Bug 1609338 - Optimize usage and implementation of UIEvent::GetRangeParent() and UIEvent::RangeOffset() r=smaug

`UIEvent::GetRangeParent()` retrieves `nsIContent` instance but it needs to
return `already_AddRefed<nsINode>` because of a WebIDL method.  However,
`nsIContent` is better type in C++ code.  Therefore, this patch renames it
to `UIEvent::GetRangeParentContent()` and makes new `UIEvent::GetRangeParent()`
and just call it.

Additionally, some callers call `UIEvent::RangeOffset()` too, but that means
that they compute same things twice because both of them use
`nsLayoutUtils::GetContainerAndOffsetAtEvent()` with same input arguments.
Thus, `UIEvent::GetRangeParentContent()` should also return offset with optional
out argument.  (Note that this does not make `RangeOffset()` use
`GetRangeParentContent()` because using out parameter for range parent causes
unnecessary computation cost for `RangeOffset()`.)

Therefore, finally, `UIEvent::GetRangeParentContent()` becomes also an alias of
raw method `UIEvent::GetRangeParentContentAndOffset()` which also returns offset
with out argument.

Differential Revision: https://phabricator.services.mozilla.com/D60095

--HG--
extra : moz-landing-system : lando

dom/events/UIEvent.cpp

@@ -132,7 +132,8 @@ void UIEvent::InitUIEvent(const nsAString& typeArg, bool canBubbleArg,
   mView = viewArg ? viewArg->GetOuterWindow() : nullptr;
 }
 
-already_AddRefed<nsINode> UIEvent::GetRangeParent() {
+already_AddRefed<nsIContent> UIEvent::GetRangeParentContentAndOffset(
+    int32_t* aOffset) {
   if (NS_WARN_IF(!mPresContext)) {
     return nullptr;
   }
@@ -142,7 +143,7 @@ already_AddRefed<nsINode> UIEvent::GetRangeParent() {
   }
   nsCOMPtr<nsIContent> container;
   nsLayoutUtils::GetContainerAndOffsetAtEvent(
-      presShell, mEvent, getter_AddRefs(container), nullptr);
+      presShell, mEvent, getter_AddRefs(container), aOffset);
   return container.forget();
 }
 

dom/events/UIEvent.h

@@ -70,11 +70,28 @@ class UIEvent : public Event {
     return 0;
   }
 
-  MOZ_CAN_RUN_SCRIPT
-  already_AddRefed<nsINode> GetRangeParent();
+  /**
+   * GetRangeParent() should be used only by JS.  C++ callers should use
+   * GetRangeParentContent() or GetRangeParentContentAndOffset() instead.
+   */
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<nsINode> GetRangeParent() {
+    return GetRangeParentContent();
+  }
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<nsIContent> GetRangeParentContent() {
+    return GetRangeParentContentAndOffset(nullptr);
+  }
+  /**
+   * aOffset is optional (i.e., can be nullptr), but when you call this with
+   * nullptr, you should use GetRangeParentContent() instead.
+   */
+  MOZ_CAN_RUN_SCRIPT already_AddRefed<nsIContent>
+  GetRangeParentContentAndOffset(int32_t* aOffset);
 
-  MOZ_CAN_RUN_SCRIPT
-  int32_t RangeOffset() const;
+  /**
+   * If you also need to compute range parent in C++ code, you should use
+   * GetRangeParentContentAndOffset() instead.
+   */
+  MOZ_CAN_RUN_SCRIPT int32_t RangeOffset() const;
 
  protected:
   ~UIEvent() {}

editor/libeditor/EditorEventListener.cpp

@@ -728,11 +728,14 @@ nsresult EditorEventListener::DragOver(DragEvent* aDragEvent) {
     return NS_OK;
   }
 
-  nsCOMPtr<nsINode> parent = aDragEvent->GetRangeParent();
-  nsCOMPtr<nsIContent> dropParent = do_QueryInterface(parent);
-  NS_ENSURE_TRUE(dropParent, NS_ERROR_FAILURE);
+  int32_t dropOffset = -1;
+  nsCOMPtr<nsIContent> dropParentContent =
+      aDragEvent->GetRangeParentContentAndOffset(&dropOffset);
+  if (NS_WARN_IF(!dropParentContent)) {
+    return NS_ERROR_FAILURE;
+  }
 
-  if (dropParent->IsEditable() && CanDrop(aDragEvent)) {
+  if (dropParentContent->IsEditable() && CanDrop(aDragEvent)) {
     aDragEvent->PreventDefault();  // consumed
 
