Merge pull request #299 from siikamiika/frontend-extract-text-scanner

Extract text scanner from Frontend

ext/bg/js/search-frontend.js

@@ -33,6 +33,7 @@ async function searchFrontendSetup() {
     window.frontendInitializationData = {depth: 1, ignoreNodes, proxy: false};
 
     const scriptSrcs = [
+        '/mixed/js/text-scanner.js',
         '/fg/js/frontend-api-receiver.js',
         '/fg/js/popup.js',
         '/fg/js/popup-proxy-host.js',

ext/bg/js/search-query-parser.js

@@ -62,7 +62,7 @@ class QueryParser {
         const scanningOptions = this.search.options.scanning;
         const scanningModifier = scanningOptions.modifier;
         if (!(
-            Frontend.isScanningModifierPressed(scanningModifier, e) ||
+            TextScanner.isScanningModifierPressed(scanningModifier, e) ||
             (scanningOptions.middleMouse && DOM.isMouseButtonDown(e, 'auxiliary'))
         )) {
             return;

ext/bg/search.html

@@ -74,6 +74,7 @@
         <script src="/mixed/js/display.js"></script>
         <script src="/mixed/js/japanese.js"></script>
         <script src="/mixed/js/scroll.js"></script>
+        <script src="/mixed/js/text-scanner.js"></script>
 
         <script src="/bg/js/search-query-parser.js"></script>
         <script src="/bg/js/search.js"></script>

ext/fg/js/frontend.js

@@ -17,29 +17,23 @@
  */
 
 
-class Frontend {
+class Frontend extends TextScanner {
     constructor(popup, ignoreNodes) {
+        super(
+            window,
+            ignoreNodes,
+            [popup.container],
+            [(x, y) => this.popup.containsPoint(x, y)]
+        );
+
         this.popup = popup;
-        this.popupTimerPromise = null;
-        this.textSourceCurrent = null;
-        this.pendingLookup = false;
         this.options = null;
-        this.ignoreNodes = (Array.isArray(ignoreNodes) && ignoreNodes.length > 0 ? ignoreNodes.join(',') : null);
 
         this.optionsContext = {
             depth: popup.depth,
             url: popup.url
         };
 
-        this.primaryTouchIdentifier = null;
-        this.preventNextContextMenu = false;
-        this.preventNextMouseDown = false;
-        this.preventNextClick = false;
-        this.preventScroll = false;
-
-        this.enabled = false;
-        this.eventListeners = [];
-
         this.isPreparedPromiseResolve = null;
         this.isPreparedPromise = new Promise((resolve) => { this.isPreparedPromiseResolve = resolve; });
 
@@ -71,162 +65,9 @@ class Frontend {
         return this.isPreparedPromise;
     }
 
