Bug 60766 - AbsoluteLayout without background captures input on Android
Summary: AbsoluteLayout without background captures input on Android
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: unspecified
Hardware: PC Windows
: --- critical
Target Milestone: ---
Assignee: E.Z. Hart [MSFT]
Depends on:
Reported: 2017-11-20 10:26 UTC by Martin Zikmund
Modified: 2018-02-01 10:49 UTC (History)
5 users (show)

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

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Description Martin Zikmund 2017-11-20 10:26:17 UTC
# Steps to reproduce
1. Create a new Xamarin.Forms solution
2. Change the MainPage.xaml content to:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
            <Button Text="Click me" Clicked="Button_OnClicked" />
            <AbsoluteLayout />
3. Change MainPage.xaml.cs content to:

    public partial class MainPage : ContentPage
        public MainPage()

        private void Button_OnClicked(object sender, EventArgs e)
            ((Button) sender).Text = "Clicked!";

4. Launch the app on Android
5. Try to click the button

# Expected behavior
The button is clicked and its text changes. This behavior works on UWP and iOS.

# Actual behavior
The button cannot be clicked as the `AbsoluteLayout` captures all input.

# Test environment (full version information)
## Xamarin.Forms version

Tested with,

## Visual Studio Version Info

Microsoft Visual Studio Enterprise 2017 
Version 15.4.4
Microsoft .NET Framework
Version 4.7.03016

Installed Version: Enterprise

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JavaScript Language Service   2.0
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JetBrains ReSharper Ultimate 2017.3 EAP 4   Build 111.0.20171102.150351-eap04
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Microsoft Azure HDInsight Azure Node   2.2.9000.1
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Microsoft Azure Hive Query Language Service   2.2.9000.1
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Microsoft Azure Service Fabric Tools for Visual Studio   1.8
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Microsoft Azure Stream Analytics Language Service   2.2.9000.1
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Microsoft Azure Tools   2.9
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Microsoft Continuous Delivery Tools for Visual Studio   0.3
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Open Command Line   2.1.179
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Package Installer   2.0.101
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ZenCoding   1.2.11
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Comment 1 Martin Zikmund 2017-11-20 10:34:50 UTC
A Github repro with the bug https://github.com/MartinZikmund/Xamarin.Forms-Click-Through-Issue
Comment 2 Martin Zikmund 2017-11-20 10:36:30 UTC
I should also note that this worked as expected previously on Android as well, I am not exactly sure which update caused it to not work.
Comment 3 Paul DiPietro [MSFT] 2017-11-20 18:48:14 UTC
I believe that this has to do with some changes which were made to bring the behavior of input into alignment:


The behavior as of the latest 2.5.0 stable build is what is expected.
Comment 4 Martin Zikmund 2017-11-21 12:40:52 UTC
But that is a big breaking change, because many apps depend on this behavior.

In my case I had a AbsoluteLayout above map control where I laid out button controls like zoom etc. But now there is no way to do that. I either have to lay out each control separately but then I can't put them in any common container. If I set InputTransparent on the AbsoluteLayout, I can manipulate the map, but can't interact with the buttons inside AbsoluteLayout. 

Is there a good solution to this? The original behavior was consistent with how XAML on WPF and UWP works.
Comment 5 Martin Zikmund 2017-11-21 17:06:00 UTC
I think this is a step back, and a bigger breaking change than is apparent. The new solution goes a bit against intuitive thinking and also mainly against the default behavior in XAML.

In WPF/UWP having an element without a set Background (e.g. Background="{x:Null}") meant the element itself was passing the interaction events to the content behind it, but its children could still be interacted with. When you however set the Background to Transparent, the input events were now handled.

I think it should be done the same way in Xamarin.Forms. When the BackgroundColor is Clear or Default, it should allow "click-through" to elements underneath. When the color is Transparent, it should handle interactions.

I think this is used in many places, but especially with mapping apps, where you have a map control and controls above it. In my case I have to render controls in a Grid above a custom map and also have a layer where I can display "context menus" when user interacts with the map. I need to be able to interact with context menu as well as with the map at the same time.
Comment 6 Martin Zikmund 2017-11-21 17:08:41 UTC
I have asked the question on StackOverflow as well and it contains a concrete example: 

<CustomMapControl />
<Grid x:Name="ControlsGrid">
      <RowDefinition Height="*" />
      <RowDefinition Height="*" />
   <Button Grid.Row="1" Text="Zoom in" />
<AboluteLayout x:Name="PlaceMenuContainer" />
Comment 8 E.Z. Hart [MSFT] 2018-01-19 21:21:11 UTC
PR: https://github.com/xamarin/Xamarin.Forms/pull/1621
Comment 9 Rui Marinho 2018-02-01 10:49:53 UTC
Should be fixed on 2.6.0-pre1