Question

我目前的代码存在问题，因为对特定项目行的关注不会成立。我创建了int focusReference以跟踪当前聚焦的行，但它似乎在每几秒后重置为0，即一旦用户选择一行，在几秒钟内，它会忘记＆＃34;忘记＆＃34;用户选择。我在下面举了一个例子：

enter image description here

从下面的代码中可以看出，我每隔几秒钟就有一个计时器。我已经被告知，每隔几秒刷一次我的清单会导致每隔几秒就失去一次焦点。

如何以编程方式将焦点设置在某个项目上，以保留用户拥有的焦点？我尝试过实施FocusItem方法，但似乎并没有起作用。这是我的程序非常重要的一个方面，我需要它才能正常工作，否则其他功能（如我正在实现的右键单击上下文菜单）也将无效：

public MainWindow()
{
    InitializeComponent();
    int focusReference = 0;
    PlotListView.SelectionChanged += (s, ee) => { PlotListView_SelectionChanged(s, ee, focusReference); };
    var dbObject = new DbConnect();
    dbObject.OpenConnection();
    RefreshPlotTimer(filterReference, focusReference);
}

public void PlotListView_SelectionChanged(object sender, SelectionChangedEventArgs e, int focusReference)
{
    if (PlotListView.SelectedItems.Count == 0) return;
    var selectedItem = (DbConnect.PlotList)PlotListView.SelectedItems[0];
    focusReference = Convert.ToInt32(selectedItem.PlotId);
    FocusItem(focusReference);
}

private void FocusItem(int focusReference)
{
    if (PlotListView.SelectedItems.Count != 0)
    {
        DbConnect.PlotList plotList =
            PlotListView.Items.OfType<DbConnect.PlotList>()
            .FirstOrDefault(p => Convert.ToInt32(p.PlotId) == focusReference);
        if (plotList != null)
        {
            //get visual container
            var container = PlotListView.ItemContainerGenerator.ContainerFromItem(plotList) as ListViewItem;
            if (container != null)
            {
                container.IsSelected = true;
                container.Focus();
            }
        }
    }
}

public void RefreshPlotTimer(int filterReference, int focusReference)
{
    var refreshTimer = new Timer();
    refreshTimer.Elapsed += (sender, e) => RefreshPlot(sender, e, filterReference, focusReference);
    refreshTimer.Interval = 2500;
    refreshTimer.Enabled = true;
}

public void RefreshPlot(object source, ElapsedEventArgs e, int filterReference, int focusReference)
{
    var dbObject = new DbConnect();
    dbObject.OpenConnection();
    dbObject.RefreshPlot();
    Dispatcher.Invoke(() =>
    {
        FocusItem(focusReference);
        if (!string.IsNullOrWhiteSpace(FilterTextBox.Text) &&
            (!Regex.IsMatch(FilterTextBox.Text, "[^0-9]")))
        {
            filterReference = Convert.ToInt32(FilterTextBox.Text);
        }
    });
    ResetPlot(filterReference);
}

public void ResetPlot(int filterReference)
{
    var dbObject = new DbConnect();
    dbObject.OpenConnection();

    List<DbConnect.PlotList> plotList = dbObject.SelectPlotLists(filterReference);
    Dispatcher.BeginInvoke(
        new ThreadStart(() => PlotListView.ItemsSource = plotList));
    int jobSum = 0;
    int bidSum = 0;
    foreach (DbConnect.PlotList item in PlotListView.Items)
    {
        jobSum += Convert.ToInt32(item.Jobs);
        bidSum += Convert.ToInt32(item.Bids);
    }

    Dispatcher.BeginInvoke(
        new ThreadStart(() => JobBidRatioTextBlock.Text = jobSum + " jobs - " + bidSum + " bids"));
}

更新2

我还原到我最初使用的代码，可能是FocusItem方法没有保留listview项焦点吗？

private void FocusItem(int focusReference)
{
    Dispatcher.Invoke(() =>
    {
        if (PlotListView.SelectedItems.Count != 0)
        {
            DbConnect.PlotList plotList =
                PlotListView.Items.OfType<DbConnect.PlotList>()
                    .FirstOrDefault(p => Convert.ToInt32(p.PlotId) == focusReference);
            if (plotList != null)
            {
                //get visual container
                var container = PlotListView.ItemContainerGenerator.ContainerFromItem(plotList) as ListViewItem;
                if (container != null)
                {
                    container.IsSelected = true;
                    container.Focus();
                }
            }
        }
    }
}

我根据控制台中写的内容，在正确的位置调用它，索引绝对是正确的。

PlotListView_SelectionChanged 4
Before refresh 4
After refresh 4
PlotListView_SelectionChanged 7
Before refresh 7
After refresh 7

