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

Extract text scanner from Frontend 

1 files changed, 378 insertions, 0 deletions

diff --git a/ext/mixed/js/text-scanner.js b/ext/mixed/js/text-scanner.js
new file mode 100644
index 00000000..ac5d68d1
--- /dev/null
+++ b/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;
+    }
+}