[Android/iOS] support locale LayoutDirection on MasterDetailPage

[paymicro]

Description of Change

Support locale LayoutDirection on MasterDetailPage.

Issues Resolved

• fixes [Android] Right-to-Left MasterDetail in Xamarin.Forms v3 Hamburger icon issue #2818

API Changes

None

Platforms Affected

• All

Behavioral/Visual Changes

Controls of MasterDetalPage shown on the correct side.

Before/After Screenshots

Screencast:
http://recordit.co/nlOXpzGDrU

Android
Before

After

iOS

Before

After

Testing Procedure

Android

• setup RTL locale on device
• run Control gallery
• check hamburger position on MasterDetailPage

iOS

• setup RTL locale on device
• run Control gallery
• tap/click on "Master" title
• check red box position

PR Checklist

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

[rmarinho]

build

[rmarinho]

Can we add iOS screenshots too?

[StephaneDelcroix]

I'm usure about this. do we follow device's RTL setting usually, or do we only follow our own FlowLayout property ?

[paymicro]

do we follow device's RTL setting usually, or do we only follow our own FlowLayout property ?

Apparently we only follow our own FlowLayout property and ignore device RTL...
But root element isn't setted to device RTL if it is implicit

[PureWeen]

@paymicro can you rebase to fix conflict please

[samhouts]

We need to make sure that we keep this statement true:

As with UWP, respecting the device's layout direction based on the selected language/locale is the developer's explicit choice and does not happen automatically. Set the FlowDirection of the root View/Page to the Device.FlowDirection value. All other child views with MatchParent will inherit this value. (#1222)

[rmarinho]

@paymicro can you confirm this only happens if setting the property explicitly like @samhouts said?

[paymicro]

@rmarinho yes. Set FlowDirection works correctly. http://recordit.co/pcNTb0wQnP
This PR is fixes if FlowDirection has not been set or it has been set to MatchParent and it has no parent, then it will be taken from device's layout.

[rmarinho]

"This PR is fixes if FlowDirection has not been set or it has been set"

But I think we should not settle locale if the user didn't specified

[samhouts]

This is not the correct fix. We don't want to use the device locale automatically. We want the user to do that explictly if that is what they want to do. We need to figure out why the hamburger button doesn't respect the FlowDirection property instead of trying to set the FlowDirection property based on the device locale. Thanks!

[candidodmv]

@samhouts I need only the navigation menu of MasterDetail page stay on rightToLeft side, everthing else stay on leftToRight, how can I succed after this update? because when I was targeting to version 3.4 working very well.