Automatically select all text on focus Xamarin

Question

How to automatically select all text on focus in Entry,Editor,Label? Use Cross Platforms.

Quantity.IsFocused = true; 

No work :(

Answer 1

As mentioned in other answers, if you are using Xamarin Forms 4.2+, you can use the CursorPosition and SelectionLength properties. However, you need to make sure you invoke on the Main/UI thread as all direct manipulation of UI elements must be done there. The app will very likely crash when deployed to a device without doing so, even if it appears to run fine in a simulator.

XAML

<Entry x:Name="MyEntry" Focused="MyEntry_Focused"  />

C#

private void MyEntry_Focused(object sender, FocusEventArgs e)
{
    Dispatcher.BeginInvokeOnMainThread(() =>
    {
        MyEntry.CursorPosition = 0;
        MyEntry.SelectionLength = MyEntry.Text != null ? MyEntry.Text.Length : 0
    });
}

For Xamarin.Forms, you can also use Device.BeginInvokeOnMainThread() rather than Dispatcher. If you're using Xamarin Essentials, there is also MainThread.BeginInvokeOnMainThread() (which does the same as Device.BeginInvokeOnMainThread()).

Xamarin.Forms has a method called Device.BeginInvokeOnMainThread(Action) that does the same thing as MainThread.BeginInvokeOnMainThread(Action). While you can use either method in a Xamarin.Forms app, consider whether or not the calling code has any other need for a dependency on Xamarin.Forms. If not, MainThread.BeginInvokeOnMainThread(Action) is likely a better option.

Answer 2

1.Add Focused Event.Cs

protected  void Txt_Focussed(object sender, FocusEventArgs e)
{
    txt.CursorPosition = 0;
    txt.SelectionLength = txt.Text.Length;
}

Set focus

protected override void OnAppearing()
{
    base.OnAppearing();
    txt.Focus();
}

XAML Code

<Entry x:Name="txt" Text="155134343" Focused="Txt_Focussed" />

Answer 3

In MainActivity add

public class MyEntryRenderer : EntryRenderer
{
    public MyEntryRenderer(Context ctx) : base(ctx) {}
    protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
    {
        base.OnElementChanged(e);
        if (e.OldElement == null)
        {
            var nativeEditText = (EditText)Control;
            nativeEditText.SetSelectAllOnFocus(true);
        }
    }
}

and to the top add :

[assembly: ExportRenderer (typeof (Entry), typeof (MyEntryRenderer))]

Answer 4

In my case, to make work @SAIJAN KP answer, i made the Focused handler async and awaited a small delay to wait the cursor to appear on Entry:

    private async void Entry_Focused(object sender, FocusEventArgs e)
    {
        await Task.Delay(100);
        entryTest.CursorPosition = x;
        entryTest.SelectionLength = y;
    }

XAML

<Entry x:Name="entryTest" Text="155134343" Focused="Entry_Focused"  />

Answer 5

@kiddailey posted a nice solution, here is a reusable solution based on that:

1. Create behavior in code behind

   public class SelectContentWhenFocusedBehavior : Behavior<Entry>
   {
       protected override void OnAttachedTo(Entry entry)
       {
           entry.Focused += OnFocused;
           base.OnAttachedTo(entry);
       }
   
       protected override void OnDetachingFrom(Entry entry)
       {
           entry.Focused -= OnFocused;
           base.OnDetachingFrom(entry);
       }
   
       private static void OnFocused(object sender, FocusEventArgs args)
       {
           Device.BeginInvokeOnMainThread(() =>
           {
               Entry myEntry = sender as Entry;
               myEntry.CursorPosition = 0;
               myEntry.SelectionLength = myEntry.Text != null ? myEntry.Text.Length : 0;
           });
       }
   }
   

2. in your view add the link to the behavior namespace

    xmlns:behav="clr-namespace:MyApp.Resources.Behaviors"
   

3. Add behavior to your Entry in the view

           <Entry Text="{Binding something, Mode=TwoWay}" Keyboard="Numeric">
               <Entry.Behaviors>
                   <behav:SelectContentWhenFocusedBehavior/>
               </Entry.Behaviors>
           </Entry>
   

Answer 6

The UWP custom entry renderer could be...

using System.ComponentModel;

using Xamarin.Forms;
using Xamarin.Forms.Platform.UWP;

[assembly: ExportRenderer(typeof(Entry), typeof(myApp.UWP.ExtendedEntryRenderer))]
namespace myApp.UWP
{
    public class ExtendedEntryRenderer : EntryRenderer
    {
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);

            if (e.PropertyName == nameof(Entry.IsFocused)
                && Control != null && Control.FocusState != Windows.UI.Xaml.FocusState.Unfocused)
                Control.SelectAll();
        }
    }
}