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'use strict';
((window) => {
const kColorIteratorLimit = 256;
const kRedSpeed = 0.1;
const kGreenSpeed = 0.2;
const kBlueSpeed = 0.15;
/**
* Renders a Heart, has its own canvas, which will be placed in the element
* set by calling #render.
*
* @class HeartRenderer
* @param {object} config configuration, extends any member of the renderer
*/
const HeartRenderer = class HeartRenderer {
constructor(config) {
/**
* The instance of the heart renderer being used
*
* @memberof HeartRenderer
* @instance
* @name canvas
* @type HTMLCanvasElement
* @default A brand new canvas
*/
this.canvas = window.document.createElement('canvas');
/**
* The maximum fps that will be used
*
* @memberof HeartRenderer
* @instance
* @name fps
* @type Number
* @default 60
*/
this.fps = 60;
/**
* The size of the heart as a percentage of the canvas smallest dimension
*
* @memberof HeartRenderer
* @instance
* @name heartSize
* @type Number
* @default 50
*/
this.heartSize = 50;
this._animating = false; // The status of the animation.
this._previousFrameTime = Date.now(); // The timestamp of the last frame for fps control
this._currentColor = { // The current color that will be painted
red: 100,
blue: 0,
green: 50
};
Object.assign(this, config);
}
/**
* Attaches the canvas to an HTML element
*
* @memberof HeartRenderer
* @function render
* @instance
* @param {HTMLElement} element the element where we will attach our canvas
*/
render(element) {
element.appendChild(this.canvas);
this.resize();
}
/**
* Resizes the canvas
*
* @memberof HeartRenderer
* @function render
* @instance
* @param {HTMLElement} element the element where we will attach our canvas
*/
resize() {
if (this.canvas.parentElement) {
this.canvas.width = this.canvas.parentElement.offsetWidth;
this.canvas.height = this.canvas.parentElement.offsetHeight;
}
}
/**
* Gets the context from the current canvas and starts the animation process
*
* @memberof HeartRenderer
* @function activate
* @instance
*/
activate() {
const context = this.canvas.getContext('2d');
this._startAnimating(context);
}
/**
* Stops the animation process
*
* @memberof HeartRenderer
* @function deactivate
* @instance
*/
deactivate() {
this._stopAnimating();
}
// Starts the animation loop
_startAnimating(context) {
this._frameDuration = 1000 / this.fps;
this._animating = true;
this._animate(context);
}
// Stops the animation on the next frame.
_stopAnimating() {
this._animating = false;
}
// Runs the animation step controlling the FPS
_animate(context) {
if (!this._animating) {
return;
}
window.requestAnimationFrame(this._animate.bind(this, context));
const currentFrameTime = Date.now();
const delta = currentFrameTime - this._previousFrameTime;
if (delta > this._frameDuration) {
this._previousFrameTime = Date.now();
this._animateStep(context, delta);
}
}
// The actual animation processing function.
_animateStep(context, delta) {
this._updateColor(delta);
this._drawHeart(context, delta);
}
// Updates the current color
_updateColor(delta) {
this._currentColor.red = Math.round(this._currentColor.red + delta * kRedSpeed) % kColorIteratorLimit;
this._currentColor.green = Math.round(this._currentColor.green + delta * kGreenSpeed) % kColorIteratorLimit;
this._currentColor.blue = Math.round(this._currentColor.blue + delta * kBlueSpeed) % kColorIteratorLimit;
}
// Draws a heart
_drawHeart(context, delta) {
const canvasHeight = this.canvas.height;
const canvasWidth = this.canvas.width;
const referenceDimension = canvasWidth < canvasHeight ? canvasWidth : canvasHeight;
const heartSize = Math.round(referenceDimension * this.heartSize * .01);
const radius = heartSize / 2;
const canvasCenterX = Math.round(canvasWidth / 2);
const canvasCenterY = Math.round(canvasHeight / 2);
const centerX = -radius;
const centerY = -radius;
// translate and rotate, adjusting for weight of the heart.
context.translate(canvasCenterX, canvasCenterY + radius / 4);
context.rotate(-45 * Math.PI / 180);
// Fill the ventricles of the heart
context.fillStyle = `rgb(${this._currentColor.red}, ${this._currentColor.green}, ${this._currentColor.blue})`;
context.fillRect(centerX, centerY, heartSize, heartSize);
// Left atrium
context.beginPath();
context.arc(centerX + radius, centerY, radius, 0, 2 * Math.PI, false);
context.fill();
context.closePath();
// Right atrium
context.beginPath();
context.arc(centerX + heartSize, centerY + radius, radius, 0, 2 * Math.PI, false);
context.fill();
context.closePath();
context.setTransform(1, 0, 0, 1, 0, 0);
}
};
window.HeartRenderer = HeartRenderer;
})(window);
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