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MyBindableCustomPicker / Xamarin.Forms
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using System; | |
using System.Collections; | |
using System.Collections.Specialized; | |
using Xamarin.Forms; | |
namespace Miso.SearchForms.Controls | |
{ | |
/// <summary> | |
/// Bindable Custom Picker | |
/// | |
/// Xamarin.Forms 2.3.4がでれば、そっちを使った方が良い | |
/// </summary> | |
public class CustomPicker : Picker | |
{ | |
public CustomPicker() | |
{ | |
//TODO: OnPropertyChangedの"SelectedIndex"でいけるかどうか? | |
this.SelectedIndexChanged += CustomPicker_SelectedIndexChanged; | |
} | |
public static readonly BindableProperty ItemsSourceProperty = | |
BindableProperty.Create(nameof(ItemsSource), typeof(IList), typeof(CustomPicker), default(IList), | |
propertyChanged: OnItemsSourceChanged); | |
public static readonly BindableProperty SelectedItemProperty = | |
BindableProperty.Create(nameof(SelectedItem), typeof(object), typeof(CustomPicker), null, BindingMode.TwoWay, | |
propertyChanged: OnSelectedItemChanged); | |
public IList ItemsSource | |
{ | |
get { return (IList)GetValue(ItemsSourceProperty); } | |
set { SetValue(ItemsSourceProperty, value); } | |
} | |
public object SelectedItem | |
{ | |
get { return GetValue(SelectedItemProperty); } | |
set { SetValue(SelectedItemProperty, value); } | |
} | |
private void CustomPicker_SelectedIndexChanged(object sender, EventArgs e) | |
{ | |
var itemsSource = this.ItemsSource; | |
if (itemsSource == null || itemsSource.Count == 0) | |
return; | |
this.SelectedItem = (itemsSource.Count >= this.SelectedIndex + 1) ? itemsSource[this.SelectedIndex] : null; | |
} | |
private static void OnItemsSourceChanged(BindableObject bindable, object oldValue, object newValue) | |
{ | |
OnItemsSourceChanged(((CustomPicker)bindable), (IList)oldValue, (IList)newValue); | |
} | |
private static void OnItemsSourceChanged(CustomPicker picker, IList oldValue, IList newValue) | |
{ | |
picker.Items.Clear(); | |
if (newValue == null) | |
return; | |
NotifyCollectionChangedEventHandler handler = (sender, e) => CollectionChanged(picker, e); | |
var oldObservable = oldValue as INotifyCollectionChanged; | |
if (oldObservable != null) | |
{ | |
oldObservable.CollectionChanged -= handler; | |
} | |
var newObservable = newValue as INotifyCollectionChanged; | |
if (newObservable != null) | |
{ | |
newObservable.CollectionChanged += handler; | |
} | |
foreach (var item in newValue) | |
{ | |
picker.Items.Add(item.ToString()); | |
} | |
} | |
static void CollectionChanged(CustomPicker picker, NotifyCollectionChangedEventArgs e) | |
{ | |
switch (e.Action) | |
{ | |
case NotifyCollectionChangedAction.Add: | |
AddItems(picker, e); | |
break; | |
case NotifyCollectionChangedAction.Remove: | |
throw new NotImplementedException(); | |
default: //Move, Replace, Reset | |
picker.Items.Clear(); | |
picker.SelectedItem = null; | |
break; | |
} | |
} | |
private static void OnSelectedItemChanged(BindableObject bindable, object oldValue, object newValue) | |
{ | |
OnSelectedItemChanged((CustomPicker)bindable, oldValue, newValue); | |
} | |
private static void OnSelectedItemChanged(CustomPicker picker, object oldValue, object newValue) | |
{ | |
if (picker.ItemsSource == null) | |
{ | |
throw new Exception("ItemSource is null"); | |
} | |
if (newValue == null) | |
{ | |
picker.SelectedIndex = -1; | |
return; | |
} | |
picker.SelectedIndex = picker.ItemsSource.IndexOf(newValue); | |
return; | |
} | |
private static void AddItems(CustomPicker picker, NotifyCollectionChangedEventArgs e) | |
{ | |
int index = e.NewStartingIndex < 0 ? picker.Items.Count : e.NewStartingIndex; | |
foreach (object newItem in e.NewItems) | |
picker.Items.Insert(index++, newItem.ToString()); | |
} | |
} | |
} |
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