Add the `color` crate (#4063)

Nate Butler created

This PR adds the `color` crate, which will be the home of a number of
color-related utilities, and also acts as an interface between
[`palette`](https://crates.io/crates/palette) and the way `gpui` colors
work.

The goal of this crate is to centralize color utilities like mixing and
blending, building color ramps and sets of colors for state and more.

## Todo:

- [x] hex -> Color
- [x] Color mixing
- [x] Color blending using blend modes (overlay, multiply, etc)
- [ ] ~~Build color ramp from color~~
- [x] Build state set from color
- [ ] ~~Update Theme to use the color crate~~

Release Notes:

- None (Internal changes: Adds the `color` crate for working with
colors.)

Change summary

Cargo.lock                |  77 +++++++++++++
crates/color/Cargo.toml   |  32 +++++
crates/color/src/color.rs | 234 +++++++++++++++++++++++++++++++++++++++++
crates/theme/Cargo.toml   |   1 
crates/zed/Cargo.toml     |   1 
5 files changed, 343 insertions(+), 2 deletions(-)

Detailed changes

Cargo.lock 🔗

@@ -1580,6 +1580,28 @@ dependencies = [
  "rustc-hash",
 ]
 
+[[package]]
+name = "color"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "fs",
+ "indexmap 1.9.3",
+ "itertools 0.11.0",
+ "palette",
+ "parking_lot 0.11.2",
+ "refineable",
+ "schemars",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "settings",
+ "story",
+ "toml 0.5.11",
+ "util",
+ "uuid 1.4.1",
+]
+
 [[package]]
 name = "color_quant"
 version = "1.1.0"
@@ -4977,6 +4999,7 @@ dependencies = [
  "approx",
  "fast-srgb8",
  "palette_derive",
+ "phf",
 ]
 
 [[package]]
@@ -5165,6 +5188,48 @@ dependencies = [
  "indexmap 2.0.0",
 ]
 
+[[package]]
+name = "phf"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ade2d8b8f33c7333b51bcf0428d37e217e9f32192ae4772156f65063b8ce03dc"
+dependencies = [
+ "phf_macros",
+ "phf_shared",
+]
+
+[[package]]
+name = "phf_generator"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48e4cc64c2ad9ebe670cb8fd69dd50ae301650392e81c05f9bfcb2d5bdbc24b0"
+dependencies = [
+ "phf_shared",
+ "rand 0.8.5",
+]
+
+[[package]]
+name = "phf_macros"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3444646e286606587e49f3bcf1679b8cef1dc2c5ecc29ddacaffc305180d464b"
+dependencies = [
+ "phf_generator",
+ "phf_shared",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.37",
+]
+
+[[package]]
+name = "phf_shared"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90fcb95eef784c2ac79119d1dd819e162b5da872ce6f3c3abe1e8ca1c082f72b"
+dependencies = [
+ "siphasher 0.3.11",
+]
+
 [[package]]
 name = "picker"
 version = "0.1.0"
@@ -7074,6 +7139,12 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b8de496cf83d4ed58b6be86c3a275b8602f6ffe98d3024a869e124147a9a3ac"
 
+[[package]]
+name = "siphasher"
+version = "0.3.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38b58827f4464d87d377d175e90bf58eb00fd8716ff0a62f80356b5e61555d0d"
+
 [[package]]
 name = "slab"
 version = "0.4.9"
@@ -7644,7 +7715,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c536faaff1a10837cfe373142583f6e27d81e96beba339147e77b67c9f260ff"
 dependencies = [
  "float-cmp",
- "siphasher",
+ "siphasher 0.2.3",
 ]
 
