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Implement AutoSizeGroup #1

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Merged
FaFre merged 2 commits into from
Feb 5, 2026
Merged

Implement AutoSizeGroup #1

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1915a05
Implement AutoSizeGroup
hig-dev Sep 5, 2025
d1af006
Use max font size instead of layout constraints
hig-dev Sep 5, 2025
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23 changes: 22 additions & 1 deletion lib/flutter_auto_size_text.dart
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Original file line number Diff line number Diff line change
@@ -1 +1,22 @@
export 'src/auto_size_text.dart';
library;

import 'dart:async';
import 'dart:math';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

part 'src/auto_size_group.dart';

part 'src/auto_size_group_builder.dart';

part 'src/auto_size_text.dart';

part 'src/text_fitter.dart';

part 'src/auto_size_builder/auto_size.dart';

part 'src/auto_size_builder/auto_size_builder.dart';

part 'src/auto_size_builder/auto_size_element.dart';

part 'src/auto_size_builder/render_auto_size.dart';
14 changes: 11 additions & 3 deletions lib/src/auto_size_builder/auto_size.dart
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
part of 'auto_size_builder.dart';
part of '../../flutter_auto_size_text.dart';

class _AutoSize extends RenderObjectWidget {
_AutoSize({
Expand All @@ -17,13 +17,15 @@ class _AutoSize extends RenderObjectWidget {
required this.textScaleFactor,
required this.minFontSize,
required this.maxFontSize,
this.groupMaxFontSize,
required this.stepGranularity,
required this.presetFontSizes,
this.onMaxPossibleFontSizeChanged,
}) {
_validateProperties();
}

final AutoSizeTextBuilder builder;
final _AutoSizeTextBuilder builder;
final Widget? overflowReplacement;

final TextSpan text;
Expand All @@ -41,6 +43,8 @@ class _AutoSize extends RenderObjectWidget {
final double maxFontSize;
final double stepGranularity;
final List<double>? presetFontSizes;
final double? groupMaxFontSize;
final void Function(double)? onMaxPossibleFontSizeChanged;

TextFitter _buildFitter() {
return TextFitter(
Expand All @@ -64,13 +68,17 @@ class _AutoSize extends RenderObjectWidget {

@override
_RenderAutoSize createRenderObject(BuildContext context) {
return _RenderAutoSize(fitter: _buildFitter());
return _RenderAutoSize(
fitter: _buildFitter(),
onMaxPossibleFontSizeChanged: onMaxPossibleFontSizeChanged,
groupMaxFontSize: groupMaxFontSize);
}

@override
void updateRenderObject(
BuildContext context, covariant _RenderAutoSize renderObject) {
renderObject.updateTextFitter(_buildFitter());
renderObject.updateGroupMaxFontSize(groupMaxFontSize);
}

@override
Expand Down
57 changes: 43 additions & 14 deletions lib/src/auto_size_builder/auto_size_builder.dart
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Original file line number Diff line number Diff line change
@@ -1,16 +1,10 @@
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_auto_size_text/src/text_fitter.dart';
part of '../../flutter_auto_size_text.dart';

part 'auto_size.dart';
part 'auto_size_element.dart';
part 'render_auto_size.dart';
typedef _AutoSizeTextBuilder = Widget Function(BuildContext context,
double textScaleFactor, double? groupMaxFontSize, bool overflow);

typedef AutoSizeTextBuilder = Widget Function(
BuildContext context, double textScaleFactor, bool overflow);

class AutoSizeBuilder extends StatefulWidget {
const AutoSizeBuilder({
class _AutoSizeBuilder extends StatefulWidget {
const _AutoSizeBuilder({
super.key,
required this.builder,
this.overflowReplacement,
Expand All @@ -30,9 +24,10 @@ class AutoSizeBuilder extends StatefulWidget {
this.maxFontSize,
this.stepGranularity,
this.presetFontSizes,
this.group,
});

final AutoSizeTextBuilder builder;
final _AutoSizeTextBuilder builder;

