feat: use lyon for easing

examples/loading_spinners/src/easing.rs

@@ -0,0 +1,132 @@
+use iced_core::Point;
+use lyon::algorithms::measure::PathMeasurements;
+use lyon::path::builder::NoAttributes;
+use lyon::path::path::BuilderImpl;
+use lyon::path::Path;
+
+use once_cell::sync::Lazy;
+
+pub static EMPHASIZED: Lazy<Easing> = Lazy::new(|| {
+    Easing::builder()
+        .cubic_bezier_to([0.05, 0.0], [0.133333, 0.06], [0.166666, 0.4])
+        .cubic_bezier_to([0.208333, 0.82], [0.25, 1.0], [1.0, 1.0])
+        .build()
+});
+
+pub static EMPHASIZED_DECELERATE: Lazy<Easing> = Lazy::new(|| {
+    Easing::builder()
+        .cubic_bezier_to([0.05, 0.7], [0.1, 1.0], [1.0, 1.0])
+        .build()
+});
+
+pub static EMPHASIZED_ACCELERATE: Lazy<Easing> = Lazy::new(|| {
+    Easing::builder()
+        .cubic_bezier_to([0.3, 0.0], [0.8, 0.15], [1.0, 1.0])
+        .build()
+});
+
+pub static STANDARD: Lazy<Easing> = Lazy::new(|| {
+    Easing::builder()
+        .cubic_bezier_to([0.2, 0.0], [0.0, 1.0], [1.0, 1.0])
+        .build()
+});
+
+pub static STANDARD_DECELERATE: Lazy<Easing> = Lazy::new(|| {
+    Easing::builder()
+        .cubic_bezier_to([0.0, 0.0], [0.0, 1.0], [1.0, 1.0])
+        .build()
+});
+
+pub static STANDARD_ACCELERATE: Lazy<Easing> = Lazy::new(|| {
+    Easing::builder()
+        .cubic_bezier_to([0.3, 0.0], [1.0, 1.0], [1.0, 1.0])
+        .build()
+});
+
+pub struct Easing {
+    path: Path,
+    measurements: PathMeasurements,
+}
+
+impl Easing {
+    pub fn builder() -> Builder {
+        Builder::new()
+    }
+
+    pub fn y_at_x(&self, x: f32) -> f32 {
+        let mut sampler = self.measurements.create_sampler(
+            &self.path,
+            lyon::algorithms::measure::SampleType::Normalized,
+        );
+        let sample = sampler.sample(x);
+
+        sample.position().y
+    }
+}
+
+pub struct Builder(NoAttributes<BuilderImpl>);
+
+impl Builder {
+    pub fn new() -> Self {
+        let mut builder = Path::builder();
+        builder.begin(lyon::geom::point(0.0, 0.0));
+
+        Self(builder)
+    }
+
+    /// Adds a line segment. Points must be between 0,0 and 1,1
+    pub fn line_to(mut self, to: impl Into<Point>) -> Self {
+        self.0.line_to(Self::point(to));
+
+        self
+    }
+
+    /// Adds a quadratic bézier curve. Points must be between 0,0 and 1,1
+    pub fn quadratic_bezier_to(
+        mut self,
+        ctrl: impl Into<Point>,
+        to: impl Into<Point>,
+    ) -> Self {
+        self.0
+            .quadratic_bezier_to(Self::point(ctrl), Self::point(to));
+
+        self
+    }
+
+    /// Adds a cubic bézier curve. Points must be between 0,0 and 1,1
+    pub fn cubic_bezier_to(
+        mut self,
+        ctrl1: impl Into<Point>,
+        ctrl2: impl Into<Point>,
+        to: impl Into<Point>,
+    ) -> Self {
+        self.0.cubic_bezier_to(
+            Self::point(ctrl1),
+            Self::point(ctrl2),
+            Self::point(to),
+        );
+
+        self
+    }
+
+    pub fn build(mut self) -> Easing {
+        self.0.line_to(lyon::geom::point(1.0, 1.0));
+        self.0.end(false);
+
+        let path = self.0.build();
+        let measurements = PathMeasurements::from_path(&path, 0.0);
+
+        Easing { path, measurements }
+    }
+
+    fn point(p: impl Into<Point>) -> lyon::geom::Point<f32> {
+        let p: Point = p.into();
+        lyon::geom::point(p.x.min(1.0).max(0.0), p.y.min(1.0).max(0.0))
+    }
+}
+
+impl Default for Builder {
+    fn default() -> Self {
+        Self::new()
+    }
+}