Make gradient spans decorator take gradients directly

gyscos · Jun 28, 2024 · f3ce44c · f3ce44c
1 parent 48cafd5
commit f3ce44c
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Showing 3 changed files with 60 additions and 9 deletions.
diff --git a/cursive-core/src/style/gradient/mod.rs b/cursive-core/src/style/gradient/mod.rs
@@ -29,6 +29,29 @@ impl Linear {
         }
     }
 
+    /// Create a simple gradient with evenly spaced colors.
+    ///
+    /// * Returns `None` if `colors` is empty.
+    /// * Returns a constant "gradient" (same start and end) if `colors.len() == 1`.
+    /// * Returns a piecewise gradient between all colors otherwise.
+    pub fn evenly_spaced<R: Copy + Into<Rgb<f32>>>(colors: &[R]) -> Option<Self> {
+        if colors.is_empty() {
+            return None;
+        }
+
+        if colors.len() == 1 {
+            return Some(Self::new(colors[0], colors[0]));
+        }
+
+        let step = 1f32 / (colors.len() - 1) as f32;
+        let mut colors = colors.iter().copied().map(Into::into).enumerate();
+        let (_, start) = colors.next().unwrap();
+        let (_, end) = colors.next_back().unwrap();
+        let middle = colors.map(|(i, color)| (step * i as f32, color)).collect();
+
+        Some(Self { start, middle, end })
+    }
+
     /// Interpolate the color for the given position.
     pub fn interpolate(&self, x: f32) -> Rgb<f32> {
         // Find the segment
@@ -63,6 +86,30 @@ impl Linear {
     }
 }
 
+impl From<(Rgb<f32>, Rgb<f32>)> for Linear {
+    fn from((start, end): (Rgb<f32>, Rgb<f32>)) -> Self {
+        Self::new(start, end)
+    }
+}
+
+impl From<[Rgb<f32>; 2]> for Linear {
+    fn from([start, end]: [Rgb<f32>; 2]) -> Self {
+        Self::new(start, end)
+    }
+}
+
+impl From<(Rgb<u8>, Rgb<u8>)> for Linear {
+    fn from((start, end): (Rgb<u8>, Rgb<u8>)) -> Self {
+        Self::new(start.as_f32(), end.as_f32())
+    }
+}
+
+impl From<[Rgb<u8>; 2]> for Linear {
+    fn from([start, end]: [Rgb<u8>; 2]) -> Self {
+        Self::new(start.as_f32(), end.as_f32())
+    }
+}
+
 /// Radial gradient.
 pub struct Radial {
     /// Where the gradient starts.

diff --git a/cursive-core/src/utils/markup/gradient.rs b/cursive-core/src/utils/markup/gradient.rs
@@ -66,25 +66,29 @@ where
 }
 
 /// Decorate a text with the given gradient.
-pub fn decorate_front<S>(text: S, start: Rgb, end: Rgb) -> StyledString
+pub fn decorate_front<S, G>(text: S, gradient: G) -> StyledString
 where
     S: Into<StyledString>,
+    G: Into<Linear>,
 {
     let text = text.into();
+    let gradient = gradient.into();
 
-    let spans = decorate_front_with(&text, |x| Linear::new(start, end).interpolate(x).as_u8());
+    let spans = decorate_front_with(&text, |x| gradient.interpolate(x).as_u8());
 
     StyledString::with_spans(text.into_source(), spans)
 }
 
 /// Decorate a text with the given gradient as background.
-pub fn decorate_back<S>(text: S, start: Rgb, end: Rgb) -> StyledString
+pub fn decorate_back<S, G>(text: S, gradient: G) -> StyledString
 where
     S: Into<StyledString>,
+    G: Into<Linear>,
 {
     let text = text.into();
+    let gradient = gradient.into();
 
-    let spans = decorate_back_with(&text, |x| Linear::new(start, end).interpolate(x).as_u8());
+    let spans = decorate_back_with(&text, |x| gradient.interpolate(x).as_u8());
 
     StyledString::with_spans(text.into_source(), spans)
 }
@@ -97,14 +101,14 @@ mod tests {
 
     #[test]
     fn simple() {
-        let gradient = decorate_front("ab", Rgb::new(255, 0, 0), Rgb::new(0, 0, 255));
+        let gradient = decorate_front("ab", (Rgb::new(255, 0, 0), Rgb::new(0, 0, 255)));
 
         assert_eq!(
             gradient,
             cursup::parse("/#FF0000{a}/#0000FF{b}").canonical()
         );
 
-        let gradient = decorate_front("abcde", Rgb::new(255, 0, 0), Rgb::new(0, 0, 255));
+        let gradient = decorate_front("abcde", (Rgb::new(255, 0, 0), Rgb::new(0, 0, 255)));
 
         assert_eq!(
             gradient,

diff --git a/cursive/examples/gradient.rs b/cursive/examples/gradient.rs
@@ -12,12 +12,12 @@ fn main() {
     let mut siv = cursive::default();
 
     let text = "So many colors! So little time!";
-    let text = gradient::decorate_front(text, Rgb::new(255, 0, 0), Rgb::new(0, 0, 255));
-    let text = gradient::decorate_back(text, Rgb::new(0, 0, 255), Rgb::new(0, 255, 0));
+    let text = gradient::decorate_front(text, (Rgb::new(255, 0, 0), Rgb::new(0, 0, 255)));
+    let text = gradient::decorate_back(text, (Rgb::new(0, 0, 255), Rgb::new(0, 255, 0)));
 
     // Add a simple view
     siv.add_layer(Dialog::new().content(TextView::new(text)).button(
-        gradient::decorate_back("Moar", Rgb::new(255, 0, 0), Rgb::new(255, 255, 0)),
+        gradient::decorate_back("Moar", (Rgb::new(255, 0, 0), Rgb::new(255, 255, 0))),
         show_more,
     ));