Add basic animation support to the mandala page (#75)

This addresses part of #71 by adding some basic animation support to the mandala page.

index.html

@@ -114,6 +114,10 @@ ul.navbar li:last-child {
   overflow: auto;
 }
 
+.sidebar .disabled {
+  color: gray;
+}
+
 .sidebar label.checkbox {
   display: block;
   margin-top: 10px;

lib/auto-sizing-svg.tsx

@@ -1,33 +1,60 @@
 import React, { useEffect, useRef, useState } from "react";
 
+type AutoSizingSvgProps = {
+  padding: number;
+  bgColor?: string;
+  sizeToElement?: React.RefObject<HTMLElement>;
+  children: JSX.Element | JSX.Element[];
+};
+
+function useResizeHandler(onResize: () => void) {
+  useEffect(() => {
+    window.addEventListener("resize", onResize);
+
+    return () => {
+      window.removeEventListener("resize", onResize);
+    };
+  });
+}
+
 /**
  * An SVG element with an optional background color that
- * automatically sizes itself to its contents.
+ * automatically sizes itself to either its contents, or
+ * if the `sizeToElement` prop is provided, to the given
+ * container.
  */
 export const AutoSizingSvg = React.forwardRef(
-  (
+  (props: AutoSizingSvgProps, ref: React.ForwardedRef<SVGSVGElement>) => {
-    props: {
+    const { bgColor, padding, sizeToElement } = props;
-      padding: number;
-      bgColor?: string;
-      children: JSX.Element | JSX.Element[];
-    },
-    ref: React.ForwardedRef<SVGSVGElement>
-  ) => {
-    const { bgColor, padding } = props;
     const [x, setX] = useState(0);
     const [y, setY] = useState(0);
     const [width, setWidth] = useState(1);
     const [height, setHeight] = useState(1);
     const gRef = useRef<SVGGElement>(null);
+    const resizeToElement = () => {
+      if (sizeToElement?.current) {
+        const bbox = sizeToElement.current.getBoundingClientRect();
+        setX(-bbox.width / 2);
+        setY(-bbox.height / 2);
+        setWidth(bbox.width);
+        setHeight(bbox.height);
+        return true;
+      }
+      return false;
+    };
+
+    useResizeHandler(resizeToElement);
 
     useEffect(() => {
-      const svgEl = gRef.current;
+      if (!resizeToElement()) {
-      if (svgEl) {
+        const svgEl = gRef.current;
-        const bbox = svgEl.getBBox();
+        if (svgEl) {
-        setX(bbox.x - padding);
+          const bbox = svgEl.getBBox();
-        setY(bbox.y - padding);
+          setX(bbox.x - padding);
-        setWidth(bbox.width + padding * 2);
+          setY(bbox.y - padding);
-        setHeight(bbox.height + padding * 2);
+          setWidth(bbox.width + padding * 2);
+          setHeight(bbox.height + padding * 2);
+        }
       }
     });
 

lib/numeric-slider.tsx

@@ -1,3 +1,4 @@
+import classNames from "classnames";
 import React from "react";
 import { float, NumericRange, slugify } from "./util";
 
@@ -7,13 +8,18 @@ export type NumericSliderProps = NumericRange & {
   onChange: (value: number) => void;
   value: number;
   valueSuffix?: string;
+  disabled?: boolean;
 };
 
 export const NumericSlider: React.FC<NumericSliderProps> = (props) => {
   const id = props.id || slugify(props.label);
 
   return (
-    <div className="thingy numeric-slider">
+    <div
+      className={classNames("thingy", "numeric-slider", {
+        disabled: props.disabled,
+      })}
+    >
       <label htmlFor={id}>{props.label}: </label>
       <span className="slider">
         <input
@@ -23,6 +29,7 @@ export const NumericSlider: React.FC<NumericSliderProps> = (props) => {
           max={props.max}
           value={props.value}
           step={props.step}
+          disabled={props.disabled}
           onChange={(e) => props.onChange(float(e.target.value))}
         />
         <span>

lib/pages/mandala-page.tsx

@@ -1,4 +1,4 @@
-import React, { useRef, useState } from "react";
+import React, { useEffect, useRef, useState } from "react";
 import { AutoSizingSvg } from "../auto-sizing-svg";
 import { getBoundingBoxCenter } from "../bounding-box";
 import { ExportWidget } from "../export-svg";
@@ -36,6 +36,7 @@ type ExtendedMandalaCircleParams = MandalaCircleParams & {
   rotation: number;
   symbolScaling: number;
   symbolRotation: number;
+  animateSymbolRotation: boolean;
 };
 
 const CIRCLE_1_DEFAULTS: ExtendedMandalaCircleParams = {
@@ -47,6 +48,7 @@ const CIRCLE_1_DEFAULTS: ExtendedMandalaCircleParams = {
   symbolScaling: 1,
   symbolRotation: 0,
   invertEveryOtherSymbol: false,
+  animateSymbolRotation: false,
 };
 
 const CIRCLE_2_DEFAULTS: ExtendedMandalaCircleParams = {
@@ -58,6 +60,7 @@ const CIRCLE_2_DEFAULTS: ExtendedMandalaCircleParams = {
   symbolScaling: 1,
   symbolRotation: 0,
   invertEveryOtherSymbol: false,
+  animateSymbolRotation: false,
 };
 
 const RADIUS: NumericRange = {
@@ -174,6 +177,25 @@ const ExtendedMandalaCircle: React.FC<
   );
 };
 
