feat: added more interpolation options

added the following interpolation options:

- cubic ease-in-out
- cosine
- exponential

src/lib.rs

@@ -34,6 +34,17 @@ pub struct Config {
     pub disable_timeout: u32,
     pub gamma_backend: GammaBackend,
     pub temp_backend: TempBackend,
+
+    pub interpolation_temp: Interpolation,
+    pub interpolation_gamma: Interpolation,
+}
+
+#[derive(Debug, PartialEq, Copy, Clone)]
+pub enum Interpolation {
+    Linear,
+    CubicEaseInOut,
+    Cosine,
+    Exponential,
 }
 
 #[derive(Debug, PartialEq, Copy, Clone)]
@@ -70,6 +81,8 @@ impl Default for Config {
             notification_timeout: 5000,
             gamma_backend: GammaBackend::Hyprctl,
             temp_backend: TempBackend::Hyprctl,
+            interpolation_temp: Interpolation::Linear,
+            interpolation_gamma: Interpolation::Linear,
         }
     }
 }
@@ -83,6 +96,7 @@ pub enum ConfigError {
     InvalidGamma(String),
     InvalidGammaBackend(String),
     InvalidTempBackend(String),
+    InvalidInterpolation(String),
     DuplicateKey(String),
 }
 
@@ -230,6 +244,20 @@ impl Config {
                                 return Err(ConfigError::InvalidTime(value.to_string()));
                             }
                         }
+                        "interpolation_temp" => match value.to_lowercase().as_str() {
+                            "linear" => config.interpolation_temp = Interpolation::Linear,
+                            "cubic" | "cubiceaseinout" => config.interpolation_temp = Interpolation::CubicEaseInOut,
+                            "cosine" => config.interpolation_temp = Interpolation::Cosine,
+                            "exponential" => config.interpolation_temp = Interpolation::Exponential,
+                            _ => return Err(ConfigError::InvalidInterpolation(value.to_string())),
+                        },
+                        "interpolation_gamma" => match value.to_lowercase().as_str() {
+                            "linear" => config.interpolation_gamma = Interpolation::Linear,
+                            "cubic" | "cubiceaseinout" => config.interpolation_gamma = Interpolation::CubicEaseInOut,
+                            "cosine" => config.interpolation_gamma = Interpolation::Cosine,
+                            "exponential" => config.interpolation_gamma = Interpolation::Exponential,
+                            _ => return Err(ConfigError::InvalidInterpolation(value.to_string())),
+                        },
                         _ => {}
                     },
                     _ => {}
@@ -256,8 +284,8 @@ impl Config {
 }
 
 /// Linearly interpolate between start and end by factor [0.0, 1.0]
-pub fn interpolate(start: u16, end: u16, factor: f64) -> u16 {
-    trace!("interpolate({start}, {end}, {factor})");
+pub fn interpolate_linear(start: u16, end: u16, factor: f64) -> u16 {
+    trace!("interpolate_linear({start}, {end}, {factor})");
     if end < start {
         (end as f64 + (start - end) as f64 * (1.0 - factor)).round() as u16
     } else {
@@ -265,6 +293,51 @@ pub fn interpolate(start: u16, end: u16, factor: f64) -> u16 {
     }
 }
 
+/// Cubic interpolation
+fn interpolate_cubic(start: u16, end: u16, factor: f64) -> u16 {
+    trace!("interpolate_cubic({start}, {end}, {factor})");
+    let factor = factor.clamp(0.0, 1.0);
+    // Convert to f64 for arithmetic
+    let start_f = start as f64;
+    let end_f = end as f64;
+    // Cubic ease-in-out: 3t^2 - 2t^3
+    let t = factor;
+    let smooth_t = (3.0 * t * t) - (2.0 * t * t * t);
+    // Interpolate
+    let result = start_f + smooth_t * (end_f - start_f);
+    // Round and clamp to u16 bounds
+    result.round().max(0.0).min(u16::MAX as f64) as u16
+}
+
+/// Cosine interpolation
+fn interpolate_cosine(start: u16, end: u16, factor: f64) -> u16 {
+    trace!("interpolate_cosine({start}, {end}, {factor})");
+    let t = (1.0 - (factor.clamp(0.0, 1.0) * std::f64::consts::PI).cos()) / 2.0;
+    interpolate_linear(start, end, t)
+}
+
+fn interpolate_exponential(start: u16, end: u16, factor: f64) -> u16 {
+    trace!("interpolate_exponential({start}, {end}, {factor})");
+    let t = factor.clamp(0.0, 1.0);
+    let t = if t < 0.5 {
+        0.5 * (2.0 * t).powf(3.0)
+    } else {
+        0.5 * (1.0 - (2.0 * (1.0 - t)).powf(3.0)) + 0.5
+    };
+    interpolate_linear(start, end, t)
+}
+
+/// Interpolation meta-function
+fn interpolate_value(start: u16, end: u16, factor: f64, interpolation: &Interpolation) -> u16 {
+    trace!("interpolate_value({start}, {end}, {factor}, {interpolation:?})");
+    match interpolation {
+        Interpolation::Linear => interpolate_linear(start, end, factor),
+        Interpolation::CubicEaseInOut => interpolate_cubic(start, end, factor),
+        Interpolation::Cosine => interpolate_cosine(start, end, factor),
+        Interpolation::Exponential => interpolate_exponential(start, end, factor),
+    }
+}
+
 /// Compute current temperature and gamma based on provided time
 pub fn compute_settings(now: Time, config: &Config) -> (u16, u16) {
     trace!("compute_settings({now:?})");
@@ -278,8 +351,8 @@ pub fn compute_settings(now: Time, config: &Config) -> (u16, u16) {
             / (config.sunset_end - config.sunset_start) as f64)
             .clamp(0.0, 1.0);
         (
-            interpolate(config.temp_day, config.temp_night, factor),
-            interpolate(config.gamma_day, config.gamma_night, factor),
+            interpolate_value(config.temp_day, config.temp_night, factor, &config.interpolation_temp),
+            interpolate_value(config.gamma_day, config.gamma_night, factor, &config.interpolation_gamma),
         )
     } else if (time_in_hours >= config.sunrise_start as f64)
         && (time_in_hours <= config.sunrise_end as f64)
@@ -290,8 +363,8 @@ pub fn compute_settings(now: Time, config: &Config) -> (u16, u16) {
                 / (config.sunrise_end - config.sunrise_start) as f64)
                 .clamp(0.0, 1.0);
         (
-            interpolate(config.temp_day, config.temp_night, factor),
-            interpolate(config.gamma_day, config.gamma_night, factor),
+            interpolate_value(config.temp_day, config.temp_night, factor, &config.interpolation_temp),
+            interpolate_value(config.gamma_day, config.gamma_night, factor, &config.interpolation_gamma),
         )
     } else if time_in_hours > config.sunset_end as f64
         || time_in_hours < config.sunrise_start as f64