dart(freeform-gradient): feat: implementation

Signed-off-by: prescientmoon <git@moonythm.dev>

dart/freeform-gradient/README.md

@@ -1,16 +1,10 @@
-# Hello World application with Flutter + Nix
+# Flutter freeform gradiant
 
 This is a demonstration project to show usage of Flutter with Nix.
 
 ## Getting Started
 
-If you have `direnv` installed, run:
+Enter in the `nix-shell`:
-
-```sh
-direnv allow
-```
-
-Otherwise, enter in the `nix-shell`:
 
 ```sh
 nix-shell
@@ -29,49 +23,3 @@ flutter run
 ```
 
 If you have any issue, you can run `flutter doctor` to get a diagnostic and potential solution to fix your issues.
-
-## How to use it with your projects
-
-Create a `shell.nix` file with this content:
-
-```nix
-{ pkgs ? import <nixpkgs> {} }:
-
-let
-  flutter = (import (builtins.fetchTarball
-    "https://github.com/babariviere/nixpkgs/archive/flutter-init.tar.gz") {}).flutter; # this will be replaced when merged into NixOS
-in pkgs.mkShell {
-  buildInputs = [ flutter ];
-}
-```
-
-After this, enter into your nix-shell and you are good to go.
-
-## Updating
-
-### To update the whole environment, do the following in order:
-
-- `niv init` will update nix/sources.nix if a new one is available
-- Make sure you have a backup of your nix/sources.json. If you're not in a git repo or use another vcs: `cp nix/sources.json nix/sources.json.bak`
-- `niv update` will update sources.json i.e. your version of nixpkgs used in this environment
-  - you may need to edit nix/android.nix if any of the attributes in there can't be found after this.
-- `direnv reload` will rebuild/reload your environment (may not be necessary if it automatically reloads)
-  - alternatively, run `nix-shell` again (?) 
-- `flutter packages update` to update flutter/dart packages and get rid of the warning that you're using a different version of flutter than what was last referenced 
-
-## Global install
-
-If you want to install `flutter` on your system, add this to your `/etc/nixos/configuration.nix`:
-
-```nix
-{
-  environment.systemPackages = [
-    (import (builtins.fetchTarball
-        "https://github.com/babariviere/nixpkgs/archive/flutter-init.tar.gz") {}).flutter
-  ];
-}
-```
-
-## Have an issue ?
-
-Create an issue on this repository with your issue and I will try to help you as much as I can !

dart/freeform-gradient/lib/main.dart

@@ -1,111 +1,212 @@
+import 'dart:math';
+
 import 'package:flutter/material.dart';
+import 'dart:ui' as ui;
+import 'dart:async';
+import 'dart:typed_data';
+import 'package:vector_math/vector_math.dart' as vector;
 
-void main() => runApp(MyApp());
+void main() => runApp(Root());
 
-class MyApp extends StatelessWidget {
+class Root extends StatefulWidget {
-  // This widget is the root of your application.
+  const Root({
-  @override
+    Key key,
-  Widget build(BuildContext context) {
+  }) : super(key: key);
-    return MaterialApp(
-      title: 'Flutter Demo',
-      theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // Try running your application with "flutter run". You'll see the
-        // application has a blue toolbar. Then, without quitting the app, try
-        // changing the primarySwatch below to Colors.green and then invoke
-        // "hot reload" (press "r" in the console where you ran "flutter run",
-        // or simply save your changes to "hot reload" in a Flutter IDE).
-        // Notice that the counter didn't reset back to zero; the application
-        // is not restarted.
-        primarySwatch: Colors.blue,
-      ),
-      home: MyHomePage(title: 'Flutter Demo Home Page'),
-    );
-  }
-}
-
-class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
-
-  // This widget is the home page of your application. It is stateful, meaning
-  // that it has a State object (defined below) that contains fields that affect
-  // how it looks.
-
-  // This class is the configuration for the state. It holds the values (in this
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
-
-  final String title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  RootState createState() => RootState();
 }
 
-class _MyHomePageState extends State<MyHomePage> {
+class RootState extends State<Root> {
-  int _counter = 0;
+  double angle = 0;
 
