xamarin/Xamarin.Forms

[Bug] Label TextColor DynamicResource does not update after DataTrigger applies TextColor

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#6,864 opened on Jul 13, 2019

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Description

Description

@PureWeen - We discussed this issue today at XamDevSummit and as you requested, I reduced it down to a more manageable code example.

I have a Label with TextColor set to a DynamicResource themeTextColor. I also have a DataTrigger added to the Label that will change the TextColor to Red. Switching between my Default and Dark theme works until I enter the condition specified by the DataTrigger. Afterwards, Switching between Default and Dark has no effect.

In my particular case, I am looking up the Color resource in the ResourceDictionary by key and changing the value. This is opposed to replacing the entire ResourceDictionary.

Steps to Reproduce

(see example project)

  1. Switch between Default and Dark a couple of times
  2. Observe DynamicResources DO update
  3. Switch "Triggered" on and off
  4. Attempt to Switch theme
  5. Observe Label TextColor doesn't change

Expected Behavior

Label updates TextColor to theme's themeTextColor

Actual Behavior

Label is stuck on themeTextColor when triggered

Repro Project Link

https://github.com/ChaseMarsh/My.Xamarin.Issues/tree/master/DynamicResouceTriggerIssue

Contributor guide

Research direction
Investigate how DynamicResource and DataTrigger interact when both set the same property (TextColor). Trace the property system to see why the DynamicResource stops updating after the DataTrigger is applied and then removed. Check if the trigger leaves a local value that overrides the dynamic resource.
Tech stack
csharp
Domain
frontendmobile
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
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
Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75