Bug 26801 - Implicit global styles partially ignored when using Forms Xaml pages
Summary: Implicit global styles partially ignored when using Forms Xaml pages
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.3.2
Hardware: All All
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2015-02-06 06:05 UTC by mario.rasch.ext
Modified: 2015-02-10 07:03 UTC (History)
4 users (show)

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

Test solution (6.46 MB, application/x-zip-compressed)
2015-02-06 06:07 UTC, mario.rasch.ext

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Description mario.rasch.ext 2015-02-06 06:05:56 UTC
Please see the attached solution.

In App.xaml there are some implicit styles defined for ContentPage and Label types.

There are two options to run the app:

a) Use the conditional compilation symbol "XAML" for the portable project "StyleTest" to run the app using the Forms Xaml Page "StyledPage".

b) Remove the conditional compilation symbol "XAML" to run the app using a ContentPage that is programmatically assigned in App.xaml.cs' constructor.

You will see the following:

when using option a), the implicit background color style for the ContentPage is ignored.
when using option b), the implicit background color style for the ContentPage is respected.

The implicit styles for the Label type are always applied, no matter if using option a) or b).

Please fix so that implicit global styles are completely (i.e. for every supported type) applied when using Forms Xaml Pages.
Comment 1 mario.rasch.ext 2015-02-06 06:07:43 UTC
Created attachment 9682 [details]
Test solution
Comment 2 Udham Singh 2015-02-06 07:18:09 UTC
I have checked this issue with the help of sample app given in comment 1 and the steps provide in bug description, and able to reproduce the reported behaviour. Please refer the screencast : 

Ide Log : https://gist.github.com/Udham1/e7e21bc8c66a089631a2
Simulator Log : https://gist.github.com/Udham1/2c77218b66358386616a

Note : I am getting the same behaviour with both Android and iOS app.

Environment Info : 

Xamarin.Forms :

=== Xamarin Studio ===

Version 5.7.1 (build 17)
Installation UUID: ce927b2a-2c07-44c5-b186-09cfdafba6dc
	Mono 3.12.0 ((detached/a813491)
	GTK+ 2.24.23 (Raleigh theme)

	Package version: 312000068

=== Apple Developer Tools ===

Xcode 6.1.1 (6611)
Build 6A2008a

=== Xamarin.iOS ===

Version: (Business Edition)
Hash: 1ee873c
Build date: 2015-01-31 17:42:21-0500

=== Xamarin.Android ===

Version: (Business Edition)
Android SDK: /Users/xamarin76/Desktop/android-sdk-macosx
	Supported Android versions:
		1.6    (API level 4)
		2.1    (API level 7)
		2.2    (API level 8)
		2.3    (API level 10)
		3.1    (API level 12)
		4.0    (API level 14)
		4.0.3  (API level 15)
		4.1    (API level 16)
		4.2    (API level 17)
		4.3    (API level 18)
		4.4    (API level 19)
		4.4.87 (API level 20)
		5.0    (API level 21)
Java SDK: /usr
java version "1.7.0_65"
Java(TM) SE Runtime Environment (build 1.7.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)

=== Xamarin.Mac ===

Version: (Business Edition)

=== Build Information ===

Release ID: 507010017
Git revision: 0bc7d3550b6b088ac25b08dcf7bbe73bcc8658b3
Build date: 2015-02-03 19:43:29-05
Xamarin addins: f7b7d34419c9ec24501bfa7c658e80a6305613e0

=== Operating System ===

Mac OS X 10.9.5
Darwin Xamarin76s-Mac-mini.local 13.4.0 Darwin Kernel Version 13.4.0
    Sun Aug 17 19:50:11 PDT 2014
    root:xnu-2422.115.4~1/RELEASE_X86_64 x86_64
Comment 3 Udham Singh 2015-02-06 07:42:47 UTC
An update to the above comment : Screencast http://www.screencast.com/t/cLWtToW0
Comment 4 Jason Smith [MSFT] 2015-02-09 19:35:24 UTC
This is how this is supposed to work. The TargetType must exactly match the type of the control you are styling. It does not match subclasses. This is to prevent any kind of surprises for other types/subclasses in your app and third party libraries.
Comment 5 mario.rasch.ext 2015-02-10 07:03:22 UTC
@Jason: so if I got you right, you think it is not possible to declare an implicit BackgroundColor style for a ContentPage, because the BackgroundColor property is declared in VisualElement that's inherited by Page that's inherited by ContentPage?

But if so, why does the Label's implicit BackgroundColor style work?

And why should a subclass be a problem at all, as a subclass is always more concrete than the class it inherits from?

I cannot style the VisualElement's BackgroundColor property as this type is the base type for many subclasses.