o, e) =>
                {
                    if (o is Frame frame)
                    {
                        frame.Margin = new Thickness(0, 0, expander.IsExpanded ? 0 : 20, 0);
                        //frame.Margin = new Thickness(0, 0, 10, 0);
                    };
                    
                    foreach (var exp in Stack.Children.Where(x => x != expander))
                        exp.IsVisible = expander.IsExpanded;
                    expander.ForceUpdateSize();
                    if (!expander.IsExpanded)
                        Scroll.ScrollToAsync(0, 0, false);
                    else
                        Scroll.ScrollToAsync(expander, ScrollToPosition.MakeVisible, false);
                });
                expander.Content = CreateList(group);
                Stack.Children.Add(expander);
            }
        }

        private ContentView CreateHeader(ExpanderViewGroup group, EventHandler ontapped)
        {
            Frame frame = new Frame();
            frame.BackgroundColor = Color.White;
            frame.HasShadow = false;
            frame.CornerRadius = 5;
            frame.BorderColor = Color.Gray;
            frame.Padding = new Thickness(2,2,5,2);
            frame.HorizontalOptions = LayoutOptions.Fill;
            frame.MinimumHeightRequest = 30;
            TapGestureRecognizer headerTap = new TapGestureRecognizer() { NumberOfTapsRequired = 1 };
            headerTap.Tapped += ontapped;
            frame.GestureRecognizers.Add(headerTap);
                
            Grid grid = new Grid();
            grid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
            grid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
                
            if (group.Image != null)
            {
                Image image = new Image() { Source = group.Image };
                image.WidthRequest = 25;
                image.HeightRequest = 25;
                image.SetValue(Grid.ColumnProperty, 0);
                grid.Children.Add(image);
            }
                
            Label label = new Label()
            {
                Text = group.Description,
                FontAttributes = FontAttributes.Bold,
                FontSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label)),
                VerticalTextAlignment = TextAlignment.Center,
                HorizontalTextAlignment = TextAlignment.Center
            };
            label.FontSize = 18;
            label.SetValue(Grid.ColumnProperty, 1);
            grid.Children.Add(label);
                
            frame.Content = grid;

            return frame;
        }

        private View CreateList(ExpanderViewGroup group)
        {
            ListView result = new ListView();
            result.SelectionMode = ListViewSelectionMode.None;
            result.HorizontalOptions = LayoutOptions.Fill;
            result.ItemTemplate = new DataTemplate(() =>
            {
                var frame = new Frame()
                {
                    BackgroundColor = Color.Transparent,
                    BorderColor = Color.Transparent,
                    Margin = 0,
                    Padding = 0,
                    HasShadow = false
                };
                var button = new Button
                {
                    MinimumHeightRequest = 30,
                    TextColor = Color.Black,
                    FontSize = Device.GetNamedSize(NamedSize.Small, typeof(Button)),
                    CornerRadius = 5,
                    BorderColor = UnselectedColor,
                    BackgroundColor = Material.Color.Surface,
                    Margin = new Thickness(2, 2, 20, 2),
                    HorizontalOptions = LayoutOptions.Fill
                };
                button.SetBinding(Button.TextProperty, "Description");
                button.Clicked += ExpanderViewItem_Clicked;
                frame.Content = button;
                return new ViewCell { View = frame };
            });

            result.ItemsSource = group.Items;
            return result;
        }
        
        private void ExpanderViewItem_Clicked(object sender, EventArgs e)
        {
            var button = (sender as Button);
            var item = button.BindingContext as ExpanderViewItem;
            item.Selected = !item.Selected;
            button.BackgroundColor = item.Selected ? SelectedColor : UnselectedColor;
            button.BorderColor = button.BackgroundColor;
            SelectionChanged?.Invoke(this,new EventArgs());
        }
    }
}