Shadow DOM container for popup iframes (#623)

* Add support for injecting stylesheets into a custom parent node

* Add api.getStylesheetContent

* Add support for injecting a CSS file's content

* Add usePopupShadowDom option

* Use a per-parentNode cache

* Add support for using a shadow DOM wrapper around popup iframes

* Ignore the popup container instead of the frame

8 files changed, 119 insertions, 20 deletions

diff --git a/ext/bg/data/options-schema.json b/ext/bg/data/options-schema.json
index f8791433..b56017bc 100644
--- a/ext/bg/data/options-schema.json
+++ b/ext/bg/data/options-schema.json
@@ -110,7 +110,8 @@
                                     "showPitchAccentPositionNotation",
                                     "showPitchAccentGraph",
                                     "showIframePopupsInRootFrame",
-                                    "useSecurePopupFrameUrl"
+                                    "useSecurePopupFrameUrl",
+                                    "usePopupShadowDom"
                                 ],
                                 "properties": {
                                     "enable": {
@@ -252,6 +253,10 @@
                                     "useSecurePopupFrameUrl": {
                                         "type": "boolean",
                                         "default": true
+                                    },
+                                    "usePopupShadowDom": {
+                                        "type": "boolean",
+                                        "default": true
                                     }
                                 }
                             },
diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index b89cb641..344706d1 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -108,6 +108,7 @@ class Backend {
             ['broadcastTab',                 {async: false, contentScript: true,  handler: this._onApiBroadcastTab.bind(this)}],
             ['frameInformationGet',          {async: true,  contentScript: true,  handler: this._onApiFrameInformationGet.bind(this)}],
             ['injectStylesheet',             {async: true,  contentScript: true,  handler: this._onApiInjectStylesheet.bind(this)}],
+            ['getStylesheetContent',         {async: true,  contentScript: true,  handler: this._onApiGetStylesheetContent.bind(this)}],
             ['getEnvironmentInfo',           {async: false, contentScript: true,  handler: this._onApiGetEnvironmentInfo.bind(this)}],
             ['clipboardGet',                 {async: true,  contentScript: true,  handler: this._onApiClipboardGet.bind(this)}],
             ['getDisplayTemplatesHtml',      {async: true,  contentScript: true,  handler: this._onApiGetDisplayTemplatesHtml.bind(this)}],
@@ -719,6 +720,13 @@ class Backend {
         });
     }
 
+    async _onApiGetStylesheetContent({url}) {
+        if (!url.startsWith('/') || url.startsWith('//') || !url.endsWith('.css')) {
+            throw new Error('Invalid URL');
+        }
+        return await requestText(url, 'GET');
+    }
+
     _onApiGetEnvironmentInfo() {
         return this.environment.getInfo();
     }
diff --git a/ext/bg/js/options.js b/ext/bg/js/options.js
index 151c945b..ccc56848 100644
--- a/ext/bg/js/options.js
+++ b/ext/bg/js/options.js
@@ -177,7 +177,8 @@ function profileOptionsCreateDefaults() {
             showPitchAccentPositionNotation: true,
             showPitchAccentGraph: false,
             showIframePopupsInRootFrame: false,
-            useSecurePopupFrameUrl: true
+            useSecurePopupFrameUrl: true,
+            usePopupShadowDom: true
         },
 
         audio: {
diff --git a/ext/bg/settings.html b/ext/bg/settings.html
index 4de70b7e..51cb14e7 100644
--- a/ext/bg/settings.html
+++ b/ext/bg/settings.html
@@ -187,6 +187,10 @@
                 </div>
 
                 <div class="checkbox options-advanced">
+                    <label><input type="checkbox" data-setting="general.usePopupShadowDom"> Use shadow DOM container for popup</label>
+                </div>
+
+                <div class="checkbox options-advanced">
                     <label><input type="checkbox" id="show-debug-info" data-setting="general.debugInfo" data-transform-pre="setDocumentAttribute" data-transform-post="setDocumentAttribute" data-document-attribute="data-options-general-debug-info"> Show debug information</label>
                 </div>
 
diff --git a/ext/fg/js/frontend.js b/ext/fg/js/frontend.js
index ae0953f9..f6b0d236 100644
--- a/ext/fg/js/frontend.js
+++ b/ext/fg/js/frontend.js
@@ -345,7 +345,7 @@ class Frontend {
     }
 
