RE: [Pythoncard-users] Comments from an extreme brain-dead newbie...

[Kevin A. <al...@se...>]

> From: Ronald D Stephens
>
> I guess what I have in mind is this. I want to set up a
> collection of several sliders, to use as data input devices. Then, I  need
> to do a calculation on the data, and send the output to a results
> slider. In other words, if S1 thorugh S5 are the input sliders, I
> need to do something like
>
> (S1 +5(S2) + 3(S3) -4(S4))/S5
>
> and then output the result to an output slider.

Okay, this is a very specific problem, which I'll go into below. In general,
you'll have to decide whether to use the widgets as data storage or whether
they simply represent a 'view' of some internal variables you keep track of
yourself. The samples have example of doing both.

You want to use the 'value' attribute of the slider. For example, if you
have a a slider with a name of 'sld1' then:
    self.components.sld1.value
will give you an integer that you can use in your calculation. Then when you
have your calculated value, do something like:

    def displayResult(self, result):
        self.components.sldResult.value = int(result)

I would wrap up the calculation in its own method (as an example I'll just
refer to it as 'calcResult'), which returns your result. You can have the
result slider dynamically changed by responding to a 'select' event for all
the sliders.

    def on_sld1_select(self, target, event):
        result = self.calcResult()
        self.displayResult(result)

You would need a separate handler for each slider, so rather than do that,
you could use a background handler. I remember you asking about background
handlers before. Your background has a name, I'll assume it is 'bgMin' like
the 'minimal.py' sample and that sliders one through five are named like the
one above.

    def on_bgMin_select(self, target, event):
        name = target.name
        if name[:3] == 'sld' and int(name[3:]) in [1,2,3,4,5]:
	      self.displayResult(self.calcResult())

There are other ways to solve your problem, but something like that should
work. Your result slider will change dynamically as you drag sliders one
through five.

You'll want to initialize all your sliders with appropriate min/mix values,
but you can change these dynamically while the program is running by setting
the 'min' and 'max' attributes or using the 'setRange(min, max) method.

If you later decide that you also want to display the results and inputs
numerically as well as via a slider you can add StaticText or TextField
(with 'editable' = 0) widgets that are updated as the slider values change.

ka