[Kdenlive-devel] Problems with signals and slots

[Marco Gittler]

Hi

I'll change this, to get it working (first on the "old" audiosignal)
You can use this then for your audiospectrum.


regards marco

Am 24.11.2010 um 09:42 schrieb Simon Eugster:

> Good Morning,
> 
> I'm battling around with Qt's signals and slots. In r5116,
> mainwindow.cpp:296 I want to connect my audiospectrum object to
> Render::audioSamplesSignal. But whatever I do, my method never
> receives the signal, although connecting works according to the return
> value, Q_ASSERT etc.
> 
> On line 298 I tried to find a reason for it and used the audio volume
> signal. It is defined as:
>  void showAudioSignal(const QByteArray);
> According to the Qt documentation and some people in #qt, Qt uses
> normalizedSignature[1] for signal/slot connections. Meaning that I
> should be able to just use
>  SIGNAL(showAudioSignal(QByteArray))
> to connect the signal. But then connecting fails, telling me that
> there is no such signal.
> 
> I do not get an error though when using
>  SIGNAL(showAudioSignal(const QByteArray)
> i.e. the connection is set up correctly. Nevertheless the connected
> slot is never called. Only if I use
>  SIGNAL(showAudioSignal(const QByteArray&)
> connecting works AND the slot gets called. Although the & is not in
> showAudioSignal's signature.
> 
> So I tried to use the & for my signal (audioSamplesSignal) as well:
>  audioSamplesSignal(const QVector<int16_t>&,int,int,int)
> with
>  void audioSamplesSignal(const QVector<int16_t>,int,int,int)
> but this fails with «no such signal». Why should I have to add a & for
> a QByteArray, but I'm forbidden to do so for the QVector?
> 
> I then tried to change everything (including the signal's signature)
> to const type& (whether making sense or not – what I noticed above
> does not make sense to me anyway). But still, no signal received.
> 
> Can anyone help me? Why is qt behaving that way? What is the problem?
> 
> thanks
> Simon
> 
> [1] http://doc.qt.nokia.com/4.7/qmetaobject.html#normalizedSignature
> 
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