[Qt-interest] problem with signal/slot
Mahendra G.R
mahendra at mahendragr.com
Wed Dec 8 21:42:10 CET 2010
Hi Brian,
Yes, i'm using eclipse actually, ok i will try the method you suggested. how
did you solve your problem?.
On Wed, Dec 8, 2010 at 8:53 PM, Brian McKinnon <bpmckinnon.qt at gmail.com>wrote:
> With the code that was pasted earlier, create your object, use the code,
> and output the strings. The class name you used should be the value in
> classname() and your function should be listed in the method() call. If
> either of those are not true then your moc file is not being generated.
>
> Are you using the visual studio integration stuff? I've had some problems
> with that in the past.
>
>
> On Wed, Dec 8, 2010 at 3:24 PM, Mahendra G.R <mahendra at mahendragr.com>wrote:
>
>> Hi,
>>
>> sorry i did not understand what Brian explained, how should i check if it
>> is moc compiled, and how should i explicitly include the moc file? (just
>> like a header?). But syntax wise its correct, i cross checked it. Thanks
>> for your reply guys.
>>
>>
>>
>>
>> On Wed, Dec 8, 2010 at 6:53 PM, Atlant Schmidt <aschmidt at dekaresearch.com
>> > wrote:
>>
>>> All:
>>>
>>>
>>>
>>> > Are you sure the moc compiler is running for you file.
>>>
>>>
>>>
>>> Not just that, but are you sure you’re then **USING** the output
>>> of the moc compiler by passing the produced foo_moc.cpp into
>>> your main cpp compilation?
>>>
>>>
>>>
>>> If all that is fine, then the usual problem is a mismatch of signatures
>>> between the slot declaration and the slot usage in the connect()
>>> statement. You show them as both having identical (void) signatures,
>>> but perhaps you simplified that for the e-mail?
>>>
>>>
>>>
>>> Atlant
>>>
>>>
>>>
>>>
>>> ------------------------------
>>>
>>> *From:* qt-interest-bounces at trolltech.com [mailto:
>>> qt-interest-bounces at trolltech.com] *On Behalf Of *Brian McKinnon
>>> *Sent:* Wednesday, December 08, 2010 12:43
>>> *To:* qt-interest
>>> *Subject:* Re: [Qt-interest] problem with signal/slot
>>>
>>>
>>>
>>> Are you sure the moc compiler is running for you file. Check the info
>>> in:
>>>
>>>
>>>
>>> const QMetaObject* metaObject = obj->metaObject();
>>>
>>>
>>>
>>> QStringList methods;
>>>
>>> methods << metaObject->className();
>>>
>>> for(int i = metaObject->methodOffset(); i < metaObject->methodCount(); ++i)
>>>
>>> methods << QString::fromLatin1(metaObject->method(i).signature());
>>>
>>>
>>>
>>> On Wed, Dec 8, 2010 at 1:20 PM, Mahendra G.R <mahendra at mahendragr.com>
>>> wrote:
>>>
>>> Hi,
>>>
>>> yes i do put it in a seperate cpp file, just to make it look shorter in
>>> the mail i did that :), but still no use, it says method is not found. any
>>> other reasons?, thanks for your reply.
>>>
>>>
>>>
>>> On Wed, Dec 8, 2010 at 6:08 PM, Xiaolei Shang <xiaolei.shang at cobham.com>
>>> wrote:
>>>
>>> Hi:
>>>
>>> Hi guys,
>>>
>>> i have a small problem with signal/slot, though i have defined my slot
>>> method, i get runtime message saying Object::connect: No such slot
>>> CustomScene::updateAlphaValue() , i have defined the method
>>> updateAlphaValue() in the customScene class
>>>
>>> this is my code :
>>>
>>> class CustomScene : public QGraphicsScene
>>> {
>>>
>>> Q_OBJECT
>>> public:
>>> CustomScene()
>>> {
>>> alphaSlider = new QSlider(Qt::Horizontal);
>>> alphaSlider->setTickInterval(1);
>>> alphaSlider->setRange(0,255);
>>> alphaSlider->setMinimumSize(105,20);
>>> alphaSlider->move(6,222);
>>> alphaSlider->setToolTip("Opacity");
>>> connect( alphaSlider, SIGNAL(valueChanged(int)),
>>> SLOT(updateAlphaValue()) );
>>> //some other stuff
>>> }
>>>
>>> public slots :
>>> void updateAlphaValue();
>>>
>>> };
>>> --
>>> http://www.mahendragr.com
>>>
>>> If you move the declaration of updateAlphaValue() to the front of the
>>> definition of the constructor, the compiler should be able to see the
>>> function. Like this:
>>>
>>>
>>> class CustomScene : public QGraphicsScene
>>> {
>>>
>>> Q_OBJECT
>>>
>>> public slots :
>>> void updateAlphaValue();
>>>
>>>
>>> public:
>>> CustomScene()
>>> {
>>> alphaSlider = new QSlider(Qt::Horizontal);
>>> alphaSlider->setTickInterval(1);
>>> alphaSlider->setRange(0,255);
>>> alphaSlider->setMinimumSize(105,20);
>>> alphaSlider->move(6,222);
>>> alphaSlider->setToolTip("Opacity");
>>> connect( alphaSlider, SIGNAL(valueChanged(int)),
>>> SLOT(updateAlphaValue()) );
>>> //some other stuff
>>> }
>>>
>>> ...
>>> };
>>>
>>> As you define your constructor in your declaration scope. You have to
>>> declare a function before you call it. Otherwise, the compiler won't see it.
>>> However, in this case, this is not a good way for defining the class as it
>>> contains many line codes. Implicitly, it's a online function. I would
>>> recommand to put the definition of the constructor in a .cpp file.
>>>
>>> Cheers
>>>
>>> Xiaolei
>>>
>>>
>>>
>>>
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>>
>>
>> --
>> http://www.mahendragr.com
>>
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