-  void _incrementCounter() {
+  @override
-    setState(() {
+  initState() {
-      // This call to setState tells the Flutter framework that something has
+    super.initState();
-      // changed in this State, which causes it to rerun the build method below
+
-      // so that the display can reflect the updated values. If we changed
+    Timer.periodic(Duration(milliseconds: 10), (timer) {
-      // _counter without calling setState(), then the build method would not be
+      setState(() {
-      // called again, and so nothing would appear to happen.
+        angle += 0.04;
-      _counter++;
+      });
     });
   }
 
   @override
   Widget build(BuildContext context) {
-    // This method is rerun every time setState is called, for instance as done
+    return MaterialApp(
-    // by the _incrementCounter method above.
+      title: 'Custom gradient',
-    //
+      theme: ThemeData(
-    // The Flutter framework has been optimized to make rerunning build methods
+        primarySwatch: Colors.purple,
-    // fast, so that you can just rebuild anything that needs updating rather
-    // than having to individually change instances of widgets.
-    return Scaffold(
-      appBar: AppBar(
-        // Here we take the value from the MyHomePage object that was created by
-        // the App.build method, and use it to set our appbar title.
-        title: Text(widget.title),
       ),
-      body: Center(
+      home: MyHomePage(
-        // Center is a layout widget. It takes a single child and positions it
+          title: 'Multi point gradient',
-        // in the middle of the parent.
+          config: MultiGradientConfig(
-        child: Column(
+              distanceScaling: 1,
-          // Column is also a layout widget. It takes a list of children and
+              blendStrength: 2,
-          // arranges them vertically. By default, it sizes itself to fit its
+              points: [
-          // children horizontally, and tries to be as tall as its parent.
+                MultiGradientPoint(
-          //
+                  color: Colors.yellow,
-          // Invoke "debug painting" (press "p" in the console, choose the
+                  intensity: 1.0,
-          // "Toggle Debug Paint" action from the Flutter Inspector in Android
+                  position: vector.Vector2(
-          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
+                      1.0 / 2 + cos(angle) * 0.3, 1.0 / 2 + sin(angle) * 0.3),
-          // to see the wireframe for each widget.
+                ),
-          //
+                MultiGradientPoint(
-          // Column has various properties to control how it sizes itself and
+                    color: Color(0xff6E10AB),
-          // how it positions its children. Here we use mainAxisAlignment to
+                    intensity: 1,
-          // center the children vertically; the main axis here is the vertical
+                    position: vector.Vector2(0.1, 0.09)),
-          // axis because Columns are vertical (the cross axis would be
+                MultiGradientPoint(
-          // horizontal).
+                    color: Color(0xff041E1C),
-          mainAxisAlignment: MainAxisAlignment.center,
+                    intensity: 2,
-          children: <Widget>[
+                    position: vector.Vector2(0.84, 0.14)),
-            Text(
+                MultiGradientPoint(
-              'You have pushed the button this many times:',
+                    color: Color(0xff015BBB),
-            ),
+                    intensity: 1,
-            Text(
+                    position: vector.Vector2(0.07, 0.93)),
-              '$_counter',
+                MultiGradientPoint(
-              style: Theme.of(context).textTheme.display1,
+                    color: Color(0xff06A599),
-            ),
+                    intensity: 1,
-          ],
+                    position: vector.Vector2(0.9, 0.94))
-        ),
+              ])),
-      ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: _incrementCounter,
-        tooltip: 'Increment',
-        child: Icon(Icons.add),
-      ), // This trailing comma makes auto-formatting nicer for build methods.
     );
   }
 }
+
+class MyHomePage extends StatelessWidget {
+  MyHomePage({Key key, this.title, this.config}) : super(key: key);
+
+  final String title;
+  final MultiGradientConfig config;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(title),
+      ),
+      body: Center(
+          child: FutureBuilder<ui.Image>(
+        future: generateImage(MediaQuery.of(context).size, config),
+        builder: (context, snapshot) {
+          if (snapshot.hasData) {
+            MediaQueryData query = MediaQuery.of(context);
+            return CustomPaint(
+                child: Container(
+                  width: query.size.width,
+                  height: query.size.height,
+                ),
+                painter: ImagePainter(image: snapshot.data));
+          }
+
+          return Text("Generating image");
+        },
+      )),
+    );
+  }
+}
+
+class ImagePainter extends CustomPainter {
+  ui.Image image;
+
+  ImagePainter({this.image});
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    canvas.drawImage(image, Offset.zero, Paint());
+  }
+
+  @override
+  bool shouldRepaint(ImagePainter oldDelegate) {
+    return oldDelegate.image != image;
+  }
+}
+
+/// Generates a [ui.Image] with certain pixel data
+Future<ui.Image> generateImage(Size size, MultiGradientConfig config) async {
+  int width = size.width.ceil();
+  int height = size.height.ceil();
+  var completer = Completer<ui.Image>();
+
+  Int32List pixels = Int32List(width * height);
+
+  for (var x = 0; x < width; x++) {
+    for (var y = 0; y < height; y++) {
+      int index = y * width + x;
+      pixels[index] = generatePixel(x, y, size, config);
+    }
+  }
+
+  ui.decodeImageFromPixels(
+    pixels.buffer.asUint8List(),
+    width,
+    height,
+    ui.PixelFormat.bgra8888,
+    (ui.Image img) {
+      completer.complete(img);
+    },
+  );
+
+  return completer.future;
+}
+
+class MultiGradientPoint {
+  double intensity;
+  vector.Vector4 color;
+  vector.Vector2 position;
+
+  MultiGradientPoint({Color color, this.position, this.intensity = 1}) {
+    this.color = vector.Vector4(color.red.toDouble(), color.green.toDouble(),
+        color.blue.toDouble(), color.opacity);
+  }
+}
+
+class MultiGradientConfig {
+  List<MultiGradientPoint> points;
+
+  double distanceScaling;
+  double blendStrength;
+  double opacityMultiplier = 1;
+
+  MultiGradientConfig(
+      {this.points,
+      this.distanceScaling = 1,
+      this.blendStrength = 3,
+      this.opacityMultiplier = 1});
+}
+
+double clamp(double min, double max, double value) {
+  if (value < min) return min;
+  if (value > max) return max;
+
+  return value;
+}
+
+/// Main area of interest, this function will
+/// return color for each particular color on our [ui.Image]
+int generatePixel(int x, int y, Size size, MultiGradientConfig config) {
+  vector.Vector4 color = vector.Vector4(0, 0, 0, 0);
+  double scale = 0;
+
+  var current = vector.Vector2(x.toDouble(), y.toDouble());
+
+  current.divide(vector.Vector2(size.width, size.height));
+
+  for (var i = 0; i < config.points.length; i++) {
+    MultiGradientPoint point = config.points[i];
+
+    var distance = pow(
+        1 - point.position.distanceTo(current) / config.distanceScaling,
+        config.blendStrength);
+    var multiplier = distance * point.intensity;
+
+    scale += multiplier;
+    color += point.color.scaled(multiplier);
+  }
+
+  if (scale != 0) {
+    color.scale(1 / scale);
+  }
+
+  return Color.fromRGBO(color.x.toInt(), color.y.toInt(), color.z.toInt(),
+          color.w * config.opacityMultiplier)
+      .value;
+}