     _ignoreElements() {
-        return this._popup === null || this._popup.isProxy() ? [] : [this._popup.getFrame()];
+        return this._popup === null || this._popup.isProxy() ? [] : [this._popup.getContainer()];
     }
 
     _ignorePoint(x, y) {
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 3b14d3d0..5ee62c9b 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -47,6 +47,9 @@ class Popup {
         this._frame.style.width = '0';
         this._frame.style.height = '0';
 
+        this._container = this._frame;
+        this._shadow = null;
+
         this._fullscreenEventListeners = new EventListenerCollection();
     }
 
@@ -180,7 +183,12 @@ class Popup {
     }
 
     async setCustomOuterCss(css, useWebExtensionApi) {
-        return await dynamicLoader.loadStyle('yomichan-popup-outer-user-stylesheet', 'code', css, useWebExtensionApi);
+        let parentNode = null;
+        if (this._shadow !== null) {
+            useWebExtensionApi = false;
+            parentNode = this._shadow;
+        }
+        return await dynamicLoader.loadStyle('yomichan-popup-outer-user-stylesheet', 'code', css, useWebExtensionApi, parentNode);
     }
 
     setChildrenSupported(value) {
@@ -195,6 +203,10 @@ class Popup {
         return this._frame.getBoundingClientRect();
     }
 
+    getContainer() {
+        return this._container;
+    }
+
     // Private functions
 
     _inject() {
@@ -330,9 +342,9 @@ class Popup {
             throw new Error('Options not initialized');
         }
 
-        const {useSecurePopupFrameUrl} = this._options.general;
+        const {useSecurePopupFrameUrl, usePopupShadowDom} = this._options.general;
 
-        this._injectStyles();
+        await this._setUpContainer(usePopupShadowDom);
 
         const {secret, token} = await this._initializeFrame(this._frame, this._targetOrigin, this._frameId, (frame) => {
             frame.removeAttribute('src');
@@ -382,9 +394,9 @@ class Popup {
     }
 
     _resetFrame() {
-        const parent = this._frame.parentNode;
+        const parent = this._container.parentNode;
         if (parent !== null) {
-            parent.removeChild(this._frame);
+            parent.removeChild(this._container);
         }
         this._frame.removeAttribute('src');
         this._frame.removeAttribute('srcdoc');
@@ -395,9 +407,31 @@ class Popup {
         this._injectPromiseComplete = false;
     }
 
+    async _setUpContainer(usePopupShadowDom) {
+        if (usePopupShadowDom && typeof this._frame.attachShadow === 'function') {
+            const container = document.createElement('div');
+            container.style.setProperty('all', 'initial', 'important');
+            const shadow = container.attachShadow({mode: 'closed', delegatesFocus: true});
+            shadow.appendChild(this._frame);
+
+            this._container = container;
+            this._shadow = shadow;
+        } else {
+            const frameParentNode = this._frame.parentNode;
+            if (frameParentNode !== null) {
+                frameParentNode.removeChild(this._frame);
+            }
+
+            this._container = this._frame;
+            this._shadow = null;
+        }
+
+        await this._injectStyles();
+    }
+
     async _injectStyles() {
         try {
-            await dynamicLoader.loadStyle('yomichan-popup-outer-stylesheet', 'file', '/fg/css/client.css', true);
+            await this._injectPopupOuterStylesheet();
         } catch (e) {
             // NOP
         }
@@ -409,6 +443,18 @@ class Popup {
         }
     }
 
+    async _injectPopupOuterStylesheet() {
+        let fileType = 'file';
+        let useWebExtensionApi = true;
+        let parentNode = null;
+        if (this._shadow !== null) {
+            fileType = 'file-content';
+            useWebExtensionApi = false;
+            parentNode = this._shadow;
+        }
+        await dynamicLoader.loadStyle('yomichan-popup-outer-stylesheet', fileType, '/fg/css/client.css', useWebExtensionApi, parentNode);
+    }
+
     _observeFullscreen(observe) {
         if (!observe) {
             this._fullscreenEventListeners.removeAllEventListeners();
@@ -425,8 +471,8 @@ class Popup {
 
