m3e_expandable 0.0.1

A Flutter package providing expressive, Material 3 expandable card lists with spring-driven animations and dynamic border radius.

M3E Expandable

A Flutter package providing expressive, Material 3 expandable card lists with dynamically rounded corners inside normal ListViews and CustomScrollViews (via slivers). Features smooth spring-driven expand/collapse animations with expressive M3 styling.

It automatically calculates and draws the corners to fit exactly the Material 3 Expressive spec for adjacent items. It gives extensive customization options including customizable splash ripples, custom border colors, custom elevation and highly tunable haptic feedback along with stiffness and damping for animations.

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🚀 Features

• Dynamic border radius: The first and last items get a larger outer radius while adjoining cards receive a smaller inner radius seamlessly.
• Sliver & Column Support: Provides Slivers and Column wrappers out of the box to beautifully tie into complex layouts.
• Physics & Animations: Spring-driven physics for expanding and collapsing.
• Highly Customizable: Complete control over gaps, radii, colors, haptics, and padding.

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📦 Installation

dependencies:
  m3e_expandable: ^0.0.1

import 'package:m3e_expandable/m3e_expandable.dart';

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🧩 Usage

Smoothly expand and collapse individual cards using motor spring animations.

🔴 Expandable M3E (Without selectedBorderRadius, allowMultipleExpanded: true)

🔴 Expandable M3E (With selectedBorderRadius, allowMultipleExpanded: true)

Usage:

M3EExpandableCardList(
  itemCount: 10,
  allowMultipleExpanded: true,
  headerBuilder: (context, index, isExpanded) => Text('Header $index'),
  bodyBuilder: (context, index) => Text('Body content for $index'),
)

Constructor Parameters:

Parameter	Type	Default	Description
itemCount	int	Required	Number of expandable items.
headerBuilder	M3EExpandableHeaderBuilder	Required	Builds the always-visible header section.
bodyBuilder	M3EExpandableBodyBuilder	Required	Builds the hidden, expandable body section.
allowMultipleExpanded	bool	false	If true, allows multiple items to be expanded simultaneously.
initiallyExpanded	Set<int>	{}	Indices of initially expanded items.
outerRadius	double	24.0	Outer radius for first/last items.
innerRadius	double	4.0	Inner radius for middle items.
gap	double	3.0	Gap between cards.
color	Color?	surfaceContainerHighest	Background colour for each card.
headerPadding	EdgeInsetsGeometry?	EdgeInsets.all(16)	Padding inside each header.
bodyPadding	EdgeInsetsGeometry?	EdgeInsets.fromLTRB(16,0,16,16)	Padding inside each body.
margin	EdgeInsetsGeometry?	null	Outer margin around each card.
border	BorderSide?	null	Border drawn around each card.
elevation	double	0	Elevation of the card.
selectedBorderRadius	BorderRadius?	null	Custom border radius for expanded items (spring-animated).
showArrow	bool	true	Shows an animated dropdown arrow in the header.
trailingIcon	Widget?	null	Custom trailing widget, replaces default arrow when provided.
openStiffness	double	380	Spring stiffness for the expand animation.
openDamping	double	0.75	Spring damping ratio for the expand animation.
closeStiffness	double	380	Spring stiffness for the collapse animation.
closeDamping	double	0.75	Spring damping ratio for the collapse animation.
haptic	int	0	Haptic feedback level on tap (0=none, 1=light, 2=medium, 3=heavy).
splashColor	Color?	null	Ink splash colour.
highlightColor	Color?	null	Ink highlight colour.
splashFactory	InteractiveInkFeatureFactory?	null	Splash factory.
enableFeedback	bool	true	Whether gestures provide acoustic/haptic feedback.
onExpansionChanged	void Function(int, bool)?	null	Called when an item is expanded or collapsed.

The M3EExpandableCardList variant also accepts controller, physics, shrinkWrap, and padding for scroll control.

Variants Available: SliverM3EExpandableCardList, M3EExpandableCardColumn

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🎯 Check the Example App for more details.

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🐞 Found a bug? or ✨ You have a Feature Request?

Feel free to open a Issue or Contribute to the project.

Hope You Love It!

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Credits

• Motor Pub Package for Expressive Animations
• Claude and Gemini for helping me with the code and documentation.

Radhe Radhe 🙏