impress-2020/src/app/components/OutfitMovieLayer.js

import React from "react";

import { loadImage, safeImageUrl } from "../util";

function OutfitMovieLayer({
  libraryUrl,
  width,
  height,
  isPaused = false,
  onLoad = null,
}) {
  const [stage, setStage] = React.useState(null);
  const [library, setLibrary] = React.useState(null);
  const [movieClip, setMovieClip] = React.useState(null);
  const canvasRef = React.useRef(null);

  const loadingDeps = useEaselDependenciesLoader();

  // Set the canvas's internal dimensions to be higher, if the device has high
  // DPI like retina. But we'll keep the layout width/height as expected!
  const internalWidth = width * window.devicePixelRatio;
  const internalHeight = height * window.devicePixelRatio;

  // This effect gives us a `stage` corresponding to the canvas element.
  React.useLayoutEffect(() => {
    if (loadingDeps || !canvasRef.current) {
      return;
    }

    setStage((stage) => {
      if (stage && stage.canvas === canvasRef.current) {
        return stage;
      }

      return new window.createjs.Stage(canvasRef.current);
    });
    return () => setStage(null);
  }, [loadingDeps]);

  // This effect gives us the `library` and `movieClip`, based on the incoming
  // `libraryUrl`.
  React.useEffect(() => {
    if (loadingDeps) {
      return;
    }

    let canceled = false;

    loadMovieLibrary(libraryUrl)
      .then((library) => {
        if (canceled) {
          return;
        }

        setLibrary(library);

        const movieClip = buildMovieClip(library, libraryUrl);
        setMovieClip(movieClip);
      })
      .catch((e) => {
        console.error("Error loading outfit movie layer", e);
      });

    return () => {
      canceled = true;
      setLibrary(null);
      setMovieClip(null);
    };
  }, [loadingDeps, libraryUrl]);

  // This effect puts the `movieClip` on the `stage`, when both are ready.
  React.useEffect(() => {
    if (!stage || !movieClip) {
      return;
    }

    stage.addChild(movieClip);

    // Render the movie's first frame. If it's animated and we're not paused,
    // then another effect will perform subsequent updates.
    stage.update();

    // This is when we trigger `onLoad`: once we're actually showing it!
    if (onLoad) {
      onLoad();
    }

    return () => stage.removeChild(movieClip);
  }, [stage, movieClip, onLoad]);

  // This effect updates the `stage` according to the `library`'s framerate,
  // but only if there's actual animation to do - i.e., there's more than one
  // frame to show, and we're not paused.
  React.useEffect(() => {
    if (!stage || !movieClip || !library) {
      return;
    }

    if (isPaused || !hasAnimations(movieClip)) {
      return;
    }

    const intervalId = setInterval(
      () => stage.update(),
      1000 / library.properties.fps
    );
    return () => clearInterval(intervalId);
  }, [stage, movieClip, library, isPaused]);

  // This effect keeps the `movieClip` scaled correctly, based on the canvas
  // size and the `library`'s natural size declaration. (If the canvas size
  // changes on window resize, then this will keep us responsive, so long as
  // the parent updates our width/height props on window resize!)
  React.useEffect(() => {
    if (!stage || !movieClip || !library) {
      return;
    }

    movieClip.scaleX = internalWidth / library.properties.width;
    movieClip.scaleY = internalHeight / library.properties.height;

    // Redraw the stage with the new dimensions - but with `tickOnUpdate` set
    // to `false`, so that we don't advance by a frame. This keeps us
    // really-paused if we're paused, and avoids skipping ahead by a frame if
    // we're playing.
    stage.tickOnUpdate = false;
    stage.update();
    stage.tickOnUpdate = true;
  }, [stage, library, movieClip, internalWidth, internalHeight]);

  return (
    <canvas
      ref={canvasRef}
      width={internalWidth}
      height={internalHeight}
      style={{ width: width, height: height }}
    />
  );
}

/**
 * useEaselDependenciesLoader loads the CreateJS scripts we use in OutfitCanvas.
 * We load it as part of OutfitCanvas, but callers can also use this to preload
 * the scripts and track loading progress.
 */
export function useEaselDependenciesLoader() {
  // NOTE: I couldn't find an official NPM source for this that worked with
  //       Webpack, and I didn't want to rely on random people's ports, and I
  //       couldn't get a bundled version to work quite right. So we load
  //       createjs async!
  const loadingEaselJS = useScriptTag(
    "https://code.createjs.com/1.0.0/easeljs.min.js"
  );
  const loadingTweenJS = useScriptTag(
    "https://code.createjs.com/1.0.0/tweenjs.min.js"
  );
  const loadingDeps = loadingEaselJS || loadingTweenJS;

  return loadingDeps;
}

function useScriptTag(src) {
  const [loading, setLoading] = React.useState(true);

