GoogleChrome · connorjclark · Mar 8, 2024 · Mar 22, 2023 · Mar 22, 2023 · Mar 22, 2023
@@ -4,7 +4,7 @@
   </head>
   <body style="margin: 0;">
     <div style="height: 2000px; background-color: yellow;">
-      <h1>This content is not 1:1 with device pixels.</h1>
+      <h1 role="bad_role_so_this_is_reported">This content is not 1:1 with device pixels.</h1>
     </div>
   </body>
 </html>
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta http-equiv="X-UA-Compatible" content="IE=edge">
+  <meta name="viewport" content="width=device-width, initial-scale=0.5">
+  <title>Document</title>
+</head>
+<body style="overflow: scroll;">
+  <h1 role="bad_role_so_this_is_reported">AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA</h1>
+</body>
+</html>
@@ -17,6 +17,7 @@ import formsAutoComplete from './test-definitions/forms-autocomplete.js';
 import fpsMax from './test-definitions/fps-max.js';
 import fpsMaxPassive from './test-definitions/fps-max-passive.js';
 import fpsScaled from './test-definitions/fps-scaled.js';
+import fpsOverflowX from './test-definitions/fps-overflow-x.js';
 import issuesMixedContent from './test-definitions/issues-mixed-content.js';
 import lanternFetch from './test-definitions/lantern-fetch.js';
 import lanternIdleCallbackLong from './test-definitions/lantern-idle-callback-long.js';
@@ -80,6 +81,7 @@ const smokeTests = [
   formsAutoComplete,
   fpsMax,
   fpsMaxPassive,
+  fpsOverflowX,
   fpsScaled,
   issuesMixedContent,
   lanternFetch,

@@ -0,0 +1,72 @@
+/**
+ * @license Copyright 2023 The Lighthouse Authors. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
+ */
+
+/** @type {LH.Config} */
+const config = {
+  extends: 'lighthouse:default',
+  settings: {
+    onlyCategories: ['performance'],
+  },
+};
+
+/**
+ * @type {Smokehouse.ExpectedRunnerResult}
+ */
+const expectations = {
+  artifacts: {
+    ViewportDimensions: {
+      innerWidth: 1325,
+      innerHeight: 2647,
+      outerWidth: 412,
+      outerHeight: 823,
+      devicePixelRatio: 1.75,
+    },
+  },
+  lhr: {
+    requestedUrl: 'http://localhost:10200/scaled-overflow-content.html',
+    finalDisplayedUrl: 'http://localhost:10200/scaled-overflow-content.html',
+    audits: {},
+    fullPageScreenshot: {
+      nodes: {
+        _includes: [
+          [
+            /-BODY$/,
+            {
+              top: 21,
+              bottom: 58,
+              left: 8,
+              right: 816,
+              width: 808,
+              height: 37,
+            },
+          ],
+          [
+            /-H1$/,
+            {
+              top: 21,
+              bottom: 58,
+              left: 8,
+              right: 816,
+              width: 808,
+              height: 37,
+            },
+          ],
+        ],
+      },
+      screenshot: {
+        height: 1646,
+        width: 824,
+      },
+    },
+  },
+};
+
+export default {
+  id: 'fps-overflow-x',
+  expectations,
+  config,
+};
+
@@ -43,6 +43,17 @@ const expectations = {
               height: 2000,
             },
           ],
+          [
+            /-H1$/,
+            {
+              top: 0,
+              bottom: 37,
+              left: 0,
+              right: 824,
+              width: 824,
+              height: 37,
+            },
+          ],
         ],
       },
       screenshot: {

