litecanvas
Version:
Lightweight HTML5 canvas 2D game engine suitable for small projects and creative coding. Inspired by PICO-8 and P5/Processing.
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JavaScript
// @ts-check
import { setupZzFX } from './zzfx.js'
import { defaultPalette } from './palette.js'
import { assert } from './dev.js'
import { version } from './version.js'
/**
* The litecanvas constructor
*
* @param {LitecanvasOptions} [settings]
* @returns {LitecanvasInstance}
*/
export default function litecanvas(settings = {}) {
const /** @type {Window} */
root = window,
math = Math,
TWO_PI = math.PI * 2,
raf = requestAnimationFrame,
/** @type {Function[]} */
_browserEventListeners = [],
/** @type {(elem: EventTarget, evt: string, callback: (event: Event) => void) => void} */
on = (elem, evt, callback) => {
elem.addEventListener(evt, callback, false)
_browserEventListeners.push(() => elem.removeEventListener(evt, callback, false))
},
/** @type {(c: CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D) => void} */
beginPath = (c) => c.beginPath(),
isNumber = Number.isFinite,
zzfx = setupZzFX(root),
/** @type {LitecanvasOptions} */
defaults = {
width: null,
height: null,
autoscale: true,
pixelart: false,
canvas: null,
global: true,
loop: null,
tapEvents: true,
keyboardEvents: true,
animate: true,
}
// setup the settings default values
settings = Object.assign(defaults, settings)
let /** @type {boolean} */
_initialized = false,
/** @type {any[]} */
_plugins = [],
/** @type {HTMLCanvasElement} _canvas */
_canvas,
/** @type {number} */
_scale = 1,
/** @type {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} */
_ctx,
/** @type {number} */
_outline_fix = 0.5,
/** @type {number} */
_timeScale = 1,
/** @type {number} */
_lastFrameTime,
/** @type {number} duration of a frame at 60 FPS (default) */
_deltaTime = 1 / 60,
/** @type {number} */
_accumulated = 0,
/** @type {number?} */
_rafid,
/** @type {string} */
_fontFamily = 'sans-serif',
/** @type {number} */
_fontSize = 20,
/** @type {number} */
_rngSeed = Date.now(),
/** @type {string[]} */
_colors = defaultPalette,
/** @type {number[]} */
_defaultSound = [0.5, 0, 1750, , , 0.3, 1, , , , 600, 0.1],
/** @type {string} */
_coreEvents = 'init,update,draw,tap,untap,tapping,tapped,resized',
/** @type {string} list of functions copied from `Math` module*/
_mathFunctions =
'PI,sin,cos,atan2,hypot,tan,abs,ceil,floor,trunc,min,max,pow,sqrt,sign,exp',
/**
* @type {Object<string,Set<Function>>} game event listeners
*/
_eventListeners = {}
/** @type {LitecanvasInstance} */
const instance = {
/** @type {number} */
W: 0,
/** @type {number} */
H: 0,
/** @type {number} */
T: 0,
/** @type {number} */
MX: -1,
/** @type {number} */
MY: -1,
/** MATH API */
/**
* Twice the value of the mathematical constant PI (π).
* Approximately 6.28318
*
* Note: TWO_PI radians equals 360°, PI radians equals 180°,
* HALF_PI radians equals 90°, and HALF_PI/2 radians equals 45°.
*
* @type {number}
*/
TWO_PI,
/**
* Half the value of the mathematical constant PI (π).
* Approximately 1.57079
*
* @type {number}
*/
HALF_PI: TWO_PI / 4,
/**
* Calculates a linear (interpolation) value over t%.
*
* @param {number} start
* @param {number} end
* @param {number} t The progress in percentage, where 0 = 0% and 1 = 100%.
* @returns {number} The unterpolated value
* @tutorial https://gamedev.net/tutorials/programming/general-and-gameplay-programming/a-brief-introduction-to-lerp-r4954/
*/
lerp: (start, end, t) => {
DEV: assert(isNumber(start), '[litecanvas] lerp() 1st param must be a number')
DEV: assert(isNumber(end), '[litecanvas] lerp() 2nd param must be a number')
DEV: assert(isNumber(t), '[litecanvas] lerp() 3rd param must be a number')
return t * (end - start) + start
},
/**
* Convert degrees to radians
*
* @param {number} degs
* @returns {number} the value in radians
*/
deg2rad: (degs) => {
DEV: assert(isNumber(degs), 'deg2rad: 1st param must be a number')
return (math.PI / 180) * degs
},
/**
* Convert radians to degrees
*
* @param {number} rads
* @returns {number} the value in degrees
*/
rad2deg: (rads) => {
DEV: assert(isNumber(rads), 'rad2deg: 1st param must be a number')
return (180 / math.PI) * rads
},
/**
* Returns the rounded value of an number to optional precision (number of digits after the decimal point).
