How to set logarithmic coordinates as a runtime option?

[pkolaczk]

I'd like to use common code for drawing a diagram in logarithmic coords as well as in linear, depending on a seting passed at runtime. I tried to use Box<dyn Ranged> to configure axis spec, but then they compiler says it is not object safe. Is there a way around this?

[pkolaczk]

I think I've found a solution:

enum YSpec {
    Linear(RangedCoordf32),
    Log(LogCoord<f32>)
}

impl Ranged for YSpec {
    type FormatOption = DefaultFormatting;
    type ValueType = f32;

    fn map(&self, value: &Self::ValueType, limit: (i32, i32)) -> i32 {
        match self {
            YSpec::Linear(range) => range.map(value, limit),
            YSpec::Log(range) => range.map(value, limit),
        }
    }

    fn key_points<Hint: KeyPointHint>(&self, hint: Hint) -> Vec<Self::ValueType> {
        match self {
            YSpec::Linear(range) => range.key_points(hint),
            YSpec::Log(range) => range.key_points(hint)
        }
    }

    fn range(&self) -> Range<Self::ValueType> {
        match self {
            YSpec::Linear(range) => range.range(),
            YSpec::Log(range) => range.range()
        }
    }
}

Then I can create the coord spec like this:

    let primary_y_spec: YSpec = match is_logarithmic {
        true => YSpec::Log((0.01f32..max_value).log_scale().into()),
        false => YSpec::Linear((0f32..max_value).into()),
    }

    let mut chart = ChartBuilder::on(&root)
        .margin(10)
        .x_label_area_size(60)
        .y_label_area_size(150)
        .build_cartesian_2d(0f32..max_time, primary_y_spec)
        .unwrap();