Using custom stepper without continue/cancel

lib/customStepper.dart

@@ -0,0 +1,663 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+import 'package:flutter/material.dart';
+
+
+// TODO(dragostis): Missing functionality:
+//   * mobile horizontal mode with adding/removing steps
+//   * alternative labeling
+//   * stepper feedback in the case of high-latency interactions
+
+/// The state of a [CustomStep] which is used to control the style of the circle and
+/// text.
+///
+/// See also:
+///
+///  * [CustomStep]
+enum CustomStepState {
+  /// A step that displays its index in its circle.
+  indexed,
+
+  /// A step that displays a pencil icon in its circle.
+  editing,
+
+  /// A step that displays a tick icon in its circle.
+  complete,
+
+  /// A step that is disabled and does not to react to taps.
+  disabled,
+
+  /// A step that is currently having an error. e.g. the use has submitted wrong
+  /// input.
+  error,
+}
+
+/// Defines the [CustomStepper]'s main axis.
+enum CustomStepperType {
+  /// A vertical layout of the steps with their content in-between the titles.
+  vertical,
+
+  /// A horizontal layout of the steps with their content below the titles.
+  horizontal,
+}
+
+const TextStyle _kCustomStepStyle = const TextStyle(
+  fontSize: 12.0,
+  color: Colors.white,
+);
+const Color _kErrorLight = Colors.red;
+final Color _kErrorDark = Colors.red.shade400;
+const Color _kCircleActiveLight = Colors.white;
+const Color _kCircleActiveDark = Colors.black87;
+const Color _kDisabledLight = Colors.black38;
+const Color _kDisabledDark = Colors.white30;
+const double _kCustomStepSize = 24.0;
+const double _kTriangleHeight = _kCustomStepSize * 0.866025; // Triangle height. sqrt(3.0) / 2.0
+
+/// A material step used in [CustomStepper]. The step can have a title and subtitle,
+/// an icon within its circle, some content and a state that governs its
+/// styling.
+///
+/// See also:
+///
+///  * [CustomStepper]
+///  * <https://material.google.com/components/steppers.html>
+///  Modification: (by @vjrj) Commented continue/cancel buttons
+@immutable
+class CustomStep {
+  /// Creates a step for a [CustomStepper].
+  ///
+  /// The [title], [content], and [state] arguments must not be null.
+  const CustomStep({
+    @required this.title,
+    this.subtitle,
+    @required this.content,
+    this.state: CustomStepState.indexed,
+    this.isActive: false,
+  }) : assert(title != null),
+      assert(content != null),
+      assert(state != null);
+
+  /// The title of the step that typically describes it.
+  final Widget title;
+
+  /// The subtitle of the step that appears below the title and has a smaller
+  /// font size. It typically gives more details that complement the title.
+  ///
+  /// If null, the subtitle is not shown.
+  final Widget subtitle;
+
+  /// The content of the step that appears below the [title] and [subtitle].
+  ///
+  /// Below the content, every step has a 'continue' and 'cancel' button.
+  final Widget content;
+
+  /// The state of the step which determines the styling of its components
+  /// and whether steps are interactive.
+  final CustomStepState state;
+
+  /// Whether or not the step is active. The flag only influences styling.
+  final bool isActive;
+}
+
+/// A material stepper widget that displays progress through a sequence of
+/// steps. CustomSteppers are particularly useful in the case of forms where one step
+/// requires the completion of another one, or where multiple steps need to be
+/// completed in order to submit the whole form.
+///
+/// The widget is a flexible wrapper. A parent class should pass [currentCustomStep]
+/// to this widget based on some logic triggered by the three callbacks that it
+/// provides.
+///
+/// See also:
+///
+///  * [CustomStep]
+///  * <https://material.google.com/components/steppers.html>
+class CustomStepper extends StatefulWidget {
+  /// Creates a stepper from a list of steps.
+  ///
+  /// This widget is not meant to be rebuilt with a different list of steps
+  /// unless a key is provided in order to distinguish the old stepper from the
+  /// new one.
+  ///
+  /// The [steps], [type], and [currentCustomStep] arguments must not be null.
+  CustomStepper({
+    Key key,
+    @required this.steps,
+    this.type: CustomStepperType.vertical,
+    this.currentCustomStep: 0,
+    this.onCustomStepTapped,
+    this.onCustomStepContinue,
+    this.onCustomStepCancel,
+  }) : assert(steps != null),
+      assert(type != null),
+      assert(currentCustomStep != null),
+      assert(0 <= currentCustomStep && currentCustomStep < steps.length),
+      super(key: key);
+
+  /// The steps of the stepper whose titles, subtitles, icons always get shown.
