Permalink
Switch branches/tags
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
154 lines (129 sloc) 5.25 KB
using System;
using System.Collections;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Windows.Input;
using Xamarin.Forms;
namespace Wibci.Forms.Controls
{
//see: https://chaseflorell.github.io/xamarin/2015/03/14/xamarinforms-gridview/
/// <summary>
/// GridView for showing control templates in a tile-like layout
/// NOTE: Not designed for many items in the ItemsSource, as cached Recycling is not built in like the ListView
/// </summary>
public class GridView : Grid
{
public static readonly BindableProperty ItemsSourceProperty = BindableProperty.Create(nameof(ItemsSource), typeof(IList), typeof(GridView), default(IList), BindingMode.TwoWay);
public static readonly BindableProperty ItemTappedCommandProperty = BindableProperty.Create(nameof(ItemTappedCommand), typeof(ICommand), typeof(GridView), null);
public static readonly BindableProperty ItemTemplateProperty = BindableProperty.Create(nameof(ItemTemplate), typeof(DataTemplate), typeof(GridView), default(DataTemplate));
public static readonly BindableProperty MaxColumnsProperty = BindableProperty.Create(nameof(MaxColumns), typeof(int), typeof(GridView), 2);
public static readonly BindableProperty TileHeightProperty = BindableProperty.Create(nameof(TileHeight), typeof(float), typeof(GridView), 100f);
public GridView()
{
PropertyChanged += GridView_PropertyChanged;
PropertyChanging += GridView_PropertyChanging;
}
public IList ItemsSource
{
get { return (IList)GetValue(ItemsSourceProperty); }
set { SetValue(ItemsSourceProperty, value); }
}
public ICommand ItemTappedCommand
{
get { return (ICommand)GetValue(ItemTappedCommandProperty); }
set { SetValue(ItemTappedCommandProperty, value); }
}
public DataTemplate ItemTemplate
{
get { return (DataTemplate)GetValue(ItemTemplateProperty); }
set { SetValue(ItemTemplateProperty, value); }
}
public int MaxColumns
{
get { return (int)GetValue(MaxColumnsProperty); }
set { SetValue(MaxColumnsProperty, value); }
}
public float TileHeight
{
get { return (float)GetValue(TileHeightProperty); }
set { SetValue(TileHeightProperty, value); }
}
private void BuildColumns()
{
ColumnDefinitions.Clear();
for (var i = 0; i < MaxColumns; i++)
{
ColumnDefinitions.Add(new ColumnDefinition());
}
}
private View BuildTile(object item1)
{
var template = ItemTemplate.CreateContent() as View;
template.BindingContext = item1;
if (ItemTappedCommand != null)
{
var tapGestureRecognizer = new TapGestureRecognizer
{
Command = ItemTappedCommand,
CommandParameter = item1
};
template.GestureRecognizers.Add(tapGestureRecognizer);
}
return template;
}
private void BuildTiles()
{
// Wipe out the previous row & Column definitions if they're there.
if (RowDefinitions.Any())
{
RowDefinitions.Clear();
}
BuildColumns();
Children.Clear();
var tiles = ItemsSource;
if (tiles != null)
{
var numberOfRows = Math.Ceiling(tiles.Count / (float)MaxColumns);
for (var i = 0; i < numberOfRows; i++)
{
RowDefinitions.Add(new RowDefinition { Height = TileHeight });
}
for (var index = 0; index < tiles.Count; index++)
{
var column = index % MaxColumns;
var row = (int)Math.Floor(index / (float)MaxColumns);
var tile = BuildTile(tiles[index]);
Children.Add(tile, column, row);
}
}
}
private void GridView_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == ItemsSourceProperty.PropertyName)
{
var items = ItemsSource as INotifyCollectionChanged;
if (items != null)
items.CollectionChanged += ItemsCollectionChanged;
BuildTiles();
}
if (e.PropertyName == MaxColumnsProperty.PropertyName || e.PropertyName == TileHeightProperty.PropertyName)
{
BuildTiles();
}
}
private void GridView_PropertyChanging(object sender, PropertyChangingEventArgs e)
{
if (e.PropertyName == ItemsSourceProperty.PropertyName)
{
var items = ItemsSource as INotifyCollectionChanged;
if (items != null)
items.CollectionChanged -= ItemsCollectionChanged;
}
}
private void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
BuildTiles();
}
}
}