*
* Note: precision is optional but must be >= 0
*
* @param {number} n number to round.
* @param {number} [precision] number of decimal digits to round to, default is 0.
* @returns {number} rounded number.
*/
round: (n, precision = 0) => {
DEV: assert(isNumber(n), '[litecanvas] round() 1st param must be a number')
DEV: assert(
null == precision || (isNumber(precision) && precision >= 0),
'[litecanvas] round() 2nd param must be a positive number or zero'
)
if (!precision) {
return math.round(n)
}
const multiplier = 10 ** precision
return math.round(n * multiplier) / multiplier
},
/**
* Constrains a number between `min` and `max`.
*
* @param {number} value
* @param {number} min
* @param {number} max
* @returns {number}
*/
clamp: (value, min, max) => {
DEV: assert(isNumber(value), '[litecanvas] clamp() 1st param must be a number')
DEV: assert(isNumber(min), '[litecanvas] clamp() 2nd param must be a number')
DEV: assert(isNumber(max), '[litecanvas] clamp() 3rd param must be a number')
DEV: assert(
max > min,
'[litecanvas] clamp() the 2nd param must be less than the 3rd param'
)
if (value < min) return min
if (value > max) return max
return value
},
/**
* Wraps a number between `min` (inclusive) and `max` (exclusive).
*
* @param {number} value
* @param {number} min
* @param {number} max
* @returns {number}
*/
wrap: (value, min, max) => {
DEV: assert(isNumber(value), '[litecanvas] wrap() 1st param must be a number')
DEV: assert(isNumber(min), '[litecanvas] wrap() 2nd param must be a number')
DEV: assert(isNumber(max), '[litecanvas] wrap() 3rd param must be a number')
DEV: assert(
max > min,
'[litecanvas] wrap() the 2nd param must be less than the 3rd param'
)
return value - (max - min) * math.floor((value - min) / (max - min))
},
/**
* Re-maps a number from one range to another.
*
* @param {number} value the value to be remapped.
* @param {number} start1 lower bound of the value's current range.
* @param {number} stop1 upper bound of the value's current range.
* @param {number} start2 lower bound of the value's target range.
* @param {number} stop2 upper bound of the value's target range.
* @param {boolean} [withinBounds=false] constrain the value to the newly mapped range
* @returns {number} the remapped number
*/
map(value, start1, stop1, start2, stop2, withinBounds) {
DEV: assert(isNumber(value), '[litecanvas] map() 1st param must be a number')
DEV: assert(isNumber(start1), '[litecanvas] map() 2nd param must be a number')
DEV: assert(isNumber(stop1), '[litecanvas] map() 3rd param must be a number')
DEV: assert(isNumber(start2), '[litecanvas] map() 4th param must be a number')
DEV: assert(isNumber(stop2), '[litecanvas] map() 5th param must be a number')
DEV: assert(
stop1 !== start1,
'[litecanvas] map() the 2nd param must be different than the 3rd param'
)
// prettier-ignore
const result = ((value - start1) / (stop1 - start1)) * (stop2 - start2) + start2
return withinBounds ? instance.clamp(result, start2, stop2) : result
},
/**
* Maps a number from one range to a value between 0 and 1.
* Identical to `map(value, min, max, 0, 1)`.
* Note: Numbers outside the range are not clamped to 0 and 1.
*
* @param {number} value
* @param {number} start
* @param {number} stop
* @returns {number} the normalized number.
*/
norm: (value, start, stop) => {
DEV: assert(isNumber(value), '[litecanvas] norm() 1st param must be a number')
DEV: assert(isNumber(start), '[litecanvas] norm() 2nd param must be a number')
DEV: assert(isNumber(stop), '[litecanvas] norm() 3rd param must be a number')
DEV: assert(
start !== stop,
'[litecanvas] norm() the 2nd param must be different than the 3rd param'
)
return instance.map(value, start, stop, 0, 1)
},
/**
* Interpolate between 2 values using a periodic function.
*
* @param {number} from - the lower bound
* @param {number} to - the higher bound
* @param {number} t - value passed to the periodic function
* @param {(n: number) => number} [fn] - the periodic function (which default to `Math.sin`)
*/
wave: (from, to, t, fn = Math.sin) => {
DEV: assert(isNumber(from), '[litecanvas] wave() 1st param must be a number')
DEV: assert(isNumber(to), '[litecanvas] wave() 2nd param must be a number')
DEV: assert(isNumber(t), '[litecanvas] wave() 3rd param must be a number')
DEV: assert(
'function' === typeof fn,
'[litecanvas] wave() 4rd param must be a function (n: number) => number'
)
return from + ((fn(t) + 1) / 2) * (to - from)
},
/** RNG API */
/**
* Generates a pseudorandom float between min (inclusive) and max (exclusive)
* using the Linear Congruential Generator (LCG) algorithm.
