Flipboard/bottomsheet

Add option to keep state between sheet displays

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#92 opened on Dec 2, 2015

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enhancementhelp wanted

Description

Due to the asynchronous handling when dismissing/showing the view it is impossible to have listeners set after re-showing.

First time:

  • add state change listener
  • show view -> listener gets called

Second time:

  • add listener
  • show view (it is already showing) -> calls dismiss and returns
  • gets dismissed -> removes all listeners (including new ones)
  • runnable shows view again -> no listeners

Adding the listeners after calling show also doesn't work (because the runnable to show again is asynchronously called from the dismiss animation callback)

My idea would be to store a local copy of the listeners in the dismiss method and clean the global fields. Then from the animation listener:

  • When it wasn't cancelled call the local listeners.
  • If it was cancelled put the local listeners back into the global fields. (To remain the state before the dismiss)

Contributor guide

Tech stack
javaandroid
Domain
mobile
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Android development basicsunderstanding of listener patterns
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Examine the BottomSheet implementation in the repository to understand how listeners are managed. The issue describes a problem with listeners being removed on dismiss, and proposes storing a local copy during dismissal. Look at the dismiss method and animation callback to identify where listeners are cleared. Comments indicate the proposed solution should work, but care is needed to handle cancellation cases. No linked PRs or recent activity; the fix is self contained.