Xamarin.Forms.Pages/DataView.cs

   1 using System.Collections.Generic;
   2 using System.Linq;
   3
   4 namespace Xamarin.Forms.Pages
   5 {
   6         public class DataView : ContentView, IDataSourceProvider
   7         {
   8                 public static readonly BindableProperty DataProperty = BindableProperty.Create(nameof(Data), typeof(IEnumerable<IDataItem>), typeof(DataView), default(IEnumerable<IDataItem>));
   9
  10                 public static readonly BindableProperty DataSourceProperty = BindableProperty.Create(nameof(DataSource), typeof(IDataSource), typeof(DataView), null, propertyChanged: OnDataSourceChanged);
  11
  12                 public static readonly BindableProperty DefaultItemTemplateProperty = BindableProperty.Create(nameof(DefaultItemTemplate), typeof(DataTemplate), typeof(DataView), default(DataTemplate));
  13
  14                 readonly HashSet<string> _maskedKeys = new HashSet<string>();
  15
  16                 public DataView()
  17                 {
  18                         SetBinding(DataProperty, new Binding("DataSource.Data", source: this));
  19                 }
  20
  21                 public IEnumerable<IDataItem> Data
  22                 {
  23                         get { return (IEnumerable<IDataItem>)GetValue(DataProperty); }
  24                         set { SetValue(DataProperty, value); }
  25                 }
  26
  27                 public DataTemplate DefaultItemTemplate
  28                 {
  29                         get { return (DataTemplate)GetValue(DefaultItemTemplateProperty); }
  30                         set { SetValue(DefaultItemTemplateProperty, value); }
  31                 }
  32
  33                 public IDataSource DataSource
  34                 {
  35                         get { return (IDataSource)GetValue(DataSourceProperty); }
  36                         set { SetValue(DataSourceProperty, value); }
  37                 }
  38
  39                 void IDataSourceProvider.MaskKey(string key)
  40                 {
  41                         _maskedKeys.Add(key);
  42                         IDataSource dataSource = DataSource;
  43                         if (dataSource != null && !dataSource.MaskedKeys.Contains(key))
  44                         {
  45                                 dataSource.MaskKey(key);
  46                         }
  47                 }
  48
  49                 void IDataSourceProvider.UnmaskKey(string key)
  50                 {
  51                         _maskedKeys.Remove(key);
  52                         DataSource?.UnmaskKey(key);
  53                 }
  54
  55                 static void OnDataSourceChanged(BindableObject bindable, object oldValue, object newValue)
  56                 {
  57                         var dataView = (DataView)bindable;
  58                         var dataSource = (IDataSource)newValue;
  59                         var oldSource = (IDataSource)oldValue;
  60
  61                         if (oldSource != null)
  62                         {
  63                                 foreach (string key in dataView._maskedKeys)
  64                                         oldSource.UnmaskKey(key);
  65                         }
  66
  67                         if (dataSource != null)
  68                         {
  69                                 foreach (string key in dataView._maskedKeys)
  70                                 {
  71                                         dataSource.MaskKey(key);
  72                                 }
  73                         }
  74                 }
  75         }
  76 }