*
* @param {number} [min=0.0]
* @param {number} [max=1.0]
* @returns {number} the random number
*/
rand: (min = 0.0, max = 1.0) => {
DEV: assert(isNumber(min), '[litecanvas] rand() 1st param must be a number')
DEV: assert(isNumber(max), '[litecanvas] rand() 2nd param must be a number')
DEV: assert(
max > min,
'[litecanvas] rand() the 1st param must be less than the 2nd param'
)
const a = 1664525
const c = 1013904223
const m = 4294967296
_rngSeed = (a * _rngSeed + c) % m
return (_rngSeed / m) * (max - min) + min
},
/**
* Generates a pseudorandom integer between min (inclusive) and max (inclusive)
*
* @param {number} [min=0]
* @param {number} [max=1]
* @returns {number} the random number
*/
randi: (min = 0, max = 1) => {
DEV: assert(isNumber(min), '[litecanvas] randi() 1st param must be a number')
DEV: assert(isNumber(max), '[litecanvas] randi() 2nd param must be a number')
DEV: assert(
max > min,
'[litecanvas] randi() the 1st param must be less than the 2nd param'
)
return math.floor(instance.rand(min, max + 1))
},
/**
* Initializes the random number generator with an explicit seed value.
*
* Note: The seed should be a integer number greater than or equal to zero.
*
* @param {number} value
*/
rseed(value) {
DEV: assert(
null == value || (isNumber(value) && value >= 0),
'[litecanvas] rseed() 1st param must be a positive number or zero'
)
_rngSeed = ~~value
},
/** BASIC GRAPHICS API */
/**
* Clear the game screen with an optional color
*
* @param {number} [color] The background color (index) or null/undefined (for transparent)
*/
cls(color) {
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] cls() 1st param must be a positive number or zero or undefined'
)
if (null == color) {
_ctx.clearRect(0, 0, _ctx.canvas.width, _ctx.canvas.height)
} else {
instance.rectfill(0, 0, _ctx.canvas.width, _ctx.canvas.height, color)
}
},
/**
* Draw a rectangle outline
*
* @param {number} x
* @param {number} y
* @param {number} width
* @param {number} height
* @param {number} [color=0] the color index
* @param {number|number[]} [radii] A number or list specifying the radii used to draw a rounded-borders rectangle
*
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/roundRect
*/
rect(x, y, width, height, color, radii) {
DEV: assert(isNumber(x), '[litecanvas] rect() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] rect() 2nd param must be a number')
DEV: assert(
isNumber(width) && width > 0,
'[litecanvas] rect() 3rd param must be a positive number'
)
DEV: assert(
isNumber(height) && height >= 0,
'[litecanvas] rect() 4th param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] rect() 5th param must be a positive number or zero'
)
DEV: assert(
null == radii || isNumber(radii) || (Array.isArray(radii) && radii.length >= 1),
'[litecanvas] rect() 6th param must be a number or array of numbers'
)
beginPath(_ctx)
_ctx[radii ? 'roundRect' : 'rect'](
~~x - _outline_fix,
~~y - _outline_fix,
~~width + _outline_fix * 2,
~~height + _outline_fix * 2,
radii
)
instance.stroke(color)
},
/**
* Draw a color-filled rectangle
*
* @param {number} x
* @param {number} y
* @param {number} width
* @param {number} height
* @param {number} [color=0] the color index
* @param {number|number[]} [radii] A number or list specifying the radii used to draw a rounded-borders rectangle
*/
rectfill(x, y, width, height, color, radii) {
DEV: assert(isNumber(x), '[litecanvas] rectfill() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] rectfill() 2nd param must be a number')
DEV: assert(
isNumber(width) && width >= 0,
'[litecanvas] rectfill() 3rd param must be a positive number or zero'
)
DEV: assert(
isNumber(height) && height >= 0,
'[litecanvas] rectfill() 4th param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] rectfill() 5th param must be a positive number or zero'
)
DEV: assert(
null == radii || isNumber(radii) || (Array.isArray(radii) && radii.length >= 1),
'[litecanvas] rectfill() 6th param must be a number or array of at least 2 numbers'
)
beginPath(_ctx)
_ctx[radii ? 'roundRect' : 'rect'](~~x, ~~y, ~~width, ~~height, radii)
