290 lines
7.3 KiB
JavaScript
290 lines
7.3 KiB
JavaScript
class Drawing {
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constructor(divId) {
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this.div = document.getElementById(divId);
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this.div.classList.add('drawing');
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this.div.classList.add('container');
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this.buttonsDiv = document.createElement('div');
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this.titleDiv = document.createElement('div');
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this.titleDiv.classList.add('title');
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this.captionDiv = document.createElement('div');
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this.captionDiv.classList.add('caption');
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this.canvas = document.createElement('canvas');
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this.div.appendChild(this.titleDiv);
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this.div.appendChild(this.buttonsDiv);
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this.div.appendChild(this.canvas);
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this.div.appendChild(this.captionDiv);
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this.ctx = this.canvas.getContext('2d');
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this.sequence = [];
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this.t = 0;
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this.rt = 0;
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this.dt = 0;
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this.points = {};
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this.stopped = true;
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this.frame = [[-10, -10], [110, 110]];
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this.frameMargin = 10;
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this.scale = 1.0;
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this.speed = 1.0;
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this.rendered = false;
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this.updateCanvasSize();
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}
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addButtons() {
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if (!this.buttonsAdded) {
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this.startButton = document.createElement('button');
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this.startButton.onclick = () => this.start();
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this.startButton.innerHTML = "Start";
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this.stopButton = document.createElement('button');
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this.stopButton.onclick = () => this.stop();
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this.stopButton.innerHTML = "Stop";
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this.buttonsDiv.appendChild(this.startButton);
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this.buttonsDiv.appendChild(this.stopButton);
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this.buttonsAdded = true;
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this.updateButtonStates();
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}
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}
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updateButtonStates() {
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if (this.stopped) {
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this.stopButton.disabled = true;
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this.startButton.disabled = false;
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} else {
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this.stopButton.disabled = false;
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this.startButton.disabled = true;
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}
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}
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setTitle(title) {
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this.titleDiv.innerHTML = title;
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}
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setCaption(caption) {
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this.captionDiv.innerHTML = caption;
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}
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start() {
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if (this.stopped) {
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this.elideInterval = true;
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this.stopped = false;
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}
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if (this.onStartFn) {
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this.onStartFn();
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}
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this.addButtons();
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this.updateButtonStates();
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this.animate();
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}
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stop() {
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this.stopped = true;
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this.updateButtonStates();
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}
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render() {
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for (let action of this.sequence) {
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action();
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}
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this.rendered = true;
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}
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animate() {
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this.ctx.reset();
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this.render();
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if (!this.stopped) {
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requestAnimationFrame((prevt) => {
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const rt = document.timeline.currentTime;
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const elapsed = rt - prevt;
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if (this.elideInterval) {
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this.dt = 0;
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this.elideInterval = false;
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} else {
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this.dt = (rt - this.rt + elapsed) * this.speed;
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}
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this.t += this.dt;
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this.rt = rt;
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this.animate();
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});
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}
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}
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pixel([x, y]) {
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return [
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(x - this.frame[0][0]) * this.scale + this.frameMargin,
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this.canvas.height - (y - this.frame[0][1]) * this.scale - this.frameMargin
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];
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}
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onStart(fn) {
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this.onStartFn = fn;
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}
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setSpeed(speed) {
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this.speed = speed;
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}
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updateCanvasSize() {
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this.canvas.width = (this.frame[1][0] - this.frame[0][0]) * this.scale + 2 * this.frameMargin;
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this.canvas.height = (this.frame[1][1] - this.frame[0][1]) * this.scale + 2 * this.frameMargin;
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if (this.rendered) {
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this.render();
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}
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}
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setFrame([x1, y1], [x2, y2]) {
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this.frame = [[x1, y1], [x2, y2]];
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this.updateCanvasSize();
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}
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setFrameMargin(frameMargin) {
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this.frameMargin = frameMargin;
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this.updateCanvasSize();
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}
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setScale(zoom) {
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this.scale = zoom;
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this.updateCanvasSize();
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}
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setStroke(style, width) {
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this.sequence.push(() => {