/// {@macro auto_size_text.overflowReplacement}
final Widget? overflowReplacement;
Expand Down Expand Up @@ -83,11 +78,29 @@ class AutoSizeBuilder extends StatefulWidget {
/// {@macro auto_size_text.presetFontSizes}
final List<double>? presetFontSizes;

/// {@macro auto_size_text.group}
final AutoSizeGroup? group;

@override
State<AutoSizeBuilder> createState() => _AutoSizeBuilderState();
State<_AutoSizeBuilder> createState() => _AutoSizeBuilderState();
}

class _AutoSizeBuilderState extends State<AutoSizeBuilder> {
class _AutoSizeBuilderState extends State<_AutoSizeBuilder> {
@override
void initState() {
super.initState();
widget.group?._register(this);
}

@override
void didUpdateWidget(covariant _AutoSizeBuilder oldWidget) {
super.didUpdateWidget(oldWidget);
if (oldWidget.group != widget.group) {
oldWidget.group?._remove(this);
widget.group?._register(this);
}
}

@override
Widget build(BuildContext context) {
final defaultTextStyle = DefaultTextStyle.of(context);
Expand Down Expand Up @@ -127,8 +140,24 @@ class _AutoSizeBuilderState extends State<AutoSizeBuilder> {
textScaleFactor: widget.textScaleFactor ?? 1,
minFontSize: widget.minFontSize ?? 12.0,
maxFontSize: widget.maxFontSize ?? double.infinity,
groupMaxFontSize: widget.group?._effectiveMaxPossibleFontSize,
stepGranularity: widget.stepGranularity ?? 1.0,
presetFontSizes: widget.presetFontSizes,
onMaxPossibleFontSizeChanged: widget.group != null
? (maxPossibleFontSize) {
widget.group?._updateFontSize(this, maxPossibleFontSize);
}
: null,
);
}

void _notifySync() {
setState(() {});
}

@override
void dispose() {
widget.group?._remove(this);
super.dispose();
}
}
6 changes: 3 additions & 3 deletions lib/src/auto_size_builder/auto_size_element.dart
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
part of 'auto_size_builder.dart';
part of '../../flutter_auto_size_text.dart';

class _AutoSizeElement extends RenderObjectElement {
_AutoSizeElement(_AutoSize super.widget);
Expand Down Expand Up @@ -40,12 +40,12 @@ class _AutoSizeElement extends RenderObjectElement {
super.unmount();
}

void _updateText(double textScaleFactor, bool overflow) {
void _updateText(double textScaleFactor, double? groupMaxFontSize, bool overflow) {
owner!.buildScope(this, () {
_overflow = overflow;
Widget built;
try {
built = widget.builder(this, textScaleFactor, overflow);
built = widget.builder(this, textScaleFactor, groupMaxFontSize, overflow);
debugWidgetBuilderValue(widget, built);
} catch (e) {
built = ErrorWidget(e);
Expand Down
29 changes: 23 additions & 6 deletions lib/src/auto_size_builder/render_auto_size.dart
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
part of 'auto_size_builder.dart';
part of '../../flutter_auto_size_text.dart';

class _AutoSizeParentData extends ParentData
with ContainerParentDataMixin<RenderBox> {}
Expand All @@ -7,23 +7,31 @@ class _RenderAutoSize extends RenderBox
with
ContainerRenderObjectMixin<RenderBox,
ContainerParentDataMixin<RenderBox>> {
_RenderAutoSize({required TextFitter fitter}) : _fitter = fitter;
_RenderAutoSize(
{required TextFitter fitter,
this.onMaxPossibleFontSizeChanged,
required this.groupMaxFontSize})
: _fitter = fitter;

var _overflow = false;
var _needsBuild = true;
double? _previousTextScaleFactor;
bool? _previousOverflow;
double? _longestWordWidth;

