Bug 1528289 - part 2: Dispatch same events on the web contents when a…

…utoscroll is canceled with a click r=Gijs,edgar Chrome behaves like this: 1. When user starts autoscroll with a middle click, `mousedown` and `mouseup` are fired, but `auxclick` nor `paste` event is not fired. 2. When user ends autoscroll with a left click, only `mouseup` event is fired. I.e, `mousedown` nor `click` event is not fired. 3. When user ends autoscroll with a middle click, only `mouseup` event is fired. I.e., `mousedown`, `auxclick` nor `paste` events is not fired. 4. When user ends autoscroll with a right click, `mouseup` and `contextmenu` events are fired, but `mousedown` and `auxclick` events are not fired. This patch emulates these Chrome's behavior as far as possible. However, unfortunately, we cannot do exactly same behavior without some big patches because each widget (`nsWindow` or `nsChildView`) discards a mouse event which rolled up a widget before dispatching it into the DOM. Therefore, for now, this patch does not fix the following issues: 1. `mousedown` event is not fired in content when clicking outside the autoscroller to close it except when pressing the secondary button or on any buttons on Linux. 2. `mouseup` event is not fired in content when clicking outside the autoscroller to close it except when pressing the primary button macOS. 3. `click` event and `auxclick` events are fired when clicking outside the autoscroller with the secondary button. So, the middle button `click`/`auxclick` events and `paste` event which is reported to the bug won't be fired with this patch. I'll file follow up bugs. Differential Revision: https://phabricator.services.mozilla.com/D104652
dothq · Mar 1, 2021 · 77d74d9 · 77d74d9
1 parent 2461631
commit 77d74d9
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Showing 10 changed files with 563 additions and 38 deletions.
diff --git a/dom/events/EventStateManager.cpp b/dom/events/EventStateManager.cpp
@@ -3232,6 +3232,30 @@ nsresult EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
         }
       }
 
+      // If MouseEvent::PreventClickEvent() was called by chrome script,
+      // we need to forget the clicking content and click count for the
+      // following eMouseUp event.
+      if (mouseEvent->mClickEventPrevented) {
+        RefPtr<EventStateManager> esm =
+            ESMFromContentOrThis(aOverrideClickTarget);
+        switch (mouseEvent->mButton) {
+          case MouseButton::ePrimary:
+            esm->mLastLeftMouseDownContent = nullptr;
+            esm->mLClickCount = 0;
+            break;
+          case MouseButton::eSecondary:
+            esm->mLastMiddleMouseDownContent = nullptr;
+            esm->mMClickCount = 0;
+            break;
+          case MouseButton::eMiddle:
+            esm->mLastRightMouseDownContent = nullptr;
+            esm->mRClickCount = 0;
+            break;
+          default:
+            break;
+        }
+      }
+
       nsCOMPtr<nsIContent> activeContent;
       // When content calls PreventDefault on pointerdown, we also call
       // PreventDefault on the subsequent mouse events to suppress default
@@ -4917,11 +4941,14 @@ nsresult EventStateManager::SetClickCount(WidgetMouseEvent* aEvent,
   switch (aEvent->mButton) {
     case MouseButton::ePrimary:
       if (aEvent->mMessage == eMouseDown) {
-        mLastLeftMouseDownContent = mouseContent;
+        mLastLeftMouseDownContent =
+            !aEvent->mClickEventPrevented ? mouseContent : nullptr;
       } else if (aEvent->mMessage == eMouseUp) {
         aEvent->mClickTarget =
-            nsContentUtils::GetCommonAncestorUnderInteractiveContent(
-                mouseContent, mLastLeftMouseDownContent);
+            !aEvent->mClickEventPrevented
+                ? nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+                      mouseContent, mLastLeftMouseDownContent)
+                : nullptr;
         if (aEvent->mClickTarget) {
           aEvent->mClickCount = mLClickCount;
           mLClickCount = 0;
@@ -4934,11 +4961,14 @@ nsresult EventStateManager::SetClickCount(WidgetMouseEvent* aEvent,
 
     case MouseButton::eMiddle:
       if (aEvent->mMessage == eMouseDown) {
-        mLastMiddleMouseDownContent = mouseContent;
+        mLastMiddleMouseDownContent =
+            !aEvent->mClickEventPrevented ? mouseContent : nullptr;
       } else if (aEvent->mMessage == eMouseUp) {
         aEvent->mClickTarget =
-            nsContentUtils::GetCommonAncestorUnderInteractiveContent(
-                mouseContent, mLastMiddleMouseDownContent);
+            !aEvent->mClickEventPrevented
+                ? nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+                      mouseContent, mLastMiddleMouseDownContent)
+                : nullptr;
         if (aEvent->mClickTarget) {
           aEvent->mClickCount = mMClickCount;
           mMClickCount = 0;
@@ -4951,11 +4981,14 @@ nsresult EventStateManager::SetClickCount(WidgetMouseEvent* aEvent,
 
