[librsvg] RawColor: Add new_rgb() and new_argb() constructors to make callers nicer

[Federico Mena Quintero <federico src gnome org>]

commit 81bbfe8e5a9815bda2f63d694900021a3c3d8a80
Author: Federico Mena Quintero <federico gnome org>
Date:   Thu May 18 13:13:18 2017 -0500

    RawColor: Add new_rgb() and new_argb() constructors to make callers nicer

 rust/src/color.rs |   65 +++++++++++++++++++++++++++++++---------------------
 1 files changed, 39 insertions(+), 26 deletions(-)
---
diff --git a/rust/src/color.rs b/rust/src/color.rs
index 62a8522..6ac2ee1 100644
--- a/rust/src/color.rs
+++ b/rust/src/color.rs
@@ -8,6 +8,26 @@ pub struct RawColor {
     pub argb: u32
 }
 
+impl RawColor {
+    pub fn new_rgb (r: u8, g: u8, b: u8) -> RawColor {
+        RawColor {
+            argb: (0xff000000       |
+                   (r as u32) << 16 |
+                   (g as u32) << 8  |
+                   (b as u32))
+        }
+    }
+
+    pub fn new_argb (a: u8, r: u8, g: u8, b: u8) -> RawColor {
+        RawColor {
+            argb: ((a as u32) << 24 |
+                   (r as u32) << 16 |
+                   (g as u32) << 8  |
+                   (b as u32))
+        }
+    }
+}
+
 impl FromStr for RawColor {
     type Err = AttributeError;
 
@@ -31,45 +51,38 @@ fn hex_digit (c: u8) -> Result<u8, ()> {
 }
 
 fn parse_hex (s: &[u8]) -> Result<RawColor, ()> {
-    let result: Result<u32, ()> = match s.len () {
+    match s.len () {
         8 => {
             // #rrggbbaa -> 0xaarrggbb
-            Ok (((hex_digit (s[0])? * 16 + hex_digit (s[1])?) as u32) << 16 |
-                ((hex_digit (s[2])? * 16 + hex_digit (s[3])?) as u32) << 8  |
-                ((hex_digit (s[4])? * 16 + hex_digit (s[5])?) as u32)       |
-                ((hex_digit (s[6])? * 16 + hex_digit (s[7])?) as u32) << 24)
+            Ok (RawColor::new_argb (hex_digit (s[6])? * 16 + hex_digit (s[7])?,
+                                    hex_digit (s[0])? * 16 + hex_digit (s[1])?,
+                                    hex_digit (s[2])? * 16 + hex_digit (s[3])?,
+                                    hex_digit (s[4])? * 16 + hex_digit (s[5])?))
         },
 
         6 => {
             // #rrggbb -> 0xffrrggbb
-            Ok (0xff000000 |
-                ((hex_digit (s[0])? * 16 + hex_digit (s[1])?) as u32) << 16 |
-                ((hex_digit (s[2])? * 16 + hex_digit (s[3])?) as u32) << 8  |
-                ((hex_digit (s[4])? * 16 + hex_digit (s[5])?) as u32))
+            Ok (RawColor::new_rgb (hex_digit (s[0])? * 16 + hex_digit (s[1])?,
+                                   hex_digit (s[2])? * 16 + hex_digit (s[3])?,
+                                   hex_digit (s[4])? * 16 + hex_digit (s[5])?))
         },
 
         4 => {
             // #rgba -> 0xaarrggbb
-            Ok (((hex_digit (s[0])? * 0x11) as u32) << 16 |
-                ((hex_digit (s[1])? * 0x11) as u32) << 8  |
-                ((hex_digit (s[2])? * 0x11) as u32)       |
-                ((hex_digit (s[3])? * 0x11) as u32) << 24)  
+            Ok (RawColor::new_argb (hex_digit (s[3])? * 0x11,
+                                    hex_digit (s[0])? * 0x11,
+                                    hex_digit (s[1])? * 0x11,
+                                    hex_digit (s[2])? * 0x11))
         },
 
         3 => {
             // #rgb -> 0xffrrggbb
-            Ok (0xff000000 |
-                ((hex_digit (s[0])? * 0x11) as u32) << 16 |
-                ((hex_digit (s[1])? * 0x11) as u32) << 8  |
-                ((hex_digit (s[2])? * 0x11) as u32))
+            Ok (RawColor::new_rgb (hex_digit (s[0])? * 0x11,
+                                   hex_digit (s[1])? * 0x11,
+                                   hex_digit (s[2])? * 0x11))
         }
 
         _ => Err (())
-    };
-
-    match result {
-        Ok (argb) => Ok (RawColor { argb: argb }),
-        Err (_)   => Err (())
     }
 }
 
@@ -80,10 +93,10 @@ mod tests {
 
     #[test]
     fn parses_hash_hex_colors () {
-        assert_eq! (RawColor::from_str ("#AB10fa20").unwrap (), RawColor { argb: 0x20ab10fa });
-        assert_eq! (RawColor::from_str ("#10fa20").unwrap (),   RawColor { argb: 0xff10fa20 });
-        assert_eq! (RawColor::from_str ("#abcd").unwrap (),     RawColor { argb: 0xddaabbcc });
-        assert_eq! (RawColor::from_str ("#123").unwrap (),      RawColor { argb: 0xff112233 });
+        assert_eq! (RawColor::from_str ("#AB10fa20").unwrap (), RawColor::new_argb (0x20, 0xab, 0x10, 0xfa));
+        assert_eq! (RawColor::from_str ("#10fa20").unwrap (),   RawColor::new_rgb  (0x10, 0xfa, 0x20));
+        assert_eq! (RawColor::from_str ("#abcd").unwrap (),     RawColor::new_argb (0xdd, 0xaa, 0xbb, 0xcc));
+        assert_eq! (RawColor::from_str ("#123").unwrap (),      RawColor::new_rgb  (0x11, 0x22, 0x33));
     }
 
     #[test]