@@ -47,17 +47,6 @@ function getObservedDeviceMetrics() {
   };
 }
 
-/**
- * The screenshot dimensions are sized to `window.outerHeight` / `window.outerWidth`,
- * however the bounding boxes of the elements are relative to `window.innerHeight` / `window.innerWidth`.
- */
-function getScreenshotAreaSize() {
-  return {
-    width: window.innerWidth,
-    height: window.innerHeight,
-  };
-}
-
 function waitForDoubleRaf() {
   return new Promise((resolve) => {
     requestAnimationFrame(() => requestAnimationFrame(resolve));
@@ -72,6 +61,21 @@ class FullPageScreenshot extends BaseGatherer {
     supportedModes: ['snapshot', 'timespan', 'navigation'],
   };
 
+  /**
+   * @param {LH.Gatherer.Context} context
+   */
+  waitForNetworkIdle(context) {
+    const session = context.driver.defaultSession;
+    const networkMonitor = context.driver.networkMonitor;
+    return waitForNetworkIdle(session, networkMonitor, {
+      pretendDCLAlreadyFired: true,
+      networkQuietThresholdMs: 1000,
+      busyEvent: 'network-critical-busy',
+      idleEvent: 'network-critical-idle',
+      isIdle: recorder => recorder.isCriticalIdle(),
+    });
+  }
+
   /**
    * @param {LH.Gatherer.Context} context
    * @param {{height: number, width: number, mobile: boolean}} deviceMetrics
@@ -89,15 +93,7 @@ class FullPageScreenshot extends BaseGatherer {
     );
     const height = Math.min(fullHeight, MAX_WEBP_SIZE);
 
-    // Setup network monitor before we change the viewport.
-    const networkMonitor = context.driver.networkMonitor;
-    const waitForNetworkIdleResult = waitForNetworkIdle(session, networkMonitor, {
-      pretendDCLAlreadyFired: true,
-      networkQuietThresholdMs: 1000,
-      busyEvent: 'network-critical-busy',
-      idleEvent: 'network-critical-idle',
-      isIdle: recorder => recorder.isCriticalIdle(),
-    });
+    const waitForNetworkIdleResult = this.waitForNetworkIdle(context);
 
     await session.sendCommand('Emulation.setDeviceMetricsOverride', {
       mobile: deviceMetrics.mobile,
@@ -123,22 +119,17 @@ class FullPageScreenshot extends BaseGatherer {
    * @return {Promise<LH.Result.FullPageScreenshot['screenshot']>}
    */
   async _takeScreenshot(context) {
+    const metrics = await context.driver.defaultSession.sendCommand('Page.getLayoutMetrics');
     const result = await context.driver.defaultSession.sendCommand('Page.captureScreenshot', {
       format: FULL_PAGE_SCREENSHOT_FORMAT,
       quality: FULL_PAGE_SCREENSHOT_QUALITY,
     });
     const data = `data:image/${FULL_PAGE_SCREENSHOT_FORMAT};base64,` + result.data;
 
-    const screenshotAreaSize =
-      await context.driver.executionContext.evaluate(getScreenshotAreaSize, {
-        args: [],
-        useIsolation: true,
-      });
-
     return {
       data,
-      width: screenshotAreaSize.width,
-      height: screenshotAreaSize.height,
+      width: metrics.cssVisualViewport.clientWidth,
+      height: metrics.cssVisualViewport.clientHeight,
     };
   }
 

@@ -9,6 +9,7 @@ import {getChromePath} from 'chrome-launcher';
 import * as LH from '../../../../types/lh.js';
 import {createMockContext} from '../../gather/mock-driver.js';
 import FullPageScreenshotGatherer from '../../../gather/gatherers/full-page-screenshot.js';
+import {fnAny} from '../../test-utils.js';
 import lighthouse from '../../../index.js';
 import {Server} from '../../../../cli/test/fixtures/static-server.js';
 
