adding recBubbles

adding common module

canvas-common/common.js

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+export function pointDistance(pointA, pointB) {
+    return Math.sqrt(Math.pow(pointA.x - pointB.x, 2) +
+        Math.pow(pointA.y - pointB.y, 2));
+}
+
+
+// https://stackoverflow.com/questions/9899372/vanilla-javascript-equivalent-of-jquerys-ready-how-to-call-a-function-whe
+export function docReady(fn) {
+    if (document.readyState === "complete" || document.readyState === "interactive") {
+        setTimeout(fn, 1);
+    } else {
+        document.addEventListener("DOMContentLoaded", fn);
+    }
+}
+
+
+export function createRainbowColors(frequency, alpha=255){
+    var colors = [];
+    var most = 2 * Math.PI / frequency;
+    for (var i = 0; i < most; ++i) {
+        var red   = Math.sin(frequency * i + 0) * 127 + 128;
+        var green = Math.sin(frequency * i + 2) * 127 + 128;
+        var blue  = Math.sin(frequency * i + 4) * 127 + 128;
+        var color = {r: red << 0, g: green << 0, b: blue << 0, a: alpha};
+        addRGBStyle(color);
+        addRGBAStyle(color);
+        colors.push(color)
+    }
+    return colors;
+}
+
+export function addRGBStyle(color) {
+    color.styleRGB = '#' + d2h(color.r) + d2h(color.g) + d2h(color.b);
+}
+
+export function addRGBAStyle(color){
+    color.styleRGBA = 'rgba(%red, %green, %blue, %alpha)'
+        .replace('%red', color.r)
+        .replace('%blue', color.b)
+        .replace('%green', color.g)
+        .replace('%alpha', color.a / 277);
+}
+
+export function d2h(d) {
+    return (d / 256 + 1 / 512).toString(16).substring(2, 4);
+}
+
+export function toRad(angle) {
+    return angle / 180 * Math.PI;
+}
+
+export function toDeg(angle) {
+    return angle * 180 / Math.PI;
+}
+
+//http://stackoverflow.com/questions/23150333/html5-javascript-dataurl-to-blob-blob-to-dataurl
+export function dataURLtoBlob(dataurl) {
+    let arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],
+        bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
+    while (n--) {
+        u8arr[n] = bstr.charCodeAt(n);
+    }
+    return new Blob([u8arr], {type: mime});
+}
+
+export function downloadCanvas(name, canvas_obj, downloadBtn) {
+    downloadBtn.download = name + '_' + new Date().toISOString() + '.png';
+
+    let imageData = canvas_obj.toDataURL({
+        format: 'png',
+        multiplier: 4
+    });
+    let blob = dataURLtoBlob(imageData);
+    downloadBtn.href = URL.createObjectURL(blob);
+}

canvas-common/package.json

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+{
+  "name": "canvas-common",
+  "version": "1.0.0",
+  "description": "",
+  "main": "common.js",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "MIT"
+}