color_scale 0.0.4

Color scale widget that tries to resemble what we have on google sheets

example/lib/main.dart

import 'dart:math';

import 'package:color_scale/color_scale.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false,
        title: 'Color Scale Demo',
        home: Scaffold(
          appBar: AppBar(
            title: const Text('Color scale'),
          ),
          body: SingleChildScrollView(
            child: Container(
              margin: const EdgeInsets.all(10),
              child: Column(
                children: [
                  const SizedBox(
                    height: 20,
                  ),
                  const Text('Example with stops'),
                  StopsValueAndColorsWidget(
                    colorStops: <double, Color>{
                      -20: Colors.red,
                      0: Colors.yellow,
                      20: Colors.green,
                    },
                  ),
                  const Text('Example with slider'),
                  const ExampleWithSlider(
                      text: 'Slide between min and max color',
                      minColor: Colors.red,
                      maxColor: Colors.green),
                  const SizedBox(
                    height: 50,
                  ),
                  const TestColorScale(
                    text: 'Colors from red to green',
                    values: [-20, -15, -10, -5, 0, 5, 10, 15],
                    minValue: -20,
                    minColor: Colors.red,
                    maxValue: 20,
                    maxColor: Colors.green,
                  ),
                  const TestColorScale(
                    text: 'Colors from blue to green',
                    values: [-20, -15, -10, -5, 0, 5, 10, 15],
                    minValue: -20,
                    minColor: Colors.blue,
                    maxValue: 20,
                    maxColor: Colors.green,
                  ),
                  const TestColorScale(
                    text: 'Colors from red to yellow',
                    values: [-20, -15, -10, -5, 0, 5, 10, 15],
                    minValue: -20,
                    minColor: Colors.red,
                    maxValue: 20,
                    maxColor: Colors.yellow,
                  ),
                  const Text('Childless example'),
                  const ClipRRect(
                    borderRadius: BorderRadius.all(Radius.circular(10)),
                    child: SizedBox(
                      width: 50,
                      height: 50,
                      child: ColorScaleWidget(
                        value: 0,
                        minValue: -20,
                        minColor: Colors.white,
                        maxValue: 20,
                        maxColor: Colors.black,
                      ),
                    ),
                  ),
                  const Text('Childless example with stops'),
                  ClipRRect(
                    borderRadius: const BorderRadius.all(Radius.circular(10)),
                    child: SizedBox(
                      width: 50,
                      height: 50,
                      child: ColorScaleStopsWidget(
                        value: 0,
                        colorStops: <double, Color>{
                          -20: Colors.red,
                          0: Colors.yellow,
                          20: Colors.green,
                        },
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ));
  }
}

class ExampleWithSlider extends StatefulWidget {
  final String text;

  final double minValue;
  final Color minColor;

  final double maxValue;
  final Color maxColor;

  const ExampleWithSlider({
    this.text = '',
    this.minValue = -20,
    this.minColor = Colors.red,
    this.maxValue = 20,
    this.maxColor = Colors.green,
    super.key,
  });

  @override
  State<ExampleWithSlider> createState() => _ExampleWithSliderState();
}

class _ExampleWithSliderState extends State<ExampleWithSlider> {
  Color minColor = Colors.red;
  double minValue = -20;

  Color maxColor = Colors.green;
  double maxValue = 20;

  double value = 0;

