Do the AppOptions.get("printResolution") lookup once in web/app.js, when initializing PDFPrintServiceFactory-instances, rather then for every printed page

There's really no point in repeating these lookups over and over, since the value should be constant for the duration of one print invocation anyway.

Author: Snuffleupagus

web/app.js

@@ -1609,10 +1609,13 @@ const PDFViewerApplication = {
 
     const pagesOverview = this.pdfViewer.getPagesOverview();
     const printContainer = this.appConfig.printContainer;
+    const printResolution = AppOptions.get("printResolution");
+
     const printService = PDFPrintServiceFactory.instance.createPrintService(
       this.pdfDocument,
       pagesOverview,
       printContainer,
+      printResolution,
       this.l10n
     );
     this.printService = printService;

web/firefox_print_service.js

@@ -13,18 +13,22 @@
  * limitations under the License.
  */
 
-import { AppOptions } from "./app_options.js";
 import { CSS_UNITS } from "./ui_utils.js";
 import { PDFPrintServiceFactory } from "./app.js";
 import { shadow } from "pdfjs-lib";
 
 // Creates a placeholder with div and canvas with right size for the page.
-function composePage(pdfDocument, pageNumber, size, printContainer) {
+function composePage(
+  pdfDocument,
+  pageNumber,
+  size,
+  printContainer,
+  printResolution
+) {
   const canvas = document.createElement("canvas");
 
   // The size of the canvas in pixels for printing.
-  const PRINT_RESOLUTION = AppOptions.get("printResolution") || 150;
-  const PRINT_UNITS = PRINT_RESOLUTION / 72.0;
+  const PRINT_UNITS = printResolution / 72.0;
   canvas.width = Math.floor(size.width * PRINT_UNITS);
   canvas.height = Math.floor(size.height * PRINT_UNITS);
 
@@ -76,21 +80,38 @@ function composePage(pdfDocument, pageNumber, size, printContainer) {
   };
 }
 
-function FirefoxPrintService(pdfDocument, pagesOverview, printContainer) {
+function FirefoxPrintService(
+  pdfDocument,
+  pagesOverview,
+  printContainer,
+  printResolution
+) {
   this.pdfDocument = pdfDocument;
   this.pagesOverview = pagesOverview;
   this.printContainer = printContainer;
+  this._printResolution = printResolution || 150;
 }
 
 FirefoxPrintService.prototype = {
   layout() {
-    const { pdfDocument, pagesOverview, printContainer } = this;
+    const {
+      pdfDocument,
+      pagesOverview,
+      printContainer,
+      _printResolution,
+    } = this;
 
     const body = document.querySelector("body");
     body.setAttribute("data-pdfjsprinting", true);
 
     for (let i = 0, ii = pagesOverview.length; i < ii; ++i) {
-      composePage(pdfDocument, i + 1, pagesOverview[i], printContainer);
+      composePage(
+        pdfDocument,
+        /* pageNumber = */ i + 1,
+        pagesOverview[i],
+        printContainer,
+        _printResolution
+      );
     }
   },
 
@@ -110,8 +131,18 @@ PDFPrintServiceFactory.instance = {
     return shadow(this, "supportsPrinting", value);
   },
 
-  createPrintService(pdfDocument, pagesOverview, printContainer) {
-    return new FirefoxPrintService(pdfDocument, pagesOverview, printContainer);
+  createPrintService(
+    pdfDocument,
+    pagesOverview,
+    printContainer,
+    printResolution
+  ) {
+    return new FirefoxPrintService(
+      pdfDocument,
+      pagesOverview,
+      printContainer,
+      printResolution
+    );
   },
 };
 

web/pdf_print_service.js

@@ -22,12 +22,17 @@ let overlayManager = null;
 
 // Renders the page to the canvas of the given print service, and returns
 // the suggested dimensions of the output page.
-function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
+function renderPage(
+  activeServiceOnEntry,
+  pdfDocument,
+  pageNumber,
+  size,
+  printResolution
+) {
   const scratchCanvas = activeService.scratchCanvas;
 
   // The size of the canvas in pixels for printing.
-  const PRINT_RESOLUTION = AppOptions.get("printResolution") || 150;
-  const PRINT_UNITS = PRINT_RESOLUTION / 72.0;
+  const PRINT_UNITS = printResolution / 72.0;
   scratchCanvas.width = Math.floor(size.width * PRINT_UNITS);
   scratchCanvas.height = Math.floor(size.height * PRINT_UNITS);
 
@@ -61,10 +66,17 @@ function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
     });
 }
 
-function PDFPrintService(pdfDocument, pagesOverview, printContainer, l10n) {
+function PDFPrintService(
+  pdfDocument,
+  pagesOverview,
+  printContainer,
+  printResolution,
+  l10n
+) {
   this.pdfDocument = pdfDocument;
   this.pagesOverview = pagesOverview;
   this.printContainer = printContainer;
+  this._printResolution = printResolution || 150;
   this.l10n = l10n || NullL10n;
   this.disableCreateObjectURL = AppOptions.get("disableCreateObjectURL");
   this.currentPage = -1;
@@ -154,7 +166,13 @@ PDFPrintService.prototype = {
       }
       const index = this.currentPage;
       renderProgress(index, pageCount, this.l10n);
-      renderPage(this, this.pdfDocument, index + 1, this.pagesOverview[index])
+      renderPage(
+        this,
+        this.pdfDocument,
+        /* pageNumber = */ index + 1,
+        this.pagesOverview[index],
+        this._printResolution
+      )
         .then(this.useRenderedPage.bind(this))
         .then(function () {
           renderNextPage(resolve, reject);
@@ -347,14 +365,21 @@ function ensureOverlay() {
 PDFPrintServiceFactory.instance = {
   supportsPrinting: true,
 
-  createPrintService(pdfDocument, pagesOverview, printContainer, l10n) {
+  createPrintService(
+    pdfDocument,
+    pagesOverview,
+    printContainer,
+    printResolution,
+    l10n
+  ) {
     if (activeService) {
       throw new Error("The print service is created and active.");
     }
     activeService = new PDFPrintService(
       pdfDocument,
       pagesOverview,
       printContainer,
+      printResolution,
       l10n
     );
     return activeService;