CODEWITHSUNDEEP
winrt-xaml
Simon
Simon

Reputation: 25983

How do I add a click event handler to a TextBox's DeleteButton?

I have a TextBox in one of my Windows Runtime app's Pages. When there is text in the TextBox, it shows a black cross which, when clicked, clears the TextBox. Apparently this is the DeleteButton from the default template, and there are loads of questions on SO about how to remove it. I don't want to remove it, but I do want to add an event handler so I know when it is clicked.

How do I add a click event handler to a TextBox's DeleteButton? I'd prefer an answer that saves me having to make a copy of the template.

Upvotes: 0

Views: 65

Answers (1)

Dani
Dani

Reputation: 1047

<TextBox x:Name="TestTextBox" Loaded="TestTextBox_Loaded" Width="300" Height="100"></TextBox>

The easiest way is to use the VisualTreeHelperExtension from the WinRTXamlToolkit (or as NuGet package).

With the TreeHelper you can easy access the button:

    private void TestTextBox_Loaded(object sender, RoutedEventArgs e)
    {
        var deleteButton = TestTextBox.GetChildByName<Button>("DeleteButton");
        deleteButton.Click += deleteButton_Click;
    }

    void deleteButton_Click(object sender, RoutedEventArgs e)
    {
        throw new NotImplementedException();
    }

I use this function:

    public static T GetChildByName<T>(this DependencyObject parent, string childName) where T : DependencyObject
    {
        // Confirm parent and childName are valid. 
        if (parent == null) { return null; }

        T foundChild = null;

        int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
        for (int i = 0; i < childrenCount; i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(parent, i);
            // If the child is not of the request child type child
            var childType = child as T;
            if (childType == null)
            {
                // recursively drill down the tree
                foundChild = GetChildByName<T>(child, childName);

                // If the child is found, break so we do not overwrite the found child. 
                if (foundChild != null) { break; }
            }
            else if (!string.IsNullOrEmpty(childName))
            {
                var frameworkElement = child as FrameworkElement;
                // If the child's name is set for search
                if (frameworkElement != null && frameworkElement.Name == childName)
                {
                    // if the child's name is of the request name
                    foundChild = (T)child;
                    break;
                }

                // Need this in case the element we want is nested
                // in another element of the same type
                foundChild = GetChildByName<T>(child, childName);
            }
            else
            {
                // child element found.
                foundChild = (T)child;
                break;
            }
        }
        return foundChild;
    }

Upvotes: 1

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