-    onMouseOver(e) {
-        if (e.target === this.popup.container) {
-            this.popupTimerClear();
-        }
-    }
-
-    onMouseMove(e) {
-        this.popupTimerClear();
-
-        if (this.pendingLookup || DOM.isMouseButtonDown(e, 'primary')) {
-            return;
-        }
-
-        const scanningOptions = this.options.scanning;
-        const scanningModifier = scanningOptions.modifier;
-        if (!(
-            Frontend.isScanningModifierPressed(scanningModifier, e) ||
-            (scanningOptions.middleMouse && DOM.isMouseButtonDown(e, 'auxiliary'))
-        )) {
-            return;
-        }
-
-        const search = async () => {
-            if (scanningModifier === 'none') {
-                if (!await this.popupTimerWait()) {
-                    // Aborted
-                    return;
-                }
-            }
-
-            await this.searchAt(e.clientX, e.clientY, 'mouse');
-        };
-
-        search();
-    }
-
-    onMouseDown(e) {
-        if (this.preventNextMouseDown) {
-            this.preventNextMouseDown = false;
-            this.preventNextClick = true;
-            e.preventDefault();
-            e.stopPropagation();
-            return false;
-        }
-
-        if (e.button === 0) {
-            this.popupTimerClear();
-            this.searchClear(true);
-        }
-    }
-
-    onMouseOut() {
-        this.popupTimerClear();
-    }
-
-    onClick(e) {
-        if (this.preventNextClick) {
-            this.preventNextClick = false;
-            e.preventDefault();
-            e.stopPropagation();
-            return false;
-        }
-    }
-
-    onAuxClick() {
-        this.preventNextContextMenu = false;
-    }
-
-    onContextMenu(e) {
-        if (this.preventNextContextMenu) {
-            this.preventNextContextMenu = false;
-            e.preventDefault();
-            e.stopPropagation();
-            return false;
-        }
-    }
-
-    onTouchStart(e) {
-        if (this.primaryTouchIdentifier !== null || e.changedTouches.length === 0) {
-            return;
-        }
-
-        this.preventScroll = false;
-        this.preventNextContextMenu = false;
-        this.preventNextMouseDown = false;
-        this.preventNextClick = false;
-
-        const primaryTouch = e.changedTouches[0];
-        if (DOM.isPointInSelection(primaryTouch.clientX, primaryTouch.clientY, window.getSelection())) {
-            return;
-        }
-
-        this.primaryTouchIdentifier = primaryTouch.identifier;
-
-        if (this.pendingLookup) {
-            return;
-        }
-
-        const textSourceCurrentPrevious = this.textSourceCurrent !== null ? this.textSourceCurrent.clone() : null;
-
-        this.searchAt(primaryTouch.clientX, primaryTouch.clientY, 'touchStart')
-        .then(() => {
-            if (
-                this.textSourceCurrent === null ||
-                this.textSourceCurrent.equals(textSourceCurrentPrevious)
-            ) {
-                return;
-            }
-
-            this.preventScroll = true;
-            this.preventNextContextMenu = true;
-            this.preventNextMouseDown = true;
-        });
-    }
-
-    onTouchEnd(e) {
-        if (
-            this.primaryTouchIdentifier === null ||
-            this.getIndexOfTouch(e.changedTouches, this.primaryTouchIdentifier) < 0
-        ) {
-            return;
-        }
-
-        this.primaryTouchIdentifier = null;
-        this.preventScroll = false;
-        this.preventNextClick = false;
-        // Don't revert context menu and mouse down prevention,
-        // since these events can occur after the touch has ended.
-        // this.preventNextContextMenu = false;
-        // this.preventNextMouseDown = false;
-    }
-
-    onTouchCancel(e) {
-        this.onTouchEnd(e);
-    }
-
-    onTouchMove(e) {
-        if (!this.preventScroll || !e.cancelable || this.primaryTouchIdentifier === null) {
-            return;
-        }
-
-        const touches = e.changedTouches;
-        const index = this.getIndexOfTouch(touches, this.primaryTouchIdentifier);
-        if (index < 0) {
-            return;
-        }
-
-        const primaryTouch = touches[index];
-        this.searchAt(primaryTouch.clientX, primaryTouch.clientY, 'touchMove');
-
-        e.preventDefault(); // Disable scroll
-    }
-
     async onResize() {
-        if (this.textSourceCurrent !== null && await this.popup.isVisibleAsync()) {
+        const textSource = this.textSourceCurrent;
-            const textSource = this.textSourceCurrent;
+        if (textSource !== null && await this.popup.isVisibleAsync()) {
             this.lastShowPromise = this.popup.showContent(
                 textSource.getRect(),
                 textSource.getWritingMode()
@@ -252,112 +93,24 @@ class Frontend {
         }
     }
 
