fork from https://github.com/mozilla/pdf.js.git

web/pdf_text_extractor.js

@@ -0,0 +1,86 @@
+/* Copyright 2024 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { internalOpt } from "./internal_evt.js";
+
+/**
+ * This class manages the interaction of extracting the text content of the page
+ * and passing it back to the external service.
+ */
+class PdfTextExtractor {
+  /** @type {BaseExternalServices} */
+  #externalServices;
+
+  /** @type {?Promise<string>} */
+  #textPromise;
+
+  #capability = Promise.withResolvers();
+
+  constructor(externalServices, pdfViewer, eventBus) {
+    this.#externalServices = externalServices;
+
+    eventBus.on(
+      "pagesinit",
+      () => {
+        this.#capability.resolve(pdfViewer);
+      },
+      internalOpt
+    );
+    eventBus.on(
+      "pagesdestroy",
+      () => {
+        this.#capability.reject(new Error("pagesdestroy"));
+        this.#textPromise = null;
+
+        this.#capability = Promise.withResolvers();
+      },
+      internalOpt
+    );
+
+    window.addEventListener("requestTextContent", ({ detail }) => {
+      this.extractTextContent(detail.requestId);
+    });
+  }
+
+  /**
+   * Builds up all of the text from a PDF.
+   *
+   * @param {number} requestId
+   */
+  async extractTextContent(requestId) {
+    if (!this.#textPromise) {
+      const textPromise = (this.#textPromise = this.#capability.promise.then(
+        pdfViewer => pdfViewer.getAllText()
+      ));
+
+      // After the text resolves, cache the text for a little bit in case
+      // multiple consumers call it.
+      textPromise.then(() => {
+        setTimeout(() => {
+          if (this.#textPromise === textPromise) {
+            this.#textPromise = null;
+          }
+        }, 5000);
+      });
+    }
+
+    this.#externalServices.reportText({
+      text: await this.#textPromise,
+      requestId,
+    });
+  }
+}
+
+export { PdfTextExtractor };