yarolegovich/DiscreteScrollView

Dragging more than one page at a time

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#70 opened on Dec 13, 2017

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 (8 comments) (3 reactions) (0 assignees)Java (5,728 stars) (768 forks)batch import
feature requesthelp wanted

Description

It appears that DiscreteScrollLayoutManager.calculateAllowedScrollIn() restricts the amount of pages that may be scrolled in such a way that the user cannot drag beyond one page to the left or right of the current selection.

It would seem to me that by enabling setSlideOnFling(true), the user should be able drag for instance from page 0 to page 3 in a single gesture (without flinging).

What are your thoughts on this? With some debugging I found that perhaps the place to look is either in the aforementioned method, or perhaps after it's invoked in DiscreteScrollLayoutManager.scrollBy()?

Contributor guide

Tech stack
java
Domain
mobile
Issue type
feature
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.
mostly clear
Prerequisites
Android developmentRecyclerView basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate the `DiscreteScrollLayoutManager.calculateAllowedScrollIn()` method to understand how it restricts scrolling to one page. Look at `scrollBy()` to see where the check is applied. Consider modifying the logic to allow multi page drags when `setSlideOnFling(true)` is enabled.