dart/freeform-gradient/pubspec.yaml

@@ -1,16 +1,6 @@
 name: hello_world
 description: A new Flutter project.
 
-# The following defines the version and build number for your application.
-# A version number is three numbers separated by dots, like 1.2.43
-# followed by an optional build number separated by a +.
-# Both the version and the builder number may be overridden in flutter
-# build by specifying --build-name and --build-number, respectively.
-# In Android, build-name is used as versionName while build-number used as versionCode.
-# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
-# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
-# Read more about iOS versioning at
-# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 version: 1.0.0+1
 
 environment:
@@ -20,21 +10,17 @@ dependencies:
   flutter:
     sdk: flutter
 
-  # The following adds the Cupertino Icons font to your application.
-  # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^0.1.2
 
 dev_dependencies:
   flutter_test:
     sdk: flutter
 
-
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec
 
 # The following section is specific to Flutter.
 flutter:
-
   # The following line ensures that the Material Icons font is
   # included with your application, so that you can use the icons in
   # the material Icons class.

dart/freeform-gradient/test/widget_test.dart

@@ -13,7 +13,7 @@ import 'package:hello_world/main.dart';
 void main() {
   testWidgets('Counter increments smoke test', (WidgetTester tester) async {
     // Build our app and trigger a frame.
-    await tester.pumpWidget(MyApp());
+    await tester.pumpWidget(Root());
 
     // Verify that our counter starts at 0.
     expect(find.text('0'), findsOneWidget);