Bug 26856 - DisplayAlert() on Android does not work with physical BACK button
Summary: DisplayAlert() on Android does not work with physical BACK button
Status: RESOLVED FIXED
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.3.3
Hardware: PC Windows
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2015-02-09 04:44 UTC by alemarko
Modified: 2015-02-13 18:41 UTC (History)
5 users (show)

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


Attachments
source code for one ContentPage with one button, example of the bug (771 bytes, text/plain)
2015-02-09 04:44 UTC, alemarko
Details


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Status:
RESOLVED FIXED

Description alemarko 2015-02-09 04:44:07 UTC
Created attachment 9704 [details]
source code for one ContentPage with one button, example of the bug

Sample code:

bool result = await DisplayAlert("Proceed?", "Would you like to proceed?", "Accept", "Cancel");
if (result)
	await DisplayAlert("", "Selected: Accept", "OK");
else
	await DisplayAlert("", "Selected: Cancel", "OK");


Behavior:
If an user taps the "Cancel" button, it works as expected.
But if an user presses the physical BACK button,
the dialog itself disappears, but the code in 'if' statement does not execute 
and the app has no idea that the dialog has been dismissed.



I made a suggestion how to fix it in the forum page: https://forums.xamarin.com/discussion/comment/94987/#Comment_94987


To briefly repeat: implementation in Xamarin.Forms.Platform.Android.AndroidActivity and Xamarin.Forms.Platform.Android.FormsApplicationActivity is missing the event handler for CancelEvent:


 alertDialog.CancelEvent += (o, args) => arguments.SetResult(false);



Current implementation:

MessagingCenter.Subscribe<Page, AlertArguments>((object) this, "Xamarin.SendAlert", (System.Action<Page, AlertArguments>) ((sender, arguments) =>
        {
          AlertDialog alertDialog = new AlertDialog.Builder((Context) this).Create();
          alertDialog.SetTitle(arguments.Title);
          alertDialog.SetMessage(arguments.Message);
          if (arguments.Accept != null)
            alertDialog.SetButton(-1, arguments.Accept, (EventHandler<DialogClickEventArgs>) ((o, args) => arguments.SetResult(true)));
          alertDialog.SetButton(-2, arguments.Cancel, (EventHandler<DialogClickEventArgs>) ((o, args) => arguments.SetResult(false)));
          alertDialog.Show();
        }), (Page) null);
Comment 1 Shruti 2015-02-09 07:18:27 UTC
I have checked this issue and able to reproduce this issue.

When I open the alert box and press the back button I observed that the disappears from the screen.

IDE logs: https://gist.github.com/RamChBachkheti/626c2f8b16f500562e33
Device logs: https://gist.github.com/RamChBachkheti/b0d768b2a8166dbb8ed9

Environment Info:

Xamarin.Forms.1.3.3.6322-pre3

Microsoft Visual Studio Professional 2013
Version 12.0.30723.00 Update 3
Microsoft .NET Framework
Version 4.5.51641

Installed Version: Professional

LightSwitch for Visual Studio 2013   06177-004-0447006-02641
Microsoft LightSwitch for Visual Studio 2013

Team Explorer for Visual Studio 2013   06177-004-0447006-02641
Microsoft Team Explorer for Visual Studio 2013

Visual Basic 2013   06177-004-0447006-02641
Microsoft Visual Basic 2013

Visual C# 2013   06177-004-0447006-02641
Microsoft Visual C# 2013

Visual C++ 2013   06177-004-0447006-02641
Microsoft Visual C++ 2013

Visual F# 2013   06177-004-0447006-02641
Microsoft Visual F# 2013

Visual Studio 2013 Code Analysis Spell Checker   06177-004-0447006-02641
Microsoft® Visual Studio® 2013 Code Analysis Spell Checker

Portions of International CorrectSpell™ spelling correction system © 1993 by Lernout & Hauspie Speech Products N.V. All rights reserved.

The American Heritage® Dictionary of the English Language, Third Edition Copyright © 1992 Houghton Mifflin Company. Electronic version licensed from Lernout & Hauspie Speech Products N.V. All rights reserved.

Windows Phone SDK 8.0 - ENU   06177-004-0447006-02641
Windows Phone SDK 8.0 - ENU

Application Insights Tools for Visual Studio Package   1.0
Application Insights Tools for Visual Studio

ASP.NET and Web Tools   12.3.50717.0
Microsoft Web Developer Tools contains the following components:
Support for creating and opening ASP.NET web projects
Browser Link: A communication channel between Visual Studio and browsers
Editor extensions for HTML, CSS, and JavaScript
Page Inspector: Inspection tool for ASP.NET web projects
Scaffolding: A framework for building and running code generators
Server Explorer extensions for Microsoft Azure Websites
Web publishing: Extensions for publishing ASP.NET web projects to hosting providers, on-premises servers, or Microsoft Azure

ASP.NET Web Frameworks and Tools 2012.2   4.1.21001.0
For additional information, visit http://go.microsoft.com/fwlink/?LinkID=309563

ASP.NET Web Frameworks and Tools 2013   5.2.20703.0
For additional information, visit http://www.asp.net/

Common Azure Tools   1.2
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Microsoft Advertising SDK for Windows Phone   
Microsoft Advertising SDK for Windows Phone
Build 

Microsoft Azure Mobile Services Tools   1.2
Microsoft Azure Mobile Services Tools

NuGet Package Manager   2.8.50926.663
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.

Office Developer Tools for Visual Studio 2013 ENU   12.0.30626
Microsoft Office Developer Tools for Visual Studio 2013 ENU

PowerShell Tools   1.2
Provides file classification services using PowerShell

PreEmptive Analytics Visualizer   1.2
Microsoft Visual Studio extension to visualize aggregated summaries from the PreEmptive Analytics product.

SQL Server Data Tools   12.0.30919.1
Microsoft SQL Server Data Tools

Windows Phone 8.1 SDK Integration   1.0
This package integrates the tools for the Windows Phone 8.1 SDK into the menus and controls of Visual Studio.

Workflow Manager Tools 1.0   1.0
This package contains the necessary Visual Studio integration components for Workflow Manager.

Xamarin   3.9.291.0 (9f3e552)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin.Android   4.20.0.34 (49a04b966feb40dfdba49d57ba16249b66d606a6)
Visual Studio plugin to enable development for Xamarin.Android.

Xamarin.iOS   8.6.1.0 (3b3ef438017c7ecf486defa9e01567a5f2b3cb2a)
Visual Studio extension to enable development for Xamarin.iOS.

Xamarin.iOS Unified Migration   1.0
Automated migration for Xamarin iOS Classic projects to Unified
Comment 2 Mark Fredrickson 2015-02-09 20:26:42 UTC
It should also not allow you to touch outside of it which currently makes it disappear.
Comment 3 Jason Smith [MSFT] 2015-02-13 06:47:44 UTC
Should be fixed in 1.3.4. Touch outside is how android alerts are meant to work, it is equal to the cancel action.
Comment 4 Mark Fredrickson 2015-02-13 18:41:10 UTC
From alemarko comments on the thread:

"This also fixes the touches from the outside of the dialog => now they also behave as the cancel button press. Preventing outside touches altogether can be done, and personally I would like that (though maybe this could be done as a user settable global setting for Android apps based on Xamarin.Forms: developers could enable outside touches if required):

alertDialog.SetCanceledOnTouchOutside(false);"

Any chance you could add this also. Most modal dialogs only allow you to use the buttons and input fields that are presented.