Add test for drawing delay with CSS-only zoom

This commit adds a test for 0603d1a.
Before the fix the test fails with 10 `pagerendered` events fired
synchronously during the test loop.

test/integration/viewer_spec.mjs

@@ -13,7 +13,12 @@
  * limitations under the License.
  */
 
-import { closePages, loadAndWait } from "./test_utils.mjs";
+import {
+  awaitPromise,
+  closePages,
+  createPromise,
+  loadAndWait,
+} from "./test_utils.mjs";
 
 describe("PDF viewer", () => {
   describe("Zoom with the mouse wheel", () => {
@@ -87,4 +92,127 @@ 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);
+    });
+
+    beforeEach(() =>
+      Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await page.evaluate(() => {
+            window.PDFViewerApplication.pdfViewer.currentScaleValue = 1;
+
+            window.pageRenderedListener = new AbortController();
+            window.firstPageRenders = 0;
+            window.PDFViewerApplication.eventBus.on(
+              "pagerendered",
+              ({ pageNumber }) => {
+                if (pageNumber === 1) {
+                  window.firstPageRenders++;
+                }
+              },
+              { signal: window.pageRenderedListener.signal }
+            );
+          });
+        })
+      )
+    );
+
+    afterEach(() =>
+      Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await page.evaluate(() => {
+            window.pageRenderedListener.abort();
+          });
+        })
+      )
+    );
+
+    function createPromiseForFirstPageRendered(page) {
+      return createPromise(page, (resolve, reject) => {
+        const controller = new AbortController();
+        window.PDFViewerApplication.eventBus.on(
+          "pagerendered",
+          ({ pageNumber }) => {
+            if (pageNumber === 1) {
+              resolve();
+              controller.abort();
+            }
+          },
+          { signal: controller.signal }
+        );
+        setTimeout(reject, 1000, new Error("Timeout"));
+      });
+    }
+
+    it("respects drawing delay when zooming out", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          for (let i = 0; i < 10; i++) {
+            await page.evaluate(() => {
+              window.PDFViewerApplication.pdfViewer.decreaseScale({
+                drawingDelay: 100,
+                scaleFactor: 0.9,
+              });
+            });
+          }
+
+          const promise = await createPromiseForFirstPageRendered(page);
+
+          let firstPageRenders = await page.evaluate(
+            () => window.firstPageRenders
+          );
+          expect(firstPageRenders).withContext(`In ${browserName}`).toBe(0);
+
+          await awaitPromise(promise);
+
+          firstPageRenders = await page.evaluate(() => window.firstPageRenders);
+          expect(firstPageRenders).withContext(`In ${browserName}`).toBe(1);
+        })
+      );
+    });
+
+    it("respects drawing delay when zooming in", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          for (let i = 0; i < 10; i++) {
+            await page.evaluate(() => {
+              window.PDFViewerApplication.pdfViewer.increaseScale({
+                drawingDelay: 100,
+                scaleFactor: 1.1,
+              });
+            });
+          }
+
+          const promise = await createPromiseForFirstPageRendered(page);
+
+          let firstPageRenders = await page.evaluate(
+            () => window.firstPageRenders
+          );
+          expect(firstPageRenders).withContext(`In ${browserName}`).toBe(0);
+
+          await awaitPromise(promise);
+
+          firstPageRenders = await page.evaluate(() => window.firstPageRenders);
+          expect(firstPageRenders).withContext(`In ${browserName}`).toBe(1);
+        })
+      );
+    });
+  });
 });

web/app.js

@@ -359,6 +359,12 @@ const PDFViewerApplication = {
           params.get("highlighteditorcolors")
         );
       }
+      if (params.has("maxcanvaspixels")) {
+        AppOptions.set(
+          "maxCanvasPixels",
+          Number(params.get("maxcanvaspixels"))
+        );
+      }
       if (params.has("supportscaretbrowsingmode")) {
         AppOptions.set(
           "supportsCaretBrowsingMode",