怎么建立网站推广,南昌建站系统外包,四川建筑从业人员查询,网站建设的产品类型是什么界面库中值得注意的一点就是对象响应事件的时候自身被删除了#xff0c;那么后续的访问自然就会出问题#xff0c;所以需要在响应事件之后先添加引用#xff0c;相关处理之后再查看自身是否已经被删除#xff0c;如果已经被删除那么就直接退出。juce中通过BailOutChecker来…界面库中值得注意的一点就是对象响应事件的时候自身被删除了那么后续的访问自然就会出问题所以需要在响应事件之后先添加引用相关处理之后再查看自身是否已经被删除如果已经被删除那么就直接退出。juce中通过BailOutChecker来进行这处检查内部实现很简单也就是通过弱引用来进行关于弱引用请看上一篇文章 ///** A class to keep an eye on a component and check for it being deleted.This is designed for use with the ListenerList::callChecked() methods, to allowthe list iterator to stop cleanly if the component is deleted by a listener callbackwhile the list is still being iterated.*/class JUCE_API BailOutChecker{public:/** Creates a checker that watches one component. */BailOutChecker (Component* component);/** Returns true if either of the two components have been deleted since this object was created. */bool shouldBailOut() const noexcept;private:const WeakReferenceComponent safePointer;JUCE_DECLARE_NON_COPYABLE (BailOutChecker)};红色部份标识了进行检查的部份 void Component::internalMouseWheel (MouseInputSource source, Pointfloat relativePos,Time time, const MouseWheelDetails wheel)
{Desktop desktop Desktop::getInstance(); BailOutChecker checker (this);const MouseEvent me (source, relativePos, source.getCurrentModifiers(), MouseInputSource::invalidPressure,this, this, time, relativePos, time, 0, false);if (isCurrentlyBlockedByAnotherModalComponent()){// allow blocked mouse-events to go to global listeners..desktop.mouseListeners.callChecked (checker, MouseListener::mouseWheelMove, me, wheel);}else{mouseWheelMove (me, wheel); if (checker.shouldBailOut())return;//历遍的过程中同样需要检查desktop.mouseListeners.callChecked (checker, MouseListener::mouseWheelMove, me, wheel);if (! checker.shouldBailOut())MouseListenerList::sendWheelEvent (*this, checker, me, wheel);}
}转载于:https://www.cnblogs.com/csxy/p/5472362.html
