Exclude documentElement from zoom calculation (#2227)

* Exclude documentElement from zoom calculation

* Add an option

* Refactor zoom coordinate conversion functions

* Convert zoom coordinates for text sources

* Rename variable

* Convert rect coordinate spaces

* Handle shadow DOM

8 files changed, 133 insertions, 36 deletions

diff --git a/ext/js/app/frontend.js b/ext/js/app/frontend.js
index f3b925c3..de3eb7fd 100644
--- a/ext/js/app/frontend.js
+++ b/ext/js/app/frontend.js
@@ -395,6 +395,7 @@ class Frontend {
         this._textScanner.setOptions({
             inputs: scanningOptions.inputs,
             deepContentScan: scanningOptions.deepDomScan,
+            normalizeCssZoom: scanningOptions.normalizeCssZoom,
             selectText: scanningOptions.selectText,
             delay: scanningOptions.delay,
             touchInputEnabled: scanningOptions.touchInputEnabled,
diff --git a/ext/js/app/popup.js b/ext/js/app/popup.js
index 9ca2165d..8b62b92a 100644
--- a/ext/js/app/popup.js
+++ b/ext/js/app/popup.js
@@ -368,7 +368,7 @@ class Popup extends EventDispatcher {
      *   `valid` is `false` for `PopupProxy`, since the DOM node is hosted in a different frame.
      */
     getFrameRect() {
-        const {left, top, right, bottom} = this._frame.getBoundingClientRect();
+        const {left, top, right, bottom} = this._getFrameBoundingClientRect();
         return {left, top, right, bottom, valid: true};
     }
 
@@ -377,7 +377,7 @@ class Popup extends EventDispatcher {
      * @returns {Promise<{width: number, height: number, valid: boolean}>} The size and whether or not it is valid.
      */
     async getFrameSize() {
-        const {width, height} = this._frame.getBoundingClientRect();
+        const {width, height} = this._getFrameBoundingClientRect();
         return {width, height, valid: true};
     }
 
@@ -680,12 +680,13 @@ class Popup extends EventDispatcher {
      * @returns {SizeRect} The calculated rectangle for where to position the popup.
      */
     _getPosition(sourceRects, writingMode, viewport) {
-        const scale = this._contentScale;
-        const scaleRatio = this._frameSizeContentScale === null ? 1.0 : scale / this._frameSizeContentScale;
-        this._frameSizeContentScale = scale;
+        sourceRects = this._convertSourceRectsCoordinateSpace(sourceRects);
+        const contentScale = this._contentScale;
+        const scaleRatio = this._frameSizeContentScale === null ? 1.0 : contentScale / this._frameSizeContentScale;
+        this._frameSizeContentScale = contentScale;
         const frameRect = this._frame.getBoundingClientRect();
-        const frameWidth = Math.max(frameRect.width * scaleRatio, this._initialWidth * scale);
-        const frameHeight = Math.max(frameRect.height * scaleRatio, this._initialHeight * scale);
+        const frameWidth = Math.max(frameRect.width * scaleRatio, this._initialWidth * contentScale);
+        const frameHeight = Math.max(frameRect.height * scaleRatio, this._initialHeight * contentScale);
 
         const horizontal = (writingMode === 'horizontal-tb' || this._verticalTextPosition === 'default');
         let preferAfter;
@@ -700,8 +701,8 @@ class Popup extends EventDispatcher {
             horizontalOffset = this._horizontalOffset2;
             verticalOffset = this._verticalOffset2;
         }
-        horizontalOffset *= scale;
-        verticalOffset *= scale;
+        horizontalOffset *= contentScale;
+        verticalOffset *= contentScale;
 