-    onError(error) {
+    getMouseEventListeners() {
-        logError(error, false);
+        return [
-    }
+            ...super.getMouseEventListeners(),
-
+            [window, 'message', this.onWindowMessage.bind(this)],
-    setEnabled(enabled) {
+            [window, 'resize', this.onResize.bind(this)]
-        if (enabled) {
+        ];
-            if (!this.enabled) {
-                this.hookEvents();
-                this.enabled = true;
-            }
-        } else {
-            if (this.enabled) {
-                this.clearEventListeners();
-                this.enabled = false;
-            }
-            this.searchClear(false);
-        }
-    }
-
-    hookEvents() {
-        this.addEventListener(window, 'message', this.onWindowMessage.bind(this));
-        this.addEventListener(window, 'mousedown', this.onMouseDown.bind(this));
-        this.addEventListener(window, 'mousemove', this.onMouseMove.bind(this));
-        this.addEventListener(window, 'mouseover', this.onMouseOver.bind(this));
-        this.addEventListener(window, 'mouseout', this.onMouseOut.bind(this));
-        this.addEventListener(window, 'resize', this.onResize.bind(this));
-
-        if (this.options.scanning.touchInputEnabled) {
-            this.addEventListener(window, 'click', this.onClick.bind(this));
-            this.addEventListener(window, 'auxclick', this.onAuxClick.bind(this));
-            this.addEventListener(window, 'touchstart', this.onTouchStart.bind(this));
-            this.addEventListener(window, 'touchend', this.onTouchEnd.bind(this));
-            this.addEventListener(window, 'touchcancel', this.onTouchCancel.bind(this));
-            this.addEventListener(window, 'touchmove', this.onTouchMove.bind(this), {passive: false});
-            this.addEventListener(window, 'contextmenu', this.onContextMenu.bind(this));
-        }
-    }
-
-    addEventListener(node, type, listener, options) {
-        node.addEventListener(type, listener, options);
-        this.eventListeners.push([node, type, listener, options]);
-    }
-
-    clearEventListeners() {
-        for (const [node, type, listener, options] of this.eventListeners) {
-            node.removeEventListener(type, listener, options);
-        }
-        this.eventListeners = [];
     }
 
     async updateOptions() {
         this.options = await apiOptionsGet(this.getOptionsContext());
-        this.setEnabled(this.options.general.enable);
         await this.popup.setOptions(this.options);
+        this.setEnabled(this.options.general.enable);
     }
 
-    async popupTimerWait() {
+    async onSearchSource(textSource, cause) {
-        const delay = this.options.scanning.delay;
-        const promise = promiseTimeout(delay, true);
-        this.popupTimerPromise = promise;
-        try {
-            return await promise;
-        } finally {
-            if (this.popupTimerPromise === promise) {
-                this.popupTimerPromise = null;
-            }
-        }
-    }
-
-    popupTimerClear() {
-        if (this.popupTimerPromise !== null) {
-            this.popupTimerPromise.resolve(false);
-            this.popupTimerPromise = null;
-        }
-    }
-
-    async searchAt(x, y, cause) {
-        try {
-            this.popupTimerClear();
-
-            if (this.pendingLookup || await this.popup.containsPoint(x, y)) {
-                return;
-            }
-
-            const textSource = docRangeFromPoint(x, y, this.options);
-            if (this.textSourceCurrent !== null && this.textSourceCurrent.equals(textSource)) {
-                return;
-            }
-
-            try {
-                await this.searchSource(textSource, cause);
-            } finally {
-                if (textSource !== null) {
-                    textSource.cleanup();
-                }
-            }
-        } catch (e) {
-            this.onError(e);
-        }
-    }
-
-    async searchSource(textSource, cause) {
         let results = null;
 
         try {
-            this.pendingLookup = true;
             if (textSource !== null) {
                 results = (
                     await this.findTerms(textSource) ||
@@ -382,10 +135,8 @@ class Frontend {
             }
         } finally {
             if (results === null && this.options.scanning.autoHideResults) {
-                this.searchClear(true);
+                this.onSearchClear(true);
             }
-
-            this.pendingLookup = false;
         }
 
         return results;
@@ -400,11 +151,6 @@ class Frontend {
             type,
             {definitions, context: {sentence, url, focus, disableHistory: true}}
         );
-
-        this.textSourceCurrent = textSource;
-        if (this.options.scanning.selectText) {
-            textSource.select();
-        }
     }
 
     async findTerms(textSource) {
@@ -433,65 +179,21 @@ class Frontend {
         return {definitions, type: 'kanji'};
     }
 
-    searchClear(changeFocus) {
+    onSearchClear(changeFocus) {
         this.popup.hide(changeFocus);
         this.popup.clearAutoPlayTimer();
-
+        super.onSearchClear(changeFocus);
-        if (this.textSourceCurrent !== null) {
-            if (this.options.scanning.selectText) {
-                this.textSourceCurrent.deselect();
-            }
-
-            this.textSourceCurrent = null;
-        }
-    }
-
-    getIndexOfTouch(touchList, identifier) {
-        for (const i in touchList) {
-            const t = touchList[i];
-            if (t.identifier === identifier) {
-                return i;
-            }
-        }
-        return -1;
-    }
-
-    setTextSourceScanLength(textSource, length) {
-        textSource.setEndOffset(length);
-        if (this.ignoreNodes === null || !textSource.range) {
-            return;
-        }
-
-        length = textSource.text().length;
-        while (textSource.range && length > 0) {
-            const nodes = TextSourceRange.getNodesInRange(textSource.range);
-            if (!TextSourceRange.anyNodeMatchesSelector(nodes, this.ignoreNodes)) {
-                break;
-            }
-            --length;
-            textSource.setEndOffset(length);
-        }
     }
 
