BMI calculator example

bmi_calculator/.gitignore

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+.DS_Store
+.dart_tool/
+
+.vscode/
+
+.packages
+.pub/
+
+.idea/
+.vagrant/
+.sconsign.dblite
+.svn/
+
+migrate_working_dir/
+
+*.swp
+profile
+
+DerivedData/
+
+.generated/
+
+*.pbxuser
+*.mode1v3
+*.mode2v3
+*.perspectivev3
+
+!default.pbxuser
+!default.mode1v3
+!default.mode2v3
+!default.perspectivev3
+
+xcuserdata
+
+*.moved-aside
+
+*.pyc
+*sync/
+Icon?
+.tags*
+
+build/
+.android/
+.ios/
+.flutter-plugins
+.flutter-plugins-dependencies
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json

bmi_calculator/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: f1875d570e39de09040c8f79aa13cc56baab8db1
+  channel: stable
+
+project_type: module

bmi_calculator/README.md

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+# bmi_calculator
+
+A person’s Body-Mass Index, or BMI, helps them check whether they’re a healthy weight for their height. If a person weighs less or more than the recommended weight for their height, it could lead to health issues in the future. While BMI is not the only factor individuals should consider while working on their health and fitness, it is a good starting point. To understand what your BMI is, you need to know your height and weight. You can then use an online BMI calculator to check your BMI, which will help you understand if you’re underweight, a healthy weight, overweight or obese. Or, you can measure your height in metres and weight in kilograms. Divide your weight by your height squared to calculate your BMI.
+
+BMI Calculator [Wiki](https://en.wikipedia.org/wiki/Body_mass_index)
+
+

bmi_calculator/analysis_options.yaml

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+include: package:flutter_lints/flutter.yaml
+
+# Additional information about this file can be found at
+# https://dart.dev/guides/language/analysis-options

bmi_calculator/lib/bmi_calculator.dart

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+import 'dart:math';
+
+import 'package:bmi_calculator/body_model.dart';
+
+// I've used weight/height^2 (kg/m^2)
+// You can expand this logic
+double calculateBMI({required BodyModel bodyModel}) {
+  return (bodyModel.weight) / pow(bodyModel.height / 100, 2);
+}

bmi_calculator/lib/body_model.dart

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+enum Sex {
+  male,
+  female,
+}
+
+// User body model class
+class BodyModel {
+  Sex sex;
+  int height;
+  int weight;
+  int age;
+
+  BodyModel({
+    required this.sex,
+    required this.height,
+    required this.weight,
+    required this.age,
+  });
+}

bmi_calculator/lib/calculator/calculate_button.dart

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+import 'package:flutter/material.dart';
+
+import '../palette.dart';
+
+class CalculateButton extends StatelessWidget {
+  const CalculateButton({
+    super.key,
+    required this.onTap,
+  });
+
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      height: MediaQuery.of(context).size.height / 12,
+      width: double.infinity,
+      decoration: BoxDecoration(
+        borderRadius: BorderRadius.circular(5),
+        color: Palette.action,
+      ),
+      child: TextButton(
+        style: ButtonStyle(
+          overlayColor:
+              MaterialStateProperty.all(Colors.white.withOpacity(0.10)),
+        ),
+        onPressed: onTap,
+        child: const Text(
+          'CALCULATE YOUR BMI',
+          style: TextStyle(
+            color: Palette.textActive,
+            fontSize: 20,
+          ),
+        ),
+      ),
+    );
+  }
+}

