Bug 1130646 - Find non-hacky way to make back button dismiss reader mode popup, r=bnicholson

mobile/android/base/GeckoApp.java

@@ -33,6 +33,7 @@ import org.mozilla.gecko.util.ActivityUtils;
 import org.mozilla.gecko.util.EventCallback;
 import org.mozilla.gecko.util.FileUtils;
 import org.mozilla.gecko.util.GeckoEventListener;
+import org.mozilla.gecko.util.GeckoRequest;
 import org.mozilla.gecko.util.HardwareUtils;
 import org.mozilla.gecko.util.NativeEventListener;
 import org.mozilla.gecko.util.NativeJSObject;
@@ -2344,31 +2345,57 @@ public abstract class GeckoApp
             return;
         }
 
-        Tabs tabs = Tabs.getInstance();
-        Tab tab = tabs.getSelectedTab();
+        final Tabs tabs = Tabs.getInstance();
+        final Tab tab = tabs.getSelectedTab();
         if (tab == null) {
             moveTaskToBack(true);
             return;
         }
 
-        if (tab.doBack())
-            return;
+        // Give Gecko a chance to handle the back press first, then fallback to the Java UI.
+        GeckoAppShell.sendRequestToGecko(new GeckoRequest("Browser:OnBackPressed", null) {
+            @Override
+            public void onResponse(NativeJSObject nativeJSObject) {
+                if (!nativeJSObject.getBoolean("handled")) {
+                    // Default behavior is Gecko didn't prevent.
+                    onDefault();
+                }
+            }
 
-        if (tab.isExternal()) {
-            moveTaskToBack(true);
-            tabs.closeTab(tab);
-            return;
-        }
+            @Override
+            public void onError(NativeJSObject error) {
+                // Default behavior is Gecko didn't prevent, via failure.
+                onDefault();
+            }
 
-        int parentId = tab.getParentId();
-        Tab parent = tabs.getTab(parentId);
-        if (parent != null) {
-            // The back button should always return to the parent (not a sibling).
-            tabs.closeTab(tab, parent);
-            return;
-        }
+            // Return from Gecko thread, then back-press through the Java UI.
+            private void onDefault() {
+                ThreadUtils.postToUiThread(new Runnable() {
+                    @Override
+                    public void run() {
+                        if (tab.doBack()) {
+                            return;
+                        }
 
-        moveTaskToBack(true);
+                        if (tab.isExternal()) {
+                            moveTaskToBack(true);
+                            tabs.closeTab(tab);
+                            return;
+                        }
+
+                        final int parentId = tab.getParentId();
+                        final Tab parent = tabs.getTab(parentId);
+                        if (parent != null) {
+                            // The back button should always return to the parent (not a sibling).
+                            tabs.closeTab(tab, parent);
+                            return;
+                        }
+
+                        moveTaskToBack(true);
+                    }
+                });
+            }
+        });
     }
 
     @Override

mobile/android/chrome/content/Reader.js

@@ -20,6 +20,39 @@ var Reader = {
     return this._hasUsedToolbar = Services.prefs.getBoolPref("reader.has_used_toolbar");
   },
 
+  /**
+   * BackPressListener (listeners / ReaderView Ids).
+   */
+  _backPressListeners: [],
+  _backPressViewIds: [],
+
+  /**
+   * Set a backPressListener for this tabId / ReaderView Id pair.
+   */
+  _addBackPressListener: function(tabId, viewId, listener) {
+    this._backPressListeners[tabId] = listener;
+    this._backPressViewIds[viewId] = tabId;
+  },
+
+  /**
+   * Remove a backPressListener for this ReaderView Id.
+   */
+  _removeBackPressListener: function(viewId) {
+    let tabId = this._backPressViewIds[viewId];
+    if (tabId != undefined) {
+      this._backPressListeners[tabId] = null;
+      delete this._backPressViewIds[viewId];
+    }
+  },
+
+  /**
+   * If the requested tab has a backPress listener, return its results, else false.
+   */
+  onBackPress: function(tabId) {
+    let listener = this._backPressListeners[tabId];
+    return { handled: (listener ? listener() : false) };
+  },
+
   observe: function Reader_observe(aMessage, aTopic, aData) {
     switch (aTopic) {
       case "Reader:FetchContent": {
@@ -66,6 +99,29 @@ var Reader = {
         });
         break;
 
+      // On DropdownClosed in ReaderView, we cleanup / clear existing BackPressListener.
+      case "Reader:DropdownClosed": {
+        this._removeBackPressListener(message.data);
+        break;
+      }
+
+      // On DropdownOpened in ReaderView, we add BackPressListener to handle a subsequent BACK request.
+      case "Reader:DropdownOpened": {
+        let tabId = BrowserApp.selectedTab.id;
+        this._addBackPressListener(tabId, message.data, () => {
+          // User hit BACK key while ReaderView has the banner font-dropdown opened.
+          // Close it and return prevent-default.
+          if (message.target.messageManager) {
+            message.target.messageManager.sendAsyncMessage("Reader:CloseDropdown");
+            return true;
+          }
+          // We can assume ReaderView banner's font-dropdown doesn't need to be closed.
+          return false;
+        });
+
+        break;
+      }
+
       case "Reader:FaviconRequest": {
         Messaging.sendRequestForResult({
           type: "Reader:FaviconRequest",

