[Android] Calling Focus on all Pickers running an API 28 devices no longer opens Picker

[varyamereon]

Description

When using API Level 28, calling Focus on a DatePicker with Visible set to false does not show the date picker dialog.

Prior to this PR https://github.com/xamarin/Xamarin.Forms/pull/4344/files#diff-446294d29d78ca8d84e4c0ddc20bbc07L132 the Picker was opened as part of the FocusRequestedEvent. PR #4344 brought DatePicker inline with the other pickers by changing it to trigger a Click on the control which then would trigger the click listener to open the picker.

On API 28 FocusRequestedEvent is still called so there is still an opportunity to react to this. The difference on API 28 is that the Focus request fails so the Click Listener never actually fires.

Possible fix ideas

• force it to focus anyway. Maybe this is a bad idea? On iOS if the control isn't visible it's still able to be set as a First Responder so this would bring it inline with iOS
• change all the pickers to open the dialog from the FocusRequestedEvent. If this is done then make sure to test what [Android] fixes Picker list showing up incorrectly when focus is set on other controls #4344 fixed

Steps to Reproduce

1. Add a date picker and a button on a Forms page. Set the visibility of the date picker to false
2. Use the button to call Focus on the date picker.
3. On API 27 and lower the dialog is shown. Not on API 28.

Expected Behavior

DatePicker dialog is shown.

Actual Behavior

Nothing happens.

Basic Information

• Version with issue: 4.0.0.135214-pre4
• Last known good version: Unknown
• IDE: Visual Studio 2019 Windows
• Platform Target Frameworks:
  • Android: API 28
• Android Support Library Version:
• Nuget Packages:
• Affected Devices: Android

Screenshots

n/a

Reproduction Link

Reproduction

[samhouts]

@PureWeen Are you looking at this one?

[PureWeen]

@varyamereon
I couldn't get your sample to run.

I've attached a quick sample based on the one you linked that works for me.

Can you try it?

DatePickerPopup.zip

[varyamereon]

@PureWeen
Interesting, I have downloaded your sample and find the same problem on my end. Building against API 28 clicking the button will not show the DatePicker, building against API 27 it works. I am running the sample on an Android Emulator running Android Pie.

EDIT
Same happens when applying to a real device running Android Pie.

[NickCullen]

Anyone found a solution to this? Currently experiencing the exact same issue when compiling against Android 28 (Pie).

On devices that are 8.1 and lower (using the same APK built against Android 28), the date time pickers work. Only happens when running on an Android 9.0 device.

[NickCullen]

I just did a bit of testing.

In the start, our xaml looks like this (notice, they start off invisible):

<DatePicker x:Name="accidentDatePicker" Date="{Binding ClaimDate}" IsVisible="False" />
<TimePicker x:Name="accidentTimePicker" Time="{Binding ClaimTime}" IsVisible="False" />

Our code was just calling ".Focus()" on one of these elements (depending on the button you click, of course).

       private void EditDateButton_Clicked(object sender, EventArgs e)
       {
           this.accidentDatePicker.Focus();
       }

If I change my code to the following, the date picker input box appears (we don't want this to happen - all we want to happen is to bring up the date/time picker dialog). BUT along with the input field appearing, the date/timer picker dialog DOES appear.

        private void EditDateButton_Clicked(object sender, EventArgs e)
        {
            accidentDatePicker.IsVisible = true;
            this.accidentDatePicker.Focus();
        }

[filmar25]

The picker not working too, not only DatePicker.
The solution .IsVisible = true not working for me.

[PureWeen]

https://developer.android.com/about/versions/pie/android-9.0-changes-28

Views with 0 area (either a width or a height is 0) are no longer focusable.

Pickers probably should have a ShowDialog method instead of just having to go via focus
Either way we'll have to figure out a way to make Focus() work on API 28 to trigger dialoge