bmi_calculator/lib/calculator/calculator_body.dart

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+import 'package:bmi_calculator/calculator/calculate_button.dart';
+import 'package:flutter/material.dart';
+import 'package:bmi_calculator/calculator/height_widget.dart';
+import 'package:bmi_calculator/calculator/int_picker_widget.dart';
+import 'package:bmi_calculator/calculator/sex_widget.dart';
+import 'package:bmi_calculator/result/result_page.dart';
+import 'package:bmi_calculator/body_model.dart';
+import 'package:bmi_calculator/palette.dart';
+
+class CalculatorBody extends StatefulWidget {
+  const CalculatorBody({
+    super.key,
+    required this.model,
+  });
+
+  final BodyModel model;
+
+  @override
+  State<CalculatorBody> createState() => _CalculatorBodyState();
+}
+
+class _CalculatorBodyState extends State<CalculatorBody> {
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      color: Palette.background,
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 24.0),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+          children: [
+            SexWidget(
+                sex: widget.model.sex,
+                onMaleTap: () => setState(() {
+                      // Set sex to male
+                      widget.model.sex = Sex.male;
+                    }),
+                onFemaleTap: () => setState(() {
+                      // Set sex to female
+                      widget.model.sex = Sex.female;
+                    })),
+            HeightWidget(
+              height: widget.model.height,
+              onHeightChanged: (height) => setState(() {
+                // Set height and round to Int
+                widget.model.height = height.toInt();
+              }),
+            ),
+            SizedBox(
+              height: (MediaQuery.of(context).size.width - 48) / 2,
+              child: Row(
+                children: [
+                  Expanded(
+                    // Weight widget
+                    child: IntPickerWidget(
+                      title: 'Weight',
+                      onIncreaseTap: () => setState(() {
+                        // Increase weight
+                        widget.model.weight++;
+                      }),
+                      onDecreaseTap: () => setState(() {
+                        // Decrease weight
+                        widget.model.weight--;
+                      }),
+                      value: widget.model.weight,
+                    ),
+                  ),
+                  const SizedBox(
+                    width: 5,
+                  ),
+                  Expanded(
+                    // Age widget
+                    child: IntPickerWidget(
+                      title: 'Age',
+                      onIncreaseTap: () => setState(() {
+                        // Increase age
+                        widget.model.age++;
+                      }),
+                      onDecreaseTap: () => setState(() {
+                        // Decrease age
+                        widget.model.age--;
+                      }),
+                      value: widget.model.age,
+                    ),
+                  )
+                ],
+              ),
+            ),
+            CalculateButton(
+              onTap: () {
+                // Navigate to Result Page
+                Navigator.push(
+                  context,
+                  MaterialPageRoute(
+                    builder: ((context) => ResultPage(model: widget.model)),
+                  ),
+                );
+              },
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

bmi_calculator/lib/calculator/calculator_page.dart

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+import 'package:bmi_calculator/calculator/calculator_body.dart';
+import 'package:flutter/material.dart';
+import 'package:bmi_calculator/body_model.dart';
+import 'package:bmi_calculator/palette.dart';
+
+class CalculatorPage extends StatelessWidget {
+  CalculatorPage({
+    Key? key,
+    required this.title,
+  }) : super(key: key);
+
+  final String title;
+
+  final BodyModel model = BodyModel(
+    sex: Sex.male,
+    height: 183,
+    weight: 74,
+    age: 19,
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(title),
+        backgroundColor: Palette.background,
+      ),
+      body: CalculatorBody(model: model),
+    );
+  }
+}

bmi_calculator/lib/calculator/height_widget.dart

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+import 'package:flutter/material.dart';
+
+import '../palette.dart';
+
+class HeightWidget extends StatelessWidget {
+  const HeightWidget({
+    super.key,
+    required this.height,
+    required this.onHeightChanged,
+  });
+
+  final int height;
+  final Function(double) onHeightChanged;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      height: (MediaQuery.of(context).size.width - 48) / 2,
+      width: double.infinity,
+      decoration: BoxDecoration(
+        borderRadius: BorderRadius.circular(5),
+        color: Palette.cardBackgroundInactive,
+      ),
+      child: Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [
+          const Text(
+            'HEIGHT',
+            style: TextStyle(
+              fontSize: 23,
+              fontWeight: FontWeight.w600,
+              color: Palette.textInactive,
+            ),
+          ),
+          Row(
+            mainAxisAlignment: MainAxisAlignment.center,
+            crossAxisAlignment: CrossAxisAlignment.baseline,
+            textBaseline: TextBaseline.alphabetic,
+            children: [
+              Text(
+                height.round().toString(),
+                style: const TextStyle(
+                  fontSize: 50,
+                  fontWeight: FontWeight.w800,
+                  color: Palette.textActive,
+                ),
+              ),
+              const Text(
+                'cm',
+                style: TextStyle(
+                  fontSize: 30,
+                  color: Palette.textInactive,
+                ),
+              ),
+            ],
+          ),
+          Padding(
+            padding: const EdgeInsets.symmetric(
+              horizontal: 24.0,
+            ),
+            child: SliderTheme(
+              data: SliderTheme.of(context).copyWith(
+                trackHeight: 1.0,
+                thumbShape: const RoundSliderThumbShape(
+                  enabledThumbRadius: 15,
+                ),
+              ),
+              child: Slider(
+                value: height.toDouble(),
+                min: 150.0,
+                max: 210.0,
+                activeColor: Palette.textActive,
+                inactiveColor: Palette.textInactive,
+                thumbColor: Palette.action,
+                onChanged: onHeightChanged,
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}