Avalonia 自定义分页控件

public class Pagination : ContentControl
{
private int _currentPage = 1;
private Button _prevPageButton = null!;
private Button _nextPageButton = null!;
private Button goToPageButton = null!;
private TextBox _pageNumberTextBox = null!;
private TextBlock _pageInfoTextBlock = null!;
private ComboBox _itemsPerPageComboBox = null!;

// 定义可绑定的 ItemsSource 属性
public static readonly StyledProperty ItemsSourceProperty =
AvaloniaProperty.Register<Pagination, IEnumerable>(nameof(ItemsSource), defaultBindingMode: BindingMode.TwoWay);

public IEnumerable ItemsSource
{
get => GetValue(ItemsSourceProperty);
set => SetValue(ItemsSourceProperty, value);
}

// 定义可绑定的 ItemsPerPage 属性
public static readonly StyledProperty ItemsPerPageProperty =
AvaloniaProperty.Register<Pagination, int>(nameof(ItemsPerPage), 10, defaultBindingMode: BindingMode.TwoWay);

public int ItemsPerPage
{
get => GetValue(ItemsPerPageProperty);
set => SetValue(ItemsPerPageProperty, value);
}

// 定义可绑定的 TotalItems 属性
public static readonly StyledProperty TotalItemsProperty =
AvaloniaProperty.Register<Pagination, int>(nameof(TotalItems), defaultValue: -1);

public int TotalItems
{
get => GetValue(TotalItemsProperty);
set => SetValue(TotalItemsProperty, value);
}

// 定义可绑定的 IsBackendPaging 属性
public static readonly StyledProperty IsBackendPagingProperty =
AvaloniaProperty.Register<Pagination, bool>(nameof(IsBackendPaging), false, defaultBindingMode: BindingMode.TwoWay);

public bool IsBackendPaging
{
get => GetValue(IsBackendPagingProperty);
set => SetValue(IsBackendPagingProperty, value);
}

// 定义事件，通知外部逻辑当前页数和每页条数,后台分页模式下返回当前页号和每页条数
public event Action<Pagination, int, int, IEnumerable> PageChanged = null!;

public Pagination()
{
InitializeControls();
}
///

/// 重写 OnApplyTemplate 方法
///

///
protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
{
base.OnApplyTemplate(e); // 传递 TemplateAppliedEventArgs 参数

// Replace the following line:
var index = _itemsPerPageComboBox.ItemsSource?
.Cast() // 将 IEnumerable 转换为 IEnumerable
.Select((value, idx) => new { Value = value, Index = idx }) // 将值和索引绑定
.FirstOrDefault(x => x.Value == ItemsPerPage)?.Index; // 查找目标值并返回索引
_itemsPerPageComboBox.SelectedIndex = index == null ? 0 : (int)index;
// 确保控件初始化完成后再添加监听
if (!IsBackendPaging)
{
// 伪分页，监听数据源属性变化
ItemsSourceProperty.Changed.AddClassHandler((x, e) => x.UpdatePagination());
}
else
{
// 后台分页，监听总数属性变化，更新分页信息
TotalItemsProperty.Changed.AddClassHandler((x, e) => x.UpdatePaginationInfo());
}

// 监听每页条数属性变化
ItemsPerPageProperty.Changed.AddClassHandler((x, e) => x.UpdatePagination());

_prevPageButton.Click += (s, e) => GoToPage(_currentPage - 1);
_nextPageButton.Click += (s, e) => GoToPage(_currentPage + 1);

goToPageButton.Click += (s, e) =>
{
if (int.TryParse(_pageNumberTextBox.Text, out int pageNumber))
{
int totalPages = CalculateTotalPages();
if (pageNumber < 1 || pageNumber > totalPages)
{
_pageNumberTextBox.Text = string.Empty; // 清空输入框
return;
}
GoToPage(pageNumber);
}
};

_itemsPerPageComboBox.SelectionChanged += (s, e) =>
{
if (_itemsPerPageComboBox.SelectedItem is int selectedItemsPerPage)
{
ItemsPerPage = selectedItemsPerPage;
_currentPage = 1; // 重置到第一页
UpdatePagination();
}
};

// 初始化分页
UpdatePagination();
}

// 初始化控件
private void InitializeControls()
{
// 创建分页控件
var paginationPanel = new StackPanel
{
Orientation = Orientation.Horizontal,
HorizontalAlignment = HorizontalAlignment.Right,
Margin = new Thickness(0, 10, 0, 0)
};

_itemsPerPageComboBox = new ComboBox
{
Width = 100,
Margin = new Thickness(0, 0, 10, 0),
ItemsSource = new[] { 10, 20, 50, 100, 500, 1000 }
};

// 上一页按钮
_prevPageButton = new Button
{
Content = "上一页",
Padding = new Thickness(5, 0),
FontSize = 14,
Height = 34,
Margin = new Thickness(0, 0, 5, 0)
};

// 下一页按钮
_nextPageButton = new Button
{
Content = "下一页",
Padding = new Thickness(5, 0),
FontSize = 14,
Height = 34,
Margin = new Thickness(5, 0, 0, 0)
};

// 页号输入框
_pageNumberTextBox = new TextBox
{
Width = 100,
Margin = new Thickness(5, 0, 5, 0),
FontSize = 14,
Height = 34,
VerticalAlignment = VerticalAlignment.Center
};

// 页号跳转按钮
goToPageButton = new Button
{
Content = "跳转",
Padding = new Thickness(5,0),
FontSize = 14,
Height = 34,
Margin = new Thickness(5, 0, 0, 0)
};

// 当前页/总页数显示
_pageInfoTextBlock = new TextBlock
{
VerticalAlignment = VerticalAlignment.Center,
Margin = new Thickness(10, 0, 10, 0)
};

paginationPanel.Children.Add(_itemsPerPageComboBox);
paginationPanel.Children.Add(_prevPageButton);
paginationPanel.Children.Add(_pageInfoTextBlock);
paginationPanel.Children.Add(_pageNumberTextBox);
paginationPanel.Children.Add(goToPageButton);
paginationPanel.Children.Add(_nextPageButton);

// 将分页控件设置为 Content
this.Content = paginationPanel;
}
//后台分页，由于只提供数据总数，所以只触发更新,不触发事件
private void UpdatePaginationInfo()
{
if (TotalItems<0) return;
_pageInfoTextBlock.Text = $"第 {_currentPage} 页 / 共 {TotalItems} 页";
_prevPageButton.IsEnabled = _currentPage > 1;
_nextPageButton.IsEnabled = _currentPage < TotalItems;
}
// 更新分页并触发Change
private void UpdatePagination()
{
if (ItemsSource == null) return;
if (!IsBackendPaging&&ItemsSource.Cast