     getOptionsContext() {
         this.optionsContext.url = this.popup.url;
         return this.optionsContext;
     }
-
-    static isScanningModifierPressed(scanningModifier, mouseEvent) {
-        switch (scanningModifier) {
-            case 'alt': return mouseEvent.altKey;
-            case 'ctrl': return mouseEvent.ctrlKey;
-            case 'shift': return mouseEvent.shiftKey;
-            case 'none': return true;
-            default: return false;
-        }
-    }
 }
 
 Frontend.windowMessageHandlers = {
     popupClose: (self) => {
-        self.searchClear(true);
+        self.onSearchClear(true);
     },
 
     selectionCopy: () => {

ext/fg/js/popup-nested.js

@@ -41,6 +41,7 @@ async function popupNestedInitialize(id, depth, parentFrameId, url) {
     window.frontendInitializationData = {id, depth, parentFrameId, ignoreNodes, url, proxy: true};
 
     const scriptSrcs = [
+        '/mixed/js/text-scanner.js',
         '/fg/js/frontend-api-sender.js',
         '/fg/js/popup.js',
         '/fg/js/popup-proxy.js',

ext/manifest.json

@@ -20,6 +20,7 @@
         "js": [
             "mixed/js/core.js",
             "mixed/js/dom.js",
+            "mixed/js/text-scanner.js",
             "fg/js/api.js",
             "fg/js/document.js",
             "fg/js/frontend-api-receiver.js",