  @override
  void initState() {
    super.initState();

    minColor = widget.minColor;
    minValue = widget.minValue;

    maxColor = widget.maxColor;
    maxValue = widget.maxValue;
  }

  @override
  Widget build(BuildContext context) {
    return Card(
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(10.0),
      ),
      elevation: 5,
      child: Container(
        margin: const EdgeInsets.all(10),
        child: Column(
          children: [
            Column(
              children: [
                const SizedBox(
                  height: 20,
                ),
                const Text('Minimum Color'),
                MyColorPicker(
                  onSelectColor: (color) => setState(() => minColor = color),
                  initialColor: minColor,
                  availableColors: [
                    Colors.red,
                    Colors.orange,
                    Colors.amberAccent,
                    Colors.purple.withOpacity(0.25),
                    Colors.pink.withOpacity(0.5)
                  ],
                ),
                const Text('Minimum Value'),
                TextField(
                  keyboardType: TextInputType.number,
                  controller: TextEditingController(text: minValue.toString()),
                  onChanged: (inputValue) => setState(() {
                    minValue = double.parse(inputValue);
                    value = max(value, minValue);
                  }),
                ),
                const Text('Maximum Color'),
                MyColorPicker(
                  onSelectColor: (color) => setState(() => maxColor = color),
                  initialColor: maxColor,
                  availableColors: [
                    Colors.green,
                    Colors.greenAccent,
                    Colors.blue,
                    Colors.cyan.withOpacity(0.25),
                    Colors.teal.withOpacity(0.5)
                  ],
                ),
                const Text('Maximum Value'),
                TextField(
                  keyboardType: TextInputType.number,
                  controller: TextEditingController(text: maxValue.toString()),
                  onChanged: (inputValue) => setState(() {
                    maxValue = double.parse(inputValue);
                    value = min(value, maxValue);
                  }),
                ),
                Slider(
                    min: minValue,
                    max: maxValue,
                    value: value,
                    onChanged: onSliderMove),
                ClipRRect(
                  borderRadius: const BorderRadius.all(Radius.circular(10.0)),
                  child: ColorScaleWidget(
                    value: value,
                    minValue: minValue,
                    minColor: minColor,
                    maxValue: maxValue,
                    maxColor: maxColor,
                    child: Container(
                      margin: const EdgeInsets.all(5),
                      child: Column(
                        children: [
                          Text(widget.text),
                          Text('value: ${value.toStringAsFixed(2)}')
                        ],
                      ),
                    ),
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  void onSliderMove(double value) {
    setState(() {
      this.value = value;
    });
  }
}

class MyColorPicker extends StatefulWidget {
  // This function sends the selected color to outside
  final Function onSelectColor;

  // List of pickable colors
  final List<Color> availableColors;

  // The default picked color
  final Color initialColor;

  // Determine shapes of color cells
  final bool circleItem;

  const MyColorPicker({
    super.key,
    required this.onSelectColor,
    required this.availableColors,
    required this.initialColor,
    this.circleItem = true,
  });

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

class _MyColorPickerState extends State<MyColorPicker> {
  // This variable used to determine where the checkmark will be
  late Color _pickedColor;

  @override
  void initState() {
    _pickedColor = widget.initialColor;
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      height: 80,
      child: GridView.builder(
        gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
            maxCrossAxisExtent: 50,
            childAspectRatio: 1 / 1,
            crossAxisSpacing: 10,
            mainAxisSpacing: 10),
        itemCount: widget.availableColors.length,
        itemBuilder: (context, index) {
          final itemColor = widget.availableColors[index];
          return InkWell(
            onTap: () {
              widget.onSelectColor(itemColor);
              setState(() {
                _pickedColor = itemColor;
              });
            },
            child: Container(
              width: 50,
              height: 50,
              decoration: BoxDecoration(
                  color: itemColor,
                  shape: widget.circleItem == true
                      ? BoxShape.circle
                      : BoxShape.rectangle,
                  border: Border.all(width: 1, color: Colors.grey.shade300)),
              child: itemColor == _pickedColor
                  ? const Center(
                      child: Icon(
                        Icons.check,
                        color: Colors.white,
                      ),
                    )
                  : Container(),
            ),
          );
        },
      ),
    );
  }
}

class TestColorScale extends StatelessWidget {
  final String text;
  final List<double> values;

  final double minValue;
  final Color minColor;

  final double maxValue;
  final Color maxColor;