         let best = null;
         const sourceRectsLength = sourceRects.length;
@@ -955,4 +956,43 @@ class Popup extends EventDispatcher {
         }
         return false;
     }
+
+    /**
+     * Gets the bounding client rect for the frame element, with a coordinate conversion applied.
+     * @returns {DOMRect} The rectangle of the frame.
+     */
+    _getFrameBoundingClientRect() {
+        return DocumentUtil.convertRectZoomCoordinates(this._frame.getBoundingClientRect(), this._container);
+    }
+
+    /**
+     * Converts the coordinate space of source rectangles.
+     * @param {Rect[]} sourceRects The list of rectangles to convert.
+     * @returns {Rect[]} Either an updated list of rectangles, or `sourceRects` if no change is required.
+     */
+    _convertSourceRectsCoordinateSpace(sourceRects) {
+        let scale = DocumentUtil.computeZoomScale(this._container);
+        if (scale === 1) { return sourceRects; }
+        scale = 1 / scale;
+        const sourceRects2 = [];
+        for (const rect of sourceRects) {
+            sourceRects2.push(this._createScaledRect(rect, scale));
+        }
+        return sourceRects2;
+    }
+
+    /**
+     * Creates a scaled rectangle.
+     * @param {Rect} rect The rectangle to scale.
+     * @param {number} scale The scale factor.
+     * @returns {Rect} A new rectangle which has been scaled.
+     */
+    _createScaledRect(rect, scale) {
+        return {
+            left: rect.left * scale,
+            top: rect.top * scale,
+            right: rect.right * scale,
+            bottom: rect.bottom * scale
+        };
+    }
 }
diff --git a/ext/js/data/options-util.js b/ext/js/data/options-util.js
index d2835adb..442007d0 100644
--- a/ext/js/data/options-util.js
+++ b/ext/js/data/options-util.js
@@ -980,10 +980,12 @@ class OptionsUtil {
     _updateVersion20(options) {
         // Version 20 changes:
         //  Added anki.downloadTimeout.
+        //  Added scanning.normalizeCssZoom.
         //  Fixed general.popupTheme invalid default.
         //  Fixed general.popupOuterTheme invalid default.
         for (const profile of options.profiles) {
             profile.options.anki.downloadTimeout = 0;
+            profile.options.scanning.normalizeCssZoom = true;
             const {general} = profile.options;
             if (general.popupTheme === 'default') {
                 general.popupTheme = 'light';
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index 8905d304..d286bd5e 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -367,6 +367,7 @@ class Display extends EventDispatcher {
             scanning: {
                 inputs: scanningOptions.inputs,
                 deepContentScan: scanningOptions.deepDomScan,
+                normalizeCssZoom: scanningOptions.normalizeCssZoom,
                 selectText: scanningOptions.selectText,
                 delay: scanningOptions.delay,
                 touchInputEnabled: scanningOptions.touchInputEnabled,
@@ -1532,6 +1533,7 @@ class Display extends EventDispatcher {
                 }
             }],
             deepContentScan: scanningOptions.deepDomScan,
+            normalizeCssZoom: scanningOptions.normalizeCssZoom,
             selectText: false,
             delay: scanningOptions.delay,
             touchInputEnabled: false,
diff --git a/ext/js/dom/document-util.js b/ext/js/dom/document-util.js
index b974387e..41f44afe 100644
--- a/ext/js/dom/document-util.js
+++ b/ext/js/dom/document-util.js
@@ -24,10 +24,9 @@
 class DocumentUtil {
     constructor() {
         this._transparentColorPattern = /rgba\s*\([^)]*,\s*0(?:\.0+)?\s*\)/;
-        this._cssZoomSupported = (typeof document.createElement('div').style.zoom === 'string');
     }
 
-    getRangeFromPoint(x, y, deepContentScan) {
+    getRangeFromPoint(x, y, {deepContentScan, normalizeCssZoom}) {
         const elements = this._getElementsFromPoint(x, y, deepContentScan);
         let imposter = null;
         let imposterContainer = null;
@@ -52,7 +51,7 @@ class DocumentUtil {
             }
         }
 
-        const range = this._caretRangeFromPointExt(x, y, deepContentScan ? elements : []);
+        const range = this._caretRangeFromPointExt(x, y, deepContentScan ? elements : [], normalizeCssZoom);
         if (range !== null) {
             if (imposter !== null) {
                 this._setImposterStyle(imposterContainer.style, 'z-index', '-2147483646');
@@ -175,6 +174,60 @@ class DocumentUtil {
         };
     }
 
