Added IsNullOrEmptyConverters Samples

samples/CommunityToolkit.Maui.Sample/Pages/Converters/IsNotNullOrEmptyConverterPage.xaml

@@ -4,12 +4,33 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
     xmlns:mct="clr-namespace:CommunityToolkit.Maui.Converters;assembly=CommunityToolkit.Maui"
     xmlns:pages="clr-namespace:CommunityToolkit.Maui.Sample.Pages"
+    xmlns:vm="clr-namespace:CommunityToolkit.Maui.Sample.ViewModels.Converters"
     x:Class="CommunityToolkit.Maui.Sample.Pages.Converters.IsNotNullOrEmptyConverterPage">
+    <pages:BasePage.BindingContext>
+        <vm:IsNotNullOrEmptyConverterViewModel />
+    </pages:BasePage.BindingContext>
+    <pages:BasePage.Resources>
+        <ResourceDictionary>
+            <mct:IsNotNullOrEmptyConverter x:Key="IsNotNullOrEmptyConverter" />
+        </ResourceDictionary>
+    </pages:BasePage.Resources>
     <pages:BasePage.Content>
-        <StackLayout>
-            <Label Text="IsNotNullOrEmptyConverter"
-                VerticalOptions="CenterAndExpand" 
-                HorizontalOptions="CenterAndExpand" />
+        <StackLayout
+            Padding="10,10"
+            HorizontalOptions="Fill"
+            Spacing="16"
+            VerticalOptions="Fill">
+            <Label Text="The IsNullOrEmptyConverter is a converter that allows users to convert an incoming binding to a bool value. This value represents if the incoming binding value is null or empty." TextColor="{StaticResource NormalLabelTextColor}" />
+            <Button VerticalOptions="CenterAndExpand" Text="Clear Selection" Command="{Binding ClearSelectionCommand}"/>
+            <Label VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" Text="This label should be false if selected item is null" TextColor="{StaticResource NormalLabelTextColor}" />
+            <Label VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" Text="{Binding Path=SelectedItem, Converter={StaticResource IsNotNullOrEmptyConverter }}" />
+            <CollectionView VerticalOptions="StartAndExpand" HorizontalOptions="Center" SelectionMode="Single" ItemsSource="{Binding DummyItemSource}" SelectedItem="{Binding SelectedItem}">
+                <CollectionView.ItemTemplate>
+                    <DataTemplate>
+                        <Label Text="{Binding .}" Margin="10" TextColor="Black" />
+                    </DataTemplate>
+                </CollectionView.ItemTemplate>
+            </CollectionView>
         </StackLayout>
     </pages:BasePage.Content>
 </pages:BasePage>

samples/CommunityToolkit.Maui.Sample/Pages/Converters/IsNullOrEmptyConverterPage.xaml

@@ -4,12 +4,33 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
     xmlns:mct="clr-namespace:CommunityToolkit.Maui.Converters;assembly=CommunityToolkit.Maui"
     xmlns:pages="clr-namespace:CommunityToolkit.Maui.Sample.Pages"
+    xmlns:vm="clr-namespace:CommunityToolkit.Maui.Sample.ViewModels.Converters"
     x:Class="CommunityToolkit.Maui.Sample.Pages.Converters.IsNullOrEmptyConverterPage">
+    <pages:BasePage.BindingContext>
+        <vm:IsNullOrEmptyConverterViewModel />
+    </pages:BasePage.BindingContext>
+    <pages:BasePage.Resources>
+        <ResourceDictionary>
+            <mct:IsNullOrEmptyConverter x:Key="IsNullOrEmptyConverter" />
+        </ResourceDictionary>
+    </pages:BasePage.Resources>
     <pages:BasePage.Content>
-        <StackLayout>
-            <Label Text="IsNullOrEmptyConverter"
-                VerticalOptions="CenterAndExpand" 
-                HorizontalOptions="CenterAndExpand" />
+        <StackLayout
+            Padding="10,10"
+            HorizontalOptions="Fill"
+            Spacing="16"
+            VerticalOptions="Fill">
+            <Label Text="The IsNullOrEmptyConverter is a converter that allows users to convert an incoming binding to a bool value. This value represents if the incoming binding value is null or empty." TextColor="{StaticResource NormalLabelTextColor}" />
+            <Button VerticalOptions="CenterAndExpand" Text="Clear Selection" Command="{Binding ClearSelectionCommand}"/>
+            <Label VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" Text="This label should be true if selected item is null" TextColor="{StaticResource NormalLabelTextColor}" />
+            <Label VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" Text="{Binding Path=SelectedItem, Converter={StaticResource IsNullOrEmptyConverter}}" />
+            <CollectionView VerticalOptions="StartAndExpand" HorizontalOptions="Center" SelectionMode="Single" ItemsSource="{Binding DummyItemSource}" SelectedItem="{Binding SelectedItem}">
+                <CollectionView.ItemTemplate>
+                    <DataTemplate>
+                        <Label Text="{Binding .}" Margin="10" TextColor="Black" />
+                    </DataTemplate>
+                </CollectionView.ItemTemplate>
+            </CollectionView>
         </StackLayout>
     </pages:BasePage.Content>
 </pages:BasePage>

samples/CommunityToolkit.Maui.Sample/ViewModels/Converters/IsNotNullOrEmptyConverterViewModel.cs

@@ -0,0 +1,9 @@
+using System;
+namespace CommunityToolkit.Maui.Sample.ViewModels.Converters;
+
+public class IsNotNullOrEmptyConverterViewModel : IsNullOrEmptyConverterViewModel
+{
+    public IsNotNullOrEmptyConverterViewModel()
+    {
+    }
+}

samples/CommunityToolkit.Maui.Sample/ViewModels/Converters/IsNullOrEmptyConverterViewModel.cs

@@ -0,0 +1,31 @@
+using System.Collections.ObjectModel;
+using Microsoft.Maui.Controls;
+using System.Windows.Input;
+using System.Collections.Generic;
+
+namespace CommunityToolkit.Maui.Sample.ViewModels.Converters;
+
+public class IsNullOrEmptyConverterViewModel : BaseViewModel
+{
+    string? selectedItem;
+
+    public IsNullOrEmptyConverterViewModel() => ClearSelectionCommand = new Command(() => SelectedItem = null);
+
+    public IReadOnlyList<string> DummyItemSource { get; } = new[]
+    {
+        "Item 0",
+        "Item 1",
+        "Item 2",
+        "Item 3",
+        "Item 4",
+        "Item 5",
+    };
+
+    public ICommand ClearSelectionCommand { get; }
+
+    public string? SelectedItem
+    {
+        get => selectedItem;
+        set => SetProperty(ref selectedItem, value);
+    }
+}