+function animateMandalaCircleParams(
+  value: ExtendedMandalaCircleParams,
+  frameNumber: number
+): ExtendedMandalaCircleParams {
+  if (value.animateSymbolRotation) {
+    value = {
+      ...value,
+      symbolRotation: frameNumber % ROTATION.max,
+    };
+  }
+  return value;
+}
+
+function isAnyMandalaCircleAnimated(
+  values: ExtendedMandalaCircleParams[]
+): boolean {
+  return values.some((value) => value.animateSymbolRotation);
+}
+
 const ExtendedMandalaCircleParamsWidget: React.FC<{
   idPrefix: string;
   value: ExtendedMandalaCircleParams;
@@ -226,10 +248,18 @@ const ExtendedMandalaCircleParamsWidget: React.FC<{
       <NumericSlider
         id={`${idPrefix}symbolRotation`}
         label="Symbol rotation"
+        disabled={value.animateSymbolRotation}
         value={value.symbolRotation}
         onChange={(symbolRotation) => onChange({ ...value, symbolRotation })}
         {...ROTATION}
       />
+      <Checkbox
+        label="Animate symbol rotation"
+        value={value.animateSymbolRotation}
+        onChange={(animateSymbolRotation) =>
+          onChange({ ...value, animateSymbolRotation })
+        }
+      />
       <Checkbox
         label="Invert every other symbol (applies only to circles with an even number of symbols)"
         value={value.invertEveryOtherSymbol}
@@ -250,8 +280,31 @@ function getRandomCircleParams(rng: Random): MandalaCircleParams {
   };
 }
 
+function useAnimation(isEnabled: boolean): number {
+  const [frameNumber, setFrameNumber] = useState(0);
+
+  useEffect(() => {
+    if (!isEnabled) {
+      setFrameNumber(0);
+      return;
+    }
+
+    const callback = () => {
+      setFrameNumber(frameNumber + 1);
+    };
+    const timeout = requestAnimationFrame(callback);
+
+    return () => {
+      cancelAnimationFrame(timeout);
+    };
+  }, [isEnabled, frameNumber]);
+
+  return frameNumber;
+}
+
 export const MandalaPage: React.FC<{}> = () => {
   const svgRef = useRef<SVGSVGElement>(null);
+  const canvasRef = useRef<HTMLDivElement>(null);
   const [circle1, setCircle1] = useState(CIRCLE_1_DEFAULTS);
   const [circle2, setCircle2] = useState(CIRCLE_2_DEFAULTS);
   const [baseCompCtx, setBaseCompCtx] = useState(createSvgCompositionContext());
@@ -263,18 +316,27 @@ export const MandalaPage: React.FC<{}> = () => {
     setCircle1({ ...circle1, ...getRandomCircleParams(rng) });
     setCircle2({ ...circle2, ...getRandomCircleParams(rng) });
   };
-
+  const isAnimated = isAnyMandalaCircleAnimated([circle1, circle2]);
+  const frameNumber = useAnimation(isAnimated);
   const symbolCtx = noFillIfShowingSpecs(baseCompCtx);
 
   const circle2SymbolCtx = invertCircle2 ? swapColors(symbolCtx) : symbolCtx;
 
   const circles = [
-    <ExtendedMandalaCircle key="first" {...circle1} {...symbolCtx} />,
+    <ExtendedMandalaCircle
+      key="first"
+      {...animateMandalaCircleParams(circle1, frameNumber)}
+      {...symbolCtx}
+    />,
   ];
 
   if (useTwoCircles) {
     circles.push(
-      <ExtendedMandalaCircle key="second" {...circle2} {...circle2SymbolCtx} />
+      <ExtendedMandalaCircle
+        key="second"
+        {...animateMandalaCircleParams(circle2, frameNumber)}
+        {...circle2SymbolCtx}
+      />
     );
     if (firstBehindSecond) {
       circles.reverse();
@@ -330,12 +392,14 @@ export const MandalaPage: React.FC<{}> = () => {
       <div
         className="canvas"
         style={{ backgroundColor: baseCompCtx.background }}
+        ref={canvasRef}
       >
         <HoverDebugHelper>
           <AutoSizingSvg
             padding={20}
             ref={svgRef}
             bgColor={baseCompCtx.background}
+            sizeToElement={canvasRef}
           >
             <SvgTransform transform={svgScale(0.5)}>{circles}</SvgTransform>
           </AutoSizingSvg>

package-lock.json

@@ -2703,6 +2703,11 @@
         }
       }
     },
+    "classnames": {
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/classnames/-/classnames-2.3.1.tgz",
+      "integrity": "sha512-OlQdbZ7gLfGarSqxesMesDa5uz7KFbID8Kpq/SxIoNGDqY8lSYs0D+hhtBXhcdB3rcbXArFr7vlHheLk1voeNA=="
+    },
     "cli-cursor": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/cli-cursor/-/cli-cursor-2.1.0.tgz",

package.json

@@ -25,6 +25,7 @@
     "@types/react-dom": "^17.0.0",
     "babel-jest": "^26.6.3",
     "cheerio": "^1.0.0-rc.5",
+    "classnames": "^2.3.1",
     "gh-pages": "^3.1.0",
     "jest": "^26.6.3",
     "parcel-bundler": "^1.12.4",