Compute lookup table at runtime using once_cell

So we don't bloat the binary size, which would be a problem especially
for WASM.

Cargo.lock

@@ -1162,6 +1162,7 @@ dependencies = [
  "color-hex",
  "document-features",
  "emath",
+ "once_cell",
  "serde",
 ]
 

Cargo.toml

@@ -81,6 +81,7 @@ home = "0.5.9"
 image = { version = "0.25", default-features = false }
 log = { version = "0.4", features = ["std"] }
 nohash-hasher = "0.2"
+once_cell = "1.19.0"
 parking_lot = "0.12"
 puffin = "0.19"
 puffin_http = "0.16"

crates/ecolor/Cargo.toml

@@ -14,7 +14,7 @@ readme = "README.md"
 repository = "https://github.com/emilk/egui"
 categories = ["mathematics", "encoding"]
 keywords = ["gui", "color", "conversion", "gamedev", "images"]
-include = ["../LICENSE-APACHE", "../LICENSE-MIT", "**/*.rs", "data/*", "Cargo.toml"]
+include = ["../LICENSE-APACHE", "../LICENSE-MIT", "**/*.rs", "Cargo.toml"]
 
 [lints]
 workspace = true
@@ -32,6 +32,7 @@ default = []
 
 [dependencies]
 emath.workspace = true
+once_cell.workspace = true
 
 #! ### Optional dependencies
 

crates/ecolor/src/color32.rs

@@ -1,7 +1,16 @@
+use once_cell::sync::Lazy;
+
 use crate::{fast_round, linear_f32_from_linear_u8, Rgba};
 
-static FROM_UNMULTIPLIED_LUT: &[u8; 256 * 256] =
-    include_bytes!("../data/color32_from_unmultiplied_lookup_table");
+static FROM_UNMULTIPLIED_LUT: Lazy<[u8; 256 * 256]> = Lazy::new(|| {
+    use crate::{gamma_u8_from_linear_f32, linear_f32_from_gamma_u8};
+    core::array::from_fn(|i| {
+        let [value, alpha] = (i as u16).to_be_bytes();
+        let value_lin = linear_f32_from_gamma_u8(value);
+        let alpha_lin = linear_f32_from_linear_u8(alpha);
+        gamma_u8_from_linear_f32(value_lin * alpha_lin)
+    })
+});
 
 /// This format is used for space-efficient color representation (32 bits).
 ///
@@ -247,24 +256,3 @@ impl Color32 {
         )
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    #[test]
-    fn from_unmultiplied_lookup_table_check() {
-        use crate::{
-            gamma_u8_from_linear_f32, linear_f32_from_gamma_u8, linear_f32_from_linear_u8,
-        };
-        for value in 0..=255u8 {
-            for alpha in 0..=255u8 {
-                let value_lin = linear_f32_from_gamma_u8(value);
-                let alpha_lin = linear_f32_from_linear_u8(alpha);
-
-                let calculated = gamma_u8_from_linear_f32(value_lin * alpha_lin);
-                let lut = FROM_UNMULTIPLIED_LUT[usize::from(u16::from_be_bytes([value, alpha]))];
-                assert_eq!(calculated, lut);
-            }
-        }
-    }
-}