WPF 中的“无限”面板

无限面板是 WPF 中一种非常有用的布局控件，它允许我们在界面中创建一个可以无限扩展的面板。这个面板可以自动添加和删除子元素，并且可以根据需要自动调整布局。在本文中，我们将探讨无限面板的使用方法，并通过一个案例来演示其强大的功能。

xml
xmlns:ext="clr-namespace:WpfExtensions.Controls;assembly=WpfExtensions"

xml

csharp
Button button1 = new Button();
button1.Content = "Button 1";
Button button2 = new Button();
button2.Content = "Button 2";
infinitePanel.Children.Add(button1);
infinitePanel.Children.Add(button2);
// 设置子元素的位置和大小
InfinitePanel.SetLocation(button1, new Point(0, 0));
InfinitePanel.SetSize(button1, new Size(100, 50));
InfinitePanel.SetLocation(button2, new Point(150, 0));
InfinitePanel.SetSize(button2, new Size(100, 50));

csharp
List dataSource = new List();
for (int i = 0; i < 1000; i++)
{
    dataSource.Add($"Item {i + 1}");
}

xml
    

csharp
private int itemHeight = 30;
private int visibleItemCount = 10;
private int itemCount = 1000;
private int startIndex = 0;
public MainWindow()
{
    InitializeComponent();
    UpdateItems();
}
private void UpdateItems()
{
    infinitePanel.Children.Clear();
    int endIndex = startIndex + visibleItemCount;
    if (endIndex > itemCount)
    {
        endIndex = itemCount;
    }
    for (int i = startIndex; i < endIndex; i++)
    {
        string item = dataSource[i];
        TextBlock textBlock = new TextBlock();
        textBlock.Text = item;
        textBlock.Height = itemHeight;
        InfinitePanel.SetLocation(textBlock, new Point(0, i * itemHeight));
        InfinitePanel.SetSize(textBlock, new Size(200, itemHeight));
        infinitePanel.Children.Add(textBlock);
    }
    startIndex = endIndex;
}
private void ScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
    ScrollViewer scrollViewer = (ScrollViewer)sender;
    double offset = scrollViewer.VerticalOffset;
    double extent = scrollViewer.ExtentHeight;
    double viewport = scrollViewer.ViewportHeight;
    if (offset + viewport >= extent)
    {
        UpdateItems();
    }
}