expandable_plus 1.2.0

expandable_plus: ^1.2.0 copied to clipboard

• ExpandableController.of(required: true) now throws when there is no ExpandableNotifier above it, in every build mode. It used to only assert, and asserts are compiled out of a release build, so a misplaced widget threw during development and then quietly did nothing in the shipped app: an ExpandableButton with a null onTap still looks like a button and ignores every tap, and a panel with no controller renders permanently open. The error names the widget that asked and says what to wrap it in.
• The README opens with what the package is for and answers ExpansionTile and expandable in its first screen, with the source lines and issue numbers behind each claim.

• The example demonstrates lazy. Twenty panels in a list, a switch for the mode, and a counter for how many expanded bodies have been built. It reads zero until you open one, and jumps to fifteen the moment the switch goes off. The feature shipped in 1.1.0 with nothing to look at.

• Add lazy to ExpandablePanel and Expandable. A cross-fade keeps both children in the tree. A collapsed panel builds its expanded body anyway. Twenty collapsed panels in a ListView build fifteen of them on the first frame, one per panel the viewport lays out, which is the shape of the report in expandable#123 that a screen "stops being usable when you have more than 10 expandables". With lazy: true a panel that has never opened builds a zero-size placeholder instead.
• The first expand swaps the real child in and keeps it. Reopening runs no second initState. A body holding scroll position or form input survives a close.
• Off by default, and test/lazy_test.dart asserts that with nothing passed. Turning it on changes when a child's initState runs, which is a decision for the caller rather than something to hand everyone in a minor release.
• Expandable is a StatefulWidget now. Its constructor is unchanged and still const.

First stable release. The API below is what 1.0 freezes.

• Fix allowAllCollapsed: false not holding at the start. The flag documents that the group "always keeps one member expanded", but the group only ever maintained that: _onMemberChanged re-expands the last open member when it closes, and nothing fires it while members are only joining. A group whose members all started collapsed (the ordinary case, since initialExpanded defaults to false) therefore sat at zero expanded indefinitely, the one state the flag exists to forbid. Randomised toggling across 100 groups and 2000 transitions hit it 24 times. Joining a group in that state now expands the first member, which is what an accordion with no explicit initialExpanded should look like. A member that joins already expanded still wins, and allowAllCollapsed: true is unchanged: those groups still start with everything closed.

The mutual-exclusion half of the invariant was already sound: the same 2000 transitions produced no case of two members open at once, in either mode.

• Fix a leak: ExpandableNotifier created its own ExpandableController whenever no controller was passed in, but never disposed it. This is the default path for a bare ExpandablePanel and for the accordion pattern (ExpandableNotifier(group: ...)). In the accordion case the effect went beyond a passive leak: ExpandableGroupController only removes a member from its dispose(), so every panel built and then discarded (a list item removed or filtered, a route popped) left a dead controller permanently registered in the group. ExpandableNotifier now disposes the controller it created for itself and leaves a caller-supplied controller alone, same as before.

• Install instructions now say pub add instead of pinning a version. The pinned number was stale by several releases and would have been stale again after the next one: the README ships frozen in the archive; a hand-edited version line is wrong the moment anything is published. This one cannot go out of date.

• Shorten the screenshot description. pub.dev accepts up to 200 characters but scores only those under 160. The previous release published cleanly and quietly gave up the documentation points it was meant to earn.

• Declare the demo in pubspec.yaml so pub.dev shows it on the package page. The recording was already in the repository and in the README, but pub.dev only renders what the screenshots: field points at. Anyone landing on the page from search saw text where the demo should have been.

• The header is now accessible. ExpandableButton exposes the button role and the panel's expanded state to the semantics tree, so a screen reader announces "collapsed" or "expanded" and announces the change when the user presses it. Before this the header was a bare tap target: no role, no state, and nothing said when it toggled, which left the widget unusable with assistive technology. Every header and header icon goes through ExpandableButton: panels and accordion groups get it with no changes, and the flag follows the controller when the panel is expanded from code.

• Docs: sharpen the pub.dev description to lead with the value and the terms people search.

First release, continuing the expandable package.

• Keeps the public API of expandable 5.0.1. Existing code works after changing the import.
• Accordion groups through ExpandableGroupController for making sibling panels mutually exclusive, with an allowAllCollapsed option to keep one panel open (expandable issue #8).
• headerPadding on ExpandableThemeData to control the space around the header (expandable issue #72).
• Body taps now toggle a standalone ExpandablePanel (expandable issue #50).
• A worked example that compiles and runs (expandable issue #114).