 [[package]]
@@ -7855,6 +7926,7 @@ name = "theme"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "color",
  "fs",
  "gpui",
  "indexmap 1.9.3",
@@ -8858,7 +8930,7 @@ dependencies = [
  "roxmltree",
  "rustybuzz",
  "simplecss",
- "siphasher",
+ "siphasher 0.2.3",
  "svgtypes",
  "ttf-parser 0.12.3",
  "unicode-bidi",
@@ -9650,6 +9722,7 @@ dependencies = [
  "client",
  "collab_ui",
  "collections",
+ "color",
  "command_palette",
  "copilot",
  "copilot_ui",

crates/color/Cargo.toml 🔗

@@ -0,0 +1,32 @@
+[package]
+name = "color"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[features]
+default = []
+stories = ["dep:itertools", "dep:story"]
+
+[lib]
+path = "src/color.rs"
+doctest = true
+
+[dependencies]
+# TODO: Clean up dependencies
+anyhow.workspace = true
+fs = { path = "../fs" }
+indexmap = "1.6.2"
+parking_lot.workspace = true
+refineable.workspace = true
+schemars.workspace = true
+serde.workspace = true
+serde_derive.workspace = true
+serde_json.workspace = true
+settings = { path = "../settings" }
+story = { path = "../story", optional = true }
+toml.workspace = true
+uuid.workspace = true
+util = { path = "../util" }
+itertools = { version = "0.11.0", optional = true }
+palette = "0.7.3"