Before refresh 7
After refresh 7

两者都在刷新情节方法......

public void RefreshPlot(object source, ElapsedEventArgs e)
{
    var dbObject = new DbConnect();
    dbObject.OpenConnection();
    dbObject.RefreshPlot();
    Console.WriteLine("\rBefore refresh " + focusReference);
    Dispatcher.Invoke(() =>
    {
        if (!string.IsNullOrWhiteSpace(FilterTextBox.Text) &&
            (!Regex.IsMatch(FilterTextBox.Text, "[^0-9]")))
        {
            filterReference = Convert.ToInt32(FilterTextBox.Text);
        }
    });
    ResetPlot(filterReference);
    Console.WriteLine("After refresh " + focusReference);
    FocusItem(focusReference);
}

重置绘图方法......

public void ResetPlot(int filterReference)
{
    // Establish MySQL connection
    var dbObject = new DbConnect();
    dbObject.OpenConnection();

    // Fill plot list view
    List<DbConnect.PlotList> plotList = dbObject.SelectPlotLists(filterReference);
    Dispatcher.BeginInvoke(
        new ThreadStart(() => PlotListView.ItemsSource = plotList));
    int jobSum = 0;
    int bidSum = 0;
    foreach (DbConnect.PlotList item in PlotListView.Items)
    {
        jobSum += Convert.ToInt32(item.Jobs);
        bidSum += Convert.ToInt32(item.Bids);
    }
    FocusItem(focusReference);

    // Determine job/bid list ratio
    Dispatcher.BeginInvoke(
        new ThreadStart(() => JobBidRatioTextBlock.Text = jobSum + " jobs - " + bidSum + " bids"));
}

Answer 1

在进行刷新之前，您需要记住SelectedItem并在刷新后将其设置为agian。这就是理论。

如果是对象，您需要找到哪个对象现在与之前的对象相同（因为它不再是同一个实例），因此您必须在新结果列表中搜索它并将其分配给SelectedItem。

最简单的方法是重新设置SelectedIndex，但因为列表可能会更改，所以迟早会重新选择错误的项目。

// Gets current selection.
public DbConnect.PlotList SelectedPlotList
{
    get
    {
        return PlotListView.SelectedItem as DbConnect.PlotList;
    }
}
public void ResetPlot(int filterReference)
{
    // Get current plot number;
    int? plotNumber = SelectedPlotList == null ? (int?)null : SelectedPlotList.PlotNumber;

    var dbObject = new DbConnect();
    dbObject.OpenConnection();

    List<DbConnect.PlotList> plotList = dbObject.SelectPlotLists(filterReference);

    // Find the plot list in the new list.  
    DbConnect.PlotList selectPlotList = 
        plotNumber.HasValue
        ? plotList.Where(x => x.PlotNumber == plotNumber.Value).FirstOrDefault();
        : null;
    Dispatcher.BeginInvoke(new ThreadStart(() => PlotListView.ItemsSource = plotList));

    // Re-select plot list if found in the new list.
    if (selectPlotList != null)
    {
        PlotListView.SelectedItem = selectPlotList;
    }
    int jobSum = 0;
    int bidSum = 0;


    foreach (DbConnect.PlotList item in PlotListView.Items)
    {
        jobSum += Convert.ToInt32(item.Jobs);
        bidSum += Convert.ToInt32(item.Bids);
    }

    Dispatcher.BeginInvoke(
        new ThreadStart(() => JobBidRatioTextBlock.Text = jobSum + " jobs - " + bidSum + " bids"));
}

编辑：

我刚刚测试了一个快速＆amp;脏的演示，它的工作原理。其他地方一定有个bug。

这将生成7个具有唯一ID的项目，如果再次绘制，则重新选择最后选择的项目：

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        List<ListViewItem> items = new List<ListViewItem>();
        Random rnd = new Random(DateTime.Now.Millisecond);
        HashSet<int> ids = new HashSet<int>();
        for (int i = 0; i < 7; i++)
        {
            int id = 0;
            do
            {
                id = rnd.Next(0, 10);
            } while (ids.Contains(id));
            ids.Add(id);
            items.Add(new ListViewItem() { Id = id, Name = "Item-" + i });
        }
        int? selectedId = listView1.SelectedItem != null ? (listView1.SelectedItem as ListViewItem).Id : (int?)null;
        listView1.ItemsSource = items;

        if (selectedId.HasValue)
        {
            listView1.SelectedItem = items.Where(x => x.Id == selectedId).FirstOrDefault();
            listView1.Focus();
        }
    }
}

class ListViewItem
{
    public int Id { get; set; }
    public string Name { get; set; }
}

当listview刷新时，焦点不是“持有”

1 个答案: