Fixed binding errors in demo app (#1765)

* Fixed binding errors for nullable Kind property

* Fixed "Select all"-Binding for first DataGrid using BindingProxy

Author: greuelpirat

MainDemo.Wpf/Domain/BindingProxy.cs

@@ -0,0 +1,18 @@
+using System.Windows;
+
+namespace MaterialDesignDemo.Domain
+{
+    public class BindingProxy : Freezable
+    {
+        protected override Freezable CreateInstanceCore() => new BindingProxy();
+
+        public object Data
+        {
+            get => GetValue(DataProperty);
+            set => SetValue(DataProperty, value);
+        }
+
+        public static readonly DependencyProperty DataProperty =
+            DependencyProperty.Register("Data", typeof(object), typeof(BindingProxy), new UIPropertyMetadata(null));
+    }
+}

MainDemo.Wpf/Domain/ListsAndGridsViewModel.cs

@@ -3,6 +3,7 @@
 using System.ComponentModel;
 using System.Runtime.CompilerServices;
 using MaterialDesignColors.WpfExample.Domain;
+using System.Linq;
 
 namespace MaterialDesignDemo.Domain
 {
@@ -11,28 +12,37 @@ public class ListsAndGridsViewModel : INotifyPropertyChanged
         private readonly ObservableCollection<SelectableViewModel> _items1;
         private readonly ObservableCollection<SelectableViewModel> _items2;
         private readonly ObservableCollection<SelectableViewModel> _items3;
-        private bool? _isAllItems3Selected;
 
         public ListsAndGridsViewModel()
         {
             _items1 = CreateData();
             _items2 = CreateData();
             _items3 = CreateData();
+
+            foreach (var model in _items3)
+            {
+                model.PropertyChanged += (sender, args) =>
+                {
+                    if (args.PropertyName == nameof(SelectableViewModel.IsSelected))
+                        OnPropertyChanged(nameof(IsAllItems3Selected));
+                };
+            }
         }
 
         public bool? IsAllItems3Selected
         {
-            get { return _isAllItems3Selected; }
+            get
+            {
+                var selected = _items3.Select(item => item.IsSelected).Distinct().ToList();
+                return selected.Count == 1 ? selected.Single() : (bool?) null;
+            }
             set
             {
-                if (_isAllItems3Selected == value) return;
-
-                _isAllItems3Selected = value;
-
-                if (_isAllItems3Selected.HasValue)
-                    SelectAll(_isAllItems3Selected.Value, Items3);
-
-                OnPropertyChanged();
+                if (value.HasValue)
+                {
+                    SelectAll(value.Value, Items3);
+                    OnPropertyChanged();
+                }
             }
         }
 

MainDemo.Wpf/Grids.xaml

@@ -5,6 +5,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
              xmlns:smtx="clr-namespace:ShowMeTheXAML;assembly=ShowMeTheXAML"
+             xmlns:domain="clr-namespace:MaterialDesignDemo.Domain"
              mc:Ignorable="d" 
              d:DesignHeight="300" d:DesignWidth="600">
     <UserControl.Resources>
@@ -20,16 +21,18 @@
             <smtx:XamlDisplay Key="grids_1">
                 <DataGrid Margin="0 8 0 0" ItemsSource="{Binding Items3}" CanUserSortColumns="True" CanUserAddRows="False" AutoGenerateColumns="False"
                           materialDesign:DataGridAssist.CellPadding="13 8 8 8" materialDesign:DataGridAssist.ColumnHeaderPadding="8" HeadersVisibility="All">
+                    <DataGrid.Resources>
+                        <domain:BindingProxy x:Key="DataContextProxy" Data="{Binding}" />
+                    </DataGrid.Resources>
                     <DataGrid.Columns>
-                        <DataGridCheckBoxColumn Binding="{Binding IsSelected}" 
+                        <DataGridCheckBoxColumn Binding="{Binding IsSelected, UpdateSourceTrigger=PropertyChanged}" 
                                                 ElementStyle="{StaticResource MaterialDesignDataGridCheckBoxColumnStyle}"
                                                 EditingElementStyle="{StaticResource MaterialDesignDataGridCheckBoxColumnEditingStyle}">
                             <DataGridCheckBoxColumn.Header>
                                 <!--padding to allow hit test to pass thru for sorting -->
                                 <Border Background="Transparent" Padding="6 0 6 0" HorizontalAlignment="Center">
                                     <CheckBox HorizontalAlignment="Center"
-                                              DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=DataContext}"
-                                              IsChecked="{Binding IsAllItems3Selected}" />
+                                              IsChecked="{Binding Data.IsAllItems3Selected, Source={StaticResource DataContextProxy}}" />
                                 </Border>
                             </DataGridCheckBoxColumn.Header>
                         </DataGridCheckBoxColumn>

MainDemo.Wpf/IconPack.xaml

@@ -84,7 +84,7 @@
                              GotFocus="TextBox_OnGotFocus"
                              Text="{Binding Kind, StringFormat='<materialDesign:PackIcon Kind="{0}" \/>'}" />
                 </materialDesign:ColorZone>
-                <materialDesign:PackIcon Kind="{Binding Kind}" VerticalAlignment="Center"
+                <materialDesign:PackIcon Kind="{Binding PackIconKind}" VerticalAlignment="Center"
                                          Visibility="{Binding Kind, Converter={StaticResource NullableToVisibilityConverter}}" />
                 <Button Margin="8 0" Command="{Binding CopyToClipboardCommand, Mode=OneTime}" CommandParameter="{Binding Kind}">
                     <StackPanel Orientation="Horizontal">

MainDemo.Wpf/IconPackViewModel.cs

@@ -39,6 +39,7 @@ public IconPackViewModel(ISnackbarMessageQueue snackbarMessageQueue)
         private IEnumerable<PackIconKindGroup> _kinds;
         private PackIconKindGroup _group;
         private string _kind;
+        private PackIconKind _packIconKind;
 
         public IEnumerable<PackIconKindGroup> Kinds
         {
@@ -55,14 +56,23 @@ public PackIconKindGroup Group
                 {
                     Kind = value?.Kind;
                 }
-                
             }
         }
 
         public string Kind
         {
             get => _kind;
-            set => this.MutateVerbose(ref _kind, value, e => PropertyChanged?.Invoke(this, e));
+            set
+            {
+                if (this.MutateVerbose(ref _kind, value, e => PropertyChanged?.Invoke(this, e)))
+                    PackIconKind = value != null ? (PackIconKind) Enum.Parse(typeof(PackIconKind), value) : default;
+            }
+        }
+
+        public PackIconKind PackIconKind
+        {
+            get => _packIconKind;
+            set => this.MutateVerbose(ref _packIconKind, value, e => PropertyChanged?.Invoke(this, e));
         }
 
         private void OpenDotCom(object obj)
@@ -79,7 +89,8 @@ private async void Search(object obj)
             {
                 Kinds = await Task.Run(() => _packIconKinds.Value
                     .Where(x => x.Aliases.Any(a => a.IndexOf(text, StringComparison.CurrentCultureIgnoreCase) >= 0))
-                    .ToList());}
+                    .ToList());
+            }
         }
 
         private void CopyToClipboard(object obj)