+    /**
+     * Computes the scaling adjustment that is necessary for client space coordinates based on the
+     * CSS zoom level.
+     * @param {Node} node A node in the document.
+     * @returns {number} The scaling factor.
+     */
+    static computeZoomScale(node) {
+        if (this._cssZoomSupported === null) {
+            this._cssZoomSupported = (typeof document.createElement('div').style.zoom === 'string');
+        }
+        if (!this._cssZoomSupported) { return 1; }
+        // documentElement must be excluded because the computer style of its zoom property is inconsistent.
+        // * If CSS `:root{zoom:X;}` is specified, the computed zoom will always report `X`.
+        // * If CSS `:root{zoom:X;}` is not specified, the computed zoom report the browser's zoom level.
+        // Therefor, if CSS root zoom is specified as a value other than 1, the adjusted {x, y} values
+        // would be incorrect, which is not new behaviour.
+        let scale = 1;
+        const {ELEMENT_NODE, DOCUMENT_FRAGMENT_NODE} = Node;
+        const {documentElement} = document;
+        for (; node !== null && node !== documentElement; node = node.parentNode) {
+            const {nodeType} = node;
+            if (nodeType === DOCUMENT_FRAGMENT_NODE) {
+                const {host} = node;
+                if (typeof host !== 'undefined') {
+                    node = host;
+                }
+                continue;
+            } else if (nodeType !== ELEMENT_NODE) {
+                continue;
+            }
+            let {zoom} = getComputedStyle(node);
+            if (typeof zoom !== 'string') { continue; }
+            zoom = Number.parseFloat(zoom);
+            if (!Number.isFinite(zoom) || zoom === 0) { continue; }
+            scale *= zoom;
+        }
+        return scale;
+    }
+
+    static convertRectZoomCoordinates(rect, node) {
+        const scale = this.computeZoomScale(node);
+        return (scale === 1 ? rect : new DOMRect(rect.left * scale, rect.top * scale, rect.width * scale, rect.height * scale));
+    }
+
+    static convertMultipleRectZoomCoordinates(rects, node) {
+        const scale = this.computeZoomScale(node);
+        if (scale === 1) { return rects; }
+        const results = [];
+        for (const rect of rects) {
+            results.push(new DOMRect(rect.left * scale, rect.top * scale, rect.width * scale, rect.height * scale));
+        }
+        return results;
+    }
+
     static isPointInRect(x, y, rect) {
         return (
             x >= rect.left && x < rect.right &&
@@ -435,7 +488,7 @@ class DocumentUtil {
         return e !== null ? [e] : [];
     }
 
-    _isPointInRange(x, y, range) {
+    _isPointInRange(x, y, range, normalizeCssZoom) {
         // Require a text node to start
         const {startContainer} = range;
         if (startContainer.nodeType !== Node.TEXT_NODE) {
@@ -443,8 +496,10 @@ class DocumentUtil {
         }
 
         // Convert CSS zoom coordinates
-        if (this._cssZoomSupported) {
-            ({x, y} = this._convertCssZoomCoordinates(x, y, startContainer));
+        if (normalizeCssZoom) {
+            const scale = DocumentUtil.computeZoomScale(startContainer);
+            x /= scale;
+            y /= scale;
         }
 
         // Scan forward
@@ -583,7 +638,7 @@ class DocumentUtil {
         }
     }
 
-    _caretRangeFromPointExt(x, y, elements) {
+    _caretRangeFromPointExt(x, y, elements, normalizeCssZoom) {
         let previousStyles = null;
         try {
             let i = 0;
@@ -596,7 +651,7 @@ class DocumentUtil {
 
