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web/pdf_attachment_viewer.js

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+/* Copyright 2012 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.
+ */
+
+/** @typedef {import("./event_utils.js").EventBus} EventBus */
+// eslint-disable-next-line max-len
+/** @typedef {import("./download_manager.js").DownloadManager} DownloadManager */
+
+import { BaseTreeViewer } from "./base_tree_viewer.js";
+import { waitOnEventOrTimeout } from "./event_utils.js";
+
+/**
+ * @typedef {Object} PDFAttachmentViewerOptions
+ * @property {HTMLDivElement} container - The viewer element.
+ * @property {EventBus} eventBus - The application event bus.
+ * @property {DownloadManager} downloadManager - The download manager.
+ */
+
+/**
+ * @typedef {Object} PDFAttachmentViewerRenderParameters
+ * @property {Object|null} attachments - A lookup table of attachment objects.
+ * @property {boolean} [keepRenderedCapability]
+ */
+
+class PDFAttachmentViewer extends BaseTreeViewer {
+  /**
+   * @param {PDFAttachmentViewerOptions} options
+   */
+  constructor(options) {
+    super(options);
+    this.downloadManager = options.downloadManager;
+
+    this.eventBus._on(
+      "fileattachmentannotation",
+      this.#appendAttachment.bind(this)
+    );
+  }
+
+  reset(keepRenderedCapability = false) {
+    super.reset();
+    this._attachments = null;
+
+    if (!keepRenderedCapability) {
+      // The only situation in which the `_renderedCapability` should *not* be
+      // replaced is when appending FileAttachment annotations.
+      this._renderedCapability = Promise.withResolvers();
+    }
+    this._pendingDispatchEvent = false;
+  }
+
+  /**
+   * @protected
+   */
+  async _dispatchEvent(attachmentsCount) {
+    this._renderedCapability.resolve();
+
+    if (attachmentsCount === 0 && !this._pendingDispatchEvent) {
+      // Delay the event when no "regular" attachments exist, to allow time for
+      // parsing of any FileAttachment annotations that may be present on the
+      // *initially* rendered page; this reduces the likelihood of temporarily
+      // disabling the attachmentsView when the `PDFSidebar` handles the event.
+      this._pendingDispatchEvent = true;
+
+      await waitOnEventOrTimeout({
+        target: this.eventBus,
+        name: "annotationlayerrendered",
+        delay: 1000,
+      });
+
+      if (!this._pendingDispatchEvent) {
+        return; // There was already another `_dispatchEvent`-call`.
+      }
+    }
+    this._pendingDispatchEvent = false;
+
+    this.eventBus.dispatch("attachmentsloaded", {
+      source: this,
+      attachmentsCount,
+    });
+  }
+
+  /**
+   * @protected
+   */
+  _bindLink(element, { content, description, filename }) {
+    if (description) {
+      element.title = description;
+    }
+    element.onclick = () => {
+      this.downloadManager.openOrDownloadData(content, filename);
+      return false;
+    };
+  }
+
+  /**
+   * @param {PDFAttachmentViewerRenderParameters} params
+   */
+  render({ attachments, keepRenderedCapability = false }) {
+    if (this._attachments) {
+      this.reset(keepRenderedCapability);
+    }
+    this._attachments = attachments || null;
+
+    if (!attachments) {
+      this._dispatchEvent(/* attachmentsCount = */ 0);
+      return;
+    }
+
+    const fragment = document.createDocumentFragment();
+    let attachmentsCount = 0;
+    for (const name in attachments) {
+      const item = attachments[name];
+
+      const div = document.createElement("div");
+      div.className = "treeItem";
+
+      const element = document.createElement("a");
+      this._bindLink(element, item);
+      element.textContent = this._normalizeTextContent(item.filename);
+
+      div.append(element);
+
+      fragment.append(div);
+      attachmentsCount++;
+    }
+
+    this._finishRendering(fragment, attachmentsCount);
+  }
+
+  /**
+   * Used to append FileAttachment annotations to the sidebar.
+   */
+  #appendAttachment(item) {
+    const renderedPromise = this._renderedCapability.promise;
+
+    renderedPromise.then(() => {
+      if (renderedPromise !== this._renderedCapability.promise) {
+        return; // The FileAttachment annotation belongs to a previous document.
+      }
+      const attachments = this._attachments || Object.create(null);
+
+      for (const name in attachments) {
+        if (item.filename === name) {
+          return; // Ignore the new attachment if it already exists.
+        }
+      }
+      attachments[item.filename] = item;
+
+      this.render({
+        attachments,
+        keepRenderedCapability: true,
+      });
+    });
+  }
+}
+
+export { PDFAttachmentViewer };