@@ -17,23 +18,36 @@ let contentSize;
 /** @type {{width?: number, height?: number, dpr: number}} */
 let screenSize;
 /** @type {{width?: number, height?: number}} */
-let screenshotAreaSize;
+let screenshotSize;
 /** @type {string[]} */
 let screenshotData;
 let mockContext = createMockContext();
+let fpsGatherer = new FullPageScreenshotGatherer();
 
 beforeEach(() => {
+  fpsGatherer = new FullPageScreenshotGatherer();
+
+  // Prevent `waitForNetworkIdle` from stalling the tests
+  fpsGatherer.waitForNetworkIdle = fnAny().mockImplementation(() => ({
+    promise: Promise.resolve(),
+    cancel: fnAny(),
+  }));
+
   contentSize = {width: 100, height: 100};
   screenSize = {width: 100, height: 100, dpr: 1};
-  screenshotAreaSize = contentSize;
+  screenshotSize = contentSize;
   screenshotData = [];
   mockContext = createMockContext();
   mockContext.driver.defaultSession.sendCommand.mockImplementation((method) => {
     if (method === 'Page.getLayoutMetrics') {
       return {
         cssContentSize: contentSize,
-        // See comment within _takeScreenshot() implementation
+        // This is only accessed on the first call to Page.getLayoutMetrics
+        // At that time the width and height should match the screen size.
         cssLayoutViewport: {clientWidth: screenSize.width, clientHeight: screenSize.height},
+        // This is only accessed on the second call to Page.getLayoutMetrics
+        // At that time the width and height should match the screenshot size.
+        cssVisualViewport: {clientWidth: screenshotSize.width, clientHeight: screenshotSize.height},
       };
     }
     if (method === 'Page.captureScreenshot') {
@@ -55,11 +69,6 @@ beforeEach(() => {
         },
         deviceScaleFactor: screenSize.dpr,
       };
-    } else if (fn.name === 'getScreenshotAreaSize') {
-      return {
-        width: screenshotAreaSize.width,
-        height: screenshotAreaSize.height,
-      };
     } else if (fn.name === 'waitForDoubleRaf') {
       return {};
     } else {
@@ -70,10 +79,9 @@ beforeEach(() => {
 
 describe('FullPageScreenshot gatherer', () => {
   it('captures a full-page screenshot', async () => {
-    const fpsGatherer = new FullPageScreenshotGatherer();
     contentSize = {width: 412, height: 2000};
     screenSize = {width: 412, height: 412};
-    screenshotAreaSize = contentSize;
+    screenshotSize = contentSize;
 
     mockContext.settings = {
       ...mockContext.settings,
@@ -99,10 +107,9 @@ describe('FullPageScreenshot gatherer', () => {
   });
 
   it('resets the emulation correctly when Lighthouse controls it', async () => {
-    const fpsGatherer = new FullPageScreenshotGatherer();
     contentSize = {width: 412, height: 2000};
     screenSize = {width: 412, height: 412};
-    screenshotAreaSize = contentSize;
+    screenshotSize = contentSize;
 
     mockContext.settings = {
       ...mockContext.settings,
@@ -133,10 +140,9 @@ describe('FullPageScreenshot gatherer', () => {
   });
 
   it('resets the emulation correctly when Lighthouse does not control it', async () => {
-    const fpsGatherer = new FullPageScreenshotGatherer();
     contentSize = {width: 500, height: 1500};
     screenSize = {width: 500, height: 500, dpr: 2};
-    screenshotAreaSize = contentSize;
+    screenshotSize = contentSize;
     mockContext.settings = {
       ...mockContext.settings,
       screenEmulation: {
@@ -179,11 +185,9 @@ describe('FullPageScreenshot gatherer', () => {
   });
 
   it('limits the screenshot height to the max Chrome can capture', async () => {
-    const fpsGatherer = new FullPageScreenshotGatherer();
-
     contentSize = {width: 412, height: 100000};
     screenSize = {width: 412, height: 412, dpr: 1};
-    screenshotAreaSize = contentSize;
+    screenshotSize = contentSize;
     mockContext.settings = {
       ...mockContext.settings,
       formFactor: 'mobile',