+  ///
+  /// The length of [steps] must not change.
+  final List<CustomStep> steps;
+
+  /// The type of stepper that determines the layout. In the case of
+  /// [CustomStepperType.horizontal], the content of the current step is displayed
+  /// underneath as opposed to the [CustomStepperType.vertical] case where it is
+  /// displayed in-between.
+  final CustomStepperType type;
+
+  /// The index into [steps] of the current step whose content is displayed.
+  final int currentCustomStep;
+
+  /// The callback called when a step is tapped, with its index passed as
+  /// an argument.
+  final ValueChanged<int> onCustomStepTapped;
+
+  /// The callback called when the 'continue' button is tapped.
+  ///
+  /// If null, the 'continue' button will be disabled.
+  final VoidCallback onCustomStepContinue;
+
+  /// The callback called when the 'cancel' button is tapped.
+  ///
+  /// If null, the 'cancel' button will be disabled.
+  final VoidCallback onCustomStepCancel;
+
+  @override
+  _CustomStepperState createState() => new _CustomStepperState();
+}
+
+class _CustomStepperState extends State<CustomStepper> {
+  List<GlobalKey> _keys;
+  final Map<int, CustomStepState> _oldStates = <int, CustomStepState>{};
+
+  @override
+  void initState() {
+    super.initState();
+    _keys = new List<GlobalKey>.generate(
+      widget.steps.length,
+        (int i) => new GlobalKey(),
+    );
+
+    for (int i = 0; i < widget.steps.length; i += 1)
+      _oldStates[i] = widget.steps[i].state;
+  }
+
+  @override
+  void didUpdateWidget(CustomStepper oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    assert(widget.steps.length == oldWidget.steps.length);
+
+    for (int i = 0; i < oldWidget.steps.length; i += 1)
+      _oldStates[i] = oldWidget.steps[i].state;
+  }
+
+  bool _isFirst(int index) {
+    return index == 0;
+  }
+
+  bool _isLast(int index) {
+    return widget.steps.length - 1 == index;
+  }
+
+  bool _isCurrent(int index) {
+    return widget.currentCustomStep == index;
+  }
+
+  bool _isDark() {
+    return Theme.of(context).brightness == Brightness.dark;
+  }
+
+  Widget _buildLine(bool visible) {
+    return new Container(
+      width: visible ? 1.0 : 0.0,
+      height: 16.0,
+      color: Colors.grey.shade400,
+    );
+  }
+
+  Widget _buildCircleChild(int index, bool oldState) {
+    final CustomStepState state = oldState ? _oldStates[index] : widget.steps[index].state;
+    final bool isDarkActive = _isDark() && widget.steps[index].isActive;
+    assert(state != null);
+    switch (state) {
+      case CustomStepState.indexed:
+      case CustomStepState.disabled:
+        return new Text(
+          '${index + 1}',
+          style: isDarkActive ? _kCustomStepStyle.copyWith(color: Colors.black87) : _kCustomStepStyle,
+        );
+      case CustomStepState.editing:
+        return new Icon(
+          Icons.edit,
+          color: isDarkActive ? _kCircleActiveDark : _kCircleActiveLight,
+        );
+      case CustomStepState.complete:
+        return new Icon(
+          Icons.check,
+          color: isDarkActive ? _kCircleActiveDark : _kCircleActiveLight,
+        );
+      case CustomStepState.error:
+        return const Text('!', style: _kCustomStepStyle);
+    }
+    return null;
+  }
+
+  Color _circleColor(int index) {
+    final ThemeData themeData = Theme.of(context);
+    if (!_isDark()) {
+      return widget.steps[index].isActive ? themeData.primaryColor : Colors.black38;
+    } else {
+      return widget.steps[index].isActive ? themeData.accentColor : themeData.backgroundColor;
+    }
+  }
+
+  Widget _buildCircle(int index, bool oldState) {
+    return new Container(
+      margin: const EdgeInsets.symmetric(vertical: 8.0),
+      width: _kCustomStepSize,
+      height: _kCustomStepSize,
+      child: new AnimatedContainer(
+        curve: Curves.fastOutSlowIn,
+        duration: kThemeAnimationDuration,
+        decoration: new BoxDecoration(
+          color: _circleColor(index),
+          shape: BoxShape.circle,
+        ),
+        child: new Center(
+          child: _buildCircleChild(index, oldState && widget.steps[index].state == CustomStepState.error),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildTriangle(int index, bool oldState) {
+    return new Container(
+      margin: const EdgeInsets.symmetric(vertical: 8.0),
+      width: _kCustomStepSize,
+      height: _kCustomStepSize,
+      child: new Center(
+        child: new SizedBox(
+          width: _kCustomStepSize,
+          height: _kTriangleHeight, // Height of 24dp-long-sided equilateral triangle.
