Allow loading pdf fonts into another document.

test/unit/custom_spec.js

@@ -107,3 +107,127 @@ describe("custom canvas rendering", function () {
       .catch(done.fail);
   });
 });
+
+describe("custom ownerDocument", function () {
+  const FontFace = globalThis.FontFace;
+
+  const checkFont = font => /g_d\d+_f1/.test(font.family);
+  const checkFontFaceRule = rule =>
+    /^@font-face {font-family:"g_d\d+_f1";src:/.test(rule);
+
+  beforeEach(() => {
+    globalThis.FontFace = function MockFontFace(name) {
+      this.family = name;
+    };
+  });
+
+  afterEach(() => {
+    globalThis.FontFace = FontFace;
+  });
+
+  function getMocks() {
+    const elements = [];
+    const createElement = name => {
+      let element =
+        typeof document !== "undefined" && document.createElement(name);
+      if (name === "style") {
+        element = {
+          tagName: name,
+          sheet: {
+            cssRules: [],
+            insertRule(rule) {
+              this.cssRules.push(rule);
+            },
+          },
+        };
+        Object.assign(element, {
+          remove() {
+            this.remove.called = true;
+          },
+        });
+      }
+      elements.push(element);
+      return element;
+    };
+    const ownerDocument = {
+      fonts: new Set(),
+      createElement,
+      documentElement: {
+        getElementsByTagName: () => [{ appendChild: () => {} }],
+      },
+    };
+
+    const CanvasFactory = isNodeJS
+      ? new NodeCanvasFactory()
+      : new DOMCanvasFactory({ ownerDocument });
+    return {
+      elements,
+      ownerDocument,
+      CanvasFactory,
+    };
+  }
+
+  it("should use given document for loading fonts (with Font Loading API)", async function () {
+    const { ownerDocument, elements, CanvasFactory } = getMocks();
+    const getDocumentParams = buildGetDocumentParams(
+      "TrueType_without_cmap.pdf",
+      {
+        disableFontFace: false,
+        ownerDocument,
+      }
+    );
+
+    const loadingTask = getDocument(getDocumentParams);
+    const doc = await loadingTask.promise;
+    const page = await doc.getPage(1);
+
+    const viewport = page.getViewport({ scale: 1 });
+    const canvasAndCtx = CanvasFactory.create(viewport.width, viewport.height);
+
+    await page.render({
+      canvasContext: canvasAndCtx.context,
+      viewport,
+    }).promise;
+
+    const style = elements.find(element => element.tagName === "style");
+    expect(style).toBeFalsy();
+    expect(ownerDocument.fonts.size).toBeGreaterThanOrEqual(1);
+    expect(Array.from(ownerDocument.fonts).find(checkFont)).toBeTruthy();
+    await doc.destroy();
+    await loadingTask.destroy();
+    CanvasFactory.destroy(canvasAndCtx);
+    expect(ownerDocument.fonts.size).toBe(0);
+  });
+
+  it("should use given document for loading fonts (with CSS rules)", async function () {
+    const { ownerDocument, elements, CanvasFactory } = getMocks();
+    ownerDocument.fonts = null;
+    const getDocumentParams = buildGetDocumentParams(
+      "TrueType_without_cmap.pdf",
+      {
+        disableFontFace: false,
+        ownerDocument,
+      }
+    );
+
+    const loadingTask = getDocument(getDocumentParams);
+    const doc = await loadingTask.promise;
+    const page = await doc.getPage(1);
+
+    const viewport = page.getViewport({ scale: 1 });
+    const canvasAndCtx = CanvasFactory.create(viewport.width, viewport.height);
+
+    await page.render({
+      canvasContext: canvasAndCtx.context,
+      viewport,
+    }).promise;
+
+    const style = elements.find(element => element.tagName === "style");
+    expect(style.sheet.cssRules.length).toBeGreaterThanOrEqual(1);
+    expect(style.sheet.cssRules.find(checkFontFaceRule)).toBeTruthy();
+    await doc.destroy();
+    await loadingTask.destroy();
+    CanvasFactory.destroy(canvasAndCtx);
+    expect(style.remove.called).toBe(true);
+  });
+});