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React Art and Paths.js

AuthorJason Brown

Intro

Paths.js is a cool library. It comes with 3 levels of generating paths.

  • Low level which helps you generate paths/lines.
  • Mid level which generates paths for shapes
  • High level which takes a set of data and generates graphs

All of these are great when working with react-art because it's just returning data. I'll say it once, and a million more but libraries that just generate data make it easy to traverse and render with react-art.

Paths

UPDATE:

Sebastian Markbage (the creator of ReactART and ART), informed me that ReactART itself has a Path implementation. I realized this but didn't think much of it. However per the discussion here https://discuss.reactjs.org/t/react-art-with-paths-js/492 the ART path is faster as it takes advantage of the current mode to create the most efficient path instead of taking a string and converting it back into native for instructions for canvas rendering.

The ReactART.Path has similar methods. Check out the discuss thread for a link to the implementation to find out the supported methods. I'm currently working on ReactART documentation so expect that soon.

Example:

var path = Path()
  .moveto(10, 20)
  .lineto(30, 50)
  .lineto(25, 28)
  .qcurveto(27, 30, 32, 27)
  .closepath();

This is can just be plugged right into react-art Shape element.

Like so

var React = require('react'),
    ReactArt = require('react-art'),
    Surface = ReactArt.Surface,
    Shape = ReactArt.Shape,
    Path = require('paths-js/path');

var Demo = React.createClass({
    getInitialState: function() {
        return {
            to: {
                x: 30,
                y: 50
            }
        }
    },
    getPath: function() {
        var path = Path()
                      .moveto(10, 20)
                      .lineto(this.state.to.x, this.state.to.y)
                      .lineto(25, 28)
                      .qcurveto(27, 30, 32, 27)
                      .closepath();

        return path.print();
    },
    startAnimating: function() {

        if (this.state.to.x === 100) {
            this.addToPosition = -1;
        } else if (this.state.to.x === 29) {
            this.addToPosition = 1;
        }

        this.state.to.x += this.addToPosition;
        this.state.to.y += this.addToPosition;

        this.setState(this.state);
    },
    componentDidMount: function() {
        this.addToPosition = 1;
        setInterval(this.startAnimating, 17)
    },
    render: function() {
        return (
            <div>
                <Surface
                    width={500}
                    height={500}
                >
                    <Shape d={this.getPath()} stroke="#000" strokeWidth={1} />
                </Surface>
            </div>
        )
    }
});

module.exports = Demo;

Simple Shapes

Now react-art already comes with a few different shapes but paths.js have a few built in as well, like Rectangle and Bezier curve.

var rectangle = Rectangle({
  top: 10,
  bottom: 3,
  left: -2,
  right: 5
});

And how that looks is very similar to the previous example

var React = require('react'),
    ReactArt = require('react-art'),
    Surface = ReactArt.Surface,
    Group = ReactArt.Group,
    Shape = ReactArt.Shape,
    Rectangle = require('paths-js/rectangle'),
    Bezier = require('paths-js/bezier');

var Demo = React.createClass({
    getPath: function() {
        var rectangle = Rectangle({
                      top: 10,
                      bottom: 3,
                      left: -2,
                      right: 5
                    });

        return rectangle.path.print();
    },
    getBez: function() {
        var points = [[1, 50], [50, 100], [100, 3], [4, 0]];
        var curve = Bezier({
          points: points,
          tension: 0.2
        });

        return curve.path.print();
    },
    render: function() {
        return (
            <div>
                <Surface
                    width={500}
                    height={500}
                >
                    <Group x={100} y={100}>
                        <Shape d={this.getPath()} stroke="#000" strokeWidth={1} />
                    </Group>
                    <Group x={200} y={200}>
                        <Shape d={this.getBez()} stroke="#000" strokeWidth={1} />
                    </Group>
                </Surface>
            </div>
        )
    }
});

module.exports = Demo;

Graphs

var pie = Pie({
  data: [
    { name: 'Italy', population: 59859996 },
    { name: 'Mexico', population: 118395054 },
    { name: 'France', population: 65806000 },
    { name: 'Argentina', population: 40117096 },
    { name: 'Japan', population: 127290000 }
  ],
  accessor: function(x) { return x.population; },
  compute: {
    color: function(i) { return somePalette[i]; }
  },
  center: [20, 15],
  r: 30,
  R: 50
});

Some code of it in action

var React = require('react'),
    ReactArt = require('react-art'),
    Surface = ReactArt.Surface,
    Group = ReactArt.Group,
    Shape = ReactArt.Shape,
    Pie = require('paths-js/Pie');


var pie = Pie({
  data: [
    { name: 'Italy', population: 59859996 },
    { name: 'Mexico', population: 118395054 },
    { name: 'France', population: 65806000 },
    { name: 'Argentina', population: 40117096 },
    { name: 'Japan', population: 127290000 }
  ],
  accessor: function(x) { return x.population; },
  compute: {
    color: function(i) { return '#000'; }
  },
  center: [20, 15],
  r: 30,
  R: 50
});

var Demo = React.createClass({

    getPie: function() {
        return pie.curves.map(function(shape) {
            return (
                <Group>
                    <Text fill="#A6BD8A" font='bold 12px "Arial"' x={shape.sector.centroid[0] - 12} y={shape.sector.centroid[1]}>{shape.item.name}</Text>
                    <Shape d={shape.sector.path.print()} stroke={shape.color} strokeWidth={1} />
                </Group>
            )
        })
    },
    render: function() {
        return (
            <div>
                <Surface
                    width={500}
                    height={500}
                >
                    <Group x={50} y={45}>
                        {this.getPie()}
                    </Group>
                </Surface>
            </div>
        )
    }
});


module.exports = Demo;

Conclusion

These examples may look boring but they just show off a bit of the control you can have with react-art and a simple path generator. Not only that but because we aren't depending on the DOM in any case these examples should also work on react-native. Combined with some tweening you could make some very effective graphs that animate. That is a topic for another time.

Demo

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