crates/color/src/color.rs 🔗

@@ -0,0 +1,234 @@
+//! # Color
+//!
+//! The `color` crate provides a set utilities for working with colors. It is a wrapper around the [`palette`](https://docs.rs/palette) crate with some additional functionality.
+//!
+//! It is used to create a manipulate colors when building themes.
+//!
+//! === In development note ===
+//!
+//! This crate is meant to sit between gpui and the theme/ui for all the color related stuff.
+//!
+//! It could be folded into gpui, ui or theme potentially but for now we'll continue
+//! to develop it in isolation.
+//!
+//! Once we have a good idea of the needs of the theme system and color in gpui in general I see 3 paths:
+//! 1. Use `palette` (or another color library) directly in gpui and everywhere else, rather than rolling our own color system.
+//! 2. Keep this crate as a thin wrapper around `palette` and use it everywhere except gpui, and convert to gpui's color system when needed.
+//! 3. Build the needed functionality into gpui and keep using it's color system everywhere.
+//!
+//! I'm leaning towards 2 in the short term and 1 in the long term, but we'll need to discuss it more.
+//!
+//! === End development note ===
+use palette::{
+    blend::Blend, convert::FromColorUnclamped, encoding, rgb::Rgb, Clamp, Mix, Srgb, WithAlpha,
+};
+
+/// The types of blend modes supported
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum BlendMode {
+    /// Multiplies the colors, resulting in a darker color. This mode is useful for creating shadows.
+    Multiply,
+    /// Lightens the color by adding the source and destination colors. It results in a lighter color.
+    Screen,
+    /// Combines Multiply and Screen blend modes. Parts of the image that are lighter than 50% gray are lightened, and parts that are darker are darkened.
+    Overlay,
+    /// Selects the darker of the base or blend color as the resulting color. Useful for darkening images without affecting the overall contrast.
+    Darken,
+    /// Selects the lighter of the base or blend color as the resulting color. Useful for lightening images without affecting the overall contrast.
+    Lighten,
+    /// Brightens the base color to reflect the blend color. The result is a lightened image.
+    Dodge,
+    /// Darkens the base color to reflect the blend color. The result is a darkened image.
+    Burn,
+    /// Similar to Overlay, but with a stronger effect. Hard Light can either multiply or screen colors, depending on the blend color.
+    HardLight,
+    /// A softer version of Hard Light. Soft Light either darkens or lightens colors, depending on the blend color.
+    SoftLight,
+    /// Subtracts the darker of the two constituent colors from the lighter color. Difference mode is useful for creating more vivid colors.
+    Difference,
+    /// Similar to Difference, but with a lower contrast. Exclusion mode produces an effect similar to Difference but with less intensity.
+    Exclusion,
+}
+
+/// Converts a hexadecimal color string to a `palette::Hsla` color.
+///
+/// This function supports the following hex formats:
+/// `#RGB`, `#RGBA`, `#RRGGBB`, `#RRGGBBAA`.
+pub fn hex_to_hsla(s: &str) -> Result<RGBAColor, String> {
+    let hex = s.trim_start_matches('#');
+
+    // Expand shorthand formats #RGB and #RGBA to #RRGGBB and #RRGGBBAA
+    let hex = match hex.len() {
+        3 => hex
+            .chars()
+            .map(|c| c.to_string().repeat(2))
+            .collect::<String>(),
+        4 => {
+            let (rgb, alpha) = hex.split_at(3);
+            let rgb = rgb
+                .chars()
+                .map(|c| c.to_string().repeat(2))
+                .collect::<String>();
+            let alpha = alpha.chars().next().unwrap().to_string().repeat(2);
+            format!("{}{}", rgb, alpha)
+        }
+        6 => format!("{}ff", hex), // Add alpha if missing
+        8 => hex.to_string(),      // Already in full format
+        _ => return Err("Invalid hexadecimal string length".to_string()),
+    };
+
+    let hex_val =
+        u32::from_str_radix(&hex, 16).map_err(|_| format!("Invalid hexadecimal string: {}", s))?;
+
+    let r = ((hex_val >> 24) & 0xFF) as f32 / 255.0;
+    let g = ((hex_val >> 16) & 0xFF) as f32 / 255.0;
+    let b = ((hex_val >> 8) & 0xFF) as f32 / 255.0;
+    let a = (hex_val & 0xFF) as f32 / 255.0;
+
+    let color = RGBAColor { r, g, b, a };
+
+    Ok(color)
+}
+
+// These derives implement to and from palette's color types.
+#[derive(FromColorUnclamped, WithAlpha, Debug, Clone)]
+#[palette(skip_derives(Rgb), rgb_standard = "encoding::Srgb")]
+pub struct RGBAColor {
+    r: f32,
+    g: f32,
+    b: f32,
+    // Let Palette know this is our alpha channel.
+    #[palette(alpha)]
+    a: f32,
+}
+
+impl FromColorUnclamped<RGBAColor> for RGBAColor {
+    fn from_color_unclamped(color: RGBAColor) -> RGBAColor {