+          child: new CustomPaint(
+            painter: new _TrianglePainter(
+              color: _isDark() ? _kErrorDark : _kErrorLight,
+            ),
+            child: new Align(
+              alignment: const Alignment(0.0, 0.8), // 0.8 looks better than the geometrical 0.33.
+              child: _buildCircleChild(index, oldState && widget.steps[index].state != CustomStepState.error),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildIcon(int index) {
+    if (widget.steps[index].state != _oldStates[index]) {
+      return new AnimatedCrossFade(
+        firstChild: _buildCircle(index, true),
+        secondChild: _buildTriangle(index, true),
+        firstCurve: const Interval(0.0, 0.6, curve: Curves.fastOutSlowIn),
+        secondCurve: const Interval(0.4, 1.0, curve: Curves.fastOutSlowIn),
+        sizeCurve: Curves.fastOutSlowIn,
+        crossFadeState: widget.steps[index].state == CustomStepState.error ? CrossFadeState.showSecond : CrossFadeState.showFirst,
+        duration: kThemeAnimationDuration,
+      );
+    } else {
+      if (widget.steps[index].state != CustomStepState.error)
+        return _buildCircle(index, false);
+      else
+        return _buildTriangle(index, false);
+    }
+  }
+
+  Widget _buildVerticalControls() {
+    Color cancelColor;
+
+    switch (Theme.of(context).brightness) {
+      case Brightness.light:
+        cancelColor = Colors.black54;
+        break;
+      case Brightness.dark:
+        cancelColor = Colors.white70;
+        break;
+    }
+
+    assert(cancelColor != null);
+
+    final ThemeData themeData = Theme.of(context);
+    final MaterialLocalizations localizations = MaterialLocalizations.of(context);
+
+    return new Container(
+      margin: const EdgeInsets.only(top: 16.0),
+      child: new ConstrainedBox(
+        constraints: const BoxConstraints.tightFor(height: 48.0),
+        child: new Row(
+          children: <Widget>[
+            /* new FlatButton(
+              onPressed: widget.onCustomStepContinue,
+              color: _isDark() ? themeData.backgroundColor : themeData.primaryColor,
+              textColor: Colors.white,
+              textTheme: ButtonTextTheme.normal,
+              child: new Text(localizations.continueButtonLabel),
+            ),
+            new Container(
+              margin: const EdgeInsetsDirectional.only(start: 8.0),
+              child: new FlatButton(
+                onPressed: widget.onCustomStepCancel,
+                textColor: cancelColor,
+                textTheme: ButtonTextTheme.normal,
+                child: new Text(localizations.cancelButtonLabel),
+              ),
+            ), */
+          ],
+        ),
+      ),
+    );
+  }
+
+  TextStyle _titleStyle(int index) {
+    final ThemeData themeData = Theme.of(context);
+    final TextTheme textTheme = themeData.textTheme;
+
+    assert(widget.steps[index].state != null);
+    switch (widget.steps[index].state) {
+      case CustomStepState.indexed:
+      case CustomStepState.editing:
+      case CustomStepState.complete:
+        return textTheme.body2;
+      case CustomStepState.disabled:
+        return textTheme.body2.copyWith(
+          color: _isDark() ? _kDisabledDark : _kDisabledLight
+        );
+      case CustomStepState.error:
+        return textTheme.body2.copyWith(
+          color: _isDark() ? _kErrorDark : _kErrorLight
+        );
+    }
+    return null;
+  }
+
+  TextStyle _subtitleStyle(int index) {
+    final ThemeData themeData = Theme.of(context);
+    final TextTheme textTheme = themeData.textTheme;
+
+    assert(widget.steps[index].state != null);
+    switch (widget.steps[index].state) {
+      case CustomStepState.indexed:
+      case CustomStepState.editing:
+      case CustomStepState.complete:
+        return textTheme.caption;
+      case CustomStepState.disabled:
+        return textTheme.caption.copyWith(
+          color: _isDark() ? _kDisabledDark : _kDisabledLight
+        );
+      case CustomStepState.error:
+        return textTheme.caption.copyWith(
+          color: _isDark() ? _kErrorDark : _kErrorLight
+        );
+    }
+    return null;
+  }
+
+  Widget _buildHeaderText(int index) {
+    final List<Widget> children = <Widget>[
+      new AnimatedDefaultTextStyle(
+        style: _titleStyle(index),
+        duration: kThemeAnimationDuration,
+        curve: Curves.fastOutSlowIn,
+        child: widget.steps[index].title,
+      ),
+    ];
+
+    if (widget.steps[index].subtitle != null)
+      children.add(
+        new Container(
+          margin: const EdgeInsets.only(top: 2.0),
+          child: new AnimatedDefaultTextStyle(
+            style: _subtitleStyle(index),
+            duration: kThemeAnimationDuration,
+            curve: Curves.fastOutSlowIn,
+            child: widget.steps[index].subtitle,
+          ),
+        ),
+      );
+
+    return new Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      mainAxisSize: MainAxisSize.min,
+      children: children
+    );
+  }
+
+  Widget _buildVerticalHeader(int index) {
+    return new Container(
+      margin: const EdgeInsets.symmetric(horizontal: 24.0),
+      child: new Row(
+        children: <Widget>[
+          new Column(
+            children: <Widget>[
+              // Line parts are always added in order for the ink splash to
+              // flood the tips of the connector lines.
