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This is a Dart implementation of the Processing API that can be used to program interactive graphics in a Flutter application.

p5.dart #

A Dart implementation of the Processing API for Flutter. Processing is a software sketchbook and a language for learning how to code within the context of the visual arts.

Note: this is an experimental library that only implements a few functions from the Processing API. Class names and structure will likely change in the future. And feel free to fork and play around with the code :-)

Getting Started #

Add the p5 package to your Flutter app. For help using packages, see Flutter's online documentation.

You need to implement the widget containing the Processing sketch, and the sketch itself.

A simple widget tree is the follwing:

import 'package:flutter/material.dart';

import "package:p5/p5.dart";
import "sketch.dart";

void main() => runApp(new MyApp());

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;
  @override
  _MyHomePageState createState() {
    return new _MyHomePageState();
  }
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'P5 Demo',
      theme: new ThemeData(
        // This is the theme of your application.
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'P5 Demo Home Page'),
    );
  }
}

class _MyHomePageState extends State<MyHomePage> with SingleTickerProviderStateMixin {
  MySketch sketch;
  PAnimator animator;

  @override
  void initState() {
    super.initState();
    sketch = new MySketch();
    // Need an animator to call the draw() method in the sketch continuously,
    // otherwise it will be called only when touch events are detected.
    animator = new PAnimator(this);
    animator.addListener(() {
      setState(() {
        sketch.redraw();
      });
    });
    animator.run();
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(title: new Text("P5 Draw!")),
      backgroundColor: const Color.fromRGBO(200, 200, 200, 1.0),
      body: new Center(
        child:new PWidget(sketch),
      ),
    );
  }
}

The MySketch class has to extend the base PPainter class in the p5 package, and implement the setup() and draw() functions, just like in Processing sketch:

class MySketch extends PPainter {
  void setup() {
    size(300, 300);
  }

  void draw() {
    background(color(255, 255, 255));
  }
}

Both pieces of code can be inside single dart file, or on separate files for better clarity.

A simple drawing sketch can be implemented by handling the mouse dragging, and storing the pointer positions in a list of PVector object holding the (x, y) coordinates, which are then used to draw lines:

class MySketch extends PPainter {
  var strokes = new List<List<PVector>>();

  void setup() {
    fullScreen();
  }

  void draw() {
    background(color(255, 255, 255));

    noFill();
    strokeWeight(10);
    stroke(color(10, 40, 200, 60));
    for (var stroke in strokes) {
      beginShape();
      for (var p in stroke) {
        vertex(p.x, p.y);
      }
      endShape();
    }
  }

  void mousePressed() {
    strokes.add([new PVector(mouseX, mouseY)]);
  }

  void mouseDragged() {
    var stroke = strokes.last;
    stroke.add(new PVector(mouseX, mouseY));
  }
}

Notice that the size of the drawing area can be made to fill the entire app by using fullScreen(). The app should give similar results for both iOS and Android.

For help getting started with Flutter, view our online documentation.

For help on editing package code, view the documentation.

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This is a Dart implementation of the Processing API that can be used to program interactive graphics in a Flutter application.

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License

Icon for licenses.BSD-3-Clause (LICENSE)

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flutter

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