inabox/InABox.Mobile/InABox.Mobile.Shared/Components/MobileToolGrid/MobileToolGrid.xaml.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Globalization;
using System.Linq;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace InABox.Mobile
{
    public class ToolGridLayoutChangedEventArgs : EventArgs
    {
        public int RowCount { get; private set; }
        public int ColCount { get; private set; }

        public ToolGridLayoutChangedEventArgs(int rowcount, int colcount)
        {
            RowCount = rowcount;
            ColCount = colcount;
        }
    }
    public delegate void ToolGridLayoutChangedEvent(object sender, ToolGridLayoutChangedEventArgs args);
    
    public class ToolGridViewModel : BindableObject
    {
        public IList<IMobileToolItem> Items { get; private set; }

        public IList<IMobileToolItem> VisibleItems { get; private set; }
        
        public int Columns { get; set; }
        
        public ToolGridViewModel()
        {
            Columns = 4;
            Items = new ObservableCollection<IMobileToolItem>();

            VisibleItems = new ObservableCollection<IMobileToolItem>();
            ((ObservableCollection<IMobileToolItem>)Items).CollectionChanged += (sender, args) =>
            {
                VisibleItems.Clear();
                DoLayout();
            };
        }

        private void DoLayout()
        {
            int iRow = 0;
            int iCol = 0;
            foreach (var item in Items.Where(x => x.IsVisible))
            {
                item.Row = iRow;
                item.Column = iCol;
                VisibleItems.Add(item);
                iCol++;
                if (iCol == Columns)
                {
                    iRow++;
                    iCol = 0;
                }
            }
            LayoutChanged?.Invoke(this,new ToolGridLayoutChangedEventArgs(iRow,Columns));
        }

        public Color BackgroundColor { get; set; }

        public event ToolGridLayoutChangedEvent LayoutChanged;

    }
    
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class MobileToolGrid
    {

        public IList<IMobileToolItem> Items => _viewModel.Items;
        
        public MobileToolGrid()
        {
            InitializeComponent();
            BindableLayout.SetItemsSource(_flexgrid, _viewModel.VisibleItems);
        }
        
        private void ImageTapped(object sender, EventArgs e)
        {
            if ((sender is Image image) && (image.BindingContext is MobileMobileToolItem item) && item.IsEnabled)
                item.DoTap();
        }

        private void _viewModel_OnLayoutChanged(object sender, ToolGridLayoutChangedEventArgs args)
        {
            _flexgrid.RowDefinitions.Clear();
            for (int i=0; i< args.RowCount; i++)
                _flexgrid.RowDefinitions.Add(new RowDefinition() { Height = GridLength.Auto});
            
            _flexgrid.ColumnDefinitions.Clear();
            for (int i=0; i< args.ColCount; i++)
                _flexgrid.ColumnDefinitions.Add(new ColumnDefinition() { Width = GridLength.Star});

        }
        
    }
}