xamarin/Xamarin.Forms

[UWP] Skipping setting "default values" for element properties in renderers is problematic

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#4,312 opened on Nov 5, 2018

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Description

https://github.com/xamarin/Xamarin.Forms/blob/ee91ac443941133a9163c62787d831ad16aaa156/Xamarin.Forms.Platform.UAP/ButtonRenderer.cs#L58

Is checking of default values really necessary in renderers?:

If ... Element.Padding != Button.PaddingProperty.DefaultValue ... UpdatePadding();

The default padding value for a Xamarin button is (0,0,0,0), while the default padding for a UWP button is (8,4,8,4). (https://msdn.microsoft.com/en-us/library/windows/apps/mt299109.aspx)

This means that if I set padding (0,0,0,0) on a Xamarin button, and I really want it to be (0,0,0,0) on UWP, the renderer will skip setting the padding property. And my UWP button will have a (8,4,8,4) padding, which is not my intent!

Does checking and skipping default property values in renderers have any meaningful purpose? It seems to me that it creates more problems than it solves.

Contributor guide

Research direction
Investigate the renderer code that skips setting default property values, and determine how to ensure that setting a value equal to the default still applies it on UWP.
Tech stack
csharp
Domain
frontend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C#
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75