SIGNAL - SLOT BUG

JOHN.CHEN

I find a bug for signal and slot :

signal function define in a thread class:
private slots:
void RefreshUI(UCHAR uCmd);

signal-slot connect :
connect(m_pDT,SIGNAL(RefreshUI(UCHAR)),this,SLOT(UpdataUI(UCHAR)),QT::QueuedConnection);

slot funcion define in a Widget class:
void UpdataUI(UCHAR uCmd);

if you call emit RefreshUI(3) UpdataUI() function doesn't trigger. but if you alter the parameter type for int or other type , not is UCHAR ,UpdataUI() function can be trigger, Do you meet it ?

joeQ

Hi , friend, You used the wrong way!

private slots:
void RefreshUI(UCHAR uCmd); // this is slot function

signal-slot connect :
connect(m_pDT,SIGNAL(RefreshUI(UCHAR)),this,SLOT(UpdataUI(UCHAR)),QT::QueuedConnection); // this is wrong way.

connect( signalObj ,SIGNAL(UpdataUI(UCHAR)), slotObj, SLOT(RefreshUI(UCHAR)), QT::QueuedConnection);

jsulm

@JOHN.CHEN It is not a bug. If you use custom data types like UCHAR you need to register them, so Qt can use them for signals/slots. See http://doc.qt.io/qt-5.7/custom-types.html
Also you should check the return value which is returned by connect(). It returns false if it could not connect. And if the connection fails you will see a warning in the console.
And you're using signals/slots wrong: void RefreshUI(UCHAR uCmd) is a slot but you use it like a signal!

JOHN.CHEN

@jsulm said in SIGNAL - SLOT BUG:

hUI(UCHAR uCmd) is a slot but you use it lik

just i modify the signal and slot function's parameter type for int type or long type,it's ok . only UCHAR type is not tigger . UCHAR define -->QT TYPE (typedef unsigned char UCHAR)

SGaist

Hi and welcome to devnet,

As @jsulm wrote, you have to register your custom type even if it's "just" a typedef, you have to make it known to the Qt meta type system.

m.sue

@JOHN.CHEN said in SIGNAL - SLOT BUG:

UCHAR define -->QT TYPE (typedef unsigned char UCHAR)

Hi,
the type uchar is defined by Qt not UCHAR.
UCHAR is defined by the WINDOWS SDK.
-Michael.