record canvas mutations (#296)

* record canvas mutations

close #60, #261

This patch implements the canvas mutation observer.
It consists of both the record and the replay side changes.

In the record side, we add a `recordCanvas` flag to indicate
whether to record canvas elements and the flag defaults to false.
Different from our other observers, the canvas observer was
disabled by default. Because some applications with heavy canvas
usage may emit a lot of data as canvas changed, especially the
scenarios that use a lot of `drawImage` API.
So the behavior should be audited by users and only record canvas
when the flag was set to true.

In the replay side, we add a `UNSAFE_replayCanvas` flag to indicate
whether to replay canvas mutations.
Similar to the `recordCanvas` flag, `UNSAFE_replayCanvas` defaults
to false. But unlike the record canvas implementation is stable and
safe, the replay canvas implementation is UNSAFE.
It's unsafe because we need to add `allow-scripts` to the replay
sandbox, which may cause some unexpected script execution. Currently,
users should be aware of this implementation detail and enable this
feature carefully.

* update canvas integration test

package.json

@@ -62,7 +62,7 @@
     "@xstate/fsm": "^1.4.0",
     "mitt": "^1.1.3",
     "pako": "^1.0.11",
-    "rrweb-snapshot": "^0.8.0",
+    "rrweb-snapshot": "^0.8.1",
     "smoothscroll-polyfill": "^0.4.3"
   }
 }

scripts/repl.ts

@@ -81,7 +81,7 @@ function getCode(): string {
         width: 1600,
         height: 900,
       },
-      args: ['--start-maximized'],
+      args: ['--start-maximized', '--ignore-certificate-errors'],
     });
     const page = await browser.newPage();
     await page.goto(url, {
@@ -94,7 +94,8 @@ function getCode(): string {
     await page.evaluate(`;${code}
       window.__IS_RECORDING__ = true
       rrweb.record({
-        emit: event => window._replLog(event)
+        emit: event => window._replLog(event),
+        recordCanvas: true
       });
     `);
     page.on('framenavigated', async () => {
@@ -103,14 +104,14 @@ function getCode(): string {
         await page.evaluate(`;${code}
           window.__IS_RECORDING__ = true
           rrweb.record({
-            emit: event => window._replLog(event)
+            emit: event => window._replLog(event),
+            recordCanvas: true
           });
         `);
       }
     });
 
-    emitter.once('done', async shouldReplay => {
+    emitter.once('done', async (shouldReplay) => {
-      console.log(`Recorded ${events.length} events`);
       await browser.close();
       if (shouldReplay) {
         await replay();
@@ -170,7 +171,9 @@ function getCode(): string {
         '<\\/script>',
       )};
       /*-->*/
-      const replayer = new rrweb.Replayer(events);
+      const replayer = new rrweb.Replayer(events, {
+        UNSAFE_replayCanvas: true
+      });
       replayer.play();
     </script>
   </body>
@@ -182,10 +185,10 @@ function getCode(): string {
   }
 
   process
-    .on('uncaughtException', error => {
+    .on('uncaughtException', (error) => {
       console.error(error);
     })
-    .on('unhandledRejection', error => {
+    .on('unhandledRejection', (error) => {
       console.error(error);
     });
 })();

src/record/index.ts

@@ -41,6 +41,7 @@ function record<T = eventWithTime>(
     packFn,
     sampling = {},
     mousemoveWait,
+    recordCanvas = false,
   } = options;
   // runtime checks for user options
   if (!emit) {
@@ -113,6 +114,7 @@ function record<T = eventWithTime>(
       blockClass,
       inlineStylesheet,
       maskInputOptions,
+      recordCanvas,
     );
 
     if (!node) {
@@ -244,11 +246,22 @@ function record<T = eventWithTime>(
                   },
                 }),
               ),
+            canvasMutationCb: (p) =>
+              wrappedEmit(
+                wrapEvent({
+                  type: EventType.IncrementalSnapshot,
+                  data: {
+                    source: IncrementalSource.CanvasMutation,
+                    ...p,
+                  },
+                }),
+              ),
             blockClass,
             ignoreClass,
             maskInputOptions,
             inlineStylesheet,
             sampling,
+            recordCanvas,
           },
           hooks,
         ),

src/record/mutation.ts

@@ -138,16 +138,19 @@ export default class MutationBuffer {
   private blockClass: blockClass;
   private inlineStylesheet: boolean;
   private maskInputOptions: MaskInputOptions;
+  private recordCanvas: boolean;
 
   constructor(
     cb: mutationCallBack,
     blockClass: blockClass,
     inlineStylesheet: boolean,
     maskInputOptions: MaskInputOptions,
+    recordCanvas: boolean,
   ) {
     this.blockClass = blockClass;
     this.inlineStylesheet = inlineStylesheet;
     this.maskInputOptions = maskInputOptions;
+    this.recordCanvas = recordCanvas;
     this.emissionCallback = cb;
   }
 
