Re: [Discuss-gnuradio] callback function called twice

[Tom Rondeau]

On Fri, Jul 26, 2013 at 10:21 AM, Marcus Leech <address@hidden> wrote:
> On some GUI slider widgets, there's a "call callback only on motion
> finished" option.  I don't know whether that's available in WxGUI, and
> whether we use it (and whether the option to use it should be exposed within
> GRC).

Yeah. There are various ways to handle motion and actions in most GUI
tools. I'm with you, though: I'm not sure what's really available in
WxGUI. But we probably want it to call the callback when the sliders
are changed (sometimes when tuning, it's nice to be able to grab the
slider and move it back and forth to see what happens) and when the
action finishes to make sure it's called with the most recent value.

> Also, doesn't the callback get called on first instantiation to set the
> default value?

No, it doesn't. We have to add a specific call to the function in the
<make> section of the XML file to do this initialization. Sometimes,
we don't have a default value set for the parameter in the callback,
so calling this by default upon instantiation is probably a bad idea.

Tom


> on Jul 26, 2013, Tom Rondeau <address@hidden> wrote:
>
> On Wed, Jul 24, 2013 at 5:17 PM, Nemanja Savic <address@hidden> wrote:
>> Actually it is not a big deal at all, I am just curious.
>> Yes, I am using WXGui slider.
>> Thank you Tom
>>
>> Nemanja
>
> Great. Just wanted to make sure it wasn't doing something else to your code.
>
> Probably just something like it responding to the 'button press' and
> 'button release' events or just jitter when moving the slider. Those
> are pretty common in GUI apps.
>
> Tom
>
>
>> On Wed, Jul 24, 2013 at 5:39 PM, Tom Rondeau <address@hidden> wrote:
>>>
>>> On Wed, Jul 24, 2013 at 8:51 AM, Nemanja Savic <address@hidden>
>>> wrote:
>>> > Hi guys,
>>> >
>>> > this is kind of very old thread, but the same problem. I started
>>> > changing my
>>> > blocks for 3.7.0 and callbacks are called twice. Is there any
>>> > explanation
>>> > for this acting?
>>> >
>>> > thanks,
>>> > Nemanja
>>> >
>>> >
>>> > On Thu, Feb 28, 2013 at 9:53 AM, Nemanja Savic <address@hidden>
>>> > wrote:
>>> >>
>>> >> Was any nonsense in previous post?
>>> >>
>>> >>
>>> >> On Wed, Feb 27, 2013 at 2:16 PM, Nemanja Savic <address@hidden>
>>> >> wrote:
>>> >>>
>>> >>> Hi again GNURADIOers,
>>> >>>
>>> >>> I have a set member function which is also used as a callback from
>>> >>> GRC.
>>> >>> It looks like this:
>>> >>>
>>> >>> void
>>> >>> test_file_sink::set_sensitivity(double milisecond)
>>> >>> {
>>> >>> d_n_samples = (unsigned
>>> >>> int)(milisecond*d_sample_rate/1000.0)*d_itemsize;
>>> >>> printf("\nd_n_samples: %d\n", d_n_samples);
>>> >>> init_old_data_buff();
>>> >>> }
>>> >>>
>>> >>> When I run flowgraph, and change "sensitivity", my callback function
>>> >>> is
>>> >>> called twice.
>>> >>> Is this normal action?
>>> >>>
>>> >>> Best
>>> >>>
>>> >>> --
>>> >>> Nemanja Savić
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> --
>>> >> Nemanja Savić
>>> >
>>> > --
>>> > Nemanja Savić
>>>
>>> Nemanja,
>>>
>>> It's unclear what you are doing when changing the sensitivity? Is this
>>> in GRC and using a GUI slider or something? Or are you triggering the
>>> callback function some other way? If it's a GUI element, it could just
>>> be that the system calls it based on a change in the state, which
>>> could mean when you press and release or when you hit a button is one
>>> update and when the update to the slider happens it gets triggered
>>> again.
>>>
>>> Is this really a big deal or are you just curious?
>>>
>>> Tom
>>
>>
>>
>>
>> --
>> Nemanja Savić
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>