Clean up code and make clippy changes

Collapse if else statements in color_difference.rs
Use !is_empty instead of `... > 0` comparisons in gradient.rs
Use strip_prefix instead of manually stripping, avoids manual indexing
Remove extraneous clones, into_iters, and closures
Simplify matching on single condition to if let
Remove format! in favor of to_string
Fix deprecated image functions in examples
Change some as casts to use direct `from` casts when applicable

palette/examples/hue.rs

@@ -3,7 +3,7 @@ use palette::{FromColor, Hsl, Hue, Lch, Pixel, Srgb};
 fn main() {
     let mut image = image::open("example-data/input/fruits.png")
         .expect("could not open 'example-data/input/fruits.png'")
-        .to_rgb();
+        .to_rgb8();
 
     //Shift hue by 180 degrees as HSL in bottom left part, and as LCh in top
     //right part. Notice how LCh manages to preserve the apparent lightness of

palette/examples/saturate.rs

@@ -5,7 +5,7 @@ use image::{GenericImage, GenericImageView};
 fn main() {
     let mut image = image::open("example-data/input/cat.png")
         .expect("could not open 'example-data/input/cat.png'")
-        .to_rgb();
+        .to_rgb8();
 
     let width = image.width();
     let height = image.height();
@@ -49,7 +49,7 @@ fn main() {
             }
         }
     }
-    
+
     let _ = std::fs::create_dir("example-data/output");
     match image.save("example-data/output/saturate.png") {
         Ok(()) => println!("see 'example-data/output/saturate.png' for the result"),

palette/src/blend/equations.rs

@@ -94,12 +94,8 @@ where
             Equation::Add => src_color.component_wise(&dst_color, |a, b| a + b),
             Equation::Subtract => src_color.component_wise(&dst_color, |a, b| a - b),
             Equation::ReverseSubtract => dst_color.component_wise(&src_color, |a, b| a - b),
-            Equation::Min => source
-                .color
-                .component_wise(&destination.color, |a, b| a.min(b)),
-            Equation::Max => source
-                .color
-                .component_wise(&destination.color, |a, b| a.max(b)),
+            Equation::Min => source.color.component_wise(&destination.color, Float::min),
+            Equation::Max => source.color.component_wise(&destination.color, Float::max),
         };
 
         let alpha = match self.alpha_equation {

palette/src/color_difference.rs

@@ -60,29 +60,23 @@ pub fn get_ciede_difference<T: FloatComponent>(this: &LabColorDiff<T>, other: &L
 
     let delta_h_prime: T = if c_one_prime == T::zero() || c_two_prime == T::zero() {
         from_f64(0.0)
+    } else if h_prime_difference <= from_f64(180.0) {
+        h_two_prime - h_one_prime
+    } else if h_two_prime <= h_one_prime {
+        h_two_prime - h_one_prime + from_f64(360.0)
     } else {
-        if h_prime_difference <= from_f64(180.0) {
-            h_two_prime - h_one_prime
-        } else {
-            if h_two_prime <= h_one_prime {
-                h_two_prime - h_one_prime + from_f64(360.0)
-            } else {
-                h_two_prime - h_one_prime - from_f64(360.0)
-            }
-        }
+        h_two_prime - h_one_prime - from_f64(360.0)
     };
 
     let delta_big_h_prime = from_f64::<T>(2.0)
         * (c_one_prime * c_two_prime).sqrt()
         * (delta_h_prime / from_f64(2.0) * pi_over_180).sin();
     let h_bar_prime = if c_one_prime == T::zero() || c_two_prime == T::zero() {
         h_one_prime + h_two_prime
+    } else if h_prime_difference > from_f64(180.0) {
+        (h_one_prime + h_two_prime + from_f64(360.0)) / from_f64(2.0)
     } else {
-        if h_prime_difference > from_f64(180.0) {
-            (h_one_prime + h_two_prime + from_f64(360.0)) / from_f64(2.0)
-        } else {
-            (h_one_prime + h_two_prime) / from_f64(2.0)
-        }
+        (h_one_prime + h_two_prime) / from_f64(2.0)
     };
 