instance.fill(color)
},
/**
* Draw a circle outline
*
* @param {number} x
* @param {number} y
* @param {number} radius
* @param {number} [color=0] the color index
*/
circ(x, y, radius, color) {
DEV: assert(isNumber(x), '[litecanvas] circ() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] circ() 2nd param must be a number')
DEV: assert(
isNumber(radius) && radius >= 0,
'[litecanvas] circ() 3rd param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] circ() 4th param must be a positive number or zero'
)
beginPath(_ctx)
_ctx.arc(~~x, ~~y, ~~radius, 0, TWO_PI)
instance.stroke(color)
},
/**
* Draw a color-filled circle
*
* @param {number} x
* @param {number} y
* @param {number} radius
* @param {number} [color=0] the color index
*/
circfill(x, y, radius, color) {
DEV: assert(isNumber(x), '[litecanvas] circfill() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] circfill() 2nd param must be a number')
DEV: assert(
isNumber(radius) && radius >= 0,
'[litecanvas] circfill() 3rd param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] circfill() 4th param must be a positive number or zero'
)
beginPath(_ctx)
_ctx.arc(~~x, ~~y, ~~radius, 0, TWO_PI)
instance.fill(color)
},
/**
* Draw a ellipse outline
*
* @param {number} x
* @param {number} y
* @param {number} radiusX
* @param {number} radiusY
* @param {number} [color=0] the color index
*/
oval(x, y, radiusX, radiusY, color) {
DEV: assert(isNumber(x), '[litecanvas] oval() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] oval() 2nd param must be a number')
DEV: assert(
isNumber(radiusX) && radiusX >= 0,
'[litecanvas] oval() 3rd param must be a positive number or zero'
)
DEV: assert(
isNumber(radiusY) && radiusY >= 0,
'[litecanvas] oval() 4th param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] oval() 5th param must be a positive number or zero'
)
beginPath(_ctx)
_ctx.ellipse(~~x, ~~y, ~~radiusX, ~~radiusY, 0, 0, TWO_PI)
instance.stroke(color)
},
/**
* Draw a color-filled ellipse
*
* @param {number} x
* @param {number} y
* @param {number} radiusX
* @param {number} radiusY
* @param {number} [color=0] the color index
*/
ovalfill(x, y, radiusX, radiusY, color) {
DEV: assert(isNumber(x), '[litecanvas] ovalfill() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] ovalfill() 2nd param must be a number')
DEV: assert(
isNumber(radiusX) && radiusX >= 0,
'[litecanvas] ovalfill() 3rd param must be a positive number or zero'
)
DEV: assert(
isNumber(radiusY) && radiusY >= 0,
'[litecanvas] ovalfill() 4th param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] ovalfill() 5th param must be a positive number or zero'
)
beginPath(_ctx)
_ctx.ellipse(~~x, ~~y, ~~radiusX, ~~radiusY, 0, 0, TWO_PI)
instance.fill(color)
},
/**
* Draw a line
*
* @param {number} x1
* @param {number} y1
* @param {number} x2
* @param {number} y2
* @param {number} [color=0] the color index
*/
line(x1, y1, x2, y2, color) {
DEV: assert(isNumber(x1), '[litecanvas] line() 1st param must be a number')
DEV: assert(isNumber(y1), '[litecanvas] line() 2nd param must be a number')
DEV: assert(
isNumber(x2),
'[litecanvas] line() 3rd param must be a positive number or zero'
)
DEV: assert(
isNumber(y2),
'[litecanvas] line() 4th param must be a positive number or zero'
)
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] line() 5th param must be a positive number or zero'
)
beginPath(_ctx)
let xfix = _outline_fix !== 0 && ~~x1 === ~~x2 ? 0.5 : 0
let yfix = _outline_fix !== 0 && ~~y1 === ~~y2 ? 0.5 : 0
_ctx.moveTo(~~x1 + xfix, ~~y1 + yfix)
_ctx.lineTo(~~x2 + xfix, ~~y2 + yfix)
instance.stroke(color)
},
/**
* Sets the thickness of lines
*
* @param {number} value
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/lineWidth
*/
linewidth(value) {
DEV: assert(
isNumber(value) && ~~value > 0,
'[litecanvas] linewidth() 1st param must be a positive number'
)
_ctx.lineWidth = ~~value
_outline_fix = 0 === ~~value % 2 ? 0 : 0.5
},
/**
* Sets the line dash pattern used when drawing lines
*
* @param {number[]} segments the line dash pattern
* @param {number} [offset=0] the line dash offset, or "phase".
