☂️ Rework Slider & RangeSlider widgets

[rydmike]

☂️ Umbrella of Slider and RangeSlider issues

Rework the Slider & RangeSlider widgets to address most if not all issues listed below.

---

Slider

Callback issues

• RangeSlider onChangeEnd method called twice when used in a showModalBottomSheet #128433
• Slider onChangeEnd is never called when arrow keys are used. #123315
• Sliders can be changed accidentally by swiping up/down to scroll the page #120596
• Slider::onChanged fires twice after window is resized horizontally. #112290
• Slider skip some onChange on divisions when fast movement #74312
• Sliders Number Problem #66341
• Slider label clips the screen #63293

Value indicator

• Slider label never goes away when clicking slider to new value #123313
• Slider label shape has poor looks with transparency #122793
• Slider does not show value indicator when focused. #113538
• Flutter Slider Label showing strange numbers #73787
• Discrete Slider/RangeSlider has interpolation (?) errors #39510

Thumb

• [Proposal] Allow default Slider thumb shape to be easily customizable  #113781
• [Slider] Thumb's center doesn't align with division's center #62567

Performance

• Slider relies on brittle paint order to work properly #98770
• Slider has a slight a lag when drag #51715

Slider error issues

• Slider in Draggable.feedback does not work as expected and throws an error LeaderLayer anchor must come before FollowerLayer in paint order, but the reverse was true.  #97292

New feature and Proposals

• Support for range value to be from anywhere in the Slider widget, separate from min/max value #63330
• [Material] Update hover + focused + pressed states for mouse on Slider and Range Slider #62214
• Flutter slider should have the feature to show value indicator all the time, not just while gesturing #34704
• Touch up/down status for slider.dart #32768

Accessibility

• Slider and RangeSlider thumb accessibility issues #114225

Documentation

• Slider.label documentation should be clearer about behavior with continuous sliders #74098

Tests

• [web][tests] Re-enable Slider tests #34251

RangeSlider

Value indicator

• RangeSlider labels for value change overlaps #76466

New features and Proposals

• Current values are missing from RangeSliderThumbShape paint() method #62486
• [Material] Add focus state, highlight state, and keyboard shortcuts to RangeSlider #53958
• [Material] Create a MaterialTapTargetSize for slider and consume in Range Slider #33795
• RangeSlider should have an option to include a current value indicator #126746

Functionality

• A discrete RangeSlider is not draggable inside a ListView. #51620
• [RangeSlider] [Flutter 3.10] LateInitializationError: Field '_startThumbCenter@280317193' has not been initialized. #126648

Accessibility

• [Android Web] TalkBack does not read out value changes on increase/decrease. Ex: RangeSlider #32229

Slider Updates Project

https://github.com/orgs/flutter/projects/44/views/2

[TahaTesser]

A simple umbrella issue is effective and feels helpful in this case, since there are a large number of open issues related to sliders.

Agree! Thank you for creating this.

Edit:

I've removed the CupertinoSlider as it is not part of material and is very different in scope as well.

[rydmike]

Sure and agreed @TahaTesser. There were not so many of them anyway. While collectiong the list, I did notice that some of the issues did seem to have some overlap between Slider/RangeSlider and CupertinoSlider as well, but not many.

By the way, the CupertinoSlider has one of the features requested for Slider (#113370) out of the box. It actually only has the mode where you always have to slide the thumb, you can not click on the track to move the thumb. In some use cases I stoped using platform adaptive Slider.adaptive, as I did not like that for the use cases in question, even on iOS. I do agree with the feature request though, for some use cases it can be the other way around, that it is a requirement to have that behavior, then currently Slider is not a suitable.

---

Edit:
Confirmed the CupertinoSlider behavior, previous entry said it was just based on memory and that I was not 100% sure it behaved that way. Now verified this by testing it in repos where I still use Slider.adaptive.

[stuartmorgan]

A simple umbrella issue is effective and feels helpful in this case, since there are a large number of open issues related to sliders.

This seems like it should be a label or project.

Our guidelines for issues are that they must be actionable, which means we should be able to describe the conditions under which the issue would be closed. What is that condition here?

[TahaTesser]

A simple umbrella issue is effective and feels helpful in this case, since there are a large number of open issues related to sliders.

This seems like it should be a label or project.

Our guidelines for issues are that they must be actionable, which means we should be able to describe the conditions under which the issue would be closed. What is that condition here?

I'm doing a major rework on these two widgets under https://github.com/orgs/flutter/projects/44/views/2.
Perhaps a better title would be needed?

[stuartmorgan]

So the goal of the project is to fix every issue on this list? It's a much longer list than the project you linked to currently has.

It would help if the issue were updated to explain what the end state is; right now the text sounds like it's describing a list of every issue in a category rather than a work list for a bounded project.

[TahaTesser]

So the goal of the project is to fix every issue on this list? It's a much longer list than the project you linked to currently has.

It would help if the issue were updated to explain what the end state is; right now the text sounds like it's describing a list of every issue in a category rather than a work list for a bounded project.

Updated description to cover areas of the widgets to be fixed and removed some out of scope engine related issues.

[rydmike]

Thanks @TahaTesser, great improvements and clarifications to the collection.

I originally added this collection issue so I could figure what issues related to Slider and RangeSlider were already known, to be able to figure out if I should add new ones or not, for all the issues I had recorded as well. I found most of them pre-existing after I collected this list, I then added more input on some of the original issues.

I also found it helpful to be able to refer FlexColorScheme and Themes Playground users to a single collection, basically to inform them that for any Slider and RangeSlider related issues, please see this collection first.

I also knew about your Slider project, that you linked above, and thought it could be useful to have a list like this, just to double check if there might be some more issues related to the project, that might be suitable to address during it. Which I can see has been done as well. Excellent and thanks again 👍🏻

[dleyba042]

@TahaTesser thanks for the reply. One quick question. I am part of a team in college trying to make some open source contributions. We were all going to try to contribute under this Umbrella issues since the issues are related and we could be working in the same area. Do you recommend us all to look elsewhere? Thanks for your time.

[Piinks]

Hey @dleyba042 I am glad to hear about your group wanting to contribute! I would recommend starting with our contributing guide, it leads to other pages in the wiki with guidance on finding something to work on.
If you and the others would like to join the discord (instructions also in the wiki) and discuss some issues, feel free to ping me (same user name). :)

[TahaTesser]

@dleyba042
Hi! Thanks for reaching out.

I am part of a team in college trying to make some open source contributions.

That sounds wonderful, I'd recommend taking a look at issues with good first contribution and easy fix labels.
https://github.com/flutter/flutter/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+contribution%22
https://github.com/flutter/flutter/issues?q=is%3Aopen+is%3Aissue+label%3A%22easy+fix%22

Any issues with documentation labels are also great to get started.
https://github.com/flutter/flutter/issues?q=is%3Aopen+is%3Aissue+label%3Adocumentation
https://github.com/flutter/flutter/issues?q=is%3Aopen+is%3Aissue+label%3A%22d%3A+api+docs%22

[dleyba042]

@Piinks Thanks for the info, I will pass that on, and I appreciate the offer for guidance on Discord!

[dleyba042]

@TahaTesser thanks for your guidance, I appreciate it!

[hit-flutter]

Hello team,

Any update on this?
Some of these issues are very important to fix as they are basic functionality for the UI framework.