WPF中确保显示ListBox选中的Item

最新推荐文章于 2024-09-03 17:14:20 发布

liuyan4794

最新推荐文章于 2024-09-03 17:14:20 发布

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文章标签： wpf action object

本文链接：https://blog.youkuaiyun.com/liuyan4794/article/details/5299382

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本文介绍了一个自定义函数，用于确保WPF ListBox中选中的项始终保持在可视区域内。通过调整滚动条的位置，使得当前选中的项不会被滚动条隐藏。

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WPF中没有提供确保显示ListBox选中的Item这个功能，因此写了个函数来实现：

public void EnsureListBoxItemVisible(ListBox listbox, ListBoxItem selectedItem)
{

int itemIndex = listbox.SelectedIndex;

ScrollViewer scrollViewer = (ScrollViewer)VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(listbox, 0), 0);

            int verticalOffset = (int)scrollViewer.VerticalOffset;
            if (itemIndex < verticalOffset)
            {
                verticalOffset = itemIndex;
            }
            else if (itemIndex > (int)(scrollViewer.ViewportHeight + verticalOffset - 1))
            {
                verticalOffset = itemIndex + 1 - (int)scrollViewer.ViewportHeight;
            }

if (verticalOffset != scrollViewer.VerticalOffset)
scrollViewer.ScrollToVerticalOffset(verticalOffset);

}

        private void TestListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            Application.Current.Dispatcher.BeginInvoke(new Action(delegate
            {
                ListBoxItem selectedItem = e.OriginalSource as ListBoxItem;

ViewModel.EnsureListBoxItemVisible(TestListBox, selectedItem);

}), System.Windows.Threading.DispatcherPriority.ApplicationIdle);
}

        private void TestListBox_ItemSelected(object sender, RoutedEventArgs e)
        {
            Application.Current.Dispatcher.BeginInvoke(new Action(delegate
            {
                ListBoxItem selectedItem = e.OriginalSource as ListBoxItem;

ViewModel.EnsureListBoxItemVisible(TestListBox, selectedItem);

}), System.Windows.Threading.DispatcherPriority.ApplicationIdle);
}