[audacity4blind] Re: sliders in audacity
- From: Robert Hänggi <aarjay.robert@xxxxxxxxx>
- To: audacity4blind@xxxxxxxxxxxxx
- Date: Wed, 1 Apr 2015 03:08:49 +0200
2015-03-31 15:10 GMT+02:00, David Bailes <david_bailes@xxxxxxxxxxx>:
>
>
> We could append the text-box value to the value of the slider position
> (0-100 %), either in the source code or the screen reader script.
>
> I think it would be better to do things like this in Audacity, so that it
> doesn't have to be done in each screen reader script. Do you think it's best
> to have the screen reader read both the slider position (0-100%) and the
> real value? I tend to think that might make it too verbose and/or confusing
> at least in some cases, though if the 0-100% bit is absent then it's more
> difficult to judge the range of adjustment. I think you'd have to use
> something like the ASlider class to do this, I don't think you could do it
> with a wxWidgets slider.
>
I tend to use the screen reader script in order to do this.
The point is that this behaviour could easier be changed--we don't
have a preference tab for accessibility settings in Audacity and won't
it have in future, presumably.
>> The examples which I gave use the ASlider class rather than a standard
>> wxSlider. The volume sliders also use this class. This class allows the
>> screen reader to read a value in any range, including floating point.
>> Unfortunately the step sizes for the pan and gain sliders haven't been
>> set
>> up very well. I don't think that the ASlider class provides modifier key
>> functionality for fine tuning, but maybe that could be added if required.
>
> There's a Boolean variable for the light-weight sliders "canUseShift",
> perhaps that's just for that.
>
> I should have has a look at the code before replying to you (smile).
Well, I failed to set it to true, I don't know where the appropriate
place should be for that.
> A more flexible approach is to expand the OnKeyEvent method in ASlider.CPP.
>
> Which sliders in Audacity do you think need a very small increment for fine
> tuning? Is the use of up/down arrow commonly used for small increments, if
> so could you give examples of programs it's used in - I haven't come across
> it myself.
I've just used those keys because they were already in the switch statement.
Normally, I'd used shift-left/right. However, I'm not sure how this
combination could/should be defined in this context. One would
naturally first test for the actual key and then if the shift modifier
is also pressed. There's a constant for shift but I expect it to be
the key in isolation.
For most cases, it should be enough to re-define the step sizes.
For instance, gain should have 1 dB, 6 dB instead of 7 dB, 36 dB, I think.
I prefer the direct increase/decrease kombinations since it allows
listening along (the default 1 dB change is a bit too much though).
It would be nice if the value of the dialog would be applied in real
time to the audio. It is currently only possible to open the dialog
during playback and the value is set after Ok.
Back to the key_events:
An interesting feature of the discrimination between left/right and
up/down keys is that one can follow another scale than the other.
For example:
Suppose we have a frequency slider then the scales could be
- left/right +/- 50 Hz.
- up/down +/- 1/3 octave or even a half step (with a=440 Hz).
The latter is trivial to calculate from minimum, maximum and the
current position.
The same with a dB slider, up and down could follow the linear scaling, e.g.
1 = 0 dB
0.9 = -0.92 dB
0.8 = -1.94 dB
0.7 = -3.1 dB
0.6 = -4.44 dB
0.5 = -6.02 dB
0.4 = -7.96 dB
0.3 = -10.46 dB
0.2 = -13.98 dB
0.1 = -20 dB
0 = -1.#INF dB
This allows a finer tuning in the upper ranges (the scale should of
course be finer than 1/10 for that).
Lots of possibilities.
Robert
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