     case MouseButton::eSecondary:
       if (aEvent->mMessage == eMouseDown) {
-        mLastRightMouseDownContent = mouseContent;
+        mLastRightMouseDownContent =
+            !aEvent->mClickEventPrevented ? mouseContent : nullptr;
       } else if (aEvent->mMessage == eMouseUp) {
         aEvent->mClickTarget =
-            nsContentUtils::GetCommonAncestorUnderInteractiveContent(
-                mouseContent, mLastRightMouseDownContent);
+            !aEvent->mClickEventPrevented
+                ? nsContentUtils::GetCommonAncestorUnderInteractiveContent(
+                      mouseContent, mLastRightMouseDownContent)
+                : nullptr;
         if (aEvent->mClickTarget) {
           aEvent->mClickCount = mRClickCount;
           mRClickCount = 0;
@@ -4986,6 +5019,10 @@ bool EventStateManager::EventCausesClickEvents(
   if (!aMouseEvent.mClickCount || !aMouseEvent.mClickTarget) {
     return false;
   }
+  // If click event was explicitly prevented, we shouldn't dispatch it.
+  if (aMouseEvent.mClickEventPrevented) {
+    return false;
+  }
   // Check that the window isn't disabled before firing a click
   // (see bug 366544).
   return !(aMouseEvent.mWidget && !aMouseEvent.mWidget->IsEnabled());

diff --git a/dom/events/MouseEvent.cpp b/dom/events/MouseEvent.cpp
@@ -154,6 +154,12 @@ void MouseEvent::InitNSMouseEvent(const nsAString& aType, bool aCanBubble,
   mouseEventBase->mInputSource = aInputSource;
 }
 
+void MouseEvent::PreventClickEvent() {
+  if (WidgetMouseEvent* mouseEvent = mEvent->AsMouseEvent()) {
+    mouseEvent->mClickEventPrevented = true;
+  }
+}
+
 int16_t MouseEvent::Button() {
   switch (mEvent->mClass) {
     case eMouseEventClass:

diff --git a/dom/events/MouseEvent.h b/dom/events/MouseEvent.h
@@ -76,6 +76,7 @@ class MouseEvent : public UIEvent {
                         bool aAltKey, bool aShiftKey, bool aMetaKey,
                         uint16_t aButton, EventTarget* aRelatedTarget,
                         float aPressure, uint16_t aInputSource);
+  void PreventClickEvent();
 
  protected:
   ~MouseEvent() = default;

diff --git a/dom/webidl/MouseEvent.webidl b/dom/webidl/MouseEvent.webidl
@@ -116,5 +116,11 @@ partial interface MouseEvent
                         optional float pressure = 0,
                         optional unsigned short inputSourceArg = 0);
 
+  /**
+   * preventClickEvent() prevents the following "click", "auxclick" and
+   * "dblclick" events of "mousedown" and "mouseup" events.
+   */
+  [ChromeOnly]
+  void preventClickEvent();
 };
 
diff --git a/toolkit/actors/AutoScrollChild.jsm b/toolkit/actors/AutoScrollChild.jsm
@@ -204,6 +204,7 @@ class AutoScrollChild extends JSWindowActorChild {
     }
 
     Services.els.addSystemEventListener(this.document, "mousemove", this, true);
+    Services.els.addSystemEventListener(this.document, "mouseup", this, true);
     this.document.addEventListener("pagehide", this, true);
 
     this._ignoreMouseEvents = true;
@@ -253,6 +254,12 @@ class AutoScrollChild extends JSWindowActorChild {
         this,
         true
       );
+      Services.els.removeSystemEventListener(
+        this.document,
+        "mouseup",
+        this,
+        true
+      );
       this.document.removeEventListener("pagehide", this, true);
       if (this._autoscrollHandledByApz) {
         Services.obs.removeObserver(
@@ -324,26 +331,38 @@ class AutoScrollChild extends JSWindowActorChild {
   }
 
   handleEvent(event) {
-    if (event.type == "mousemove") {
-      this._screenX = event.screenX;
-      this._screenY = event.screenY;
-    } else if (event.type == "mousedown") {
-      if (
-        event.isTrusted & !event.defaultPrevented &&
-        event.button == 1 &&
-        !this._scrollable &&
-        !this.isAutoscrollBlocker(event.originalTarget)
-      ) {
-        this.startScroll(event);
-      }
-    } else if (event.type == "pagehide") {
-      if (this._scrollable) {
-        var doc = this._scrollable.ownerDocument || this._scrollable.document;
-        if (doc == event.target) {
-          this.sendAsyncMessage("Autoscroll:Cancel");
-          this.stopScroll();
+    switch (event.type) {
+      case "mousemove":
+        this._screenX = event.screenX;
+        this._screenY = event.screenY;
+        break;
+      case "mousedown":
+        if (
+          event.isTrusted &&
+          !event.defaultPrevented &&
+          event.button === 1 &&
+          !this._scrollable &&
+          !this.isAutoscrollBlocker(event.originalTarget)
+        ) {
+          this.startScroll(event);
         }
-      }
+      // fallthrough
+      case "mouseup":
+        if (this._ignoreMouseEvents) {
+          // Middle mouse click event shouldn't be fired in web content for
+          // compatibility with Chrome.
+          event.preventClickEvent();
+        }
+        break;
+      case "pagehide":
+        if (this._scrollable) {
+          var doc = this._scrollable.ownerDocument || this._scrollable.document;
+          if (doc == event.target) {
+            this.sendAsyncMessage("Autoscroll:Cancel");
+            this.stopScroll();
+          }
+        }
+        break;
     }
   }
 

diff --git a/toolkit/content/tests/browser/browser.ini b/toolkit/content/tests/browser/browser.ini
@@ -61,6 +61,8 @@ skip-if = true # bug 1399845 tracks re-enabling this test.
 [browser_bug594509.js]
 [browser_bug982298.js]
 [browser_charsetMenu_swapBrowsers.js]
+[browser_click_event_during_autoscrolling.js]
+skip-if = !e10s
 [browser_content_url_annotation.js]
 skip-if = !e10s || !crashreporter
 [browser_contentTitle.js]