@@ -187,6 +190,7 @@ export default class MutationBuffer {
           true,
           this.inlineStylesheet,
           this.maskInputOptions,
+          this.recordCanvas,
         )!,
       });
     };

src/record/observer.ts

@@ -8,6 +8,7 @@ import {
   getWindowWidth,
   isBlocked,
   isTouchEvent,
+  patch,
 } from '../utils';
 import {
   mutationCallBack,
@@ -30,6 +31,7 @@ import {
   mediaInteractionCallback,
   MediaInteractions,
   SamplingStrategy,
+  canvasMutationCallback,
 } from '../types';
 import MutationBuffer from './mutation';
 
@@ -38,6 +40,7 @@ function initMutationObserver(
   blockClass: blockClass,
   inlineStylesheet: boolean,
   maskInputOptions: MaskInputOptions,
+  recordCanvas: boolean,
 ): MutationObserver {
   // see mutation.ts for details
   const mutationBuffer = new MutationBuffer(
@@ -45,6 +48,7 @@ function initMutationObserver(
     blockClass,
     inlineStylesheet,
     maskInputOptions,
+    recordCanvas,
   );
   const observer = new MutationObserver(mutationBuffer.processMutations);
   observer.observe(document, {
@@ -357,6 +361,75 @@ function initMediaInteractionObserver(
   };
 }
 
+function initCanvasMutationObserver(
+  cb: canvasMutationCallback,
+  blockClass: blockClass,
+): listenerHandler {
+  const props = Object.getOwnPropertyNames(CanvasRenderingContext2D.prototype);
+  const handlers: listenerHandler[] = [];
+  for (const prop of props) {
+    try {
+      if (
+        typeof CanvasRenderingContext2D.prototype[
+          prop as keyof CanvasRenderingContext2D
+        ] !== 'function'
+      ) {
+        continue;
+      }
+      const restoreHandler = patch(
+        CanvasRenderingContext2D.prototype,
+        prop,
+        function (original) {
+          return function (
+            this: CanvasRenderingContext2D,
+            ...args: Array<unknown>
+          ) {
+            if (!isBlocked(this.canvas, blockClass)) {
+              setTimeout(() => {
+                const recordArgs = [...args];
+                if (prop === 'drawImage') {
+                  if (
+                    recordArgs[0] &&
+                    recordArgs[0] instanceof HTMLCanvasElement
+                  ) {
+                    recordArgs[0] = recordArgs[0].toDataURL();
+                  }
+                }
+                cb({
+                  id: mirror.getId((this.canvas as unknown) as INode),
+                  property: prop,
+                  args: recordArgs,
+                });
+              }, 0);
+            }
+            return original.apply(this, args);
+          };
+        },
+      );
+      handlers.push(restoreHandler);
+    } catch {
+      const hookHandler = hookSetter<CanvasRenderingContext2D>(
+        CanvasRenderingContext2D.prototype,
+        prop,
+        {
+          set(v) {
+            cb({
+              id: mirror.getId((this.canvas as unknown) as INode),
+              property: prop,
+              args: [v],
+              setter: true,
+            });
+          },
+        },
+      );
+      handlers.push(hookHandler);
+    }
+  }
+  return () => {
+    handlers.forEach((h) => h());
+  };
+}
+
 function mergeHooks(o: observerParam, hooks: hooksParam) {
   const {
     mutationCb,
@@ -367,6 +440,7 @@ function mergeHooks(o: observerParam, hooks: hooksParam) {
     inputCb,
     mediaInteractionCb,
     styleSheetRuleCb,
+    canvasMutationCb,
   } = o;
   o.mutationCb = (...p: Arguments<mutationCallBack>) => {
     if (hooks.mutation) {
@@ -416,6 +490,12 @@ function mergeHooks(o: observerParam, hooks: hooksParam) {
     }
     styleSheetRuleCb(...p);
   };
+  o.canvasMutationCb = (...p: Arguments<canvasMutationCallback>) => {
+    if (hooks.canvasMutation) {
+      hooks.canvasMutation(...p);
+    }
+    canvasMutationCb(...p);
+  };
 }
 