ext/mixed/js/text-scanner.js

@@ -0,0 +1,378 @@
+/*
+ * Copyright (C) 2019  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+
+class TextScanner {
+    constructor(node, ignoreNodes, ignoreElements, ignorePoints) {
+        this.node = node;
+        this.ignoreNodes = (Array.isArray(ignoreNodes) && ignoreNodes.length > 0 ? ignoreNodes.join(',') : null);
+        this.ignoreElements = ignoreElements;
+        this.ignorePoints = ignorePoints;
+
+        this.scanTimerPromise = null;
+        this.textSourceCurrent = null;
+        this.pendingLookup = false;
+        this.options = null;
+
+        this.enabled = false;
+        this.eventListeners = [];
+
+        this.primaryTouchIdentifier = null;
+        this.preventNextContextMenu = false;
+        this.preventNextMouseDown = false;
+        this.preventNextClick = false;
+        this.preventScroll = false;
+    }
+
+    onMouseOver(e) {
+        if (this.ignoreElements.includes(e.target)) {
+            this.scanTimerClear();
+        }
+    }
+
+    onMouseMove(e) {
+        this.scanTimerClear();
+
+        if (this.pendingLookup || DOM.isMouseButtonDown(e, 'primary')) {
+            return;
+        }
+
+        const scanningOptions = this.options.scanning;
+        const scanningModifier = scanningOptions.modifier;
+        if (!(
+            TextScanner.isScanningModifierPressed(scanningModifier, e) ||
+            (scanningOptions.middleMouse && DOM.isMouseButtonDown(e, 'auxiliary'))
+        )) {
+            return;
+        }
+
+        const search = async () => {
+            if (scanningModifier === 'none') {
+                if (!await this.scanTimerWait()) {
+                    // Aborted
+                    return;
+                }
+            }
+
+            await this.searchAt(e.clientX, e.clientY, 'mouse');
+        };
+
+        search();
+    }
+
+    onMouseDown(e) {
+        if (this.preventNextMouseDown) {
+            this.preventNextMouseDown = false;
+            this.preventNextClick = true;
+            e.preventDefault();
+            e.stopPropagation();
+            return false;
+        }
+
+        if (DOM.isMouseButtonDown(e, 'primary')) {
+            this.scanTimerClear();
+            this.onSearchClear(true);
+        }
+    }
+
+    onMouseOut() {
+        this.scanTimerClear();
+    }
+
+    onClick(e) {
+        if (this.preventNextClick) {
+            this.preventNextClick = false;
+            e.preventDefault();
+            e.stopPropagation();
+            return false;
+        }
+    }
+
+    onAuxClick() {
+        this.preventNextContextMenu = false;
+    }
+
+    onContextMenu(e) {
+        if (this.preventNextContextMenu) {
+            this.preventNextContextMenu = false;
+            e.preventDefault();
+            e.stopPropagation();
+            return false;
+        }
+    }
+
+    onTouchStart(e) {
+        if (this.primaryTouchIdentifier !== null || e.changedTouches.length === 0) {
+            return;
+        }
+
+        this.preventScroll = false;
+        this.preventNextContextMenu = false;
+        this.preventNextMouseDown = false;
+        this.preventNextClick = false;
+
+        const primaryTouch = e.changedTouches[0];
+        if (DOM.isPointInSelection(primaryTouch.clientX, primaryTouch.clientY, this.node.getSelection())) {
+            return;
+        }
+
+        this.primaryTouchIdentifier = primaryTouch.identifier;
+
+        if (this.pendingLookup) {
+            return;
+        }
+
+        const textSourceCurrentPrevious = this.textSourceCurrent !== null ? this.textSourceCurrent.clone() : null;
+
+        this.searchAt(primaryTouch.clientX, primaryTouch.clientY, 'touchStart')
+        .then(() => {
+            if (
+                this.textSourceCurrent === null ||
+                this.textSourceCurrent.equals(textSourceCurrentPrevious)
+            ) {
+                return;
+            }
+
+            this.preventScroll = true;
+            this.preventNextContextMenu = true;
+            this.preventNextMouseDown = true;
+        });
+    }
+
+    onTouchEnd(e) {
+        if (
+            this.primaryTouchIdentifier === null ||
+            TextScanner.getIndexOfTouch(e.changedTouches, this.primaryTouchIdentifier) < 0
+        ) {
+            return;
+        }
+
+        this.primaryTouchIdentifier = null;
+        this.preventScroll = false;
+        this.preventNextClick = false;
+        // Don't revert context menu and mouse down prevention,
+        // since these events can occur after the touch has ended.
+        // this.preventNextContextMenu = false;
+        // this.preventNextMouseDown = false;
+    }
+
+    onTouchCancel(e) {
+        this.onTouchEnd(e);
+    }
+
+    onTouchMove(e) {
+        if (!this.preventScroll || !e.cancelable || this.primaryTouchIdentifier === null) {
+            return;
+        }
+
+        const touches = e.changedTouches;
+        const index = TextScanner.getIndexOfTouch(touches, this.primaryTouchIdentifier);
+        if (index < 0) {
+            return;
+        }
+
+        const primaryTouch = touches[index];
+        this.searchAt(primaryTouch.clientX, primaryTouch.clientY, 'touchMove');
+
+        e.preventDefault(); // Disable scroll
+    }
+
+    async onSearchSource(_textSource, _cause) {
+        throw new Error('Override me');
+    }
+
+    onError(error) {
+        logError(error, false);
+    }
+
+    async scanTimerWait() {
+        const delay = this.options.scanning.delay;