                 const startContainer = range.startContainer;
                 if (startContinerPre !== startContainer) {
-                    if (this._isPointInRange(x, y, range)) {
+                    if (this._isPointInRange(x, y, range, normalizeCssZoom)) {
                         return range;
                     }
                     startContinerPre = startContainer;
@@ -668,18 +723,6 @@ class DocumentUtil {
     _isElementUserSelectAll(element) {
         return getComputedStyle(element).userSelect === 'all';
     }
-
-    _convertCssZoomCoordinates(x, y, node) {
-        const ELEMENT_NODE = Node.ELEMENT_NODE;
-        for (; node !== null; node = node.parentNode) {
-            if (node.nodeType !== ELEMENT_NODE) { continue; }
-            let {zoom} = getComputedStyle(node);
-            if (typeof zoom !== 'string') { continue; }
-            zoom = Number.parseFloat(zoom);
-            if (!Number.isFinite(zoom) || zoom === 0) { continue; }
-            x /= zoom;
-            y /= zoom;
-        }
-        return {x, y};
-    }
 }
+// eslint-disable-next-line no-underscore-dangle
+DocumentUtil._cssZoomSupported = null;
diff --git a/ext/js/dom/text-source-element.js b/ext/js/dom/text-source-element.js
index fe3fe083..b5fc1683 100644
--- a/ext/js/dom/text-source-element.js
+++ b/ext/js/dom/text-source-element.js
@@ -16,6 +16,7 @@
  */
 
 /* global
+ * DocumentUtil
  * StringUtil
  */
 
@@ -95,11 +96,11 @@ class TextSourceElement {
     }
 
     getRect() {
-        return this._element.getBoundingClientRect();
+        return DocumentUtil.convertRectZoomCoordinates(this._element.getBoundingClientRect(), this._element);
     }
 
     getRects() {
-        return this._element.getClientRects();
+        return DocumentUtil.convertMultipleRectZoomCoordinates(this._element.getClientRects(), this._element);
     }
 
     getWritingMode() {
diff --git a/ext/js/dom/text-source-range.js b/ext/js/dom/text-source-range.js
index 5e3e814c..6c35c4cb 100644
--- a/ext/js/dom/text-source-range.js
+++ b/ext/js/dom/text-source-range.js
@@ -91,11 +91,11 @@ class TextSourceRange {
     }
 
     getRect() {
-        return this._range.getBoundingClientRect();
+        return DocumentUtil.convertRectZoomCoordinates(this._range.getBoundingClientRect(), this._range.startContainer);
     }
 
     getRects() {
-        return this._range.getClientRects();
+        return DocumentUtil.convertMultipleRectZoomCoordinates(this._range.getClientRects(), this._range.startContainer);
     }
 
     getWritingMode() {
diff --git a/ext/js/language/text-scanner.js b/ext/js/language/text-scanner.js
index 93de4dd4..3b8a8b47 100644
--- a/ext/js/language/text-scanner.js
+++ b/ext/js/language/text-scanner.js
@@ -54,6 +54,7 @@ class TextScanner extends EventDispatcher {
         this._selectionRestoreInfo = null;
 
         this._deepContentScan = false;
+        this._normalizeCssZoom = true;
         this._selectText = false;
         this._delay = 0;
         this._touchInputEnabled = false;
@@ -151,6 +152,7 @@ class TextScanner extends EventDispatcher {
     setOptions({
         inputs,
         deepContentScan,
+        normalizeCssZoom,
         selectText,
         delay,
         touchInputEnabled,
@@ -167,6 +169,9 @@ class TextScanner extends EventDispatcher {
         if (typeof deepContentScan === 'boolean') {
             this._deepContentScan = deepContentScan;
         }
+        if (typeof normalizeCssZoom === 'boolean') {
+            this._normalizeCssZoom = normalizeCssZoom;
+        }
         if (typeof selectText === 'boolean') {
             this._selectText = selectText;
         }
@@ -932,7 +937,10 @@ class TextScanner extends EventDispatcher {
                 return;
             }
 
-            const textSource = this._documentUtil.getRangeFromPoint(x, y, this._deepContentScan);
+            const textSource = this._documentUtil.getRangeFromPoint(x, y, {
+                deepContentScan: this._deepContentScan,
+                normalizeCssZoom: this._normalizeCssZoom
+            });
             try {
                 await this._search(textSource, searchTerms, searchKanji, inputInfo);
             } finally {