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

web/draw_layer_builder.js

@@ -0,0 +1,84 @@
+/* Copyright 2022 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 { DrawLayer } from "pdfjs-lib";
+
+/**
+ * @typedef DrawLayerBuilderOptions
+ *   Configuration for {@linkcode DrawLayerBuilder}.
+ * @property {number} pageIndex
+ *   Zero-based page index.
+ * @property {Element | null} [textLayer]
+ *   Text layer element (optional).
+ * @property {Object | null} [filterFactory]
+ *   Filter factory used to style selections (optional).
+ * @property {Object | null} [pageColors]
+ *   Page foreground/background colors for HCM (optional).
+ */
+
+/**
+ * @typedef {Object} DrawLayerBuilderRenderOptions
+ * @property {string} [intent] - The default value is "display".
+ */
+
+class DrawLayerBuilder {
+  #drawLayer = null;
+
+  /**
+   * @param {DrawLayerBuilderOptions} options
+   *   Configuration.
+   * @returns
+   *   Instance.
+   */
+  constructor(options) {
+    this.pageIndex = options.pageIndex;
+    this.textLayer = options.textLayer || null;
+    this.filterFactory = options.filterFactory || null;
+    this.pageColors = options.pageColors || null;
+  }
+
+  /**
+   * @param {DrawLayerBuilderRenderOptions} options
+   * @returns {Promise<void>}
+   */
+  async render({ intent = "display" }) {
+    if (intent !== "display" || this.#drawLayer || this._cancelled) {
+      return;
+    }
+    this.#drawLayer = new DrawLayer({
+      pageIndex: this.pageIndex,
+      textLayer: this.textLayer,
+      filterFactory: this.filterFactory,
+      pageColors: this.pageColors,
+    });
+  }
+
+  cancel() {
+    this._cancelled = true;
+
+    this.#drawLayer?.destroy();
+    this.#drawLayer = null;
+  }
+
+  setParent(parent) {
+    this.#drawLayer?.setParent(parent);
+  }
+
+  getDrawLayer() {
+    return this.#drawLayer;
+  }
+}
+
+export { DrawLayerBuilder };