     // If we handle the dragged item, we need should adjust drop effect here
@@ -756,10 +759,8 @@ nsresult EditorEventListener::DragOver(DragEvent* aDragEvent) {
       return NS_OK;
     }
 
-    int32_t offset = aDragEvent->RangeOffset();
-
     mCaret->SetVisible(true);
-    mCaret->SetCaretPosition(dropParent, offset);
+    mCaret->SetCaretPosition(dropParentContent, dropOffset);
 
     return NS_OK;
   }
@@ -818,8 +819,7 @@ nsresult EditorEventListener::Drop(DragEvent* aDragEvent) {
     return NS_OK;
   }
 
-  nsCOMPtr<nsINode> dropParentNode = aDragEvent->GetRangeParent();
-  nsIContent* dropParentContent = nsIContent::FromNodeOrNull(dropParentNode);
+  nsCOMPtr<nsIContent> dropParentContent = aDragEvent->GetRangeParentContent();
   if (NS_WARN_IF(!dropParentContent)) {
     return NS_ERROR_FAILURE;
   }
@@ -911,13 +911,13 @@ bool EditorEventListener::CanDrop(DragEvent* aEvent) {
     return true;
   }
 
-  nsCOMPtr<nsINode> parent = aEvent->GetRangeParent();
-  if (!parent) {
+  int32_t dropOffset = -1;
+  nsCOMPtr<nsIContent> dropParentContent =
+      aEvent->GetRangeParentContentAndOffset(&dropOffset);
+  if (!dropParentContent) {
     return false;
   }
 
-  int32_t offset = aEvent->RangeOffset();
-
   uint32_t rangeCount = selection->RangeCount();
   for (uint32_t i = 0; i < rangeCount; i++) {
     RefPtr<nsRange> range = selection->GetRangeAt(i);
@@ -927,7 +927,7 @@ bool EditorEventListener::CanDrop(DragEvent* aEvent) {
     }
 
     IgnoredErrorResult rv;
-    bool inRange = range->IsPointInRange(*parent, offset, rv);
+    bool inRange = range->IsPointInRange(*dropParentContent, dropOffset, rv);
     if (!rv.Failed() && inRange) {
       // Okay, now you can bail, we are over the orginal selection
       return false;

editor/libeditor/HTMLEditorEventListener.cpp

@@ -286,10 +286,12 @@ nsresult HTMLEditorEventListener::MouseDown(MouseEvent* aMouseEvent) {
     NS_ENSURE_TRUE(selection, NS_OK);
 
     // Get location of mouse within target node
-    nsCOMPtr<nsINode> parent = aMouseEvent->GetRangeParent();
-    NS_ENSURE_TRUE(parent, NS_ERROR_FAILURE);
-
-    int32_t offset = aMouseEvent->RangeOffset();
+    int32_t offset = -1;
+    nsCOMPtr<nsIContent> parentContent =
+        aMouseEvent->GetRangeParentContentAndOffset(&offset);
+    if (NS_WARN_IF(!parentContent)) {
+      return NS_ERROR_FAILURE;
+    }
 
     // Detect if mouse point is within current selection for context click
     bool nodeIsInSelection = false;
@@ -305,7 +307,7 @@ nsresult HTMLEditorEventListener::MouseDown(MouseEvent* aMouseEvent) {
 
         IgnoredErrorResult err;
         nodeIsInSelection =
-            range->IsPointInRange(*parent, offset, err) && !err.Failed();
+            range->IsPointInRange(*parentContent, offset, err) && !err.Failed();
 
         // Done when we find a range that we are in
         if (nodeIsInSelection) {
@@ -318,7 +320,7 @@ nsresult HTMLEditorEventListener::MouseDown(MouseEvent* aMouseEvent) {
       if (!element) {
         if (isContextClick) {
           // Set the selection to the point under the mouse cursor:
-          selection->Collapse(parent, offset);
+          selection->Collapse(parentContent, offset);
         } else {
           // Get enclosing link if in text so we can select the link
           Element* linkElement =
@@ -332,7 +334,7 @@ nsresult HTMLEditorEventListener::MouseDown(MouseEvent* aMouseEvent) {
       //   and not the entire body, or table-related elements
       if (element) {
         if (isContextClick && !HTMLEditUtils::IsImage(node)) {
-          selection->Collapse(parent, offset);
+          selection->Collapse(parentContent, offset);
         } else {
           htmlEditor->SelectElement(element);
         }

