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-rw-r--r--ext/js/comm/frame-offset-forwarder.js70
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diff --git a/ext/js/comm/frame-offset-forwarder.js b/ext/js/comm/frame-offset-forwarder.js
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+/*
+ * Copyright (C) 2020-2021 Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * FrameAncestryHandler
+ * api
+ */
+
+class FrameOffsetForwarder {
+ constructor(frameId) {
+ this._frameId = frameId;
+ this._frameAncestryHandler = new FrameAncestryHandler(frameId);
+ }
+
+ prepare() {
+ this._frameAncestryHandler.prepare();
+ api.crossFrame.registerHandlers([
+ ['FrameOffsetForwarder.getChildFrameRect', {async: false, handler: this._onMessageGetChildFrameRect.bind(this)}]
+ ]);
+ }
+
+ async getOffset() {
+ if (this._frameAncestryHandler.isRootFrame()) {
+ return [0, 0];
+ }
+
+ const ancestorFrameIds = await this._frameAncestryHandler.getFrameAncestryInfo();
+
+ let childFrameId = this._frameId;
+ const promises = [];
+ for (const frameId of ancestorFrameIds) {
+ promises.push(api.crossFrame.invoke(frameId, 'FrameOffsetForwarder.getChildFrameRect', {frameId: childFrameId}));
+ childFrameId = frameId;
+ }
+
+ const results = await Promise.all(promises);
+
+ let xOffset = 0;
+ let yOffset = 0;
+ for (const {x, y} of results) {
+ xOffset += x;
+ yOffset += y;
+ }
+ return [xOffset, yOffset];
+ }
+
+ // Private
+
+ _onMessageGetChildFrameRect({frameId}) {
+ const frameElement = this._frameAncestryHandler.getChildFrameElement(frameId);
+ if (frameElement === null) { return null; }
+
+ const {x, y, width, height} = frameElement.getBoundingClientRect();
+ return {x, y, width, height};
+ }
+}