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this.ctx.strokeStyle = style;
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this.ctx.lineWidth = width;
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});
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}
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setFill(style) {
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this.sequence.push(() => {
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this.ctx.fillStyle = style;
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});
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}
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definePoint(name, fn) {
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this.points[name] = fn;
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}
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getPoint(p) {
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if (typeof p === 'string') {
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const fn = this.points[p];
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if (!fn) {
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const e = new Error;
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e.message = `Point '${p}' is not defined`;
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throw e;
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}
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return fn();
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} else {
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return p;
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}
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}
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line(p1, p2) {
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this.sequence.push(() => {
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this.ctx.beginPath();
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this.ctx.moveTo(...this.pixel(this.getPoint(p1)));
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this.ctx.lineTo(...this.pixel(this.getPoint(p2)));
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this.ctx.stroke();
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});
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}
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arrow(p1, p2) {
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this.sequence.push(() => {
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this.ctx.beginPath();
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this.ctx.moveTo(...this.pixel(this.getPoint(p1)));
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this.ctx.lineTo(...this.pixel(this.getPoint(p2)));
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this.ctx.stroke();
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});
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}
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polyline(...points) {
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this.sequence.push(() => {
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this.ctx.beginPath();
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this.ctx.moveTo(...this.pixel(points[0]));
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for (let i = 1; i < points.length; i++) {
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this.ctx.lineTo(...this.pixel(points[i]));
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}
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this.ctx.stroke();
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});
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}
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oscillatingValue(x1, x2, period, initialPhase = 0) {
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const center = (x1 + x2) / 2;
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const amplitude = (x2 - x1) / 2;
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return center + amplitude * Math.sin(2*Math.PI*this.t/period + initialPhase);
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}
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oscillatingPoint([x1, y1], [x2, y2], period) {
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const x = this.oscillatingValue(x1, x2, period);
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const y = this.oscillatingValue(y1, y2, period);
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return [x, y];
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}
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object(p, opts, fn) {
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let history = [];
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const maxAge = opts?.trace?.age ?? 0;
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const dashLength = 5;
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let distance = 0;
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this.sequence.push(() => {
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const [x, y] = this.getPoint(p);
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let ds = 0;
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if (history.length) {
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const dx = x - history[history.length - 1].p[0];
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const dy = y - history[history.length - 1].p[1];
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ds = Math.sqrt(dx**2 + dy**2);
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}
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distance += ds;
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history.push({t: this.t, p: [x, y], distance});
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const oldest = history.findIndex(({t}) => this.t - t <= maxAge);
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if (oldest >= 0) {
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history = history.slice(oldest);
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}
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this.ctx.strokeStyle = 'gray';
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this.ctx.lineWidth = 1;
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this.ctx.beginPath();
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this.ctx.moveTo(...this.pixel(history[0].p));
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for (let i = 1; i < history.length; i++) {
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if (Math.floor(history[i].distance / dashLength) % 2) {
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this.ctx.moveTo(...this.pixel(history[i].p));
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} else {
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this.ctx.lineTo(...this.pixel(history[i].p));
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}
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}
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this.ctx.stroke();
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fn(x, y);
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});
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return {
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reset: () => {
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history = [];
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distance = 0;
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}
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};
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}
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square(p, opts) {
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const size = opts?.size ?? 10;
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return this.object(p, opts, (x, y) => {
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this.ctx.fillRect(...this.pixel([x - size / 2, y + size / 2]), size * this.scale, size * this.scale);
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});
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}
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circle(p, opts) {
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const radius = opts?.radius ?? 5;
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return this.object(p, opts, (x, y) => {
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this.ctx.beginPath();
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this.ctx.ellipse(...this.pixel([x, y]), radius * this.scale, radius * this.scale, 0, 0, 2*Math.PI);
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this.ctx.fill();
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});
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}
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func(opts, fn) {
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const origin = opts?.origin ?? [0, 0];
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const domain = opts?.domain ?? [this.frame[0][0], this.frame[1][0]];
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const step = opts?.step ?? 1;
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this.sequence.push(() => {
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this.ctx.beginPath();
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this.ctx.moveTo(...this.pixel([domain[0], fn(domain[0])]));
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for (let x = domain[0] + step; x <= domain[1]; x += step) {
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this.ctx.lineTo(...this.pixel([x, fn(x)]));
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}
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this.ctx.lineTo(...this.pixel([domain[1], fn(domain[1])]));
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this.ctx.stroke();
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})
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}
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} |