  React.useEffect(() => {
    const existingScript = document.querySelector(
      `script[src=${CSS.escape(src)}]`
    );
    if (existingScript) {
      setLoading(false);
      return;
    }

    let canceled = false;
    loadScriptTag(src).then(() => {
      if (!canceled) {
        setLoading(false);
      }
    });

    return () => {
      canceled = true;
      setLoading(true);
    };
  }, [src, setLoading]);

  return loading;
}

function loadScriptTag(src) {
  return new Promise((resolve, reject) => {
    const script = document.createElement("script");
    script.onload = () => resolve(script);
    script.onerror = (e) => reject(e);
    script.src = src;
    document.body.appendChild(script);
  });
}

export async function loadMovieLibrary(librarySrc) {
  // These library JS files are interesting in their operation. It seems like
  // the idea is, it pushes an object to a global array, and you need to snap
  // it up and see it at the end of the array! And I don't really see a way to
  // like, get by a name or ID that we know by this point. So, here we go, just
  // try to grab it once it arrives!
  //
  // I'm not _sure_ this method is reliable, but it seems to be stable so far
  // in Firefox for me. The things I think I'm observing are:
  //   - Script execution order should match insert order,
  //   - Onload execution order should match insert order,
  //   - BUT, script executions might be batched before onloads.
  //   - So, each script grabs the _first_ composition from the list, and
  //     deletes it after grabbing. That way, it serves as a FIFO queue!
  // I'm not suuure this is happening as I'm expecting, vs I'm just not seeing
  // the race anymore? But fingers crossed!
  await loadScriptTag(safeImageUrl(librarySrc));
  const [compositionId, composition] = Object.entries(
    window.AdobeAn.compositions
  )[0];
  if (Object.keys(window.AdobeAn.compositions).length > 1) {
    console.warn(
      `Grabbing composition ${compositionId}, but there are >1 here: `,
      Object.keys(window.AdobeAn.compositions).length
    );
  }
  delete window.AdobeAn.compositions[compositionId];
  const library = composition.getLibrary();

  // One more loading step as part of loading this library is loading the
  // images it uses for sprites.
  //
  // TODO: I guess the manifest has these too, so if we could use our DB cache
  //       to get the manifest to us faster, then we could avoid a network RTT
  //       on the critical path by preloading these images before the JS file
  //       even gets to us?
  const librarySrcDir = librarySrc.split("/").slice(0, -1).join("/");
  const manifestImages = new Map(
    library.properties.manifest.map(({ id, src }) => [
      id,
      loadImage({
        src: safeImageUrl(librarySrcDir + "/" + src),
        crossOrigin: "anonymous",
      }),
    ])
  );
  await Promise.all(manifestImages.values());

  // Finally, once we have the images loaded, the library object expects us to
  // mutate it (!) to give it the actual sprite sheet objects based on the
  // loaded images. That's how the MovieClip's objects will access the loaded
  // versions!
  const spriteSheets = composition.getSpriteSheet();
  for (const { name, frames } of library.ssMetadata) {
    const image = await manifestImages.get(name);
    spriteSheets[name] = new window.createjs.SpriteSheet({
      images: [image],
      frames,
    });
  }

  return library;
}

export function buildMovieClip(library, libraryUrl) {
  let constructorName;
  try {
    const fileName = libraryUrl.split("/").pop();
    const fileNameWithoutExtension = fileName.split(".")[0];
    constructorName = fileNameWithoutExtension.replace(/[ -]/g, "");
    if (constructorName.match(/^[0-9]/)) {
      constructorName = "_" + constructorName;
    }
  } catch (e) {
    throw new Error(
      `Movie libraryUrl ${JSON.stringify(
        libraryUrl
      )} did not match expected format: ${e.message}`
    );
  }

  const LibraryMovieClipConstructor = library[constructorName];
  if (!LibraryMovieClipConstructor) {
    throw new Error(
      `Expected JS movie library ${libraryUrl} to contain a constructor ` +
        `named ${constructorName}, but it did not: ${Object.keys(library)}`
    );
  }
  const movieClip = new LibraryMovieClipConstructor();

  return movieClip;
}

/**
 * Recursively scans the given MovieClip (or child createjs node), to see if
 * there are any animated areas.
 */
export function hasAnimations(createjsNode) {
  return (
    createjsNode.totalFrames > 1 ||
    (createjsNode.children || []).some(hasAnimations)
  );
}

export default OutfitMovieLayer;