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vendor/yomitan/js/display/media-drawing-worker.js

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+/*
+ * Copyright (C) 2024-2025  Yomitan 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/>.
+ */
+
+import {API} from '../comm/api.js';
+import {createApiMap, invokeApiMapHandler} from '../core/api-map.js';
+import {ExtensionError} from '../core/extension-error.js';
+import {log} from '../core/log.js';
+import {WebExtension} from '../extension/web-extension.js';
+
+export class MediaDrawingWorker {
+    constructor() {
+        /** @type {number} */
+        this._generation = 0;
+
+        /** @type {MessagePort?} */
+        this._dbPort = null;
+
+        /** @type {import('api').PmApiMap} */
+        this._fromApplicationApiMap = createApiMap([
+            ['drawMedia', this._onDrawMedia.bind(this)],
+            ['connectToDatabaseWorker', this._onConnectToDatabaseWorker.bind(this)],
+        ]);
+
+        /** @type {import('api').PmApiMap} */
+        this._fromDatabaseApiMap = createApiMap([
+            ['drawBufferToCanvases', this._onDrawBufferToCanvases.bind(this)],
+            ['drawDecodedImageToCanvases', this._onDrawDecodedImageToCanvases.bind(this)],
+        ]);
+
+        /** @type {Map<number, OffscreenCanvas[]>} */
+        this._canvasesByGeneration = new Map();
+
+        /**
+         * @type {API}
+         */
+        this._api = new API(new WebExtension());
+    }
+
+    /**
+     *
+     */
+    async prepare() {
+        addEventListener('message', (event) => {
+            /** @type {import('api').PmApiMessageAny} */
+            // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+            const message = event.data;
+            return invokeApiMapHandler(this._fromApplicationApiMap, message.action, message.params, [event.ports], () => {});
+        });
+        addEventListener('messageerror', (event) => {
+            const error = new ExtensionError('MediaDrawingWorker: Error receiving message from application');
+            error.data = event;
+            log.error(error);
+        });
+    }
+
+    /** @type {import('api').PmApiHandler<'drawMedia'>} */
+    async _onDrawMedia({requests}) {
+        this._generation++;
+        this._canvasesByGeneration.set(this._generation, requests.map((request) => request.canvas));
+        this._cleanOldGenerations();
+        const newRequests = requests.map((request, index) => ({...request, canvas: null, generation: this._generation, canvasIndex: index, canvasWidth: request.canvas.width, canvasHeight: request.canvas.height}));
+        if (this._dbPort !== null) {
+            this._dbPort.postMessage({action: 'drawMedia', params: {requests: newRequests}});
+        } else {
+            log.error('no database port available');
+        }
+    }
+
+    /** @type {import('api').PmApiHandler<'drawBufferToCanvases'>} */
+    async _onDrawBufferToCanvases({buffer, width, height, canvasIndexes, generation}) {
+        try {
+            const canvases = this._canvasesByGeneration.get(generation);
+            if (typeof canvases === 'undefined') {
+                return;
+            }
+            const imageData = new ImageData(new Uint8ClampedArray(buffer), width, height);
+            for (const ci of canvasIndexes) {
+                const c = canvases[ci];
+                c.getContext('2d')?.putImageData(imageData, 0, 0);
+            }
+        } catch (e) {
+            log.error(e);
+        }
+    }
+
+    /** @type {import('api').PmApiHandler<'drawDecodedImageToCanvases'>} */
+    async _onDrawDecodedImageToCanvases({decodedImage, canvasIndexes, generation}) {
+        try {
+            const canvases = this._canvasesByGeneration.get(generation);
+            if (typeof canvases === 'undefined') {
+                return;
+            }
+            for (const ci of canvasIndexes) {
+                const c = canvases[ci];
+                c.getContext('2d')?.drawImage(decodedImage, 0, 0, c.width, c.height);
+            }
+        } catch (e) {
+            log.error(e);
+        }
+    }
+
+    /** @type {import('api').PmApiHandler<'connectToDatabaseWorker'>} */
+    async _onConnectToDatabaseWorker(_params, ports) {
+        if (ports === null) {
+            return;
+        }
+        const dbPort = ports[0];
+        this._dbPort = dbPort;
+        dbPort.addEventListener('message', (/** @type {MessageEvent<import('api').PmApiMessageAny>} */ event) => {
+            const message = event.data;
+            return invokeApiMapHandler(this._fromDatabaseApiMap, message.action, message.params, [event.ports], () => {});
+        });
+        dbPort.addEventListener('messageerror', (event) => {
+            const error = new ExtensionError('MediaDrawingWorker: Error receiving message from database worker');
+            error.data = event;
+            log.error(error);
+        });
+        dbPort.start();
+    }
+
+    /**
+     * @param {number} keepNGenerations Number of generations to keep, defaults to 2 (the current generation and the one before it).
+     */
+    _cleanOldGenerations(keepNGenerations = 2) {
+        const generations = [...this._canvasesByGeneration.keys()];
+        for (const g of generations) {
+            if (g <= this._generation - keepNGenerations) {
+                this._canvasesByGeneration.delete(g);
+            }
+        }
+    }
+}
+
+const mediaDrawingWorker = new MediaDrawingWorker();
+await mediaDrawingWorker.prepare();