+              _buildLine(!_isFirst(index)),
+              _buildIcon(index),
+              _buildLine(!_isLast(index)),
+            ]
+          ),
+          new Container(
+            margin: const EdgeInsetsDirectional.only(start: 12.0),
+            child: _buildHeaderText(index)
+          )
+        ]
+      )
+    );
+  }
+
+  Widget _buildVerticalBody(int index) {
+    return new Stack(
+      children: <Widget>[
+        new PositionedDirectional(
+          start: 24.0,
+          top: 0.0,
+          bottom: 0.0,
+          child: new SizedBox(
+            width: 24.0,
+            child: new Center(
+              child: new SizedBox(
+                width: _isLast(index) ? 0.0 : 1.0,
+                child: new Container(
+                  color: Colors.grey.shade400,
+                ),
+              ),
+            ),
+          ),
+        ),
+        new AnimatedCrossFade(
+          firstChild: new Container(height: 0.0),
+          secondChild: new Container(
+            margin: const EdgeInsetsDirectional.only(
+              start: 60.0,
+              end: 24.0,
+              bottom: 24.0,
+            ),
+            child: new Column(
+              children: <Widget>[
+                widget.steps[index].content,
+                _buildVerticalControls(),
+              ],
+            ),
+          ),
+          firstCurve: const Interval(0.0, 0.6, curve: Curves.fastOutSlowIn),
+          secondCurve: const Interval(0.4, 1.0, curve: Curves.fastOutSlowIn),
+          sizeCurve: Curves.fastOutSlowIn,
+          crossFadeState: _isCurrent(index) ? CrossFadeState.showSecond : CrossFadeState.showFirst,
+          duration: kThemeAnimationDuration,
+        ),
+      ],
+    );
+  }
+
+  Widget _buildVertical() {
+    final List<Widget> children = <Widget>[];
+
+    for (int i = 0; i < widget.steps.length; i += 1) {
+      children.add(
+        new Column(
+          key: _keys[i],
+          children: <Widget>[
+            new InkWell(
+              onTap: widget.steps[i].state != CustomStepState.disabled ? () {
+                // In the vertical case we need to scroll to the newly tapped
+                // step.
+                Scrollable.ensureVisible(
+                  _keys[i].currentContext,
+                  curve: Curves.fastOutSlowIn,
+                  duration: kThemeAnimationDuration,
+                );
+
+                if (widget.onCustomStepTapped != null)
+                  widget.onCustomStepTapped(i);
+              } : null,
+              child: _buildVerticalHeader(i)
+            ),
+            _buildVerticalBody(i)
+          ]
+        )
+      );
+    }
+
+    return new ListView(
+      shrinkWrap: true,
+      children: children,
+    );
+  }
+
+  Widget _buildHorizontal() {
+    final List<Widget> children = <Widget>[];
+
+    for (int i = 0; i < widget.steps.length; i += 1) {
+      children.add(
+        new InkResponse(
+          onTap: widget.steps[i].state != CustomStepState.disabled ? () {
+            if (widget.onCustomStepTapped != null)
+              widget.onCustomStepTapped(i);
+          } : null,
+          child: new Row(
+            children: <Widget>[
+              new Container(
+                height: 72.0,
+                child: new Center(
+                  child: _buildIcon(i),
+                ),
+              ),
+              new Container(
+                margin: const EdgeInsetsDirectional.only(start: 12.0),
+                child: _buildHeaderText(i),
+              ),
+            ],
+          ),
+        ),
+      );
+
+      if (!_isLast(i)) {
+        children.add(
+          new Expanded(
+            child: new Container(
+              margin: const EdgeInsets.symmetric(horizontal: 8.0),
+              height: 1.0,
+              color: Colors.grey.shade400,
+            ),
+          ),
+        );
+      }
+    }
+
+    return new Column(
+      children: <Widget>[
+        new Material(
+          elevation: 2.0,
+          child: new Container(
+            margin: const EdgeInsets.symmetric(horizontal: 24.0),
+            child: new Row(
+              children: children,