  const TestColorScale({
    this.text = '',
    this.values = const [],
    this.minValue = -20,
    this.minColor = Colors.red,
    this.maxValue = 20,
    this.maxColor = Colors.green,
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text(text),
        Wrap(
          children: values
              .map(
                (value) => Container(
                  margin: const EdgeInsets.all(10),
                  child: ClipRRect(
                    borderRadius: const BorderRadius.all(Radius.circular(10.0)),
                    child: Container(
                      alignment: Alignment.bottomRight,
                      width: 60,
                      child: ColorScaleWidget(
                          value: value,
                          minValue: minValue,
                          minColor: minColor,
                          maxValue: maxValue,
                          maxColor: maxColor,
                          child: Container(
                            margin: const EdgeInsets.all(5),
                            child: Wrap(
                              crossAxisAlignment: WrapCrossAlignment.center,
                              alignment: WrapAlignment.end,
                              children: [
                                Text(
                                  'Value: ',
                                  style: Theme.of(context)
                                      .textTheme
                                      .bodyText2!
                                      .copyWith(fontSize: 10),
                                ),
                                Center(
                                  child: FittedBox(
                                      fit: BoxFit.scaleDown,
                                      child: Text(
                                        '${value.toStringAsFixed(2)}%',
                                      )),
                                ),
                              ],
                            ),
                          )),
                    ),
                  ),
                ),
              )
              .toList(),
        ),
        const SizedBox(
          height: 50,
        )
      ],
    );
  }
}

class StopsValueAndColorsWidget extends StatefulWidget {
  final Map<double, Color> colorStops;

  const StopsValueAndColorsWidget({
    required this.colorStops,
    super.key,
  });

  @override
  State<StopsValueAndColorsWidget> createState() =>
      _StopsValueAndColorsWidgetState();
}

class _StopsValueAndColorsWidgetState extends State<StopsValueAndColorsWidget> {
  Map<double, Color> colorStops = {};
  double value = 0;

  @override
  void initState() {
    super.initState();

    colorStops = widget.colorStops;
  }

  @override
  Widget build(BuildContext context) {
    int i = 0;

    return Card(
      child: Container(
        margin: const EdgeInsets.all(10),
        child: Column(
          children: [
            Column(
              children: colorStops.keys.map((stopValue) {
                i++;
                Color stopColor = colorStops[stopValue]!;
                return Column(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    MyColorPicker(
                      onSelectColor: (color) => setState(() {
                        colorStops[stopValue] = color;
                      }),
                      initialColor: stopColor,
                      availableColors: [
                        Colors.red,
                        Colors.green,
                        Colors.yellow,
                        Colors.purple.withOpacity(0.25),
                        Colors.pink.withOpacity(0.5)
                      ],
                    ),
                    Container(
                      width: 100,
                      margin: const EdgeInsets.only(bottom: 10),
                      child: TextField(
                        keyboardType: TextInputType.number,
                        controller:
                            TextEditingController(text: stopValue.toString()),
                        onChanged: (inputValue) => setState(() {
                          double newValue = double.parse(inputValue);
                          colorStops.remove(stopValue);
                          colorStops[newValue] = stopColor;
                        }),
                        decoration: InputDecoration(
                          label: Text('Stop $i'),
                        ),
                      ),
                    ),
                  ],
                );
              }).toList(),
            ),
            Slider(
                min: colorStops.keys.first,
                max: colorStops.keys.last,
                value: value,
                onChanged: onSliderMove),
            ClipRRect(
              borderRadius: const BorderRadius.all(Radius.circular(10.0)),
              child: ColorScaleStopsWidget(
                value: value,
                colorStops: colorStops,
                child: Container(
                  margin: const EdgeInsets.all(5),
                  child: Column(
                    children: [
                      const Text('Slide between diferent stops'),
                      Text('value: ${value.toStringAsFixed(2)}')
                    ],
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  void onSliderMove(double value) {
    setState(() {
      this.value = value;
    });
  }
}