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A slider widget for OpenSesame 3.2

edited October 2019 in OpenSesame

I've seen quite a few questions about slider widgets for OpenSesame forms. A few examples of slider widgets are floating around on this forum, but these examples aren't compatible with OpenSesame 3.2. Therefore I attached a demonstration experiment (for OpenSesame 3.2) that defines a slider widget, and shows how you can use it, both in an inline_script and in a form_base item.

I hope this is useful!

(See a link to the experiment in my comment below. It appears to have gotten lost during a forum upgrade.)


  • Hi @sebastiaan and @eduard

    Sorry if I missed this in your code, is there a way to control for the gradations when filling the slider? I think the way it is now, it is from 0 to a 100 steps to fill in the entire slider.
    But if I wanted to have a more narrow range, say 0 to 10 with increments, or 0 to 1 in increments of 0.1 (to match the current scale), is there are way to control that directly in your code?


  • Hi Helio,

    The sliders goes from 0 to 1, but I would leave it that way, because that's easily converted to whatever range you need later on. If you want to control the gradation, you can adjust the script to, for example, round self._fill to 1 digit of precision, so that there are 10 steps (0, 0.1, 0.2, etc.).

    You can do this in SliderWidget.coroutine(), right before self._set_fill() is called. For example like so:

        def coroutine(self):
            retval = None
            while True:
                d = yield retval            
                if u'pos' not in d:
                click_x, click_y = d[u'pos']
                x, y, w, h = self.rect
                if self._orientation == u'horizontal':
                    self._fill = 1. * (click_x - x) / w
                elif self._orientation == u'vertical':
                    self._fill = 1. * (y + h - click_y) / h
                    raise ValueError(u'Invalid orientation: %s' % self._orientation)
                self._fill = round(self._fill, 1)


  • Thanks loads @sebastiaan
    works perfectly.


  • Hi,

    Please forgive me for my ignorance but I can't find the "attached a demonstration experiment".

    any help?


  • Neither did I, but here it is!

  • Hi,

    Thank you for the code. It's a very useful widget!

    I am trying to customize the slider to my needs. I want to add an image, under the slider, that changes according to the amount of fill in the slider. I am having a hard time implementing this.

    I managed to add an image, but I couldn't make it change according to the fill.

    I would appreciate your help.

    Thank you


  • Hi Naama,

    I can't open the attachment, but conceptually, you have to draw the image to a canvas (as you probably already have and then change the image depending on the fill For example:

    cv = Canvas()
    cv['stim'] = Image(filepath)
    <do stuff to get current fill>
    cv['stim'].image = path_to_updated_file

    Does that make sense?


  • It should be downloadable again! (We've been having some issues with the forum lately, and some attachments got lost.)

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