Why is touch event triggered even when I touch outside the sprite? - cocos2d-x

Question

I have a ui::ScrollView containing a number of sprites.
I have created each sprite and added a touch listener to each sprite by doing something like:
for(int i=0; i < 5; i++){
Sprite* foo = Sprite::createWithSpriteFrameName("foo");
myScrollView->addChild(foo);
auto listener = EventListenerTouchOneByOne::create();
listener->onTouchBegan = [this,somestring](Touch* touch, Event* event){
......some code
};
listener->onTouchMoved = [foo,this,somestring](Touch* touch, Event* event){
......some code
};
listener->onTouchEnded = [foo,this,somestring](Touch* touch, Event* event){
......some code
};
foo->getEventDispatcher->addEventListenerWithSceneGraphPriority(listener1,foo);
}
The problem is, if I click ANYWHERE on screen, it seems to trigger the touch events of ALL the sprites created in the loop. Is there something incorrect in how I am creating the listener, or does it have to do with some conflict with touches in a ui::ScrollView ?
I am using v 3.10

Answer 1

Because that is how TouchListener works in cocos2d-x. All touch listener will be called unless someone has swallowed the touch event. Your code would be:
auto touchSwallower = EventListenerTouchOneByOne::create();
touchSwallower ->setSwallowed(true);
touchSwallower->onTouchBegan = [](){ return true;};
getEventDispatcher->addEventListenerWithSceneGraphPriority(touchSwallower ,scrollview);
for(int i=0; i < 5; i++){
Sprite* foo = Sprite::createWithSpriteFrameName("foo");
myScrollView->addChild(foo);
auto listener = EventListenerTouchOneByOne::create();
listener->setSwallowed(true);
listener->onTouchBegan = [this,somestring](Touch* touch, Event* event){
......some code
Vec2 touchPos = myScrollView->convertTouchToNodeSpace(touch);
return foo->getBoundingBox()->containsPoint(touchPos);
};
listener->onTouchMoved = [foo,this,somestring](Touch* touch, Event* event){
......some code
};
listener->onTouchEnded = [foo,this,somestring](Touch* touch, Event* event){
......some code
};
foo->getEventDispatcher->addEventListenerWithSceneGraphPriority(listener1,foo);
}

Answer 2

cocos2dx will dispatch the touch-event to every Node attached a touch-event, unless someone swallow the it.
But if you want the "node" default judge whether touch-location in the content, try to use "UIWidget" with "addTouchEventListener". It will calculate by itself.
bool Widget::onTouchBegan(Touch *touch, Event *unusedEvent)
{
_hitted = false;
if (isVisible() && isEnabled() && isAncestorsEnabled() && isAncestorsVisible(this) )
{
_touchBeganPosition = touch->getLocation();
auto camera = Camera::getVisitingCamera();
if(hitTest(_touchBeganPosition, camera, nullptr))
{
if (isClippingParentContainsPoint(_touchBeganPosition)) {
_hittedByCamera = camera;
_hitted = true;
}
}
}
if (!_hitted)
{
return false;
}
setHighlighted(true);
/*
* Propagate touch events to its parents
*/
if (_propagateTouchEvents)
{
this->propagateTouchEvent(TouchEventType::BEGAN, this, touch);
}
pushDownEvent();
return true;
}