canvas

A simple object to draw on an HTML canvas.

Node Repository

https://www.npmjs.com/package/@pelevesque/canvas

Example

@see index.html

Installation

npm install @pelevesque/canvas

Tests

Standard Style

npm test

Methods

• setOptions sets options
• resize resizes the canvas
• clear clears the canvas
• loadImage loads an image
• loadImages loads multiple images
• image draws an image
• imageResized draws an image with resizing
• imageClipped draws an image with clipping
• text draws text
• textCompressed draws text with a max width
• line draws a line
• lines draws multiple lines
• polyline draws a line with many segments
• quadraticCurve draws a quadratic curve
• polygon draws a polygon
• circle draws a circle
• rectangle draws a rectangle
• square draws a square
• getMousePosition gets the mouse position

Usage

Initialization

When initializing canvas, you must provide it with the HTML id of the canvas you wish to use. Optionally, you may also override some default params by passing an object as the second argument.

// Initialize canvas without params.
const canvas = new Canvas(id)

// Initialize canvas with overriding some params.
const canvas = new Canvas(id, {
  backgroundColor: '#555555',
  color: '#ffffff'
})

// List of default params.
defaultParams = {
  globalCompositeOperationDefault: 'source-over',
  backgroundColor: 'none',
  backgroundImage: 'none',
  color: '#000000',
  border: 'none',
  font: '16px Arial',
  textAlign: 'center',
  textBaseline: 'middle',
  cursor: 'default'
}

Set Options

Sets options.

const options = {
  backgroundColor: '#336600',
  border: '1px solid #006600',
}
canvas.setOptions(options)

Resize

Resizes the canvas.

const width = 500
const height = 200
canvas.resize(width, height)

Clear

Clears the canvas.

canvas.clear()

Load Image

Loads an image.

canvas.loadImage(src)

Load Images

Loads multiple images.

canvas.loadImages(sources)

Image

Draws an image.

required params

canvas.image(src, x, y)

with optional params

canvas.image(src, x, y, globalCompositeOperation)

Image Resized

Draws an image with resizing.

required params

canvas.imageResized(src, x, y, width, height)

with optional params

canvas.imageResized(src, x, y, width, height, globalCompositeOperation)

Image Resized

Draws an image with clipping.

required params

canvas.imageClipped(src, sx, sy, swidth, sheight, x, y, width, height)

with optional params

canvas.imageClipped(src, sx, sy, swidth, sheight, x, y, width, height, globalCompositeOperation)

Text

Draws text.

fillStyle, font, textAlign, and textBaseline are optional.

const text = 'hello cruel world!'
const x = 10
const y = 10
const fillStyle = '#444444'
const font = '24px Helvetica'
const textAlign = 'left'
const textBaseline = 'bottom'
canvas.text(text, x, y, fillStyle, font, textAlign, textBaseline)

Text Compressed

Draws text with a max width.

fillStyle, font, textAlign, and textBaseline are optional.

const text = 'hello cruel world!'
const x = 10
const y = 10
const maxWidth = 30
const fillStyle = '#444444'
const font = '24px Helvetica'
const textAlign = 'left'
const textBaseline = 'bottom'
canvas.textCompressed(text, x, y, maxWidth, fillStyle, font, textAlign, textBaseline)

Line

Draws a line.

strokeStyle and strokeWidth are optional.

const x1 = 10
const y1 = 10
const x2 = 100
const y2 = 120
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.line(x1, y1, x2, y2, strokeStyle, strokeWidth)

Lines

Draws multiple lines.

strokeStyle and strokeWidth are optional.

const lines = [
  [10, 10, 100, 100],
  [25, 25, 200, 120],
  [30, 30, 400, 300]  
]
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.lines(lines, strokeStyle, strokeWidth)

Polyline

Draws a line with many segments.

strokeStyle and strokeWidth are optional.

const lines = [
  [10, 10],
  [25, 25],
  [200, 150],
  [120, 50]
]
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.polyline(lines, strokeStyle, strokeWidth)

Quadratic Curve

Draws a quadratic curve.

strokeStyle and strokeWidth are optional.

const x1 = 10
const y1 = 10
const x2 = 100
const y2 = 120
const qx = 50
const qy = 100
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.quadraticCurve(x1, y1, x2, y2, qx, qy, strokeStyle, strokeWidth)

Polygon

Draws a polygon.

fillStyle, strokeStyle, and strokeWidth are optional.

const coords = [
  [10, 10],
  [200, 20],
  [130, 100],
  [45, 70]
]
const fillStyle = '#ff0000'
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.polygon(coords, fillStyle, strokeStyle, strokeWidth)

Circle

Draws a circle.

fillStyle, strokeStyle, and strokeWidth are optional.

const cx = 10
const cy = 10
const radius = 40
const fillStyle = '#ff0000'
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.circle(cx, cy, radius, fillStyle, strokeStyle, strokeWidth)

Rectangle

Draws a rectangle.

fillStyle, strokeStyle, and strokeWidth are optional.

const x = 15
const y = 15
const w = 100
const h = 200
const fillStyle = '#ff0000'
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.rectangle(x, y, w, h, fillStyle, strokeStyle, strokeWidth)

Square

Draws a square.

fillStyle, strokeStyle, and strokeWidth are optional.

const x = 25
const y = 300
const w = 100
const fillStyle = '#ff0000'
const strokeStyle = '#666666'
const strokeWidth = '2'
canvas.square(x, y, w, fillStyle, strokeStyle, strokeWidth)

Get Mouse Position

Gets the mouse position.

const mousePosition = canvas.getMousePosition()
const x = mousePosition.x
const y = mousePosition.y