How to use execute stored animation in Cocos2d? - c++

Question

I am fairly new to Cocos2d-x v3 and Recently I was attempting to use the listener key press functionality in order to get my Sprite to move with the animations I have created for it. All the code Compiles with no error, but when the game runs if I press the specified Key in the switch case the window is suspend and it brings me to the action.h header file and highlights the "void setTarget" method of the class where it states error "this was a nullptr" perhaps I forgot to initialize a variable somewhere?
My header looks like so:
#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__
#include "cocos2d.h"
using namespace cocos2d;
class HelloWorld : public cocos2d::Layer
{
private:
Sprite* sarah;
Animate* walking;
Action* action;
public:
static cocos2d::Scene* createScene();
virtual bool init();
void menuCloseCallback(cocos2d::Ref* pSender);
CREATE_FUNC(HelloWorld);
void onKeyPressed(EventKeyboard::KeyCode keyCode, Event *eventer);
void onKeyReleased(EventKeyboard::KeyCode keyCode, Event *eventer);
Sprite* GetSprite();
Animate* GetAnimation();
}
#endif // __HELLOWORLD_SCENE_H__
and the part in my cpp that is causing me problems looks like so:
void HelloWorld::onKeyPressed(EventKeyboard::KeyCode keyCode, Event * event){
auto action1 = event->getCurrentTarget()->getActionByTag(1);
auto node = event->getCurrentTarget();
switch (keyCode){
case EventKeyboard::KeyCode::KEY_LEFT_ARROW:
action1->setTarget(node);
node->runAction(action1);
default:
break;
}
}
void HelloWorld::onKeyReleased(EventKeyboard::KeyCode keyCode,Event *event) {
auto action1 = event->getCurrentTarget()->getActionByTag(1);
auto node = event->getCurrentTarget();
Vec2 loc = event->getCurrentTarget()->getPosition();
switch (keyCode){
case EventKeyboard::KeyCode::KEY_UP_ARROW:
action1->getTarget()->stopActionByTag(1);
node->setPosition(--loc.x, --loc.y);
default:
break;
}
}
sarah = Sprite::create("standing.png");
sarah->setAnchorPoint(Vec2(0, 0));
sarah->setPosition(100, 100);
Vector<SpriteFrame*> walkingframeskleft;
walkingframeskleft.reserve(3);
walkingframeskleft.pushBack(SpriteFrame::create("walk2.png", Rect(0, 0, 65, 81)));
walkingframeskleft.pushBack(SpriteFrame::create("walk3.png", Rect(0, 0, 65, 81)));
walkingframeskleft.pushBack(SpriteFrame::create("walk4.png", Rect(0, 0, 65, 81)));
Animation* walkinganimation = Animation::createWithSpriteFrames(walkingframeskleft, .1f);
walking = Animate::create(walkinganimation);
action = RepeatForever::create(walking);
action->setTag(1);
this->addChild(sarah);
auto listener = EventListenerKeyboard::create();
listener->onKeyPressed = CC_CALLBACK_2(HelloWorld::onKeyPressed,this);
listener->onKeyReleased = CC_CALLBACK_2(HelloWorld::onKeyReleased,this);
this->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener, sarah);
return true;
}
in my switch cases i only have the left arrow set up since i just wanted to test if a key would work to begin with

Answer 1

As far as I can tell, your error is caused by the fact that your action is null at the moment when you try to run it.
That is because:
After you create your action with this line:
action = RepeatForever::create(walking);
The action gets added to the autorelease pool. So, if you don't use it immediately(run it on a sprite) action->release(); will be called on it which will delete it. So, when you are creating actions that you will want to use later(or reuse) in your code, be sure to manually retain them after creation and release them when you are sure you won't use them again:
action = RepeatForever::create(walking);
action->retain();
This way your action won't be released(deleted) until you call release() yourself.