[Core] Shapes not rendering changing Shell tabs

[jsuarezruiz]

Description of Change

Shapes not rendering changing Shell tabs.

Issues Resolved

• fixes [Bug] Shapes not loading in Xamarin ShellContent Tab once it is navigated back from other Tab #11924
• fixes [Bug] Android Shapes drawing Line disappears on page pop and returning back to the page won't draw again #11656
• fixes [Bug] Path not rendered on page reload #12844

API Changes

None

Platforms Affected

• Core/XAML (all platforms)

Behavioral/Visual Changes

None

Before/After Screenshots

Testing Procedure

Launch Core Gallery and navigate to the issue 11924. Navigate to the second Tab and then navigate back to the first tab, and verify if the Ellipse is rendering.

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[martinkabraham]

@jsuarezruiz .Tried with Nuget 4.8.0.1269 pre-release in Xamarin Shell. Not Working while Tab is selected from second time. First time it is working.

Below shape I placed in second tab ShapePage when I navigate to AboutPage and again back to ShapePage ellipse not rendering.

<FlyoutItem FlyoutDisplayOptions="AsMultipleItems"> <ShellContent Title="About" Icon="tab_about.png" Route="AboutPage" ContentTemplate="{DataTemplate local:AboutPage}" /> <ShellContent Title="Browse" Icon="tab_feed.png" ContentTemplate="{DataTemplate local:ShapePage}" /> </FlyoutItem>

<Ellipse Fill="DarkBlue" Stroke="Red" StrokeThickness="4" WidthRequest="150" HeightRequest="50" HorizontalOptions="Start" />

[martinkabraham]

[jsuarezruiz]

Thanks for the feedback @martinkabraham. Will do more tests. Testing with https://github.com/xamarin/Xamarin.Forms/blob/34bbf5d6fbf920a16717686766f220e13348cf0b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue11924.cs the Ellipse is always rendering (I did the change of tabs more than 10 times).

[Cfun1]

There is a case where it is still happening, the case where you have 3 pages inside a Tab with condition that the shapes are contained in Page3:

Steps to reproduce:

1- Define the below Shell pages structure.
2- Navigate from Page1 to Page3.
3- Navigate to Page1 then come back to Page3

Version with issue: 5.0.0-pre4

  <FlyoutItem FlyoutDisplayOptions="AsMultipleItems">
        <Tab Title="Tab1">
            <ShellContent Title="Page1"
                          ContentTemplate="{DataTemplate local:Parent}"/>

            <ShellContent Title="Page2"
                          ContentTemplate="{DataTemplate local:Page2}"/>

            <ShellContent Title="Page3"
                          ContentTemplate="{DataTemplate local:Page3}"/> <!-- Contains shapes -->
        </Tab>
    </FlyoutItem>

[jsuarezruiz]

I'm going to close this PR because this fix is now in #13284