webkit中hover的几个小知识

1。每个元素都有一个hover状态，通过hovered和setHover来控制，该函数在WebCore::Node上：

bool hovered() const { return getFlag(IsHoveredFlag); } .... virtual void setHovered(bool f = true) { setFlag(f, IsHoveredFlag); }

 

2. setHover是个虚函数，WebCore::ContainerNode重载了它，并且能够更新界面

void ContainerNode::setHovered(bool over) {     if (over == hovered()) return;     Node::setHovered(over);     // note that we need to recalc the style     // FIXME: Move to Element     if (renderer()) {         if (renderer()->style()->affectedByHoverRules())             setNeedsStyleRecalc();         if (renderer() && renderer()->style()->hasAppearance())             renderer()->theme()->stateChanged(renderer(), HoverState);     } }

3. 参照上面的代码，判断一个节点是否有Hover的CSS关联方法：renderer()->style()->affectedByHoverRules()

 

4. WebCore::Document元素保存一个当前的hover指针：

void Document::setHoverNode(PassRefPtr<Node> newHoverNode) {     m_hoverNode = newHoverNode; }

 

5. 重新设置一个hover节点完整的方法：

static RenderObject* commonAncestor(RenderObject* obj1, RenderObject* obj2) {     if (!obj1 || !obj2)         return 0;     for (RenderObject* currObj1 = obj1; currObj1; currObj1 = currObj1->hoverAncestor())         for (RenderObject* currObj2 = obj2; currObj2; currObj2 = currObj2->hoverAncestor())             if (currObj1 == currObj2)                 return currObj1;     return 0; } static void switchHover(Document *document, Node* oldHoveredNode, Node* newHoveredNode) {     RenderObject *ancestor = commonAncestor(oldHoveredNode ? oldHoveredNode->renderer(): NULL, newHoveredNode ? newHoveredNode->renderer() : NULL);     if(oldHoveredNode){         oldHoveredNode->setHovered(false);         for (RenderObject* curr = oldHoveredNode->renderer(); curr && curr != ancestor; curr = curr->hoverAncestor()) {             if (curr->node() && !curr->isText() /*&& curr->node()->inActiveChain()*/)                 curr->node()->setHovered(false);         }     }     document->setHoverNode(newHoveredNode);     if(newHoveredNode)     {         for (RenderObject* curr = newHoveredNode->renderer(); curr; curr = curr->hoverAncestor()) {             if (curr->node() && !curr->isText() /*&& curr->node()->inActiveChain()*/)                 curr->node()->setHovered(true);         }         newHoveredNode->setHovered(true);     } }

 

6. EventHandler的fakeMouseMoveEvent: 产生一个假的鼠标移动事件，在窗口位置、状态变化后重新hover，但实际上用户并没有移动鼠标：

  1) 定义

class EventHandler { .... Timer<EventHandler> m_fakeMouseMoveEventTimer; .... };

  2) 初始化

EventHandler::EventHandler(Frame* frame)     : m_frame(frame)     ....     , m_fakeMouseMoveEventTimer(this, &EventHandler::fakeMouseMoveEventTimerFired) ......