librsvg source for verification 2026-05-22

rsvg/build.rs

@@ -0,0 +1,70 @@
+use std::env;
+use std::fs::File;
+use std::io::{BufWriter, Write};
+use std::path::Path;
+
+#[cfg(docsrs)]
+fn probe_system_deps() {
+    // do not probe libraries since the docs.rs environment doesn't have them
+}
+
+#[cfg(not(docsrs))]
+fn probe_system_deps() {
+    if let Err(e) = system_deps::Config::new().probe() {
+        eprintln!("{e}");
+        std::process::exit(1);
+    }
+}
+
+fn main() {
+    probe_system_deps();
+    generate_srgb_tables();
+}
+
+/// Converts an sRGB color value to a linear sRGB color value (undoes the gamma correction).
+///
+/// The input and the output are supposed to be in the [0, 1] range.
+#[inline]
+fn linearize(c: f64) -> f64 {
+    if c <= (12.92 * 0.0031308) {
+        c / 12.92
+    } else {
+        ((c + 0.055) / 1.055).powf(2.4)
+    }
+}
+
+/// Converts a linear sRGB color value to a normal sRGB color value (applies the gamma correction).
+///
+/// The input and the output are supposed to be in the [0, 1] range.
+#[inline]
+fn unlinearize(c: f64) -> f64 {
+    if c <= 0.0031308 {
+        12.92 * c
+    } else {
+        1.055 * c.powf(1f64 / 2.4) - 0.055
+    }
+}
+
+fn print_table<W, F>(w: &mut W, name: &str, f: F, len: u32)
+where
+    W: Write,
+    F: Fn(f64) -> f64,
+{
+    writeln!(w, "const {name}: [u8; {len}] = [").unwrap();
+
+    for i in 0..len {
+        let x = f(i as f64 / 255.0);
+        let v = (x * 255.0).round() as u8;
+        writeln!(w, "    {v},").unwrap();
+    }
+
+    writeln!(w, "];").unwrap();
+}
+
+fn generate_srgb_tables() {
+    let path = Path::new(&env::var("OUT_DIR").unwrap()).join("srgb-codegen.rs");
+    let mut file = BufWriter::new(File::create(path).unwrap());
+
+    print_table(&mut file, "LINEARIZE", linearize, 256);
+    print_table(&mut file, "UNLINEARIZE", unlinearize, 256);
+}