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use super::ast::{Color, ColorStop, Distance};
use crate::color::{is_transparent, parse_color_to_rgb};
#[derive(Debug, Clone, PartialEq)]
pub struct NormalizedColorStop {
pub color: String,
pub offset: f64,
}
pub fn color_to_string(color: &Color) -> String {
match color {
Color::Hex(value) => format!("#{value}"),
Color::Literal(value) => value.clone(),
Color::Rgb(values) => format!("rgb({})", values.join(",")),
Color::Rgba(values) => format!("rgba({})", values.join(",")),
Color::Hsl(values) => format!("hsl({})", values.join(",")),
Color::Hsla(values) => format!("hsla({})", values.join(",")),
Color::Var(value) => format!("var({value})"),
}
}
fn clamp01(value: f64) -> f64 {
value.clamp(0.0, 1.0)
}
fn resolve_stop_offset(stop: &ColorStop, gradient_length: f64) -> Option<f64> {
match stop.length.as_ref()? {
Distance::Percent(value) => value.parse::<f64>().ok().map(|v| v / 100.0),
Distance::Px(value) => value.parse::<f64>().ok().map(|v| v / gradient_length),
Distance::Em(value) => value
.parse::<f64>()
.ok()
.map(|v| (v * 16.0) / gradient_length),
_ => None,
}
}
fn fix_transparent_stops(stops: &[(String, Option<f64>)]) -> Vec<(String, Option<f64>)> {
let mut result = stops.to_vec();
for i in 0..result.len() {
if !is_transparent(&result[i].0) {
continue;
}
let mut donor = None;
for j in (0..i).rev() {
if !is_transparent(&result[j].0) {
donor = parse_color_to_rgb(&result[j].0);
if donor.is_some() {
break;
}
}
}
if donor.is_none() {
for item in result.iter().skip(i + 1) {
if !is_transparent(&item.0) {
donor = parse_color_to_rgb(&item.0);
if donor.is_some() {
break;
}
}
}
}
if let Some(donor) = donor {
result[i].0 = format!("rgba({},{},{},0)", donor.r, donor.g, donor.b);
}
}
result
}
pub fn normalize_color_stops(
color_stops: &[ColorStop],
gradient_length: f64,
) -> Vec<NormalizedColorStop> {
let mapped: Vec<(String, Option<f64>)> = color_stops
.iter()
.map(|stop| {
(
color_to_string(&stop.color),
resolve_stop_offset(stop, gradient_length),
)
})
.collect();
let fixed = fix_transparent_stops(&mapped);
let mut resolved = fixed;
let known_indices: Vec<usize> = resolved
.iter()
.enumerate()
.filter_map(|(index, stop)| stop.1.map(|_| index))
.collect();
if known_indices.is_empty() {
let step = if resolved.len() > 1 {
1.0 / (resolved.len() - 1) as f64
} else {
1.0
};
for (index, stop) in resolved.iter_mut().enumerate() {
stop.1 = Some(step * index as f64);
}
return resolved
.into_iter()
.map(|(color, offset)| NormalizedColorStop {
color,
offset: clamp01(offset.unwrap_or(0.0)),
})
.collect();
}
let first_known = known_indices[0];
if resolved[first_known].1.is_none() {
resolved[first_known].1 = Some(0.0);
}
for index in 0..first_known {
let next_offset = resolved[first_known].1.unwrap_or(0.0);
resolved[index].1 = Some((next_offset * index as f64) / first_known as f64);
}
for window in known_indices.windows(2) {
let start_index = window[0];
let end_index = window[1];
let start_offset = resolved[start_index].1.unwrap_or(0.0);
let end_offset = resolved[end_index].1.unwrap_or(start_offset);
let gap = end_index - start_index;
if gap <= 1 {
continue;
}
let step = (end_offset - start_offset) / gap as f64;
for index in 1..gap {
resolved[start_index + index].1 = Some(start_offset + step * index as f64);
}
}
let last_known = known_indices[known_indices.len() - 1];
let last_offset = resolved[last_known].1.unwrap_or(1.0);
if last_known < resolved.len() - 1 {
let gap = resolved.len() - 1 - last_known;
let step = (1.0 - last_offset) / gap as f64;
for index in 1..=gap {
resolved[last_known + index].1 = Some(last_offset + step * index as f64);
}
}
resolved
.into_iter()
.map(|(color, offset)| NormalizedColorStop {
color,
offset: clamp01(offset.unwrap_or(0.0)),
})
.collect()
}
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