getMinModel() should return diff between current and initial models, not between current and default models

URL problem 1: https://github.com/vizabi/vizabi/issues/1338

URL problem 2: consider the following situation:

default model would have a certain config: color is constant page would overwrite that config: color now be world regions user would change color to constant refresh page: color is world regions!

why? because when user sets color=constant this is equal to model defaults and is not returned by getMinModel()

for the discussion: let’s define operation “+" as deep-extend (leaves are replaced) let’s define operation “–" as diff between two models

model config + tool config = default model default model + page config = initial model initial model + user actions = current model

now we have: page config – (current model – default model) = url model

we should have: current model – initial model = url model

i took this expression page config – (current model – default model) = url model inserted “initial model” instead “default model” decoded all elements from definitions above opened brackets like in math and i got… – user actions = url model

[jheeffer]

Okay, I added commit https://github.com/vizabi/vizabi/commit/fdfba2f4aa8a12f7896ba6cdcb1ed477b4c88345

What do you think @dab2000 ?

This is now the code of external page needed for URL persistence. It could be even smaller, but I think then Vizabi would start to know what happens outside it.

var page_model = {
    ...
}

var url_model = decodeURIComponent(location.hash)

var init_model = Vizabi.utils.deepExtend(config, url_model);

var viz = Vizabi('bubbleChart', init_model);

viz.on('persistentChange', function() {
    location.hash = encodeURIComponent(viz.getPersistentMinimalModel(page_model));
})

!this means tools page code needs updating when merging this!

[jheeffer]

@angieskazka when merging make sure to update tools page