Updating glyph style from JavaScript

On Aug 5, 2015, at 6:08 AM, miguel.dardenne@gmail.com wrote:

Hi,

I am building a dashboard visualization with bokeh 0.9.2 and a flask server.

Currently I am struggling with updating glyph style attributes from JS callback code.
Say I want to update a segment color or alpha from a JS callback of a slider widget.

I have now this:

segment = Segment(...)
alpha_cb = Callback(args=dict(segment=segment), code="""
    new_alpha = cb_obj.get('value')
    alpha = segment.get('line_alpha')
    alpha['value'] = new_alpha
    segment.set('line_alpha', alpha)
    segment.trigger('change')
"""
alpha_slider = Slider(..., callback=alpha_cb)

I can see the property getting updated through inspector but the segment alpha (or color, similarly) never gets redrawn with the new styling.

What am I doing wrong ?

Thanks in advance and keep up the good work !
Miguel

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Le mercredi 5 août 2015 14:21:15 UTC+2, Bryan Van de ven a écrit :

A few notes:

• trigger should not be needed when setting a Backbone property, that will generate a change event on its own. trigger is only needed when “reaching in” to a data source column and changing values in place without a call to .set

• there may be some missing or broken plumbing on the glyph renderer, can you file a GH issue with a minimal complete example? (Edit: yup looks like it: https://github.com/bokeh/bokeh/blob/master/bokehjs/src/coffee/renderer/glyph/glyph_renderer.coffee#L43 Please still file the GH issue)

• As a workaround, you could put the alpha as a column in the data source, and change that. If you have a large number of segments, that’s probably not ideal, but should definitely work until the plumbing is fixed.

Bryan

On Aug 5, 2015, at 6:08 AM, miguel....@gmail.com wrote:

Hi,

I am building a dashboard visualization with bokeh 0.9.2 and a flask server.

Currently I am struggling with updating glyph style attributes from JS callback code.

Say I want to update a segment color or alpha from a JS callback of a slider widget.

I have now this:

segment = Segment(…)

alpha_cb = Callback(args=dict(segment=segment), code=“”"

new_alpha = cb_obj.get('value')

alpha = segment.get('line_alpha')

alpha['value'] = new_alpha

segment.set('line_alpha', alpha)

segment.trigger('change')

“”"

alpha_slider = Slider(…, callback=alpha_cb)

I can see the property getting updated through inspector but the segment alpha (or color, similarly) never gets redrawn with the new styling.

What am I doing wrong ?

Thanks in advance and keep up the good work !

Miguel

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Le mercredi 5 août 2015 15:39:11 UTC+2, Miguel Dardenne a écrit :

Also I would like to give a try to the workaround you propose. As I am using AjaxDataSource, how could I avoid to have to push back to the flask server the new value of the alpha?

Unsure if this is clear

Rephrasing: say my AjaxDataSource contains columns x, y and now an empty one named alpha. I would prefer some way that the datasource keeps an empty alpha column that gets overriden locally by some code running in the browser. Is this possible ?