 export default function initObservers(
@@ -428,6 +508,7 @@ export default function initObservers(
     o.blockClass,
     o.inlineStylesheet,
     o.maskInputOptions,
+    o.recordCanvas,
   );
   const mousemoveHandler = initMoveObserver(o.mousemoveCb, o.sampling);
   const mouseInteractionHandler = initMouseInteractionObserver(
@@ -453,6 +534,9 @@ export default function initObservers(
     o.blockClass,
   );
   const styleSheetObserver = initStyleSheetObserver(o.styleSheetRuleCb);
+  const canvasMutationObserver = o.recordCanvas
+    ? initCanvasMutationObserver(o.canvasMutationCb, o.blockClass)
+    : () => {};
 
   return () => {
     mutationObserver.disconnect();
@@ -463,5 +547,6 @@ export default function initObservers(
     inputHandler();
     mediaInteractionHandler();
     styleSheetObserver();
+    canvasMutationObserver();
   };
 }

src/replay/index.ts

@@ -25,6 +25,7 @@ import {
   mutationData,
   scrollData,
   inputData,
+  canvasMutationData,
 } from '../types';
 import { mirror, polyfill, TreeIndex } from '../utils';
 import getInjectStyleRules from './styles/inject-style';
@@ -50,6 +51,7 @@ const defaultConfig: playerConfig = {
   liveMode: false,
   insertStyleRules: [],
   triggerFocus: true,
+  UNSAFE_replayCanvas: false,
 };
 
 export class Replayer {
@@ -76,6 +78,8 @@ export class Replayer {
   private treeIndex!: TreeIndex;
   private fragmentParentMap!: Map<INode, INode>;
 
+  private imageMap: Map<eventWithTime, HTMLImageElement> = new Map();
+
   constructor(
     events: Array<eventWithTime | string>,
     config?: Partial<playerConfig>,
@@ -289,7 +293,11 @@ export class Replayer {
     this.wrapper.appendChild(this.mouse);
 
     this.iframe = document.createElement('iframe');
-    this.iframe.setAttribute('sandbox', 'allow-same-origin');
+    const attributes = ['allow-same-origin'];
+    if (this.config.UNSAFE_replayCanvas) {
+      attributes.push('allow-scripts');
+    }
+    this.iframe.setAttribute('sandbox', attributes.join(' '));
     this.disableInteract();
     this.wrapper.appendChild(this.iframe);
   }
@@ -413,6 +421,9 @@ export class Replayer {
     }
     this.emitter.emit(ReplayerEvents.FullsnapshotRebuilded, event);
     this.waitForStylesheetLoad();
+    if (this.config.UNSAFE_replayCanvas) {
+      this.preloadAllImages();
+    }
   }
 
