From 4733ba6a4aa4ad806ea5c7a68d9b068b55f0efd9 Mon Sep 17 00:00:00 2001
From: Mikael Finstad <finstaden@gmail.com>
Date: Sat, 26 Feb 2022 15:04:02 +0800
Subject: [PATCH] try to improve canvas player #272

---
 src/Canvas.jsx      | 51 +++++++++++++++--------------
 src/CanvasPlayer.js | 80 ++++++++++++++++++++++++---------------------
 2 files changed, 70 insertions(+), 61 deletions(-)

diff --git a/src/Canvas.jsx b/src/Canvas.jsx
index 46772e8f241..e4ba8ad64cc 100644
--- a/src/Canvas.jsx
+++ b/src/Canvas.jsx
@@ -1,42 +1,45 @@
-import React, { memo, useEffect, useRef, useMemo, useState } from 'react';
-import useDebounce from 'react-use/lib/useDebounce';
+import React, { memo, useEffect, useRef, useMemo } from 'react';
+import { useDebounce } from 'use-debounce';
 
 import CanvasPlayer from './CanvasPlayer';
 
 const Canvas = memo(({ rotate, filePath, width, height, playerTime, streamIndex, commandedTime, playing }) => {
   const canvasRef = useRef();
 
-  const canvasPlayer = useMemo(() => CanvasPlayer({ path: filePath, width, height, streamIndex }), [filePath, width, height, streamIndex]);
+  const canvasPlayer = useMemo(() => CanvasPlayer({ path: filePath, width, height, streamIndex, getCanvas: () => canvasRef.current }), [filePath, width, height, streamIndex]);
 
-  useEffect(() => {
-    canvasPlayer.setCanvas(canvasRef.current);
-
-    return () => {
-      canvasPlayer.setCanvas();
-      canvasPlayer.dispose();
-    };
+  useEffect(() => () => {
+    canvasPlayer.terminate();
   }, [canvasPlayer]);
 
-  const [debouncedPlayerTime, setDebouncedPlayerTime] = useState(0);
-  const [debouncedCommandedTime, setDebouncedCommandedTime] = useState(0);
+  const state = useMemo(() => {
+    if (playing) {
+      return { time: commandedTime, playing };
+    }
+    return { time: playerTime, playing };
+  }, [commandedTime, playerTime, playing]);
 
-  const [, cancelPlayerTimeDebounce] = useDebounce(() => {
-    setDebouncedPlayerTime(playerTime);
-  }, 100, [playerTime]);
+  const [debouncedState, { cancel }] = useDebounce(state, 300, { leading: true, equalityFn: ({ time: time1, playing: playing1 }, { time: time2, playing: playing2 }) => time1 === time2 && playing1 === playing2 });
 
-  const [, cancelCommandedTimeDebounce] = useDebounce(() => {
-    setDebouncedCommandedTime(commandedTime);
-  }, 300, [commandedTime]);
+  /* useEffect(() => {
+    console.log('state', state);
+  }, [state]); */
 
   useEffect(() => () => {
-    cancelPlayerTimeDebounce();
-    cancelCommandedTimeDebounce();
-  }, [cancelPlayerTimeDebounce, cancelCommandedTimeDebounce]);
+    cancel();
+  }, [cancel]);
 
   useEffect(() => {
-    if (playing) canvasPlayer.play(debouncedCommandedTime);
-    else canvasPlayer.pause(debouncedPlayerTime);
-  }, [canvasPlayer, debouncedCommandedTime, debouncedPlayerTime, playing]);
+    // console.log('debouncedState', debouncedState);
+
+    if (debouncedState.time == null) return;
+
+    if (debouncedState.playing) {
+      canvasPlayer.play(debouncedState.time);
+    } else {
+      canvasPlayer.pause(debouncedState.time);
+    }
+  }, [debouncedState, canvasPlayer]);
 
   const canvasStyle = useMemo(() => ({ display: 'block', width: '100%', height: '100%', objectFit: 'contain', transform: rotate ? `rotate(${rotate}deg)` : undefined }), [rotate]);
 
diff --git a/src/CanvasPlayer.js b/src/CanvasPlayer.js
index 24e9aeedefe..4c32f7ef774 100644
--- a/src/CanvasPlayer.js
+++ b/src/CanvasPlayer.js
@@ -3,15 +3,14 @@ import { encodeLiveRawStream, getOneRawFrame } from './ffmpeg';
 // TODO keep everything in electron land?
 const strtok3 = window.require('strtok3');
 
