Add Plot::allow_auto_bounds

[haricot]

Whether to allow auto bounds. Default: true.
If false, when the bounds is modified it will not be recalculated.

[emilk]

This needs a better docstring; I don't understand it.

[haricot]

This represents an example of use and does not describe the functionality.
I meant " If false, when the bounds is modified it will not be recalculated." but that doesn't seem necessary.

[emilk]

I think you should try to explain what it means for the user to set this to true or false.

Does "bounds" here mean the view of the plot (zoom/pan)?
How does this relate to PlotUi::set_plot_bounds?
What bounds will be used when this is set to false?

[haricot]

I suggest this:

If false, it set bounds_modified to true to prevent auto adjusting bounds,
also it check if the user double clicked to reset bounds. If so, it set bounds_modified to false.

It's needed when a new plot is started, such as when resetting egui memory and pan/zoom that
have not been used before, as the limits can be saved as persistent data.

Currently, if allow_auto_bounds(false) and plot_ui.set_plot_bounds(PlotBounds) are used in
same time set_plot_bounds will be ignored.

TODO: Refactor Plot::allow_auto_bounds and Plot::set_plot_bounds feature to work together.

Possible solution for allow_auto_bounds and set_plot_bounds by passing something like this when initializing plot:
Plot::new("myplot").allow_auto_bounds(false).preset_bounds(plotbounds) or something a enum.

[haricot]

or something like:

enum LogicBound{
  SkipRecalculated,
  Bounds(PlotBounds)
}

Plot::set_plot_bounds( LogicBounds::SkipRecalculated )

I will try to test this.

[haricot]

or rather just this:

widgets/plot/mod.rs

        .unwrap_or_else(|| 
            PlotMemory {
            bounds_modified: if let Some(custom_bounds) = custom_bounds {
                true.into()
                } else { 
                false.into()
                }  ,
            hovered_entry: None,
            hidden_items: Default::default(),
            last_plot_transform: PlotTransform::new(
                rect,
                if let Some(custom_bounds) = custom_bounds {
                    custom_bounds
                    } else { 
                        min_auto_bounds
                    },
                center_axis.x,
                center_axis.y,
            ),
            last_click_pos_for_zoom: None,
        });

[haricot]

I opened issue #3371 related this pull request, how i think it resolve this indirect approach.

Also i realize i think we can add set_bounds and dynamic zoom and translate under process default bounds (currently enforce aspect ratio) like vec ![bounds_modifications] but in setting by using factor_delta_changed slider.

let data_zoom_aspect = scalar_aspect_zoom.current ;
let last_data_aspect_zoom  = scalar_aspect_zoom.last_changed;

let data_zoom_aspect  = if last_data_aspect_zoom > data_zoom_aspect {
    1.0 * (data_zoom_aspect / last_data_aspect_zoom)
} else {
    (data_zoom_aspect / last_data_aspect_zoom) / 1.0
};

scalar_aspect_zoom.last_changed  =  scalar_aspect_zoom.current ;

scalar_aspect_zoom.factor_delta_changed  =  data_zoom_aspect;

[haricot]

With allow_auto_bounds:

Without allow_auto_bounds:

Branch about this demo : https://github.com/haricot/egui/tree/allow_auto_bounds_demo

[emilk]

I think this has already been added by a different PR:

https://docs.rs/egui_plot/latest/egui_plot/struct.PlotUi.html#method.set_auto_bounds