❤️ 完整开源界面和内核 https://github.com/siyuan-note/siyuan/issues/5013

app/src/asset/pdf/struct_tree_layer_builder.js

@@ -0,0 +1,137 @@
+/* Copyright 2021 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.
+ */
+
+const PDF_ROLE_TO_HTML_ROLE = {
+  // Document level structure types
+  Document: null, // There's a "document" role, but it doesn't make sense here.
+  DocumentFragment: null,
+  // Grouping level structure types
+  Part: "group",
+  Sect: "group", // XXX: There's a "section" role, but it's abstract.
+  Div: "group",
+  Aside: "note",
+  NonStruct: "none",
+  // Block level structure types
+  P: null,
+  // H<n>,
+  H: "heading",
+  Title: null,
+  FENote: "note",
+  // Sub-block level structure type
+  Sub: "group",
+  // General inline level structure types
+  Lbl: null,
+  Span: null,
+  Em: null,
+  Strong: null,
+  Link: "link",
+  Annot: "note",
+  Form: "form",
+  // Ruby and Warichu structure types
+  Ruby: null,
+  RB: null,
+  RT: null,
+  RP: null,
+  Warichu: null,
+  WT: null,
+  WP: null,
+  // List standard structure types
+  L: "list",
+  LI: "listitem",
+  LBody: null,
+  // Table standard structure types
+  Table: "table",
+  TR: "row",
+  TH: "columnheader",
+  TD: "cell",
+  THead: "columnheader",
+  TBody: null,
+  TFoot: null,
+  // Standard structure type Caption
+  Caption: null,
+  // Standard structure type Figure
+  Figure: "figure",
+  // Standard structure type Formula
+  Formula: null,
+  // standard structure type Artifact
+  Artifact: null,
+};
+
+const HEADING_PATTERN = /^H(\d+)$/;
+
+/**
+ * @typedef {Object} StructTreeLayerBuilderOptions
+ * @property {PDFPageProxy} pdfPage
+ */
+
+class StructTreeLayerBuilder {
+  /**
+   * @param {StructTreeLayerBuilderOptions} options
+   */
+  constructor({ pdfPage }) {
+    this.pdfPage = pdfPage;
+  }
+
+  render(structTree) {
+    return this._walk(structTree);
+  }
+
+  _setAttributes(structElement, htmlElement) {
+    if (structElement.alt !== undefined) {
+      htmlElement.setAttribute("aria-label", structElement.alt);
+    }
+    if (structElement.id !== undefined) {
+      htmlElement.setAttribute("aria-owns", structElement.id);
+    }
+    if (structElement.lang !== undefined) {
+      htmlElement.setAttribute("lang", structElement.lang);
+    }
+  }
+
+  _walk(node) {
+    if (!node) {
+      return null;
+    }
+
+    const element = document.createElement("span");
+    if ("role" in node) {
+      const { role } = node;
+      const match = role.match(HEADING_PATTERN);
+      if (match) {
+        element.setAttribute("role", "heading");
+        element.setAttribute("aria-level", match[1]);
+      } else if (PDF_ROLE_TO_HTML_ROLE[role]) {
+        element.setAttribute("role", PDF_ROLE_TO_HTML_ROLE[role]);
+      }
+    }
+
+    this._setAttributes(node, element);
+
+    if (node.children) {
+      if (node.children.length === 1 && "id" in node.children[0]) {
+        // Often there is only one content node so just set the values on the
+        // parent node to avoid creating an extra span.
+        this._setAttributes(node.children[0], element);
+      } else {
+        for (const kid of node.children) {
+          element.appendChild(this._walk(kid));
+        }
+      }
+    }
+    return element;
+  }
+}
+
+export { StructTreeLayerBuilder };