+            ),
+          ),
+        ),
+        new Expanded(
+          child: new ListView(
+            padding: const EdgeInsets.all(24.0),
+            children: <Widget>[
+              new AnimatedSize(
+                curve: Curves.fastOutSlowIn,
+                duration: kThemeAnimationDuration,
+                //vsync: this,
+                child: widget.steps[widget.currentCustomStep].content,
+              ),
+              _buildVerticalControls(),
+            ],
+          ),
+        ),
+      ],
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    assert(debugCheckHasMaterial(context));
+    assert(() {
+      if (context.ancestorWidgetOfExactType(CustomStepper) != null)
+        throw new FlutterError(
+          'CustomSteppers must not be nested. The material specification advises '
+            'that one should avoid embedding steppers within steppers. '
+            'https://material.google.com/components/steppers.html#steppers-usage\n'
+        );
+      return true;
+    }());
+    assert(widget.type != null);
+    switch (widget.type) {
+      case CustomStepperType.vertical:
+        return _buildVertical();
+      case CustomStepperType.horizontal:
+        return _buildHorizontal();
+    }
+    return null;
+  }
+}
+
+// Paints a triangle whose base is the bottom of the bounding rectangle and its
+// top vertex the middle of its top.
+class _TrianglePainter extends CustomPainter {
+  _TrianglePainter({
+    this.color
+  });
+
+  final Color color;
+
+  @override
+  bool hitTest(Offset point) => true; // Hitting the rectangle is fine enough.
+
+  @override
+  bool shouldRepaint(_TrianglePainter oldPainter) {
+    return oldPainter.color != color;
+  }
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final double base = size.width;
+    final double halfBase = size.width / 2.0;
+    final double height = size.height;
+    final List<Offset> points = <Offset>[
+      new Offset(0.0, height),
+      new Offset(base, height),
+      new Offset(halfBase, 0.0),
+    ];
+
+    canvas.drawPath(
+      new Path()..addPolygon(points, true),
+      new Paint()..color = color,
+    );
+  }
+}

lib/fireAlert.dart

@@ -3,6 +3,7 @@ import 'package:comunes_flutter/comunes_flutter.dart';
 import 'package:flutter/material.dart';
 import 'package:share/share.dart';
 import 'package:url_launcher/url_launcher.dart';
+import 'customStepper.dart';
 
 import 'generated/i18n.dart';
 import 'placesAutocompleteUtils.dart';
@@ -55,13 +56,13 @@ class _FireAlertState extends State<FireAlert> {
     );
   }
 
-  List<Step> listWithoutNulls(List<Step> children) =>
+  List<CustomStep> listWithoutNulls(List<CustomStep> children) =>
       children.where(notNull).toList();
 
   @override
   Widget build(BuildContext context) {
-    List fireSteps = listWithoutNulls(<Step>[
-      new Step(
+    List<CustomStep> fireSteps = listWithoutNulls(<CustomStep>[
+      new CustomStep(
           title: new Text(S.of(context).callEmergencyServicesTitle),
           // subtitle:
           content: new Column(children: <Widget>[
@@ -70,7 +71,7 @@ class _FireAlertState extends State<FireAlert> {
             buildCallButton()
           ])),
       // TODO conditional: this only in Spain
-      new Step(
+      new CustomStep(
           title: new Text(S.of(context).tweetAboutAFireTitle),
           // subtitle: new Text(S.of(context).tweetAboutAFireDescription),
           content: new Column(children: <Widget>[
@@ -91,14 +92,12 @@ class _FireAlertState extends State<FireAlert> {
     return Scaffold(
         key: _scaffoldKey,
         appBar: new AppBar(title: new Text(S.of(context).notifyAFire)),
-        body: new Stepper(
-            currentStep: _currentStep,
+        body: new CustomStepper(
+            currentCustomStep: _currentStep,
             // type: StepperType.horizontal,
-            onStepTapped: (num) => setState(() {
+            onCustomStepTapped: (num) => setState(() {
                   _currentStep = num;
                 }),
-            onStepContinue: stepInc,
-            onStepCancel: stepInc,
             steps: fireSteps));
   }
 }