mobile/android/chrome/content/browser.js

@@ -193,6 +193,8 @@ lazilyLoadedObserverScripts.forEach(function (aScript) {
   ["Reader", [
     ["Reader:AddToList", false],
     ["Reader:ArticleGet", false],
+    ["Reader:DropdownClosed", true], // 'true' allows us to survive mid-air cycle-collection.
+    ["Reader:DropdownOpened", false],
     ["Reader:FaviconRequest", false],
     ["Reader:ListStatusRequest", false],
     ["Reader:RemoveFromList", false],
@@ -4747,6 +4749,11 @@ var BrowserEventHandler = {
 
     InitLater(() => BrowserApp.deck.addEventListener("click", InputWidgetHelper, true));
     InitLater(() => BrowserApp.deck.addEventListener("click", SelectHelper, true));
+
+    // ReaderViews support backPress listeners.
+    Messaging.addListener(() => {
+      return Reader.onBackPress(BrowserApp.selectedTab.id);
+    }, "Browser:OnBackPressed");
   },
 
   handleEvent: function(aEvent) {

toolkit/components/reader/AboutReader.jsm

@@ -38,6 +38,7 @@ var AboutReader = function(mm, win, articlePromise) {
   this._mm.addMessageListener("Reader:Removed", this);
   this._mm.addMessageListener("Sidebar:VisibilityChange", this);
   this._mm.addMessageListener("ReadingList:VisibilityStatus", this);
+  this._mm.addMessageListener("Reader:CloseDropdown", this);
 
   this._docRef = Cu.getWeakReference(doc);
   this._winRef = Cu.getWeakReference(win);
@@ -178,6 +179,15 @@ AboutReader.prototype = {
     return this._toolbarVertical = Services.prefs.getBoolPref("reader.toolbar.vertical");
   },
 
+  // Provides unique view Id.
+  get viewId() {
+    let _viewId = Cc["@mozilla.org/uuid-generator;1"].
+      getService(Ci.nsIUUIDGenerator).generateUUID().toString();
+    Object.defineProperty(this, "viewId", { value: _viewId });
+
+    return _viewId;
+  },
+
   receiveMessage: function (message) {
     switch (message.name) {
       case "Reader:Added": {
@@ -190,6 +200,14 @@ AboutReader.prototype = {
         }
         break;
       }
+
+      // Triggered by Android user pressing BACK while the banner font-dropdown is open.
+      case "Reader:CloseDropdown": {
+        // Just close it.
+        this._closeDropdown();
+        break;
+      }
+
       case "Reader:Removed": {
         if (message.data.url == this._article.url) {
           if (this._isReadingListItem != 0) {
@@ -246,10 +264,14 @@ AboutReader.prototype = {
         break;
 
       case "unload":
+        // Close the Banners Font-dropdown, cleanup Android BackPressListener.
+        this._closeDropdown();
+
         this._mm.removeMessageListener("Reader:Added", this);
         this._mm.removeMessageListener("Reader:Removed", this);
         this._mm.removeMessageListener("Sidebar:VisibilityChange", this);
         this._mm.removeMessageListener("ReadingList:VisibilityStatus", this);
+        this._mm.removeMessageListener("Reader:CloseDropdown", this);
         this._windowUnloaded = true;
         break;
     }
@@ -584,8 +606,7 @@ AboutReader.prototype = {
   },
 
   _setToolbarVisibility: function(visible) {
-    let dropdown = this._doc.getElementById("style-dropdown");
-    dropdown.classList.remove("open");
+    this._closeDropdown();
 
     if (this._getToolbarVisibility() === visible) {
       return;
@@ -943,13 +964,41 @@ AboutReader.prototype = {
       event.stopPropagation();
 
       if (dropdown.classList.contains("open")) {
-        dropdown.classList.remove("open");
+        this._closeDropdown();
       } else {
-        dropdown.classList.add("open");
+        this._openDropdown();
         if (this._isToolbarVertical) {
           updatePopupPosition();
         }
       }
     }, true);
   },
+
+  /*
+   * If the ReaderView banner font-dropdown is closed, open it.
+   */
+  _openDropdown: function() {
+    let dropdown = this._doc.getElementById("style-dropdown");
+    if (dropdown.classList.contains("open")) {
+      return;
+    }
+
+    // Trigger BackPressListener initialization in Android.
+    dropdown.classList.add("open");
+    this._mm.sendAsyncMessage("Reader:DropdownOpened", this.viewId);
+  },
+
+  /*
+   * If the ReaderView banner font-dropdown is opened, close it.
+   */
+  _closeDropdown: function() {
+    let dropdown = this._doc.getElementById("style-dropdown");
+    if (!dropdown.classList.contains("open")) {
+      return;
+    }
+
+    // Trigger BackPressListener cleanup in Android.
+    dropdown.classList.remove("open");
+    this._mm.sendAsyncMessage("Reader:DropdownClosed", this.viewId);
+  },
 };