c# - WPF C# - DataGrid 在用户按键上选择项目

Question

我创建了这个函数来在用户按键时选择 DataGrid 上的项目。如果用户键是“A”，它将选择用户名以字母“A”开头的第一项。如果用户 key 再次为“A”，它将选择用户名以字母“A”开头的下一个项目，依此类推。该功能效果很好，但我想要的是当不再有用户名以“A”开头的项目重新开始时(选择第一个项目)，它目前保留在用户名以字母“A”开头的最后一个项目上。

private static Key lastKey;
private static int lastFoundIndex = 0;

public static void AccountsDataGrid_SearchByKey(object sender, KeyEventArgs e)
{
    DataGrid dataGrid = sender as DataGrid;

    if ((dataGrid.Items.Count == 0) && !(e.Key >= Key.A && e.Key <= Key.Z))
    {
        return;
    }

    if ((lastKey != e.Key) || (lastFoundIndex == dataGrid.Items.Count - 1))
    {
        lastFoundIndex = 0;
    }

    for (int i = lastFoundIndex; i < dataGrid.Items.Count; i++)
    {
        if (dataGrid.SelectedIndex == i)
        {
            continue;
        }

        Account account = dataGrid.Items[i] as Account;

        if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
        {
            dataGrid.ScrollIntoView(account);
            dataGrid.SelectedItem = account;

            lastFoundIndex = i;

            break;
        }
    }

    lastKey = e.Key;
}

更新(带解决方案):

受 Danielle 想法的启发，我更改了如下代码，效果非常好。

private static Key lastKey;
private static int lastFoundIndex = 0;

public static void AccountsDataGrid_SearchByKey(object sender, KeyEventArgs e)
{
    DataGrid dataGrid = sender as DataGrid;

    if ((dataGrid.Items.Count == 0) && !(e.Key >= Key.A && e.Key <= Key.Z))
    {
        return;
    }

    if ((lastKey != e.Key) || (lastFoundIndex == dataGrid.Items.Count - 1))
    {
        lastFoundIndex = 0;
    }

    Func<object, bool> itemCompareMethod = (item) =>
    {
        Account account = item as Account;

        if (account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.CurrentCulture))
        {
            return true;
        }

        return false;
    };

    lastFoundIndex = FindDataGridRecordWithinRange(dataGrid, lastFoundIndex, dataGrid.Items.Count, itemCompareMethod);

    if (lastFoundIndex == -1)
    {
        lastFoundIndex = FindDataGridRecordWithinRange(dataGrid, 0, dataGrid.Items.Count, itemCompareMethod);
    }

    if (lastFoundIndex != -1)
    {
        dataGrid.ScrollIntoView(dataGrid.Items[lastFoundIndex]);
        dataGrid.SelectedIndex = lastFoundIndex;
    }

    if (lastFoundIndex == -1)
    {
        lastFoundIndex = 0;
        dataGrid.SelectedItem = null;
    }

    lastKey = e.Key;
}

private static int FindDataGridRecordWithinRange(DataGrid dataGrid, int min, int max, Func<object, bool> itemCompareMethod)
{
    for (int i = min; i < max; i++)
    {
        if (dataGrid.SelectedIndex == i)
        {
            continue;
        }

        if (itemCompareMethod(dataGrid.Items[i]))
        {
            return i;
        }
    }

    return -1;
}

Answer 1

您最终采用的解决方案过于复杂，并且会检查不需要检查的行。也不需要维护状态的两个静态变量。试试这个:

    public void MainGrid_SearchByKey(object sender, KeyEventArgs e)
    {
        DataGrid dataGrid = sender as DataGrid;
        if (dataGrid.Items.Count == 0 || e.Key < Key.A || e.Key > Key.Z)
        {
            return;
        }

        Func<object, bool> doesItemStartWithChar = (item) =>
        {
            Account account = item as Account;
            return account.Username.StartsWith(e.Key.ToString(), true, CultureInfo.InvariantCulture);
        };

        int currentIndex = dataGrid.SelectedIndex;
        int foundIndex = currentIndex;

        // Search in following rows
        foundIndex = FindMatchingItemInRange(dataGrid, currentIndex, dataGrid.Items.Count - 1, doesItemStartWithChar);

        // If not found, search again in the previous rows
        if (foundIndex == -1)
        {
            foundIndex = FindMatchingItemInRange(dataGrid, 0, currentIndex - 1, doesItemStartWithChar);
        }

        if (foundIndex > -1) // Found
        {
            dataGrid.ScrollIntoView(dataGrid.Items[foundIndex]);
            dataGrid.SelectedIndex = foundIndex;
        }
    }

    private static int FindMatchingItemInRange(DataGrid dataGrid, int min, int max, Func<object, bool> doesItemStartWithChar)
    {
        for (int i = min; i <= max; i++)
        {
            if (dataGrid.SelectedIndex == i) // Skip the current selection
            {
                continue;
            }

            if (doesItemStartWithChar(dataGrid.Items[i])) // If current item matches the string, return index
            {
                return i;
            }
        }

        return -1;
    }

关于您的评论，只需添加此检查:

        if (Keyboard.Modifiers.HasFlag(ModifierKeys.Control))
        {
            return;
        }