-export default ({ path, width: inWidth, height: inHeight, streamIndex }) => {
-  let canvas;
-
+export default ({ path, width: inWidth, height: inHeight, streamIndex, getCanvas }) => {
   let terminated;
-  let cancel;
+  let aborters = [];
   let commandedTime;
   let playing;
 
   function drawOnCanvas(rgbaImage, width, height) {
+    const canvas = getCanvas();
     if (!canvas || rgbaImage.length === 0) return;
 
     canvas.width = width;
@@ -23,52 +22,59 @@ export default ({ path, width: inWidth, height: inHeight, streamIndex }) => {
     ctx.putImageData(new ImageData(Uint8ClampedArray.from(rgbaImage), width, height), 0, 0);
   }
 
-  async function run() {
+  async function command() {
     let process;
-    let cancelled;
+    let aborted = false;
+
+    function killProcess() {
+      if (process) {
+        process.kill();
+        process = undefined;
+      }
+    }
 
-    cancel = () => {
-      cancelled = true;
-      if (process) process.cancel();
-      cancel = undefined;
-    };
+    function abort() {
+      aborted = true;
+      killProcess();
+      aborters = aborters.filter(((aborter) => aborter !== abort));
+    }
+    aborters.push(abort);
 
-    if (playing) {
-      try {
+    try {
+      if (playing) {
         const { process: processIn, channels, width, height } = encodeLiveRawStream({ path, inWidth, inHeight, streamIndex, seekTo: commandedTime });
         process = processIn;
 
         // process.stderr.on('data', data => console.log(data.toString('utf-8')));
 
         const tokenizer = await strtok3.fromStream(process.stdout);
+        if (aborted) return;
 
         const size = width * height * channels;
-        const buf = Buffer.allocUnsafe(size);
+        const rgbaImage = Buffer.allocUnsafe(size);
 
-        while (!cancelled) {
+        while (!aborted) {
           // eslint-disable-next-line no-await-in-loop
-          await tokenizer.readBuffer(buf, { length: size });
-          if (!cancelled) drawOnCanvas(buf, width, height);
+          await tokenizer.readBuffer(rgbaImage, { length: size });
+          if (aborted) return;
+          drawOnCanvas(rgbaImage, width, height);
         }
-      } catch (err) {
-        if (!err.isCanceled) console.warn(err.message);
-      }
-    } else {
-      try {
+      } else {
         const { process: processIn, width, height } = getOneRawFrame({ path, inWidth, inHeight, streamIndex, seekTo: commandedTime, outSize: 1000 });
         process = processIn;
         const { stdout: rgbaImage } = await process;
-
-        if (!cancelled) drawOnCanvas(rgbaImage, width, height);
-      } catch (err) {
-        if (!err.isCanceled) console.warn(err.message);
+        if (aborted) return;
+        drawOnCanvas(rgbaImage, width, height);
       }
+    } catch (err) {
+      if (!err.killed) console.warn(err.message);
+    } finally {
+      killProcess();
     }
   }
 
-  function command() {
-    if (cancel) cancel();
-    run();
+  function abortAll() {
+    aborters.forEach((aborter) => aborter());
   }
 
   function pause(seekTo) {
@@ -76,6 +82,8 @@ export default ({ path, width: inWidth, height: inHeight, streamIndex }) => {
     if (!playing && commandedTime === seekTo) return;
     playing = false;
     commandedTime = seekTo;
+
+    abortAll();
     command();
   }
 
@@ -84,22 +92,20 @@ export default ({ path, width: inWidth, height: inHeight, streamIndex }) => {
     if (playing && commandedTime === playFrom) return;
     playing = true;
     commandedTime = playFrom;
-    command();
-  }
 
-  function setCanvas(c) {
-    canvas = c;
+    abortAll();
+    command();
   }
 
-  function dispose() {
+  function terminate() {
+    if (terminated) return;
     terminated = true;
-    if (cancel) cancel();
+    abortAll();
   }
 
   return {
     play,
     pause,
-    setCanvas,
-    dispose,
+    terminate,
   };
 };