Struct ScaleColorSteps 

pub struct ScaleColorSteps { /* private fields */ }

Binned (stepped) continuous colour scale — R’s scale_*_steps / scale_*_stepsn / scale_*_fermenter.

A continuous variable is bucketed into n_bins equal-width bins over the trained domain, and each bin is filled with a discrete colour sampled from the gradient. It reports as discrete, so the legend shows one stepped swatch per bin (a guide_bins/guide_coloursteps-style legend).

Implementations

impl ScaleColorSteps

pub fn new( aesthetic: Aesthetic, stops: Vec<(u8, u8, u8)>, n_bins: usize, ) -> Self

Build from evenly-spaced gradient stops (>= 1) and a bin count.

pub fn two( aesthetic: Aesthetic, low: (u8, u8, u8), high: (u8, u8, u8), n_bins: usize, ) -> Self

Two-colour low→high binned scale.

Trait Implementations

impl Clone for ScaleColorSteps

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Scale for ScaleColorSteps

fn aesthetic(&self) -> Aesthetic

Which aesthetic this scale is for.

fn train(&mut self, values: &[Value])

Incorporate data values to determine domain.

fn map(&self, _value: &Value) -> f64

Map a data value to a [0, 1] normalized position (position scales) or to a concrete visual value index (color/size scales).

fn breaks(&self) -> Vec<(f64, String)>

Generate break positions and labels for axis/legend.

fn name(&self) -> &str

Human-readable name (axis title).

fn set_name(&mut self, name: &str)

Set the scale name.

fn is_discrete(&self) -> bool

Whether this is a discrete scale.

fn map_to_color(&self, value: &Value) -> Option<(u8, u8, u8)>

Map a data value to an RGB color. Default returns None.

fn domain(&self) -> Option<(f64, f64)>

Return the trained data domain (min, max) for continuous scales. Used by the colorbar legend to pass data-space values to map_to_color().

fn clone_box(&self) -> Box<dyn Scale>

Clone this scale into a boxed trait object.

fn reset_training(&mut self)

Reset training state so the scale can be retrained on new data.

fn transform(&self, value: &Value) -> Value

Apply transformation to raw data (e.g., log10).

fn map_to_shape(&self, _value: &Value) -> Option<PointShape>

Map a data value to a point shape. Default returns None.

fn map_to_linetype(&self, _value: &Value) -> Option<Linetype>

Map a data value to a linetype. Default returns None.

fn map_to_size(&self, _value: &Value) -> Option<f64>

Map a data value to a point size (radius in pixels). Default returns None.

fn map_to_alpha(&self, _value: &Value) -> Option<f64>

Map a data value to an alpha (opacity) value. Default returns None.

fn sec_axis(&self) -> Option<&SecAxis>

Get the secondary axis specification, if any.

fn set_default_locale(&mut self, _locale: &Locale)

Adopt a plot-level default Locale for the default break labels (number marks, month names, date formats), unless the scale already has its own. Called by the plot builder when GGPlot::locale is set. Default: ignored (scales without numeric/date labels).

fn locale(&self) -> Option<&Locale>

The locale this scale’s default labels are rendered with, if any.

fn set_limits(&mut self, _min: f64, _max: f64)

Override the trained domain limits (used by coord_cartesian zoom).

fn filter_limits(&self) -> Option<(f64, f64)>

Return OOB filter limits if this scale was created with explicit limits (e.g., via xlim/ylim). Data outside these limits should be removed before stats.

fn expanded_domain(&self) -> Option<(f64, f64)>

The data values at the panel edges (normalized 0 and 1) for a trained continuous position scale — the limits after expansion, in the scale’s transformed space. None for discrete / untrained / non-position scales.

fn axis_position_opposite(&self) -> bool

Whether this axis is drawn on the opposite side (x → top, y → right).

fn set_expand(&mut self, _mult: f64, _add: f64)

Set the expansion multiplier/additive constant (R’s expand = c(mult, add)), applied symmetrically to both ends. Used by CoordSf::train_scales (expand(false) passes (0.0, 0.0)) to pin an explicit xlim/ylim to the panel exactly. Default: no-op (discrete / non-position scales have no expansion to set).

fn map_fraction_to_size(&self, _fraction: f64) -> Option<f64>

Map an already-computed [0, 1] scale fraction (as returned alongside each label by breaks) directly to an output size, bypassing the round trip through map — a discrete-style legend key only has the break’s rendered label, not its original data value, so a continuous scale can’t recover the fraction by re-mapping the label text. Default: None.

fn validate(&self, _warnings: &mut Vec<String>)

Validate this scale’s configuration once training is complete (e.g. a transform undefined at the domain’s own limits) and push a human-readable warning for each problem found. Called once per scale after the final training pass, with the plot’s warnings sink — map/map_to_size run per mark at draw time and have no such access, so a scale-level problem must be reported here instead. Default: no-op.