Bug 44844 - The RaiseChild() and LowerChild() methods on the Layout class do not correctly change the visual order of native controls
Summary: The RaiseChild() and LowerChild() methods on the Layout class do not correctl...
Status: CONFIRMED
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 2.2.0
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2016-09-28 20:02 UTC by Dan Rigby
Modified: 2016-10-13 21:10 UTC (History)
4 users (show)

Tags: Android ac
Is this bug a regression?: ---
Last known good build:

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Status:
CONFIRMED

Description Dan Rigby 2016-09-28 20:02:47 UTC
Description: The RaiseChild() and LowerChild() methods on the Layout class do not correctly change the visual order of any native controls (either custom renderer or hosted native control) contained within the supplied view on Android.

Expected Behavior: Visual order of native controls should change as a result of these methods calls just as the built in Xamarin.Forms controls do.

Customer has indicated that this behavior is present on versions of Xamarin.Forms ranging from 1.5.0.6447 through 2.2.0.45 and on Android 4.4.2, 5.0, and 5.1. Newer versions of Xamarin.Forms and Android have not been tested.

Customer has created a sample repository demonstrating the behavior on GitHub:
https://github.com/SimplexAuctor/XamarinNativeControlLayering
Comment 1 adrianknight89 2016-10-11 01:48:04 UTC
I don't think the video was provided in that project? I'm getting can't play error.
Comment 2 Dan Rigby 2016-10-13 21:10:01 UTC
Notes from a call with Jason:

In Android, there are two widget orderings: drawing order & layout order.
When Xamarin.Forms rearranges widgets with LowerChild() or RaiseChild(), rather than pulling elements from hierarchy/putting in new location, which triggers relayout/other expensive operations, it just updates the z-index and triggers a redraw.

This doesn't work with hardware accelerated controls such as a video player.
For controls like this, you actually have to remove/re-add the child in order to change the layout order.

Layout order is order that views are added to the screen; Ex. getChildAt(0) gets the first child in layout order.
Add/remove child is the only way to change the layout order.