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/setLineDash
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/lineDashOffset
*/
linedash(segments, offset = 0) {
DEV: assert(
Array.isArray(segments) && segments.length > 0,
'[litecanvas] linedash() 1st param must be an array of numbers'
)
DEV: assert(isNumber(offset), '[litecanvas] linedash() 2nd param must be a number')
_ctx.setLineDash(segments)
_ctx.lineDashOffset = offset
},
/** TEXT RENDERING API */
/**
* Draw text
*
* @param {number} x
* @param {number} y
* @param {string} message the text message
* @param {number} [color=3] the color index
* @param {string} [fontStyle] can be "normal" (default), "italic" and/or "bold".
*/
text(x, y, message, color = 3, fontStyle = 'normal') {
DEV: assert(isNumber(x), '[litecanvas] text() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] text() 2nd param must be a number')
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] text() 4th param must be a positive number or zero'
)
DEV: assert(
'string' === typeof fontStyle,
'[litecanvas] text() 5th param must be a string'
)
_ctx.font = `${fontStyle} ${_fontSize}px ${_fontFamily}`
_ctx.fillStyle = _colors[~~color % _colors.length]
_ctx.fillText(message, ~~x, ~~y)
},
/**
* Set the font family
*
* @param {string} family
*/
textfont(family) {
DEV: assert(
'string' === typeof family,
'[litecanvas] textfont() 1st param must be a string'
)
_fontFamily = family
},
/**
* Set the font size
*
* @param {number} size
*/
textsize(size) {
DEV: assert(isNumber(size), '[litecanvas] textsize() 1st param must be a number')
_fontSize = size
},
/**
* Sets the alignment used when drawing texts
*
* @param {CanvasTextAlign} align the horizontal alignment. Possible values: "left", "right", "center", "start" or "end"
* @param {CanvasTextBaseline} baseline the vertical alignment. Possible values: "top", "bottom", "middle", "hanging" or "ideographic"
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/textBaseline
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/textAlign
*/
textalign(align, baseline) {
DEV: assert(
null == align || ['left', 'right', 'center', 'start', 'end'].includes(align),
'[litecanvas] textalign() 1st param must be null or one of the following strings: center, left, right, start or end.'
)
DEV: assert(
null == baseline ||
['top', 'bottom', 'middle', 'hanging', 'alphabetic', 'ideographic'].includes(
baseline
),
'[litecanvas] textalign() 2nd param must be null or one of the following strings: middle, top, bottom, hanging, alphabetic or ideographic.'
)
if (align) _ctx.textAlign = align
if (baseline) _ctx.textBaseline = baseline
},
/** IMAGE GRAPHICS API */
/**
* Draw an image
*
* @param {number} x
* @param {number} y
* @param {CanvasImageSource} source
*/
image(x, y, source) {
DEV: assert(isNumber(x), '[litecanvas] image() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] image() 2nd param must be a number')
_ctx.drawImage(source, ~~x, ~~y)
},
/**
* Draw in an OffscreenCanvas and returns its image.
*
* @param {number} width
* @param {number} height
* @param {string[]|drawCallback} drawing
* @param {object} [options]
* @param {number} [options.scale=1]
* @param {OffscreenCanvas} [options.canvas]
* @returns {ImageBitmap}
* @see https://developer.mozilla.org/en-US/docs/Web/API/OffscreenCanvas
*/
paint(width, height, drawing, options = {}) {
DEV: assert(
isNumber(width) && width >= 1,
'[litecanvas] paint() 1st param must be a positive number'
)
DEV: assert(
isNumber(height) && height >= 1,
'[litecanvas] paint() 2nd param must be a positive number'
)
DEV: assert(
'function' === typeof drawing || Array.isArray(drawing),
'[litecanvas] paint() 3rd param must be a function or array'
)
DEV: assert(
(options && null == options.scale) || isNumber(options.scale),
'[litecanvas] paint() 4th param (options.scale) must be a number'
)
DEV: assert(
(options && null == options.canvas) || options.canvas instanceof OffscreenCanvas,
'[litecanvas] paint() 4th param (options.canvas) must be an OffscreenCanvas'
)
const /** @type {OffscreenCanvas} */
canvas = options.canvas || new OffscreenCanvas(1, 1),
scale = options.scale || 1,
contextOriginal = _ctx
canvas.width = width * scale
canvas.height = height * scale
_ctx = canvas.getContext('2d')
_ctx.scale(scale, scale)
// draw pixel art if `draw` is a array
if (Array.isArray(drawing)) {
let x = 0,
y = 0
_ctx.imageSmoothingEnabled = false
for (const str of drawing) {
for (const color of str) {
if (' ' !== color && '.' !== color) {
// support for 16-color palette using hex (from 0 to f)
instance.rectfill(x, y, 1, 1, parseInt(color, 16))
}
x++
}
y++
x = 0
}
} else {
drawing(_ctx)
}
_ctx = contextOriginal // restore the context
return canvas.transferToImageBitmap()
},
/** ADVANCED GRAPHICS API */
/**
* Get or set the canvas context 2D
*
* @param {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D} [context]
* @returns {CanvasRenderingContext2D|OffscreenCanvasRenderingContext2D}
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D
*/
ctx(context) {
if (context) {
_ctx = context
}
return _ctx
},
/**
* saves the current drawing style settings and transformations
*
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/save
*/
push: () => _ctx.save(),
/**
* restores the drawing style settings and transformations
*
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/restore
*/
pop: () => _ctx.restore(),
/**
* Adds a translation to the transformation matrix.