+        color
+    }
+}
+
+impl<S> FromColorUnclamped<Rgb<S, f32>> for RGBAColor
+where
+    Srgb: FromColorUnclamped<Rgb<S, f32>>,
+{
+    fn from_color_unclamped(color: Rgb<S, f32>) -> RGBAColor {
+        let srgb = Srgb::from_color_unclamped(color);
+        RGBAColor {
+            r: srgb.red,
+            g: srgb.green,
+            b: srgb.blue,
+            a: 1.0,
+        }
+    }
+}
+
+impl<S> FromColorUnclamped<RGBAColor> for Rgb<S, f32>
+where
+    Rgb<S, f32>: FromColorUnclamped<Srgb>,
+{
+    fn from_color_unclamped(color: RGBAColor) -> Self {
+        let srgb = Srgb::new(color.r, color.g, color.b);
+        Self::from_color_unclamped(srgb)
+    }
+}
+
+impl Clamp for RGBAColor {
+    fn clamp(self) -> Self {
+        RGBAColor {
+            r: self.r.min(1.0).max(0.0),
+            g: self.g.min(1.0).max(0.0),
+            b: self.b.min(1.0).max(0.0),
+            a: self.a.min(1.0).max(0.0),
+        }
+    }
+}
+
+impl RGBAColor {
+    /// Creates a new color from the given RGBA values.
+    ///
+    /// This color can be used to convert to any [`palette::Color`] type.
+    pub fn new(r: f32, g: f32, b: f32, a: f32) -> Self {
+        RGBAColor { r, g, b, a }
+    }
+
+    /// Returns a set of states for this color.
+    pub fn states(self, is_light: bool) -> ColorStates {
+        states_for_color(self, is_light)
+    }
+
+    /// Mixes this color with another [`palette::Hsl`] color at the given `mix_ratio`.
+    pub fn mixed(&self, other: RGBAColor, mix_ratio: f32) -> Self {
+        let srgb_self = Srgb::new(self.r, self.g, self.b);
+        let srgb_other = Srgb::new(other.r, other.g, other.b);
+
+        // Directly mix the colors as sRGB values
+        let mixed = srgb_self.mix(srgb_other, mix_ratio);
+        RGBAColor::from_color_unclamped(mixed)
+    }
+
+    pub fn blend(&self, other: RGBAColor, blend_mode: BlendMode) -> Self {
+        let srgb_self = Srgb::new(self.r, self.g, self.b);
+        let srgb_other = Srgb::new(other.r, other.g, other.b);
+
+        let blended = match blend_mode {
+            // replace hsl methods with the respective sRGB methods
+            BlendMode::Multiply => srgb_self.multiply(srgb_other),
+            _ => unimplemented!(),
+        };
+
+        Self {
+            r: blended.red,
+            g: blended.green,
+            b: blended.blue,
+            a: self.a,
+        }
+    }
+}
+
+/// A set of colors for different states of an element.
+#[derive(Debug, Clone)]
+pub struct ColorStates {
+    /// The default color.
+    pub default: RGBAColor,
+    /// The color when the mouse is hovering over the element.
+    pub hover: RGBAColor,
+    /// The color when the mouse button is held down on the element.
+    pub active: RGBAColor,
+    /// The color when the element is focused with the keyboard.
+    pub focused: RGBAColor,
+    /// The color when the element is disabled.
+    pub disabled: RGBAColor,
+}
+
+/// Returns a set of colors for different states of an element.
+///
+/// todo!("This should take a theme and use appropriate colors from it")
+pub fn states_for_color(color: RGBAColor, is_light: bool) -> ColorStates {
+    let adjustment_factor = if is_light { 0.1 } else { -0.1 };
+    let hover_adjustment = 1.0 - adjustment_factor;
+    let active_adjustment = 1.0 - 2.0 * adjustment_factor;
+    let focused_adjustment = 1.0 - 3.0 * adjustment_factor;
+    let disabled_adjustment = 1.0 - 4.0 * adjustment_factor;
+
+    let make_adjustment = |color: RGBAColor, adjustment: f32| -> RGBAColor {
+        // Adjust lightness for each state
+        // Note: Adjustment logic may differ; simplify as needed for sRGB
+        RGBAColor::new(
+            color.r * adjustment,
+            color.g * adjustment,
+            color.b * adjustment,
+            color.a,
+        )
+    };
+
+    let color = color.clamp();
+
+    ColorStates {
+        default: color.clone(),
+        hover: make_adjustment(color.clone(), hover_adjustment),
+        active: make_adjustment(color.clone(), active_adjustment),
+        focused: make_adjustment(color.clone(), focused_adjustment),
+        disabled: make_adjustment(color.clone(), disabled_adjustment),
+    }
+}

crates/theme/Cargo.toml 🔗

@@ -34,6 +34,7 @@ story = { path = "../story", optional = true }
 toml.workspace = true
 uuid.workspace = true
 util = { path = "../util" }
+color = {path = "../color"}
 itertools = { version = "0.11.0", optional = true }
 
 [dev-dependencies]

crates/zed/Cargo.toml 🔗

@@ -29,6 +29,7 @@ command_palette = { path = "../command_palette" }
 # component_test = { path = "../component_test" }
 client = { path = "../client" }
 # clock = { path = "../clock" }
+color = { path = "../color" }
 copilot = { path = "../copilot" }
 copilot_ui = { path = "../copilot_ui" }
 diagnostics = { path = "../diagnostics" }