   /**
@@ -465,6 +476,44 @@ export class Replayer {
     }
   }
 
+  /**
+   * pause when there are some canvas drawImage args need to be loaded
+   */
+  private preloadAllImages() {
+    let beforeLoadState = this.service.state;
+    const { unsubscribe } = this.service.subscribe((state) => {
+      beforeLoadState = state;
+    });
+    let count = 0;
+    let resolved = 0;
+    for (const event of this.service.state.context.events) {
+      if (
+        event.type === EventType.IncrementalSnapshot &&
+        event.data.source === IncrementalSource.CanvasMutation &&
+        event.data.property === 'drawImage' &&
+        typeof event.data.args[0] === 'string' &&
+        !this.imageMap.has(event)
+      ) {
+        count++;
+        const image = document.createElement('img');
+        image.src = event.data.args[0];
+        this.imageMap.set(event, image);
+        image.onload = () => {
+          resolved++;
+          if (resolved === count) {
+            if (beforeLoadState.matches('playing')) {
+              this.play(this.getCurrentTime());
+            }
+            unsubscribe();
+          }
+        };
+      }
+    }
+    if (count !== resolved) {
+      this.service.send({ type: 'PAUSE' });
+    }
+  }
+
   private applyIncremental(
     e: incrementalSnapshotEvent & { timestamp: number },
     isSync: boolean,
@@ -643,6 +692,43 @@ export class Replayer {
         }
         break;
       }
+      case IncrementalSource.CanvasMutation: {
+        if (!this.config.UNSAFE_replayCanvas) {
+          return;
+        }
+        const target = mirror.getNode(d.id);
+        if (!target) {
+          return this.debugNodeNotFound(d, d.id);
+        }
+        try {
+          const ctx = ((target as unknown) as HTMLCanvasElement).getContext(
+            '2d',
+          )!;
+          if (d.setter) {
+            // skip some read-only type checks
+            // tslint:disable-next-line:no-any
+            (ctx as any)[d.property] = d.args[0];
+            return;
+          }
+          const original = ctx[
+            d.property as keyof CanvasRenderingContext2D
+          ] as Function;
+          /**
+           * We have serialized the image source into base64 string during recording,
+           * which has been preloaded before replay.
+           * So we can get call drawImage SYNCHRONOUSLY which avoid some fragile cast.
+           */
+          if (d.property === 'drawImage' && typeof d.args[0] === 'string') {
+            const image = this.imageMap.get(e);
+            d.args[0] = image;
+            original.apply(ctx, d.args);
+          } else {
+            original.apply(ctx, d.args);
+          }
+        } catch (error) {
+          this.warnCanvasMutationFailed(d, d.id, error);
+        }
+      }
       default:
     }
   }
@@ -914,6 +1000,19 @@ export class Replayer {
     console.warn(REPLAY_CONSOLE_PREFIX, `Node with id '${id}' not found in`, d);
   }
 
+  private warnCanvasMutationFailed(
+    d: canvasMutationData,
+    id: number,
+    error: unknown,
+  ) {
+    console.warn(
+      REPLAY_CONSOLE_PREFIX,
+      `Has error on update canvas '${id}'`,
+      d,
+      error,
+    );
+  }
+
   private debugNodeNotFound(d: incrementalData, id: number) {
     /**
      * There maybe some valid scenes of node not being found.

src/types.ts

@@ -70,6 +70,7 @@ export enum IncrementalSource {
   TouchMove,
   MediaInteraction,
   StyleSheetRule,
+  CanvasMutation,
 }
 
 export type mutationData = {
@@ -106,6 +107,10 @@ export type styleSheetRuleData = {
   source: IncrementalSource.StyleSheetRule;
 } & styleSheetRuleParam;
 
+export type canvasMutationData = {
+  source: IncrementalSource.CanvasMutation;
+} & canvasMutationParam;
+
 export type incrementalData =
   | mutationData
   | mousemoveData
@@ -114,7 +119,8 @@ export type incrementalData =
   | viewportResizeData
   | inputData
   | mediaInteractionData
-  | styleSheetRuleData;
+  | styleSheetRuleData
+  | canvasMutationData;
 
 export type event =
   | domContentLoadedEvent
@@ -165,6 +171,7 @@ export type recordOptions<T> = {
   hooks?: hooksParam;
   packFn?: PackFn;
   sampling?: SamplingStrategy;
+  recordCanvas?: boolean;
   // departed, please use sampling options
   mousemoveWait?: number;
 };
@@ -182,7 +189,9 @@ export type observerParam = {
   maskInputOptions: MaskInputOptions;
   inlineStylesheet: boolean;
   styleSheetRuleCb: styleSheetRuleCallback;
+  canvasMutationCb: canvasMutationCallback;
   sampling: SamplingStrategy;
+  recordCanvas: boolean;
 };
 
 export type hooksParam = {
@@ -194,6 +203,7 @@ export type hooksParam = {
   input?: inputCallback;
   mediaInteaction?: mediaInteractionCallback;
   styleSheetRule?: styleSheetRuleCallback;
+  canvasMutation?: canvasMutationCallback;
 };
 
 // https://dom.spec.whatwg.org/#interface-mutationrecord
@@ -309,6 +319,15 @@ export type styleSheetRuleParam = {
 
 export type styleSheetRuleCallback = (s: styleSheetRuleParam) => void;
 