     _onFullscreenChanged() {
         const parent = this._getFrameParentElement();
-        if (parent !== null && this._frame.parentNode !== parent) {
-            parent.appendChild(this._frame);
+        if (parent !== null && this._container.parentNode !== parent) {
+            parent.appendChild(this._container);
         }
     }
 
diff --git a/ext/mixed/js/api.js b/ext/mixed/js/api.js
index c54196e2..5c17d50e 100644
--- a/ext/mixed/js/api.js
+++ b/ext/mixed/js/api.js
@@ -121,6 +121,10 @@ const api = (() => {
             return this._invoke('injectStylesheet', {type, value});
         }
 
+        getStylesheetContent(url) {
+            return this._invoke('getStylesheetContent', {url});
+        }
+
         getEnvironmentInfo() {
             return this._invoke('getEnvironmentInfo');
         }
diff --git a/ext/mixed/js/dynamic-loader.js b/ext/mixed/js/dynamic-loader.js
index 37f85112..981d1ee5 100644
--- a/ext/mixed/js/dynamic-loader.js
+++ b/ext/mixed/js/dynamic-loader.js
@@ -21,14 +21,36 @@
 
 const dynamicLoader = (() => {
     const injectedStylesheets = new Map();
+    const injectedStylesheetsWithParent = new WeakMap();
 
-    async function loadStyle(id, type, value, useWebExtensionApi=false) {
+    function getInjectedStylesheet(id, parentNode) {
+        if (parentNode === null) {
+            return injectedStylesheets.get(id);
+        }
+        const map = injectedStylesheetsWithParent.get(parentNode);
+        return typeof map !== 'undefined' ? map.get(id) : void 0;
+    }
+
+    function setInjectedStylesheet(id, parentNode, value) {
+        if (parentNode === null) {
+            injectedStylesheets.set(id, value);
+            return;
+        }
+        let map = injectedStylesheetsWithParent.get(parentNode);
+        if (typeof map === 'undefined') {
+            map = new Map();
+            injectedStylesheetsWithParent.set(parentNode, map);
+        }
+        map.set(id, value);
+    }
+
+    async function loadStyle(id, type, value, useWebExtensionApi=false, parentNode=null) {
         if (useWebExtensionApi && yomichan.isExtensionUrl(window.location.href)) {
             // Permissions error will occur if trying to use the WebExtension API to inject into an extension page
             useWebExtensionApi = false;
         }
 
-        let styleNode = injectedStylesheets.get(id);
+        let styleNode = getInjectedStylesheet(id, parentNode);
         if (typeof styleNode !== 'undefined') {
             if (styleNode === null) {
                 // Previously injected via WebExtension API
@@ -38,21 +60,30 @@ const dynamicLoader = (() => {
             styleNode = null;
         }
 
+        if (type === 'file-content') {
+            value = await api.getStylesheetContent(value);
+            type = 'code';
+            useWebExtensionApi = false;
+        }
+
         if (useWebExtensionApi) {
             // Inject via WebExtension API
             if (styleNode !== null && styleNode.parentNode !== null) {
                 styleNode.parentNode.removeChild(styleNode);
             }
 
-            injectedStylesheets.set(id, null);
+            setInjectedStylesheet(id, parentNode, null);
             await api.injectStylesheet(type, value);
             return null;
         }
 
         // Create node in document
-        const parentNode = document.head;
-        if (parentNode === null) {
-            throw new Error('No parent node');
+        let parentNode2 = parentNode;
+        if (parentNode2 === null) {
+            parentNode2 = document.head;
+            if (parentNode2 === null) {
+                throw new Error('No parent node');
+            }
         }
 
         // Create or reuse node
@@ -74,12 +105,12 @@ const dynamicLoader = (() => {
         }
 
         // Update parent
-        if (styleNode.parentNode !== parentNode) {
-            parentNode.appendChild(styleNode);
+        if (styleNode.parentNode !== parentNode2) {
+            parentNode2.appendChild(styleNode);
         }
 
         // Add to map
-        injectedStylesheets.set(id, styleNode);
+        setInjectedStylesheet(id, parentNode, styleNode);
         return styleNode;
     }