Add an option to enable/disable hardware acceleration (bug 1902012)

src/core/default_appearance.js

@@ -242,7 +242,7 @@ class FakeUnicodeFont {
     this.fontFamily = fontFamily;
 
     const canvas = new OffscreenCanvas(1, 1);
-    this.ctxMeasure = canvas.getContext("2d");
+    this.ctxMeasure = canvas.getContext("2d", { willReadFrequently: true });
 
     if (!FakeUnicodeFont._fontNameId) {
       FakeUnicodeFont._fontNameId = 1;

src/display/api.js

@@ -213,6 +213,8 @@ const DefaultStandardFontDataFactory =
  *   when creating canvases. The default value is {new DOMCanvasFactory()}.
  * @property {Object} [filterFactory] - A factory instance that will be used
  *   to create SVG filters when rendering some images on the main canvas.
+ * @property {boolean} [enableHWA] - Enables hardware acceleration for
+ *   rendering. The default value is `false`.
  */
 
 /**
@@ -297,6 +299,7 @@ function getDocument(src) {
   const disableStream = src.disableStream === true;
   const disableAutoFetch = src.disableAutoFetch === true;
   const pdfBug = src.pdfBug === true;
+  const enableHWA = src.enableHWA === true;
 
   // Parameters whose default values depend on other parameters.
   const length = rangeTransport ? rangeTransport.length : src.length ?? NaN;
@@ -315,7 +318,7 @@ function getDocument(src) {
           isValidFetchUrl(cMapUrl, document.baseURI) &&
           isValidFetchUrl(standardFontDataUrl, document.baseURI));
   const canvasFactory =
-    src.canvasFactory || new DefaultCanvasFactory({ ownerDocument });
+    src.canvasFactory || new DefaultCanvasFactory({ ownerDocument, enableHWA });
   const filterFactory =
     src.filterFactory || new DefaultFilterFactory({ docId, ownerDocument });
 

src/display/base_factory.js

@@ -46,10 +46,13 @@ class BaseFilterFactory {
 }
 
 class BaseCanvasFactory {
-  constructor() {
+  #enableHWA = false;
+
+  constructor({ enableHWA = false } = {}) {
     if (this.constructor === BaseCanvasFactory) {
       unreachable("Cannot initialize BaseCanvasFactory.");
     }
+    this.#enableHWA = enableHWA;
   }
 
   create(width, height) {
@@ -59,7 +62,9 @@ class BaseCanvasFactory {
     const canvas = this._createCanvas(width, height);
     return {
       canvas,
-      context: canvas.getContext("2d"),
+      context: canvas.getContext("2d", {
+        willReadFrequently: !this.#enableHWA,
+      }),
     };
   }
 

src/display/display_utils.js

@@ -477,8 +477,8 @@ class DOMFilterFactory extends BaseFilterFactory {
 }
 
 class DOMCanvasFactory extends BaseCanvasFactory {
-  constructor({ ownerDocument = globalThis.document } = {}) {
-    super();
+  constructor({ ownerDocument = globalThis.document, enableHWA = false } = {}) {
+    super({ enableHWA });
     this._document = ownerDocument;
   }
 

src/display/editor/tools.js

@@ -98,7 +98,7 @@ class ImageManager {
     // behavior in Safari.
     const svg = `data:image/svg+xml;charset=UTF-8,<svg viewBox="0 0 1 1" width="1" height="1" xmlns="http://www.w3.org/2000/svg"><rect width="1" height="1" style="fill:red;"/></svg>`;
     const canvas = new OffscreenCanvas(1, 3);
-    const ctx = canvas.getContext("2d");
+    const ctx = canvas.getContext("2d", { willReadFrequently: true });
     const image = new Image();
     image.src = svg;
     const promise = image.decode().then(() => {

src/display/text_layer.js

@@ -447,7 +447,10 @@ class TextLayer {
       canvas.className = "hiddenCanvasElement";
       canvas.lang = lang;
       document.body.append(canvas);
-      canvasContext = canvas.getContext("2d", { alpha: false });
+      canvasContext = canvas.getContext("2d", {
+        alpha: false,
+        willReadFrequently: true,
+      });
       this.#canvasContexts.set(lang, canvasContext);
     }
     return canvasContext;