[librsvg] color.rs: Declare ColorKind and ColorSpec that we can represent in C

[Federico Mena Quintero <federico src gnome org>]

commit 68f2eee9bbac7903b48cf729b2634d6c876cb001
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri May 19 19:53:57 2017 -0500

    color.rs: Declare ColorKind and ColorSpec that we can represent in C

 rust/src/color.rs |   73 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 rust/src/lib.rs   |    3 ++
 2 files changed, 76 insertions(+), 0 deletions(-)
---
diff --git a/rust/src/color.rs b/rust/src/color.rs
index efa0fae..bb8d888 100644
--- a/rust/src/color.rs
+++ b/rust/src/color.rs
@@ -5,6 +5,45 @@ use error::*;
 
 use ::cssparser;
 
+// Keep this in sync with rsvg-css.h:RsvgCssColorKind
+#[repr(C)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum ColorKind {
+    Inherit,
+    CurrentColor,
+    ARGB,
+    ParseError
+}
+
+// Keep this in sync with rsvg-css.h:RsvgCssColorSpec
+#[repr(C)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub struct ColorSpec {
+    kind: ColorKind,
+    argb: u32
+}
+
+impl From<cssparser::Color> for ColorSpec {
+    fn from (color: cssparser::Color) -> ColorSpec {
+        match color {
+            cssparser::Color::CurrentColor =>
+                ColorSpec {
+                    kind: ColorKind::CurrentColor,
+                    argb: 0
+                },
+
+            cssparser::Color::RGBA (rgba) =>
+                ColorSpec {
+                    kind: ColorKind::ARGB,
+                    argb: ((rgba.alpha as u32) << 24 |
+                           (rgba.red as u32)   << 16 |
+                           (rgba.green as u32) << 8  |
+                           (rgba.blue as u32))
+                }
+        }
+    }
+}
+
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub struct RawColor {
     pub argb: u32
@@ -80,4 +119,38 @@ mod tests {
         assert! (RawColor::from_str ("").is_err ());
         assert! (RawColor::from_str ("foo").is_err ());
     }
+
+    fn make_color (a: u8, r: u8, g: u8, b: u8) -> cssparser::Color {
+        cssparser::Color::RGBA (cssparser::RGBA::new (r, g, b, a))
+    }
+
+    fn make_color_spec (a: u8, r: u8, g: u8, b: u8) -> ColorSpec {
+        ColorSpec {
+            kind: ColorKind::ARGB,
+            argb: ((a as u32) << 24 |
+                   (r as u32) << 16 |
+                   (g as u32) << 8  |
+                   (b as u32))
+        }
+    }
+
+    fn make_color_spec_current_color () -> ColorSpec {
+        ColorSpec {
+            kind: ColorKind::CurrentColor,
+            argb: 0
+        }
+    }
+
+    #[test]
+    fn color_spec_from_css_color () {
+        assert_eq! (ColorSpec::from (make_color (255, 0, 0, 0)), make_color_spec (255, 0, 0, 0));
+        assert_eq! (ColorSpec::from (make_color (0, 255, 0, 0)), make_color_spec (0, 255, 0, 0));
+        assert_eq! (ColorSpec::from (make_color (0, 0, 255, 0)), make_color_spec (0, 0, 255, 0));
+        assert_eq! (ColorSpec::from (make_color (0, 0, 0, 255)), make_color_spec (0, 0, 0, 255));
+    }
+
+    #[test]
+    fn color_spec_from_css_current_color () {
+        assert_eq! (ColorSpec::from (cssparser::Color::CurrentColor), make_color_spec_current_color ());
+    }
 }
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 3358586..b9abb49 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -26,6 +26,9 @@ pub use cnode::{
     rsvg_rust_cnode_get_impl
 };
 
+pub use color::{
+};
+
 pub use gradient::{
     gradient_linear_new,
     gradient_radial_new,