+export type canvasMutationCallback = (p: canvasMutationParam) => void;
+
+export type canvasMutationParam = {
+  id: number;
+  property: string;
+  args: Array<unknown>;
+  setter?: true;
+};
+
 export type viewportResizeDimention = {
   width: number;
   height: number;
@@ -362,6 +381,7 @@ export type playerConfig = {
   liveMode: boolean;
   insertStyleRules: string[];
   triggerFocus: boolean;
+  UNSAFE_replayCanvas: boolean;
   unpackFn?: UnpackFn;
 };
 

src/utils.ts

@@ -124,18 +124,18 @@ export function patch(
   // tslint:disable-next-line:no-any
   replacement: (...args: any[]) => any,
 ): () => void {
-  if (!(name in source)) {
+  try {
-    return () => {};
+    if (!(name in source)) {
-  }
+      return () => {};
+    }
 
-  const original = source[name] as () => unknown;
+    const original = source[name] as () => unknown;
-  const wrapped = replacement(original);
+    const wrapped = replacement(original);
 
-  // Make sure it's a function first, as we need to attach an empty prototype for `defineProperties` to work
+    // Make sure it's a function first, as we need to attach an empty prototype for `defineProperties` to work
-  // otherwise it'll throw "TypeError: Object.defineProperties called on non-object"
+    // otherwise it'll throw "TypeError: Object.defineProperties called on non-object"
-  // tslint:disable-next-line:strict-type-predicates
+    // tslint:disable-next-line:strict-type-predicates
-  if (typeof wrapped === 'function') {
+    if (typeof wrapped === 'function') {
-    try {
       wrapped.prototype = wrapped.prototype || {};
       Object.defineProperties(wrapped, {
         __rrweb_original__: {
@@ -143,17 +143,18 @@ export function patch(
           value: original,
         },
       });
-    } catch {
-      // This can throw if multiple fill happens on a global object like XMLHttpRequest
-      // Fixes https://github.com/getsentry/sentry-javascript/issues/2043
     }
+
+    source[name] = wrapped;
+
+    return () => {
+      source[name] = original;
+    };
+  } catch {
+    return () => {};
+    // This can throw if multiple fill happens on a global object like XMLHttpRequest
+    // Fixes https://github.com/getsentry/sentry-javascript/issues/2043
   }
-
-  source[name] = wrapped;
-
-  return () => {
-    source[name] = original;
-  };
 }
 
 export function getWindowHeight(): number {

test/__snapshots__/integration.test.ts.snap

@@ -333,6 +333,230 @@ exports[`block 1`] = `
 ]"
 `;
 