editor/libeditor/TextEditorDataTransfer.cpp

@@ -210,8 +210,10 @@ nsresult TextEditor::OnDrop(DragEvent* aDropEvent) {
 
   // We have to figure out whether to delete and relocate caret only once
   // Parent and offset are under the mouse cursor.
-  EditorDOMPoint droppedAt(aDropEvent->GetRangeParent(),
-                           aDropEvent->RangeOffset());
+  int32_t dropOffset = -1;
+  nsCOMPtr<nsIContent> dropParentContent =
+      aDropEvent->GetRangeParentContentAndOffset(&dropOffset);
+  EditorDOMPoint droppedAt(dropParentContent, dropOffset);
   if (NS_WARN_IF(!droppedAt.IsSet()) ||
       NS_WARN_IF(!droppedAt.GetContainerAsContent())) {
     return NS_ERROR_FAILURE;

layout/xul/nsXULPopupManager.cpp

@@ -166,7 +166,7 @@ nsXULPopupManager::Observe(nsISupports* aSubject, const char* aTopic,
       mKeyListener->RemoveEventListener(NS_LITERAL_STRING("keyup"), this, true);
       mKeyListener = nullptr;
     }
-    mRangeParent = nullptr;
+    mRangeParentContent = nullptr;
     // mOpeningPopup is cleared explicitly soon after using it.
     nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
     if (obs) {
@@ -556,10 +556,6 @@ nsMenuChainItem* nsXULPopupManager::GetTopVisibleMenu() {
   return nullptr;
 }
 
-nsINode* nsXULPopupManager::GetMouseLocationParent() { return mRangeParent; }
-
-int32_t nsXULPopupManager::MouseLocationOffset() { return mRangeOffset; }
-
 void nsXULPopupManager::InitTriggerEvent(Event* aEvent, nsIContent* aPopup,
                                          nsIContent** aTriggerContent) {
   mCachedMousePoint = LayoutDeviceIntPoint(0, 0);
@@ -577,8 +573,9 @@ void nsXULPopupManager::InitTriggerEvent(Event* aEvent, nsIContent* aPopup,
 
   RefPtr<UIEvent> uiEvent = aEvent ? aEvent->AsUIEvent() : nullptr;
   if (uiEvent) {
-    mRangeParent = uiEvent->GetRangeParent();
-    mRangeOffset = uiEvent->RangeOffset();
+    mRangeOffset = -1;
+    mRangeParentContent =
+        uiEvent->GetRangeParentContentAndOffset(&mRangeOffset);
 
     // get the event coordinates relative to the root frame of the document
     // containing the popup.
@@ -628,7 +625,7 @@ void nsXULPopupManager::InitTriggerEvent(Event* aEvent, nsIContent* aPopup,
       }
     }
   } else {
-    mRangeParent = nullptr;
+    mRangeParentContent = nullptr;
     mRangeOffset = 0;
   }
 }
@@ -1355,7 +1352,7 @@ void nsXULPopupManager::FirePopupShowingEvent(nsIContent* aPopup,
   }
 
   // clear these as they are no longer valid
-  mRangeParent = nullptr;
+  mRangeParentContent = nullptr;
   mRangeOffset = 0;
 
   // get the frame again in case it went away

layout/xul/nsXULPopupManager.h

@@ -414,8 +414,8 @@ class nsXULPopupManager final : public nsIDOMEventListener,
   // the rangeOffset of the event supplied to ShowPopup or ShowPopupAtScreen.
   // This is used by the implementation of Document::GetPopupRangeParent
   // and Document::GetPopupRangeOffset.
-  nsINode* GetMouseLocationParent();
-  int32_t MouseLocationOffset();
+  nsIContent* GetMouseLocationParent() const { return mRangeParentContent; }
+  int32_t MouseLocationOffset() const { return mRangeOffset; }
 
   /**
    * Open a <menu> given its content node. If aSelectFirstItem is
@@ -795,7 +795,7 @@ class nsXULPopupManager final : public nsIDOMEventListener,
   nsCOMPtr<nsIWidget> mWidget;
 
   // range parent and offset set in SetTriggerEvent
-  nsCOMPtr<nsINode> mRangeParent;
+  nsCOMPtr<nsIContent> mRangeParentContent;
   int32_t mRangeOffset;
   // Device pixels relative to the showing popup's presshell's
   // root prescontext's root frame.