     let l_bar = (this.l + other.l) / from_f64(2.0);
@@ -103,13 +97,7 @@ pub fn get_ciede_difference<T: FloatComponent>(this: &LabColorDiff<T>, other: &L
         * (-(((h_bar_prime - from_f64(275.0)) / from_f64(25.0))
             * ((h_bar_prime - from_f64(275.0)) / from_f64(25.0))))
         .exp();
-    let c_bar_prime_pow_seven = c_bar_prime
-        * c_bar_prime
-        * c_bar_prime
-        * c_bar_prime
-        * c_bar_prime
-        * c_bar_prime
-        * c_bar_prime;
+    let c_bar_prime_pow_seven = c_bar_prime.powi(7);
     let r_c: T = from_f64::<T>(2.0)
         * (c_bar_prime_pow_seven / (c_bar_prime_pow_seven + twenty_five_pow_seven)).sqrt();
     let r_t = -r_c * (from_f64::<T>(2.0) * delta_theta * pi_over_180).sin();

palette/src/component.rs

@@ -160,9 +160,9 @@ macro_rules! convert_double_to_uint {
 impl IntoComponent<f32> for u8 {
     #[inline]
     fn into_component(self) -> f32 {
-        let comp_u = self as u32 + C23;
+        let comp_u = u32::from(self) + C23;
         let comp_f = f32::from_bits(comp_u) - f32::from_bits(C23);
-        let max_u = core::u8::MAX as u32 + C23;
+        let max_u = u32::from(core::u8::MAX) + C23;
         let max_f = (f32::from_bits(max_u) - f32::from_bits(C23)).recip();
         comp_f * max_f
     }
@@ -172,9 +172,9 @@ impl IntoComponent<f32> for u8 {
 impl IntoComponent<f64> for u8 {
     #[inline]
     fn into_component(self) -> f64 {
-        let comp_u = self as u64 + C52;
+        let comp_u = u64::from(self) + C52;
         let comp_f = f64::from_bits(comp_u) - f64::from_bits(C52);
-        let max_u = core::u8::MAX as u64 + C52;
+        let max_u = u64::from(core::u8::MAX) + C52;
         let max_f = (f64::from_bits(max_u) - f64::from_bits(C52)).recip();
         comp_f * max_f
     }
@@ -218,7 +218,7 @@ macro_rules! convert_uint_to_uint {
 impl IntoComponent<f64> for f32 {
     #[inline]
     fn into_component(self) -> f64 {
-        self as f64
+        f64::from(self)
     }
 }
 convert_float_to_uint!(f32; direct (u8, u16); via f64 (u32, u64, u128););

palette/src/gradient.rs

@@ -31,7 +31,7 @@ impl<C: Mix + Clone> Gradient<C> {
         C::Scalar: FromF64,
     {
         let mut points: Vec<_> = colors.into_iter().map(|c| (C::Scalar::zero(), c)).collect();
-        assert!(points.len() > 0);
+        assert!(!points.is_empty());
         let step_size = C::Scalar::one() / from_f64(max(points.len() - 1, 1) as f64);
 
         for (i, &mut (ref mut p, _)) in points.iter_mut().enumerate() {
@@ -45,7 +45,7 @@ impl<C: Mix + Clone> Gradient<C> {
     /// be at least one color and they are expected to be ordered by their
     /// position value.
     pub fn with_domain(colors: Vec<(C::Scalar, C)>) -> Gradient<C> {
-        assert!(colors.len() > 0);
+        assert!(!colors.is_empty());
 
         //Maybe sort the colors?
         Gradient(colors)

palette/src/relative_contrast.rs

@@ -52,7 +52,7 @@ pub trait RelativeContrast {
     /// The type of the contrast ratio.
     type Scalar: FromF64 + PartialOrd;
 
-    /// Calculate contrast ratio between two colors.
+    /// Calculate the contrast ratio between two colors.
     fn get_contrast_ratio(&self, other: &Self) -> Self::Scalar;
     /// Verify the contrast between two colors satisfies SC 1.4.3. Contrast
     /// is at least 4.5:1 (Level AA).
@@ -81,13 +81,10 @@ pub trait RelativeContrast {
     }
 }
 
