Xamarin forms Picker on android change Cancel text

Question

Xamarin.Forms on Android. Clicking picker opens dialog and the negative button has default text of "Cancel". How can I change it?

I looked in open source project of Xamarin and they set the positive button text like this

builder.SetNegativeButton(global::Android.Resource.String.Cancel, (s, a) => ...

This method is private so I cant override the class method.

Neither I can copy paste implementation of this class because its members are private to Xamarn dll-s...

Link to that picker implementation on Xamarin.Forms andoid:

https://github.com/xamarin/Xamarin.Forms/blob/master/Xamarin.Forms.Platform.Android/Renderers/PickerRenderer.cs

And replace the code? and include it in my project instead of xamarin nuget package? — mister_giga
Could you just use your own renderer? Just almost copypaste the implementation from Xamarin and extend it to have a way to change the text. — tjugg
just for changing a string value is never a good idea to reinvent whole bicycle — mister_giga
Well, it's pretty obvious you have two options, either do a PR and wait for it to be accepted to the official repository or then you do your own implementation and use it? — tjugg

Eren Shen Eren Shen · Accepted Answer · 2017-11-07T07:12:24

Xamarin forms Picker on android change Cancel text

As an alternative choice, you could rewrite the whole dialog in your PickerRenderer :

public class MyPickerRenderer : Xamarin.Forms.Platform.Android.PickerRenderer
{
    private IElementController ElementController => Element as IElementController;
    private AlertDialog _dialog;

    protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
    {
        base.OnElementChanged(e);

        if (e.NewElement == null || e.OldElement != null)
            return;

        Control.Click += Control_Click;
    }

    protected override void Dispose(bool disposing)
    {
        Control.Click -= Control_Click;
        base.Dispose(disposing);
    }

    private void Control_Click(object sender, EventArgs e)
    {
        Picker model = Element;

        var picker = new NumberPicker(Context);
        if (model.Items != null && model.Items.Any())
        {
            picker.MaxValue = model.Items.Count - 1;
            picker.MinValue = 0;
            picker.SetDisplayedValues(model.Items.ToArray());
            picker.WrapSelectorWheel = false;
            picker.DescendantFocusability = DescendantFocusability.BlockDescendants;
            picker.Value = model.SelectedIndex;
        }

        var layout = new LinearLayout(Context) { Orientation = Orientation.Vertical };
        layout.AddView(picker);

        ElementController.SetValueFromRenderer(VisualElement.IsFocusedProperty, true);

        var builder = new AlertDialog.Builder(Context);
        builder.SetView(layout);
        builder.SetTitle(model.Title ?? "");
        builder.SetNegativeButton("Cancel =-= ", (s, a) =>
        {
            ElementController.SetValueFromRenderer(VisualElement.IsFocusedProperty, false);
            // It is possible for the Content of the Page to be changed when Focus is changed.
            // In this case, we'll lose our Control.
            Control?.ClearFocus();
            _dialog = null;
        });
        builder.SetPositiveButton("Ok 0.0", (s, a) =>
        {
            ElementController.SetValueFromRenderer(Picker.SelectedIndexProperty, picker.Value);
            // It is possible for the Content of the Page to be changed on SelectedIndexChanged.
            // In this case, the Element & Control will no longer exist.
            if (Element != null)
            {
                if (model.Items.Count > 0 && Element.SelectedIndex >= 0)
                    Control.Text = model.Items[Element.SelectedIndex];
                ElementController.SetValueFromRenderer(VisualElement.IsFocusedProperty, false);
                // It is also possible for the Content of the Page to be changed when Focus is changed.
                // In this case, we'll lose our Control.
                Control?.ClearFocus();
            }
            _dialog = null;
        });

        _dialog = builder.Create();
        _dialog.DismissEvent += (ssender, args) =>
        {
            ElementController?.SetValueFromRenderer(VisualElement.IsFocusedProperty, false);
        };
        _dialog.Show();
    }
}

Effect.

Xamarin forms Picker on android change Cancel text

2 Answers