*
* @param {number} x
* @param {number} y
*/
translate: (x, y) => {
DEV: assert(isNumber(x), '[litecanvas] translate() 1st param must be a number')
DEV: assert(isNumber(y), '[litecanvas] translate() 2nd param must be a number')
return _ctx.translate(~~x, ~~y)
},
/**
* Adds a scaling transformation to the canvas units horizontally and/or vertically.
*
* @param {number} x
* @param {number} [y]
*/
scale: (x, y) => {
DEV: assert(isNumber(x), '[litecanvas] scale() 1st param must be a number')
DEV: assert(null == y || isNumber(y), '[litecanvas] scale() 2nd param must be a number')
return _ctx.scale(x, y || x)
},
/**
* Adds a rotation to the transformation matrix.
*
* @param {number} radians
*/
rotate: (radians) => {
DEV: assert(isNumber(radians), '[litecanvas] rotate() 1st param must be a number')
return _ctx.rotate(radians)
},
/**
* Sets the alpha (opacity) value to apply when drawing new shapes and images
*
* @param {number} value float from 0 to 1 (e.g: 0.5 = 50% transparent)
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/globalAlpha
*/
alpha(value) {
DEV: assert(isNumber(value), '[litecanvas] alpha() 1st param must be a number')
_ctx.globalAlpha = instance.clamp(value, 0, 1)
},
/**
* Fills the current path with a given color.
*
* @param {number} [color=0]
*/
fill(color) {
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] fill() 1st param must be a positive number or zero'
)
_ctx.fillStyle = _colors[~~color % _colors.length]
_ctx.fill()
},
/**
* Outlines the current path with a given color.
*
* @param {number} [color=0]
*/
stroke(color) {
DEV: assert(
null == color || (isNumber(color) && color >= 0),
'[litecanvas] stroke() 1st param must be a positive number or zero'
)
_ctx.strokeStyle = _colors[~~color % _colors.length]
_ctx.stroke()
},
/**
* Turns a path (in the callback) into the current clipping region.
*
* @param {clipCallback} callback
* @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/clip
*/
clip(callback) {
DEV: assert(
'function' === typeof callback,
'[litecanvas] clip() 1st param must be a function'
)
beginPath(_ctx)
callback(_ctx)
_ctx.clip()
},
/** SOUND API */
/**
* Play a sound effects using ZzFX library.
* If the first argument is omitted, plays an default sound.
*
* @param {number[]} [zzfxParams] a ZzFX array of params
* @param {number} [pitchSlide] a value to increment/decrement the pitch
* @param {number} [volumeFactor] the volume factor
* @returns {number[] | boolean} The sound that was played or `false`
*
* @see https://github.com/KilledByAPixel/ZzFX
*/
sfx(zzfxParams, pitchSlide = 0, volumeFactor = 1) {
DEV: assert(
null == zzfxParams || Array.isArray(zzfxParams),
'[litecanvas] sfx() 1st param must be an array'
)
DEV: assert(isNumber(pitchSlide), '[litecanvas] sfx() 2nd param must be a number')
DEV: assert(isNumber(volumeFactor), '[litecanvas] sfx() 3rd param must be a number')
if (
!root.zzfxV ||
(navigator.userActivation && !navigator.userActivation.hasBeenActive)
) {
return false
}
zzfxParams = zzfxParams || _defaultSound
// if has other arguments, copy the sound to not change the original
if (pitchSlide !== 0 || volumeFactor !== 1) {
zzfxParams = zzfxParams.slice()
zzfxParams[0] = volumeFactor * (zzfxParams[0] || 1)
zzfxParams[10] = ~~zzfxParams[10] + pitchSlide
}
zzfx.apply(0, zzfxParams)
return zzfxParams
},
/**
* Set the ZzFX's global volume factor.
* Note: use 0 to mute all sound effects.