+exports[`canvas 1`] = `
+"[
+  {
+    \\"type\\": 0,
+    \\"data\\": {}
+  },
+  {
+    \\"type\\": 1,
+    \\"data\\": {}
+  },
+  {
+    \\"type\\": 4,
+    \\"data\\": {
+      \\"href\\": \\"about:blank\\",
+      \\"width\\": 1920,
+      \\"height\\": 1080
+    }
+  },
+  {
+    \\"type\\": 2,
+    \\"data\\": {
+      \\"node\\": {
+        \\"type\\": 0,
+        \\"childNodes\\": [
+          {
+            \\"type\\": 1,
+            \\"name\\": \\"html\\",
+            \\"publicId\\": \\"\\",
+            \\"systemId\\": \\"\\",
+            \\"id\\": 2
+          },
+          {
+            \\"type\\": 2,
+            \\"tagName\\": \\"html\\",
+            \\"attributes\\": {
+              \\"lang\\": \\"en\\"
+            },
+            \\"childNodes\\": [
+              {
+                \\"type\\": 2,
+                \\"tagName\\": \\"head\\",
+                \\"attributes\\": {},
+                \\"childNodes\\": [
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 5
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"meta\\",
+                    \\"attributes\\": {
+                      \\"charset\\": \\"UTF-8\\"
+                    },
+                    \\"childNodes\\": [],
+                    \\"id\\": 6
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 7
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"meta\\",
+                    \\"attributes\\": {
+                      \\"name\\": \\"viewport\\",
+                      \\"content\\": \\"width=device-width, initial-scale=1.0\\"
+                    },
+                    \\"childNodes\\": [],
+                    \\"id\\": 8
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 9
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"title\\",
+                    \\"attributes\\": {},
+                    \\"childNodes\\": [
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"canvas\\",
+                        \\"id\\": 11
+                      }
+                    ],
+                    \\"id\\": 10
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n  \\",
+                    \\"id\\": 12
+                  }
+                ],
+                \\"id\\": 4
+              },
+              {
+                \\"type\\": 3,
+                \\"textContent\\": \\"\\\\n  \\",
+                \\"id\\": 13
+              },
+              {
+                \\"type\\": 2,
+                \\"tagName\\": \\"body\\",
+                \\"attributes\\": {},
+                \\"childNodes\\": [
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 15
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"canvas\\",
+                    \\"attributes\\": {
+                      \\"id\\": \\"myCanvas\\",
+                      \\"width\\": \\"200\\",
+                      \\"height\\": \\"100\\",
+                      \\"style\\": \\"border: 1px solid #000000;\\",
+                      \\"rr_dataURL\\": \\"data:image/png;base64,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\\"
+                    },
+                    \\"childNodes\\": [
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"id\\": 17
+                      }
+                    ],
+                    \\"id\\": 16
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 18
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"script\\",
+                    \\"attributes\\": {},
+                    \\"childNodes\\": [
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
+                        \\"id\\": 20
+                      }
+                    ],
+                    \\"id\\": 19
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n  \\\\n    \\",
+                    \\"id\\": 21
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"script\\",
+                    \\"attributes\\": {},
+                    \\"childNodes\\": [
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
+                        \\"id\\": 23
+                      }
+                    ],
+                    \\"id\\": 22
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
+                    \\"id\\": 24
+                  }
+                ],
+                \\"id\\": 14
+              }
+            ],
+            \\"id\\": 3
+          }
+        ],
+        \\"id\\": 1
+      },
+      \\"initialOffset\\": {
+        \\"left\\": 0,
+        \\"top\\": 0
+      }
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 9,
+      \\"id\\": 16,
+      \\"property\\": \\"moveTo\\",
+      \\"args\\": [
+        0,
+        0
+      ]
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 9,
+      \\"id\\": 16,
+      \\"property\\": \\"lineTo\\",
+      \\"args\\": [
+        200,
+        100
+      ]
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 9,
+      \\"id\\": 16,
+      \\"property\\": \\"stroke\\",
+      \\"args\\": []
+    }
+  }
+]"
+`;
+
 exports[`character-data 1`] = `
 "[
   {

test/html/canvas.html

@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>canvas</title>
+  </head>
+  <body>
+    <canvas
+      id="myCanvas"
+      width="200"
+      height="100"
+      style="border: 1px solid #000000;"
+    >
+    </canvas>
+    <script>
+      var c = document.getElementById('myCanvas');
+      var ctx = c.getContext('2d');
+      // Create gradient
+      var grd = ctx.createLinearGradient(0, 0, 200, 0);
+      grd.addColorStop(0, 'red');
+      grd.addColorStop(1, 'white');
+
+      // Fill with gradient
+      ctx.fillStyle = grd;
+      ctx.fillRect(10, 10, 150, 80);
+      setTimeout(() => {
+        ctx.moveTo(0, 0);
+        ctx.lineTo(200, 100);
+        ctx.stroke();
+      }, 10);
+    </script>
+  </body>
+</html>

test/integration.test.ts

@@ -33,7 +33,8 @@ describe('record integration tests', function (this: ISuite) {
           window.snapshots.push(event);
         },
         maskAllInputs: ${options.maskAllInputs},
-        maskInputOptions: ${JSON.stringify(options.maskAllInputs)}
+        maskInputOptions: ${JSON.stringify(options.maskAllInputs)},
+        recordCanvas: ${options.recordCanvas}
       });
     </script>
     </body>
@@ -244,6 +245,19 @@ describe('record integration tests', function (this: ISuite) {
     assertSnapshot(snapshots, __filename, 'react-styled-components');
   });
 
+  it('should record canvas mutations', async () => {
+    const page: puppeteer.Page = await this.browser.newPage();
+    await page.goto('about:blank');
+    await page.setContent(
+      getHtml.call(this, 'canvas.html', {
+        recordCanvas: true,
+      }),
+    );
+    await page.waitFor(50);
+    const snapshots = await page.evaluate('window.snapshots');
+    assertSnapshot(snapshots, __filename, 'canvas');
+  });
+
   it('will serialize node before record', async () => {
     const page: puppeteer.Page = await this.browser.newPage();
     await page.goto('about:blank');