Merge pull request #18218 from nicolo-ribaudo/test-maxCanvasPixels

Respect `maxCanvasPixels` when computing canvas dimensions

test/integration/test_utils.mjs

@@ -38,8 +38,13 @@ function loadAndWait(filename, selector, zoom, pageSetup, options) {
 
       let app_options = "";
       if (options) {
+        const optionsObject =
+          typeof options === "function"
+            ? await options(page, session.name)
+            : options;
+
         // Options must be handled in app.js::_parseHashParams.
-        for (const [key, value] of Object.entries(options)) {
+        for (const [key, value] of Object.entries(optionsObject)) {
           app_options += `&${key}=${encodeURIComponent(value)}`;
         }
       }

test/integration/viewer_spec.mjs

@@ -174,24 +174,6 @@ describe("PDF viewer", () => {
   });
 
   describe("CSS-only zoom", () => {
-    let pages;
-
-    beforeAll(async () => {
-      pages = await loadAndWait(
-        "tracemonkey.pdf",
-        ".textLayer .endOfContent",
-        null,
-        null,
-        {
-          maxCanvasPixels: 0,
-        }
-      );
-    });
-
-    afterAll(async () => {
-      await closePages(pages);
-    });
-
     function createPromiseForFirstPageRendered(page) {
       return createPromise(page, (resolve, reject) => {
         const controller = new AbortController();
@@ -209,6 +191,23 @@ describe("PDF viewer", () => {
       });
     }
 
+    describe("forced (maxCanvasPixels: 0)", () => {
+      let pages;
+
+      beforeAll(async () => {
+        pages = await loadAndWait(
+          "tracemonkey.pdf",
+          ".textLayer .endOfContent",
+          null,
+          null,
+          { maxCanvasPixels: 0 }
+        );
+      });
+
+      afterAll(async () => {
+        await closePages(pages);
+      });
+
       it("respects drawing delay when zooming out", async () => {
         await Promise.all(
           pages.map(async ([browserName, page]) => {
@@ -255,4 +254,121 @@ describe("PDF viewer", () => {
         );
       });
     });
+
+    describe("triggers when going bigger than maxCanvasPixels", () => {
+      let pages;
+
+      const MAX_CANVAS_PIXELS = new Map();
+
+      beforeAll(async () => {
+        pages = await loadAndWait(
+          "tracemonkey.pdf",
+          ".textLayer .endOfContent",
+          null,
+          null,
+          async (page, browserName) => {
+            const ratio = await page.evaluate(() => window.devicePixelRatio);
+            const maxCanvasPixels = 1_000_000 * ratio ** 2;
+            MAX_CANVAS_PIXELS.set(browserName, maxCanvasPixels);
+
+            return { maxCanvasPixels };
+          }
+        );
+      });
+
+      beforeEach(async () => {
+        await Promise.all(
+          pages.map(async ([browserName, page]) => {
+            await page.evaluate(() => {
+              window.PDFViewerApplication.pdfViewer.currentScale = 0.5;
+            });
+          })
+        );
+      });
+
+      afterAll(async () => {
+        await closePages(pages);
+      });
+
+      function getCanvasSize(page) {
+        return page.evaluate(() => {
+          const canvas = window.document.querySelector(".canvasWrapper canvas");
+          return canvas.width * canvas.height;
+        });
+      }
+
+      // MAX_CANVAS_PIXELS must be big enough that the originally rendered
+      // canvas still has enough space to grow before triggering CSS-only zoom
+      it("test correctly configured", async () => {
+        await Promise.all(
+          pages.map(async ([browserName, page]) => {
+            const canvasSize = await getCanvasSize(page);
+
+            expect(canvasSize)
+              .withContext(`In ${browserName}`)
+              .toBeLessThan(MAX_CANVAS_PIXELS.get(browserName) / 4);
+            expect(canvasSize)
+              .withContext(`In ${browserName}`)
+              .toBeGreaterThan(MAX_CANVAS_PIXELS.get(browserName) / 16);
+          })
+        );
+      });
+
+      it("does not trigger CSS-only zoom below maxCanvasPixels", async () => {
+        await Promise.all(
+          pages.map(async ([browserName, page]) => {
+            const originalCanvasSize = await getCanvasSize(page);
+            const factor = 2;
+
+            await page.evaluate(scaleFactor => {
+              window.PDFViewerApplication.pdfViewer.increaseScale({
+                drawingDelay: 0,
+                scaleFactor,
+              });
+            }, factor);
+
+            const canvasSize = await getCanvasSize(page);
+
+            expect(canvasSize)
+              .withContext(`In ${browserName}`)
+              .toBe(originalCanvasSize * factor ** 2);
+
+            expect(canvasSize)
+              .withContext(`In ${browserName}, MAX_CANVAS_PIXELS`)
+              .toBeLessThan(MAX_CANVAS_PIXELS.get(browserName));
+          })
+        );
+      });
+
+      it("triggers CSS-only zoom above maxCanvasPixels", async () => {
+        await Promise.all(
+          pages.map(async ([browserName, page]) => {
+            const originalCanvasSize = await getCanvasSize(page);
+            const factor = 4;
+
+            await page.evaluate(scaleFactor => {
+              window.PDFViewerApplication.pdfViewer.increaseScale({
+                drawingDelay: 0,
+                scaleFactor,
+              });
+            }, factor);
+
+            const canvasSize = await getCanvasSize(page);
+
+            expect(canvasSize)
+              .withContext(`In ${browserName}`)
+              .toBeLessThan(originalCanvasSize * factor ** 2);
+
+            expect(canvasSize)
+              .withContext(`In ${browserName}, <= MAX_CANVAS_PIXELS`)
+              .toBeLessThanOrEqual(MAX_CANVAS_PIXELS.get(browserName));
+
+            expect(canvasSize)
+              .withContext(`In ${browserName}, > MAX_CANVAS_PIXELS * 0.99`)
+              .toBeGreaterThan(MAX_CANVAS_PIXELS.get(browserName) * 0.99);
+          })
+        );
+      });
+    });
+  });
 });