*
* @param {number} value
*/
volume(value) {
DEV: assert(
isNumber(value) && value >= 0,
'[litecanvas] volume() 1st param must be a positive number or zero'
)
root.zzfxV = value
},
/** PLUGINS API */
/**
* Returns the canvas
*
* @returns {HTMLCanvasElement}
*/
canvas: () => _canvas,
/**
* Prepares a plugin to be loaded
*
* @param {pluginCallback} callback
*/
use(callback, config = {}) {
DEV: assert(
'function' === typeof callback,
'[litecanvas] use() 1st param must be a function'
)
DEV: assert(
'object' === typeof config,
'[litecanvas] use() 2nd param must be an object'
)
if (_initialized) {
// load the plugin now
loadPlugin(callback, config)
} else {
// schedule to load the plugin right before the "init" event
_plugins.push([callback, config])
}
},
/**
* Add a game event listener
*
* @param {string} eventName the event type name
* @param {Function} callback the function that is called when the event occurs
* @returns {Function} a function to remove the listener
*/
listen(eventName, callback) {
DEV: assert(
'string' === typeof eventName,
'[litecanvas] listen() 1st param must be a string'
)
DEV: assert(
'function' === typeof callback,
'[litecanvas] listen() 2nd param must be a function'
)
eventName = eventName.toLowerCase()
_eventListeners[eventName] = _eventListeners[eventName] || new Set()
_eventListeners[eventName].add(callback)
// return a function to remove this event listener
return () => _eventListeners && _eventListeners[eventName].delete(callback)
},
/**
* Call all listeners attached to a game event
*
* @param {string} eventName The event type name
* @param {*} [arg1] any data to be passed over the listeners
* @param {*} [arg2] any data to be passed over the listeners
* @param {*} [arg3] any data to be passed over the listeners
* @param {*} [arg4] any data to be passed over the listeners
*/
emit(eventName, arg1, arg2, arg3, arg4) {
DEV: assert(
'string' === typeof eventName,
'[litecanvas] emit() 1st param must be a string'
)
if (_initialized) {
eventName = eventName.toLowerCase()
triggerEvent('before:' + eventName, arg1, arg2, arg3, arg4)
triggerEvent(eventName, arg1, arg2, arg3, arg4)
triggerEvent('after:' + eventName, arg1, arg2, arg3, arg4)
}
},
/**
* Set or reset the color palette
*
* @param {string[]} [colors]
*/
pal(colors = defaultPalette) {
DEV: assert(
Array.isArray(colors) && colors.length > 0,
'[litecanvas] pal() 1st param must be a array of strings'
)
_colors = colors
},
/**
* Define or update a instance property.
*
* @param {string} key
* @param {*} value
*/
def(key, value) {
DEV: assert('string' === typeof key, '[litecanvas] def() 1st param must be a string')
DEV: if (null == value) {
console.warn(
`[litecanvas] def() changed the key "${key}" to null (previous value was ${instance[key]})`
)
}
instance[key] = value
if (settings.global) {
root[key] = value
}
},
/**
* The scale of the game's delta time (dt).
* Values higher than 1 increase the speed of time, while values smaller than 1 decrease it.
* A value of 0 freezes time and is effectively equivalent to pausing.
*
* @param {number} value
*/
timescale(value) {
DEV: assert(
isNumber(value) && value >= 0,
'[litecanvas] timescale() 1st param must be a positive number or zero'
)
_timeScale = value
},
/**
* Set the target FPS (frames per second).
*
* @param {number} value
*/
framerate(value) {
DEV: assert(
isNumber(value) && value >= 1,
'[litecanvas] framerate() 1st param must be a positive number'
)
_deltaTime = 1 / ~~value
},
/**
* Returns information about that engine instance.
*
* @param {number} n
* @returns {any}
*/
stat(n) {
DEV: assert(isNumber(n) && n >= 0, '[litecanvas] stat() 1st param must be a number')
const list = [
// 0
settings,
// 1
_initialized,
// 2
_deltaTime,
// 3
_scale,
// 4
_eventListeners,
// 5
_colors,
// 6
_defaultSound,
// 7
_timeScale,
// 8
root.zzfxV,
// 9
_rngSeed,
// 10
_fontSize,
// 11
_fontFamily,
]
const data = { index: n, value: list[n] }
// plugins can modify or create stat values
instance.emit('stat', data)
return data.value
},
/**
* Stops the litecanvas instance and remove all event listeners.
*/
quit() {
// stop the game loop (update & draw)
instance.pause()
// emit "quit" event to manual clean ups
instance.emit('quit')
// clear all engine event listeners
_eventListeners = {}
// clear all browser event listeners
for (const removeListener of _browserEventListeners) {
removeListener()
}
// maybe clear global context
if (settings.global) {
for (const key in instance) {
delete root[key]
}
delete root.ENGINE
}
// unset that flag
_initialized = false
},
/**
* Pauses the engine loop (update & draw).
