155 lines
3.5 KiB
JavaScript
155 lines
3.5 KiB
JavaScript
class Drawing {
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constructor() {
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const div = document.createElement('div');
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const buttonsDiv = document.createElement('div');
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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.canvas = document.createElement('canvas');
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this.canvas.width = 200;
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this.canvas.height = 200;
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buttonsDiv.appendChild(this.startButton);
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buttonsDiv.appendChild(this.stopButton);
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div.appendChild(buttonsDiv);
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div.appendChild(this.canvas);
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document.body.appendChild(div);
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this.ctx = this.canvas.getContext('2d');
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this.offset = {x: 0, y: 0};
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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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}
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pixel([x, y]) {
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return [
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this.offset.x + x,
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this.canvas.height - this.offset.y - y
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];
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}
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setOffset([x, y]) {
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this.sequence.push(() => {
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this.offset = {x, y};
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});
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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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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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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) {
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return x1 + (x2 - x1) * Math.sin(2*Math.PI*this.t/period);
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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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square(p) {
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this.sequence.push(() => {
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const [x, y] = this.getPoint(p);
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this.ctx.fillRect(...this.pixel([x - 5, y - 5]), 10, 10);
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})
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}
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circle(p) {
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this.sequence.push(() => {
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this.ctx.beginPath();
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this.ctx.ellipse(...this.pixel(this.getPoint(p)), 5, 5, 0, 0, 2*Math.PI);
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this.ctx.fill();
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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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render() {
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for (let action of this.sequence) {
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action();
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}
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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;
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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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stop() {
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this.stopped = true;
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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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this.animate();
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}
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} |