WPF:在输入时将焦点移至 ItemsControl 中的下一项

问题描述

WPF:当用户在 ItemsControl 的文本框内按下 Enter 键时，我想将焦点移到 ItemsControl 中下一个项目中的文本框，或者如果用户在最后一个项目中，则创建一个新的文本框.

WPF: When user presses the enter key while inside a texbox in a ItemsControl, I want to move focus to a textbox in the next item in ItemsControl, or create a new one if user was in the last item.

更清楚:

场景 1

ItemsControl items:
[ textbox in item 1 ] <- user is here
[ textbox in item 2 ]
[ textbox in item 3 ]

按回车后:

[ textbox in item 1 ]
[ textbox in item 2 ] <- user is here
[ textbox in item 3 ]

场景 2

ItemsControl 项:

ItemsControl items:

[ textbox in item 1 ]
[ textbox in item 2 ]
[ textbox in item 3 ] <- user is here

按回车后:

[ textbox in item 1 ]
[ textbox in item 2 ]
[ textbox in item 3 ]
[ textbox in item 4 ] <- user is here

如果有帮助，这里是项目数据模板的代码:

If it helps, here is the code for item data template:

<ItemsControl.ItemTemplate>
    <DataTemplate>
        <Grid Background="White">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="32"/>
            </Grid.ColumnDefinitions>
            <TextBox Text="{Binding Path=PartName, FallbackValue='----',TargetNullValue='----', NotifyOnSourceUpdated=True}" KeyDown="TextBox_KeyDown"/>
            <Button Grid.Column="1" FontSize="10" x:Name="DeletePartButton" Click="DeletePartButton_Click" Height="22">Usuń</Button>
        </Grid>
    </DataTemplate>
</ItemsControl.ItemTemplate>

编辑 2:我使用 ItemsControl 是因为不需要选择功能.

EDIT 2:I use ItemsControl because selecting feature is not wanted.

编辑 3:我找到了部分解决方案.它适用于将焦点移到下一个元素，而不是新元素(这是这里最重要的功能)

EDIT 3:I have found a partial solution. It works for moving a focus to a next element, but not a new one (which is the most important functionality here)

    private void PartNameTextBox_KeyDown(object sender, KeyEventArgs e)
    {
        var box = (TextBox)sender;

        if (e.Key == Key.Enter)
        {
            var part = (PiecePart)box.DataContext;
            int index = part.ParentPiece.Parts.IndexOf(part);
            if (index == part.ParentPiece.PartCount - 1)
            {
                part.ParentPiece.Parts.Add(new PiecePart(GetNewPartName(part.ParentPiece)));
                bool success = PartListBox.ApplyTemplate();
                // try to force wpf to build a visual tree for the new item success = false :(
            }
// throws out of bounds exception if a new item was added (and wasn't added to a visual tree)
            var el = ((UIElement)VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(PartListBox, 0),0),1),0),0),++index),0),0));
            el.Focus();
        }
    }

推荐答案

On PreviewKeyDown of TextBox

On PreviewKeyDown of TextBox

private void TextBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
 if (e.Key == Key.Enter)
  {
   var txt= sender as TextBox;
   var selecteditem=FindParent<ListBoxItem>(txt);
   int index = ListBox.ItemContainerGenerator.IndexFromContainer(selecteditem);
   if(index<ListBox.Items.Count)
    {
    var afterItem=(ListBoxItem)ListBox.ItemContainerGenerator.ContainerFromIndex(index+1);
    TextBox tbFind = GetDescendantByType(afterItem, typeof (TextBox), "TextBox") as TextBox;
    if (tbFind != null)
    {
     FocusHelper.Focus(tbFind);
    }
   }
  }
}

public static Visual GetDescendantByType(Visual element, Type type, string name)
{
 if (element == null) return null;
 if (element.GetType() == type)
 {
  FrameworkElement fe = element as FrameworkElement;
  if (fe != null)
  {
     if (fe.Name == name)
     {
        return fe;
     }
  }
 }
Visual foundElement = null;
if (element is FrameworkElement)
  (element as FrameworkElement).ApplyTemplate();
for (int i = 0;
    i < VisualTreeHelper.GetChildrenCount(element);
    i++)
{
  Visual visual = VisualTreeHelper.GetChild(element, i) as Visual;
  foundElement = GetDescendantByType(visual, type, name);
  if (foundElement != null)
     break;
}
return foundElement;
}

public static T FindParent<T>(DependencyObject child) where T : DependencyObject
{
 //get parent item
DependencyObject parentObject = VisualTreeHelper.GetParent(child);

//we've reached the end of the tree
if (parentObject == null) return null;

//check if the parent matches the type we're looking for
T parent = parentObject as T;
if (parent != null)
    return parent;
else
    return FindParent<T>(parentObject);
}

另外一个用于在 TextBox 上设置焦点的助手:

One more helper to set the Focus on the TextBox:

public static class FocusHelper
{
public static void Focus(UIElement element)
{
 element.Dispatcher.BeginInvoke(DispatcherPriority.Input, new ThreadStart(delegate()
 {
    element.Focus();
 }));
}
}

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