*/
pause() {
cancelAnimationFrame(_rafid)
_rafid = 0
},
/**
* Resumes (if paused) the engine loop.
*/
resume() {
if (!_rafid && _initialized) {
_rafid = raf(drawFrame)
}
},
/**
* Returns `true` if the engine loop is paused.
*
* @returns {boolean}
*/
paused() {
return !_rafid
},
}
// prettier-ignore
for (const k of _mathFunctions.split(',')) {
// import native Math functions
instance[k] = math[k]
}
function init() {
// setup default event listeners
const source = settings.loop ? settings.loop : root
for (const event of _coreEvents.split(',')) {
DEV: if (root === source && source[event]) {
console.info(`[litecanvas] using window.${event}()`)
}
if (source[event]) instance.listen(event, source[event])
}
// load plugins
for (const [callback, config] of _plugins) {
loadPlugin(callback, config)
}
// listen window resize event when "autoscale" is enabled
if (settings.autoscale) {
on(root, 'resize', resizeCanvas)
}
// default mouse/touch handlers
if (settings.tapEvents) {
const _getXY =
/**
* @param {MouseEvent | Touch} ev
*/
(ev) => [
(ev.pageX - _canvas.offsetLeft) / _scale,
(ev.pageY - _canvas.offsetTop) / _scale,
],
_taps = new Map(),
_registerTap =
/**
* @param {number} id
* @param {number} [x]
* @param {number} [y]
*/
(id, x, y) => {
const tap = {
// current x
x,
// current y
y,
// initial x
xi: x,
// initial y
yi: y,
// timestamp
t: performance.now(),
}
_taps.set(id, tap)
return tap
},
_updateTap =
/**
* @param {number} id
* @param {number} x
* @param {number} y
*/
(id, x, y) => {
const tap = _taps.get(id) || _registerTap(id)
tap.x = x
tap.y = y
},
_checkTapped =
/**
* @param {{t: number}} tap
*/
(tap) => tap && performance.now() - tap.t <= 300,
preventDefault =
/**
* @param {Event} ev
*/
(ev) => ev.preventDefault()
let _pressingMouse = false
on(
_canvas,
'mousedown',
/**
* @param {MouseEvent} ev
*/
(ev) => {
if (ev.button === 0) {
preventDefault(ev)
const [x, y] = _getXY(ev)
instance.emit('tap', x, y, 0)
_registerTap(0, x, y)
_pressingMouse = true
}
}
)
on(
_canvas,
'mouseup',
/**
* @param {MouseEvent} ev
*/
(ev) => {
if (ev.button === 0) {
preventDefault(ev)
const tap = _taps.get(0)
const [x, y] = _getXY(ev)
if (_checkTapped(tap)) {
instance.emit('tapped', tap.xi, tap.yi, 0)
}
instance.emit('untap', x, y, 0)
_taps.delete(0)
_pressingMouse = false
}
}
)
on(
root,
'mousemove',
/**
* @param {MouseEvent} ev
*/
(ev) => {
preventDefault(ev)
const [x, y] = _getXY(ev)
instance.def('MX', x)
instance.def('MY', y)
if (!_pressingMouse) return
instance.emit('tapping', x, y, 0)
_updateTap(0, x, y)
}
)
on(
_canvas,
'touchstart',
/**
* @param {TouchEvent} ev
*/
(ev) => {
preventDefault(ev)
/** @type {TouchList} touches */
const touches = ev.changedTouches
for (const touch of touches) {
const [x, y] = _getXY(touch)
instance.emit('tap', x, y, touch.identifier + 1)
_registerTap(touch.identifier + 1, x, y)
}
}
)
on(
_canvas,
'touchmove',
/**
* @param {TouchEvent} ev
*/
(ev) => {
preventDefault(ev)
const touches = ev.changedTouches
for (const touch of touches) {
const [x, y] = _getXY(touch)
instance.emit('tapping', x, y, touch.identifier + 1)
_updateTap(touch.identifier + 1, x, y)
}
}
)
/**
* @param {TouchEvent} ev
*/
const _touchEndHandler = (ev) => {
preventDefault(ev)
const existing = []
if (ev.targetTouches.length > 0) {
for (const touch of ev.targetTouches) {
existing.push(touch.identifier + 1)
}
}
for (const [id, tap] of _taps) {
if (existing.includes(id)) continue
if (_checkTapped(tap)) {
instance.emit('tapped', tap.xi, tap.yi, id)
}
instance.emit('untap', tap.x, tap.y, id)
_taps.delete(id)
}
}
on(_canvas, 'touchend', _touchEndHandler)