morphnext
Morph into what’s next.
morphnext turns bundled Flutter IconData glyphs into interruptible,
spring-driven vector morphs without requiring per-pair animation assets.
Install
flutter pub add morphnext
Requires Dart >=3.9.0 and Flutter >=3.32.0.
Implicit morph
Change icon; AnimatedMorphIcon starts from the shape currently on screen,
even when a new target interrupts an active transition.
import 'package:flutter/material.dart';
import 'package:morphnext/morphnext.dart';
IconButton(
onPressed: () => setState(() => open = !open),
icon: AnimatedMorphIcon(
icon: open ? Icons.close : Icons.menu,
semanticLabel: open ? 'Close menu' : 'Open menu',
),
)
Use onEnd when the next action must wait for the spring to finish and the
target to settle on its final vector frame.
AnimatedMorphIcon uses MorphSprings.snappy by default. Select
MorphSprings.smooth for a critically damped transition, or pass Flutter's
SpringDescription directly for custom physics.
The widgets accept the same visual font controls as Flutter's Icon:
fill, weight, grade, opticalSize, shadows, blendMode, and
fontWeight. Values not supplied directly are inherited from IconTheme.
Controlled morph
Use any Animation<double> for gestures, scrolling, or a timeline. Progress is
clamped to 0–1.
MorphIcon(
from: Icons.favorite_border,
to: Icons.favorite,
progress: controller,
size: 32,
color: Colors.red,
semanticLabel: 'Favorite',
)
Font compatibility
There is no fontAsset argument. IconData identifies a code point, font
family, package, and fallback families—not an asset path. morphnext uses those
fields and Flutter's font manifest to resolve fonts bundled through
pubspec.yaml.
If a font is loaded only at runtime, missing, malformed, or unsupported,
morphnext preserves the widget layout and displays regular Flutter icons
instead. The UI remains usable, but that transition is not a continuous vector
morph.
Flutter conventions
size, color, opacity, variable axes, shadows, optional text scaling, and
directionality follow IconTheme, MediaQuery, and Directionality like
Flutter's Icon.
matchTextDirection is honored in RTL layouts. Set semanticLabel for one
semantic image node; leave it null for a decorative icon. When
MediaQuery.disableAnimations is true, AnimatedMorphIcon settles immediately.
Fonts and morph plans are loaded lazily and cached with bounded memory use.
Animation repaints directly without rebuilding the widget on every frame.
The application-wide morph cache has limits similar to Flutter's image cache.
It is shared by morphnext widgets in the current Dart isolate. The defaults
work without configuration. Applications that need explicit limits can set
both before runApp:
MorphCache.configure(
maxMorphs: 100,
maxBytes: 16 * 1024 * 1024,
);
maxMorphs counts completed morphs retained for reuse. A → B and B → A, LTR and RTL, and different font parameters are separate morphs. One-off
morphs from an interrupted intermediate shape are not retained. A morph larger
than maxBytes is still built and used by the current animation, but it is not
cached and does not evict existing entries.
currentMorphs and currentBytes expose the current cache statistics. Pending
morphs are not counted. currentBytes is the size of vector buffers owned by
retained morphs; it excludes decoded fonts, sampled source shapes, Dart object
overhead, and memory owned by Flutter. Use MorphCache.clear() to empty the
cache, MorphCache.disable() to empty and disable it, and MorphCache.reset()
to restore defaultMaxMorphs and defaultMaxBytes. configure throws
ArgumentError unless both limits are positive.
Limitations
morphnext preserves filled contour topology and keeps holes open, but arbitrary
icon pairs can still produce an artistically surprising intermediate shape.
The renderer is monochrome and accepts bundled font-backed IconData; it does
not morph arbitrary Flutter Path objects or SVG artwork.
Examples
example/example.dart is the compact pub.dev example. The app in
example/lib/main.dart powers the GitHub Pages showcase and interactive
playground.
License and attribution
morphnext is MIT licensed. Parts of its geometry behavior are adapted from
MIT-licensed Morphicons, and its font reader is derived from the MIT-licensed
icon_font_generator; exact revisions and notices are in
THIRD_PARTY_NOTICES.md.
This is an independent project. It is not affiliated with or endorsed by the
Flutter project or the Morphicons project.
morphnext 是一个 Flutter 库，把内置的 IconData 字形变成图标之间可中断的、弹簧驱动的矢量变形动画，无需为每对图标准备单独的动画资产。