shape-builder.js

A library to draw shapes and text in JavaScript.

Install

npm install shape-builder
# or
yarn add shape-builder

The dist folder of this package contains files:

• shape-builder.min.js. A minified JavaScript code for running in a browser.
• shape-builder.node.js. For running in Node.

Usage

import { Builder, shapes } from "shape-builder";

const { Point, Rectangle } = shapes;

// Get a context
const context = document.getElementById("canvas").getContext("2d");

// Create a shape builder
const builder = new Builder();

builder
    // Add the shapes
    .addShape(
        new Rectangle(new Point(0, 0), 300, 300, {
            fillColor: "lightskyblue",
        })
    )
    .addShape(
        new Rectangle(new Point(10, 10), 180, 180, {
            fillColor: "yellow",
            borderColor: "orange",
        })
    )

    // An alternative way to add the shapes
    // .addShapes(
    //     new Rectangle(new Point(0, 0), 300, 300, {
    //         fillColor: "lightskyblue",
    //     }),
    //     new Rectangle(new Point(10, 10), 180, 180, {
    //         fillColor: "yellow",
    //         borderColor: "orange",
    //     })
    // )

    // Remove last shape if needed
    // .removeShapes(1)
    // or remove all shapes
    // .removeShapes()

    // Draw the shapes in the image context
    .draw(context);

// or use svg
const playground = document.getElementById("playground");

playground.innerHTML = builder.draw(
    playground.getClientRects()[0].width, 
    playground.getClientRects()[0].height
);

You can draw a shape without creating the shape builder:

new Rectangle(new Point(0, 0), 300, 300, {
    fillColor: "lightskyblue",
}).draw(context);

Another way to use the shape builder is to first create a shape array:

// Add the shapes to a shape array
const shapeArray = [];

shapeArray.push(
    new Rectangle(new Point(0, 0), 300, 300, {
        fillColor: "lightskyblue",
    })
);

shapeArray.push(
    new Rectangle(new Point(10, 10), 180, 180, {
        fillColor: "yellow",
        borderColor: "orange",
    })
);

// Create a shape builder
const builder = new Builder(shapes);

// Draw the shapes
builder.draw(context);

The Point object is used to set a coordinate point. The image coordinates are counted from the top-left corner.

See more examples in logo.js and sine.js. To view the page in a browser, please clone the repo and run a server:

npm start

Running in Node.js

You need to install an additional package node-canvas to run the shape-builder in Node.js.

npm install canvas

The following code shows an example of usage the node-canvas and the shape-builder in Node.js.

const { createCanvas } = require("canvas");
const { shapes, Builder } = require("shape-builder");

const { Point, Rectangle } = shapes;

const canvas = createCanvas(400, 400);
const context = canvas.getContext("2d");

// Create a shape builder
const builder = new Builder();

builder
    // Add the shapes
    .addShape(
        new Rectangle(new Point(0, 0), 300, 300, {
            fillColor: "lightskyblue",
        })
    )
    .addShape(
        new Rectangle(new Point(10, 10), 180, 180, {
            fillColor: "yellow",
            borderColor: "orange",
        })
    )
    // Draw the shapes in the image context
    .draw(context);

console.log('<img src="' + canvas.toDataURL() + '" />');

// or use svg
const svg = builder.draw(500, 500);

console.log(svg);

Shapes

The current version includes the following shapes:

Circle

Circle (
    center: Point, 
    radius: number, 
    options?: {
        fillColor?: string,
        borderColor?: string,
        thickness?: number,
        dash?: number[]
    }
)

Curve

Curve(
    points: Point[], 
    options?: {
        fillColor?: string,
        borderColor?: string,
        thickness?: number,
        dash?: number[]
    }
)

Line

Line(
    start: Point, 
    end: Point, 
    options?: {
        color?: string,
        thickness?: number,
        dash?: number[]
    }
)

Rectangle

Rectangle(
    coordinates: Point, 
    width: number, 
    height: number, 
    options?: {
        fillColor?: string;
        borderColor?: string;
        thickness?: number;
        dash?: number[];
    }
)

Text

Text(
    coordinates: Point,
    text: string, 
    options?: {
        color?: string,
        font?: {
            family?: string,
            size?: string,
            weight?: string,
            style?: string,
            kerning?: CanvasFontKerning,
            stretch?: CanvasFontStretch,
            variant?: CanvasFontVariantCaps,
            lineHeight?: string
        },
        text?: {
            align: CanvasTextAlign,
            baseline: CanvasTextBaseline,
        },
        rotate?: number;
    }
)

To measure a text you can use the measure method. This static method returns the TextMetrics interface.

Text.measure(
    context: CanvasRenderingContext2D,
    text: string,
    font?: {
        family?: string,
        size?: string,
        weight?: string,
        style?: string,
        kerning?: CanvasFontKerning,
        stretch?: CanvasFontStretch,
        variant?: CanvasFontVariantCaps,
        lineHeight?: string
    }
);

To fit a text into a box use the fitIntoBox method. This static method returns a font size in pixels to fill the text in the box.

Text.fitIntoBox(
    context: CanvasRenderingContext2D,
    text: string,
    boxSize: { width: number, height: number },
    font?: {
        family?: string,
        size?: string, // in px
        weight?: string,
        style?: string,
        kerning?: CanvasFontKerning,
        stretch?: CanvasFontStretch,
        variant?: CanvasFontVariantCaps,
        lineHeight?: string
    }
)

License (MIT)

See License File.