Apply fading effect on DetailPage for MasterDetailPage on iOS

[akamud]

Description of Change

Something that bugs me is the fact that iOS's MasterDetailPage doesn't fade the Detail page when opening the Menu. This leads to a bad UX, since both the menu and the detail are shown at the same z-axis level, with no "background feel" applied to the Detail page.
Android's implementation doesn't suffer from this, neither does iOS Shell implementation.

Once I noticed Shell "fixed" this behavior, I wanted to do the same for the MasterDetailPage on Xamarin.Forms for iOS.

So this PR pretty much uses the same logic used in iOS Shell to fade the Detail page when MasterDetail menu is opened.

Platforms Affected

• iOS

Behavioral/Visual Changes

The visual rendering for MasterDetailPage would change for every Xamarin.Forms application.

I have 2 specific points that I would like to get a review:

• Since this would be a visual breaking change, maybe we could hide this behind a PlatformSpecific?
• If no background color is provided for the detail page, a white background is used, this gives the impression that the detail page is clearing instead of going to the background. Because of this I am forcing a "black fade", this could cause problems if someone is changing the background color of the Detail page for some reason. Should we suggest on documentation that people can put a black background color if they want this behavior? Maybe we can expose a way of customizing this specific color with another property?

Before/After Screenshots

Before

After

Testing Procedure

Open any MasterDetailPage (like the ControlGallery) and play with the Menu.

Not sure how I could write an automated test for this.

PR Checklist

• Has automated tests
• Rebased on top of the target branch at time of PR
• Changes adhere to coding standard

[VladislavAntonyuk]

I think it should be controlled by flag IsFadingEffectEnabled or we should have a possibility to set Opacity

[rmarinho]

Hi, thanks for your contribution.

This could be an Effect, our a Platform specific property. But never the way it's done in this PR because it's a breaking change for everyone.
Maybe add a PlatformSpecific for this .

[akamud]

Totally agree that this needs a PlatformSpecific because of the breaking change. I had an implementation using an effect and one using a custom renderer, but I couldn't attach myself in the middle of animations to provide a fluid experience every time, I was stuck with some visual glitches because of that, that's why I decided to send the PR.

I thought Xamarin's team had to define the name of the PlatformSpecific because of the impact of this. Can I just push changes using a name I pick?

[rmarinho]

Yeah sure, naming is hard, we will validade your name makes sense when you do the pr. :)

[rmarinho]

@akamud did you got some time to get this as a PS ?

[akamud]

Sorry for taking so long. I'll work on this over the weekend.

[rmarinho]

ping @akamud :)

[akamud]

I apologize for the delay, I finally had the time to make the changes proposed. Pushed new changes using a Platform specific and added a sample in the MasterDetailPageiOS from the gallery.

[rmarinho]

Works fine, just a little comment.

[akamud]

Is there anything else I must do on this?

[rmarinho]

@akamud needs rebase, it's failing build on OSX

[akamud]

Done.

[akamud]

I see the Windows step is failing. Is there something I should do?

[rmarinho]

@akamud do you mind rebase again, i think it's a issue we found that is nos fixed since i merged the branches up this morning . Sorry

[akamud]

Is this going to be added to the documentation?