Function(double, bool)? _buildCallback;
void updateBuildCallback(Function(double, bool)? buildCallback) {
Function(double, double?, bool)? _buildCallback;
double? groupMaxFontSize;
final void Function(double)? onMaxPossibleFontSizeChanged;

void updateBuildCallback(Function(double, double?, bool)? buildCallback) {
if (_buildCallback == buildCallback) return;
_previousTextScaleFactor = null;
_buildCallback = buildCallback;
markNeedsLayout();
}

TextFitter _fitter;

void updateTextFitter(TextFitter fitter) {
if (_fitter == fitter) return;
if (_fitter.text != fitter.text) {
Expand All @@ -34,6 +42,12 @@ class _RenderAutoSize extends RenderBox
markNeedsLayout();
}

void updateGroupMaxFontSize(double? newGroupMaxFontSize) {
if (groupMaxFontSize == newGroupMaxFontSize) return;
groupMaxFontSize = newGroupMaxFontSize;
markNeedsLayout();
}

RenderBox get child => _overflow ? lastChild! : firstChild!;

bool get hasReplacement => !identical(firstChild, lastChild);
Expand Down Expand Up @@ -115,8 +129,11 @@ class _RenderAutoSize extends RenderBox
_previousTextScaleFactor = result.scale;
_previousOverflow = result.overflow;
_needsBuild = false;
invokeLayoutCallback(
(_) => _buildCallback!(result.scale, result.overflow));
final fontSize = _fitter.text.style?.fontSize ?? _kDefaultFontSize;
final maxPossibleFontSize = fontSize * result.scale;
onMaxPossibleFontSizeChanged?.call(maxPossibleFontSize);
invokeLayoutCallback((_) =>
_buildCallback!(result.scale, groupMaxFontSize, result.overflow));
}

_overflow = result.overflow;
Expand Down
49 changes: 49 additions & 0 deletions lib/src/auto_size_group.dart
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Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
part of '../flutter_auto_size_text.dart';

/// Controller to synchronize the fontSize of multiple AutoSizeTexts.
class AutoSizeGroup {
final _listeners = <_AutoSizeBuilderState, double>{};
var _widgetsNotified = false;

void _register(_AutoSizeBuilderState text) {
_listeners[text] = double.infinity;
}

double get _effectiveMaxPossibleFontSize {
final minMaxPossibleFontSize = _listeners.values.fold<double>(
double.infinity,
(previousValue, element) =>
element < previousValue ? element : previousValue);
return minMaxPossibleFontSize;
}

void _updateFontSize(_AutoSizeBuilderState text, double maxPossibleFontSize) {
final oldEffectiveMaxPossibleFontSize = _effectiveMaxPossibleFontSize;
_listeners[text] = maxPossibleFontSize;
final newEffectiveMaxPossibleFontSize = _effectiveMaxPossibleFontSize;

if (oldEffectiveMaxPossibleFontSize != newEffectiveMaxPossibleFontSize) {
_widgetsNotified = false;
scheduleMicrotask(_notifyListeners);
}
}

void _notifyListeners() {
if (_widgetsNotified) {
return;
} else {
_widgetsNotified = true;
}

for (final textState in _listeners.keys) {
if (textState.mounted) {
textState._notifySync();
}
}
}

void _remove(_AutoSizeBuilderState text) {
_updateFontSize(text, double.infinity);
_listeners.remove(text);
}
}
22 changes: 22 additions & 0 deletions lib/src/auto_size_group_builder.dart
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Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
part of '../flutter_auto_size_text.dart';

/// A Flutter widget that provides an [AutoSizeGroup] to its builder function.
class AutoSizeGroupBuilder extends StatefulWidget {
final Widget Function(BuildContext context, AutoSizeGroup autoSizeGroup)
builder;

/// Creates an [AutoSizeGroupBuilder] widget.
const AutoSizeGroupBuilder({super.key, required this.builder});

@override
_AutoSizeGroupBuilderState createState() => _AutoSizeGroupBuilderState();
}

class _AutoSizeGroupBuilderState extends State<AutoSizeGroupBuilder> {
final _group = AutoSizeGroup();

@override
Widget build(BuildContext context) {
return widget.builder(context, _group);
}
}
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