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use crate::gradient::{ColorStop, Gradient, Position};
use crate::{Color, Point};
#[derive(Debug, Clone, PartialEq)]
pub struct Linear {
pub start: Point,
pub end: Point,
pub color_stops: Vec<ColorStop>,
}
#[derive(Debug)]
pub struct Builder {
start: Point,
end: Point,
stops: Vec<ColorStop>,
error: Option<BuilderError>,
}
impl Builder {
pub fn new(position: Position) -> Self {
let (start, end) = match position {
Position::Absolute { start, end } => (start, end),
Position::Relative {
top_left,
size,
start,
end,
} => (
start.to_absolute(top_left, size),
end.to_absolute(top_left, size),
),
};
Self {
start,
end,
stops: vec![],
error: None,
}
}
pub fn add_stop(mut self, offset: f32, color: Color) -> Self {
if offset.is_finite() && (0.0..=1.0).contains(&offset) {
match self.stops.binary_search_by(|stop| {
stop.offset.partial_cmp(&offset).unwrap()
}) {
Ok(_) => {
self.error = Some(BuilderError::DuplicateOffset(offset))
}
Err(index) => {
self.stops.insert(index, ColorStop { offset, color });
}
}
} else {
self.error = Some(BuilderError::InvalidOffset(offset))
};
self
}
pub fn build(self) -> Result<Gradient, BuilderError> {
if self.stops.is_empty() {
Err(BuilderError::MissingColorStop)
} else if let Some(error) = self.error {
Err(error)
} else {
Ok(Gradient::Linear(Linear {
start: self.start,
end: self.end,
color_stops: self.stops,
}))
}
}
}
#[derive(Debug, thiserror::Error)]
pub enum BuilderError {
#[error("Gradients must contain at least one color stop.")]
MissingColorStop,
#[error("Offset {0} must be a unique, finite number.")]
DuplicateOffset(f32),
#[error("Offset {0} must be between 0.0..=1.0.")]
InvalidOffset(f32),
}