-/// Calculate a ratio between two `luma` values.
+/// Calculate the ratio between two `luma` values.
 pub fn contrast_ratio<T>(luma1: T, luma2: T) -> T
 where
-    T: Add<Output = T>,
-    T: Div<Output = T>,
-    T: FromF64,
-    T: Component,
+    T: Component + FromF64 + Add<Output = T> + Div<Output = T>,
 {
     if luma1 > luma2 {
         (luma1 + from_f64(0.05)) / (luma2 + from_f64(0.05))

palette/src/rgb/rgb.rs

@@ -1060,7 +1060,7 @@ impl<S: RgbStandard> FromStr for Rgb<S, u8> {
     // Parses a color hex code of format '#ff00bb' or '#abc' into a
     // Rgb<S, u8> instance.
     fn from_str(hex: &str) -> Result<Self, Self::Err> {
-        let hex_code = if hex.starts_with('#') { &hex[1..] } else { hex };
+        let hex_code = hex.strip_prefix('#').map_or(hex, |stripped| stripped);
         match hex_code.len() {
             3 => {
                 let red = u8::from_str_radix(&hex_code[..1], 16)?;

palette_derive/src/alpha/with_alpha.rs

@@ -20,7 +20,7 @@ pub fn derive(item: TokenStream) -> ::std::result::Result<TokenStream, Vec<::syn
         attrs,
         ..
     } = syn::parse(item).map_err(|error| vec![error])?;
-    let generics = original_generics.clone();
+    let generics = original_generics;
 
     let item_meta: TypeItemAttributes = parse_namespaced_attributes(attrs)?;
 

palette_derive/src/convert/from_color_unclamped.rs

@@ -105,9 +105,7 @@ fn prepare_from_impl(
     generics: &Generics,
     generic_component: bool,
 ) -> Result<Vec<FromImplParameters>> {
-    let included_colors = COLOR_TYPES
-        .into_iter()
-        .filter(|&&color| !skip.contains(color));
+    let included_colors = COLOR_TYPES.iter().filter(|&&color| !skip.contains(color));
     let linear_path = util::path(&["encoding", "Linear"], meta.internal);
 
     let mut parameters = Vec::new();

palette_derive/src/encoding/pixel.rs

@@ -111,7 +111,7 @@ pub fn derive(tokens: TokenStream) -> std::result::Result<TokenStream, Vec<syn::
     } else {
         errors.push(syn::Error::new(
             Span::call_site(),
-            format!("`Pixel` can only be derived for structs with one or more fields"),
+            "`Pixel` can only be derived for structs with one or more fields".to_string(),
         ));
 
         return Err(errors);
@@ -127,23 +127,20 @@ fn is_repr_c(attributes: &[Attribute]) -> std::result::Result<bool, Vec<syn::Err
     for attribute in attributes {
         let attribute_name = attribute.path.get_ident().map(ToString::to_string);
 
-        match attribute_name.as_deref() {
-            Some("repr") => {
-                let items = match meta::parse_tuple_attribute(attribute.tokens.clone()) {
-                    Ok(items) => items,
-                    Err(error) => {
-                        errors.push(error);
-                        continue;
-                    }
-                };
+        if let Some("repr") = attribute_name.as_deref() {
+            let items = match meta::parse_tuple_attribute(attribute.tokens.clone()) {
+                Ok(items) => items,
+                Err(error) => {
+                    errors.push(error);
+                    continue;
+                }
+            };
 
-                let contains_c = items.into_iter().find(|item: &Ident| item == "C").is_some();
+            let contains_c = items.iter().any(|item: &Ident| item == "C");
 
-                if contains_c {
-                    return Ok(true);
-                }
+            if contains_c {
+                return Ok(true);
             }
-            _ => {}
         }
     }
 

palette_derive/src/meta/mod.rs

@@ -157,7 +157,7 @@ pub fn parse_tuple_attribute<T: Parse>(tts: TokenStream) -> Result<Vec<T>> {
         Ok(tuple)
     }
 
-    parse_generic_tuple.parse2(tts.clone())
+    parse_generic_tuple.parse2(tts)
 }
 
 fn parse_meta_list(buffer: &ParseBuffer) -> syn::Result<Punctuated<NestedMeta, Token![,]>> {

palette_derive/src/util.rs

@@ -5,7 +5,7 @@ use syn::{parse_quote, Ident, Type};
 pub fn path<'a, P: AsRef<[&'a str]>>(path: P, internal: bool) -> TokenStream {
     let path = path
         .as_ref()
-        .into_iter()
+        .iter()
         .map(|&ident| Ident::new(ident, Span::call_site()));
 
     if internal {
@@ -18,7 +18,7 @@ pub fn path<'a, P: AsRef<[&'a str]>>(path: P, internal: bool) -> TokenStream {
 
 pub fn path_type(path: &[&str], internal: bool) -> Type {
     let path = path
-        .into_iter()
+        .iter()
         .map(|&ident| Ident::new(ident, Span::call_site()));
 
     if internal {