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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.

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