web/pdf_page_view.js

@@ -34,9 +34,9 @@ import {
 import {
   approximateFraction,
   DEFAULT_SCALE,
+  floorToDivide,
   OutputScale,
   RenderingStates,
-  roundToDivide,
   TextLayerMode,
 } from "./ui_utils.js";
 import { AnnotationEditorLayerBuilder } from "./annotation_editor_layer_builder.js";
@@ -1016,11 +1016,11 @@ class PDFPageView {
     const sfx = approximateFraction(outputScale.sx);
     const sfy = approximateFraction(outputScale.sy);
 
-    canvas.width = roundToDivide(width * outputScale.sx, sfx[0]);
+    canvas.width = floorToDivide(width * outputScale.sx, sfx[0]);
-    canvas.height = roundToDivide(height * outputScale.sy, sfy[0]);
+    canvas.height = floorToDivide(height * outputScale.sy, sfy[0]);
     const { style } = canvas;
-    style.width = roundToDivide(width, sfx[1]) + "px";
+    style.width = floorToDivide(width, sfx[1]) + "px";
-    style.height = roundToDivide(height, sfy[1]) + "px";
+    style.height = floorToDivide(height, sfy[1]) + "px";
 
     // Add the viewport so it's known what it was originally drawn with.
     this.#viewportMap.set(canvas, viewport);

web/ui_utils.js

@@ -263,6 +263,7 @@ function binarySearchFirstItem(items, condition, start = 0) {
  *  @param {number} x - Positive float number.
  *  @returns {Array} Estimated fraction: the first array item is a numerator,
  *                   the second one is a denominator.
+ *                   They are both natural numbers.
  */
 function approximateFraction(x) {
   // Fast paths for int numbers or their inversions.
@@ -309,9 +310,12 @@ function approximateFraction(x) {
   return result;
 }
 
-function roundToDivide(x, div) {
+/**
-  const r = x % div;
+ * @param {number} x - A positive number to round to a multiple of `div`.
-  return r === 0 ? x : Math.round(x - r + div);
+ * @param {number} div - A natural number.
+ */
+function floorToDivide(x, div) {
+  return x - (x % div);
 }
 
 /**
@@ -866,6 +870,7 @@ export {
   DEFAULT_SCALE_DELTA,
   DEFAULT_SCALE_VALUE,
   docStyle,
+  floorToDivide,
   getActiveOrFocusedElement,
   getPageSizeInches,
   getVisibleElements,
@@ -884,7 +889,6 @@ export {
   ProgressBar,
   removeNullCharacters,
   RenderingStates,
-  roundToDivide,
   SCROLLBAR_PADDING,
   scrollIntoView,
   ScrollMode,