Modal Page does not have transparent background when root page is NavigationPage

[dinesh4official]

Description

In the Xamarin.Forms v4,6, I've tried to push the Modal page whose root page is a NavigationPage. But the output shows the white background. I've tried with all enum ModalPresentationStyle but no result.

ios:Page.ModalPresentationStyle="OverFullScreen"

Navigation.PushModalAsync(new NavigationPage(new TransparentPage());

Steps to Reproduce

Step 1 : Run the application in iOS platform and select the TabbedPage Translucent TabBar item. It will navigate to TabbedPage.
Step 2 : . Select the Return to Platform-Specifics List button in the view. It will push a new Modal page.
Issue : You can see the except the content and background color is turned to Black as like below pic.

Expected Behavior

• Modal page should be transparent when root is NavigationPage.

Actual Behavior

• Modal page renders with white background when root is NavigationPage.

Basic Information

• Version with issue: v4.6.0.800
• Last known good version: NA

Screenshots

Reproduction Link

TransparentPageIssue.zip

[dinesh4official]

@samhouts , as a work around, i achieved through renderers.

[jsuarezruiz]

@dinesh4official I have created a small sample where working fine.

Attached sample:
Issue10861.zip

Could you take a look to the sample?. Let me know if I can help you with something.

[dinesh4official]

@jsuarezruiz , thanks.

Please change the Existing line as like Modified line below, you can replicate the issue in your sample.

Existing Line :
Navigation.PushModalAsync(new ModalPage(), true);

Modified Line :
Navigation.PushModalAsync(new Xamarin.Forms.NavigationPage(new ModalPage()), true);

This is due to while parent page of ModalPage is NavigationPage, its ModalPresentationStyle is not updated in Xamarin Forms Source. Only ModalPage's subview
ModalPresentationStyle is updated in ModalwrapperController. Through custom render's I've achieved as like below code example,

`public override void DidMoveToParentViewController(UIViewController parent)
{
base.DidMoveToParentViewController(parent);

        if (ParentViewController != null && TransitionNavigationPage.NeedTransparentPage)
            ParentViewController.ModalPresentationStyle = UIModalPresentationStyle.OverCurrentContext;

}`

Like I've exposed a property in the custom Navigation page to decide whether the page need to be transparent and based on that I've updated.

[jsuarezruiz]

@dinesh4official Thanks for the detailed feedback.