+        const promise = promiseTimeout(delay, true);
+        this.scanTimerPromise = promise;
+        try {
+            return await promise;
+        } finally {
+            if (this.scanTimerPromise === promise) {
+                this.scanTimerPromise = null;
+            }
+        }
+    }
+
+    scanTimerClear() {
+        if (this.scanTimerPromise !== null) {
+            this.scanTimerPromise.resolve(false);
+            this.scanTimerPromise = null;
+        }
+    }
+
+    setEnabled(enabled) {
+        if (enabled) {
+            if (!this.enabled) {
+                this.hookEvents();
+                this.enabled = true;
+            }
+        } else {
+            if (this.enabled) {
+                this.clearEventListeners();
+                this.enabled = false;
+            }
+            this.onSearchClear(false);
+        }
+    }
+
+    hookEvents() {
+        let eventListeners = this.getMouseEventListeners();
+        if (this.options.scanning.touchInputEnabled) {
+            eventListeners = eventListeners.concat(this.getTouchEventListeners());
+        }
+
+        for (const [node, type, listener, options] of eventListeners) {
+            this.addEventListener(node, type, listener, options);
+        }
+    }
+
+    getMouseEventListeners() {
+        return [
+            [this.node, 'mousedown', this.onMouseDown.bind(this)],
+            [this.node, 'mousemove', this.onMouseMove.bind(this)],
+            [this.node, 'mouseover', this.onMouseOver.bind(this)],
+            [this.node, 'mouseout', this.onMouseOut.bind(this)]
+        ];
+    }
+
+    getTouchEventListeners() {
+        return [
+            [this.node, 'click', this.onClick.bind(this)],
+            [this.node, 'auxclick', this.onAuxClick.bind(this)],
+            [this.node, 'touchstart', this.onTouchStart.bind(this)],
+            [this.node, 'touchend', this.onTouchEnd.bind(this)],
+            [this.node, 'touchcancel', this.onTouchCancel.bind(this)],
+            [this.node, 'touchmove', this.onTouchMove.bind(this), {passive: false}],
+            [this.node, 'contextmenu', this.onContextMenu.bind(this)]
+        ];
+    }
+
+    addEventListener(node, type, listener, options) {
+        node.addEventListener(type, listener, options);
+        this.eventListeners.push([node, type, listener, options]);
+    }
+
+    clearEventListeners() {
+        for (const [node, type, listener, options] of this.eventListeners) {
+            node.removeEventListener(type, listener, options);
+        }
+        this.eventListeners = [];
+    }
+
+    setOptions(options) {
+        this.options = options;
+    }
+
+    async searchAt(x, y, cause) {
+        try {
+            this.scanTimerClear();
+
+            if (this.pendingLookup) {
+                return;
+            }
+
+            for (const ignorePointFn of this.ignorePoints) {
+                if (await ignorePointFn(x, y)) {
+                    return;
+                }
+            }
+
+            const textSource = docRangeFromPoint(x, y, this.options);
+            if (this.textSourceCurrent !== null && this.textSourceCurrent.equals(textSource)) {
+                return;
+            }
+
+            try {
+                this.pendingLookup = true;
+                const result = await this.onSearchSource(textSource, cause);
+                if (result !== null) {
+                    this.textSourceCurrent = textSource;
+                    if (this.options.scanning.selectText) {
+                        textSource.select();
+                    }
+                }
+                this.pendingLookup = false;
+            } finally {
+                if (textSource !== null) {
+                    textSource.cleanup();
+                }
+            }
+        } catch (e) {
+            this.onError(e);
+        }
+    }
+
+    setTextSourceScanLength(textSource, length) {
+        textSource.setEndOffset(length);
+        if (this.ignoreNodes === null || !textSource.range) {
+            return;
+        }
+
+        length = textSource.text().length;
+        while (textSource.range && length > 0) {
+            const nodes = TextSourceRange.getNodesInRange(textSource.range);
+            if (!TextSourceRange.anyNodeMatchesSelector(nodes, this.ignoreNodes)) {
+                break;
+            }
+            --length;
+            textSource.setEndOffset(length);
+        }
+    }
+
+    onSearchClear(_) {
+        if (this.textSourceCurrent !== null) {
+            if (this.options.scanning.selectText) {
+                this.textSourceCurrent.deselect();
+            }
+            this.textSourceCurrent = null;
+        }
+    }
+
+    getCurrentTextSource() {
+        return this.textSourceCurrent;
+    }
+
+    setCurrentTextSource(textSource) {
+        return this.textSourceCurrent = textSource;
+    }
+
+    static isScanningModifierPressed(scanningModifier, mouseEvent) {
+        switch (scanningModifier) {
+            case 'alt': return mouseEvent.altKey;
+            case 'ctrl': return mouseEvent.ctrlKey;
+            case 'shift': return mouseEvent.shiftKey;
+            case 'none': return true;
+            default: return false;
+        }
+    }
+
+    static getIndexOfTouch(touchList, identifier) {
+        for (const i in touchList) {
+            const t = touchList[i];
+            if (t.identifier === identifier) {
+                return i;
+            }
+        }
+        return -1;
+    }
+}