feat: Add page navigation enhancements

Author: DerekGooding

SimpleDataGrid.Example/Converters/ItemCountConverter.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Globalization;
+using System.Windows.Data;
+
+namespace SimpleDataGrid.Example.Converters
+{
+    public class ItemCountConverter : IMultiValueConverter
+    {
+        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (values.Length == 4 && values[0] is int count && values[1] is int page && values[2] is int total && values[3] is int pageSize)
+            {
+                var start = (page - 1) * pageSize + 1;
+                var end = start + count - 1;
+                return $"Showing items {start}-{end} of {total}";
+            }
+            return string.Empty;
+        }
+
+        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

SimpleDataGrid.Example/MainWindow.xaml

@@ -6,8 +6,12 @@
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:local="clr-namespace:SimpleDataGrid.Example"
         xmlns:controls="clr-namespace:SimpleDataGrid.Controls;assembly=SimpleDataGrid"
+        xmlns:converters="clr-namespace:SimpleDataGrid.Example.Converters"
         mc:Ignorable="d"
         Title="MainWindow" Height="450" Width="800">
+    <Window.Resources>
+        <converters:ItemCountConverter x:Key="ItemCountConverter"/>
+    </Window.Resources>
     <Window.DataContext>
         <local:MainViewModel />
     </Window.DataContext>
@@ -31,11 +35,31 @@
         <controls:PagedDataGrid x:Name="PagedDataGrid" Grid.Row="1" PagedSource="{Binding People}" AutoGenerateColumns="True" />
 
         <StackPanel Grid.Row="2" Orientation="Horizontal" HorizontalAlignment="Center">
-            <Button Content="Previous" Click="PreviousButton_Click" Margin="5" />
-            <TextBlock Text="{Binding People.CurrentPage}" VerticalAlignment="Center" Margin="5" />
-            <TextBlock Text="/" VerticalAlignment="Center" />
-            <TextBlock Text="{Binding People.TotalPages}" VerticalAlignment="Center" Margin="5" />
-            <Button Content="Next" Click="NextButton_Click" Margin="5" />
+            <Button Content="First" Click="FirstButton_Click" Margin="5" IsEnabled="{Binding People.HasPrevious}"/>
+            <Button Content="Previous" Click="PreviousButton_Click" Margin="5" IsEnabled="{Binding People.HasPrevious}"/>
+            <TextBlock VerticalAlignment="Center" Margin="5">
+                <TextBlock.Text>
+                    <MultiBinding StringFormat="Page {0} of {1}">
+                        <Binding Path="People.CurrentPage"/>
+                        <Binding Path="People.TotalPages"/>
+                    </MultiBinding>
+                </TextBlock.Text>
+            </TextBlock>
+            <Button Content="Next" Click="NextButton_Click" Margin="5" IsEnabled="{Binding People.HasNext}"/>
+            <Button Content="Last" Click="LastButton_Click" Margin="5" IsEnabled="{Binding People.HasNext}"/>
+            <TextBlock Text="Go to page:" VerticalAlignment="Center" Margin="5,0,0,0"/>
+            <TextBox x:Name="PageTextBox" Width="30" Margin="5,0,0,0"/>
+            <Button Content="Go" Click="GoToPageButton_Click" Margin="5,0,0,0"/>
+            <TextBlock VerticalAlignment="Center" Margin="10,0,0,0">
+                <TextBlock.Text>
+                    <MultiBinding Converter="{StaticResource ItemCountConverter}">
+                        <Binding Path="People.CurrentPageItems.Count"/>
+                        <Binding Path="People.CurrentPage"/>
+                        <Binding Path="People.TotalItems"/>
+                        <Binding Path="People.PageSize"/>
+                    </MultiBinding>
+                </TextBlock.Text>
+            </TextBlock>
         </StackPanel>
     </Grid>
 </Window>

SimpleDataGrid.Example/MainWindow.xaml.cs

@@ -39,4 +39,25 @@ private void ClearFilterButton_Click(object sender, RoutedEventArgs e)
         var viewModel = (MainViewModel)DataContext;
         viewModel.ClearFilter();
     }
+
+    private void FirstButton_Click(object sender, RoutedEventArgs e)
+    {
+        var viewModel = (MainViewModel)DataContext;
+        viewModel.People.GoToFirstPage();
+    }
+
+    private void LastButton_Click(object sender, RoutedEventArgs e)
+    {
+        var viewModel = (MainViewModel)DataContext;
+        viewModel.People.GoToLastPage();
+    }
+
+    private void GoToPageButton_Click(object sender, RoutedEventArgs e)
+    {
+        var viewModel = (MainViewModel)DataContext;
+        if (int.TryParse(PageTextBox.Text, out var page))
+        {
+            viewModel.People.GoToPage(page);
+        }
+    }
 }

SimpleDataGrid/Pagination/PagedCollection.cs

@@ -12,6 +12,10 @@ public class PagedCollection<T> : IPagedCollection, INotifyPropertyChanged
 {
     private readonly int _pageSize;
     private int _currentPage;
+    /// <summary>
+    /// Gets the number of items to display per page.
+    /// </summary>
+    public int PageSize => _pageSize;
     private IReadOnlyList<T> _source = [];
     private IReadOnlyList<T> _filtered = [];
 
@@ -174,7 +178,12 @@ private static string WildcardToRegex(string pattern)
     /// <summary>
     /// Gets the total number of pages.
     /// </summary>
-    public int TotalPages => (int)Math.Ceiling((double)_filtered.Count / _pageSize);
+    public int TotalPages => Math.Max(1, (int)Math.Ceiling((double)_filtered.Count / _pageSize));
+
+    /// <summary>
+    /// Gets the total number of items in the filtered collection.
+    /// </summary>
+    public int TotalItems => _filtered.Count;
 
     /// <summary>
     /// Gets a value indicating whether there is a next page.
@@ -216,6 +225,39 @@ public void PreviousPage()
         }
     }
 
+    /// <summary>
+    /// Moves to a specific page.
+    /// </summary>
+    /// <param name="page">The page to move to.</param>
+    public void GoToPage(int page)
+    {
+        var newPage = Math.Clamp(page - 1, 0, TotalPages - 1);
+        if (newPage != _currentPage)
+        {
+            _currentPage = newPage;
+            OnPropertyChanged(nameof(CurrentPageItems));
+            OnPropertyChanged(nameof(CurrentPage));
+            OnPropertyChanged(nameof(HasNext));
+            OnPropertyChanged(nameof(HasPrevious));
+        }
+    }
+
+    /// <summary>
+    /// Moves to the first page.
+    /// </summary>
+    public void GoToFirstPage()
+    {
+        GoToPage(1);
+    }
+
+    /// <summary>
+    /// Moves to the last page.
+    /// </summary>
+    public void GoToLastPage()
+    {
+        GoToPage(TotalPages);
+    }
+
     private void RaiseAllChanged()
     {
         OnPropertyChanged(nameof(CurrentPageItems));