Add BGRA and BGR support.

README.md

@@ -59,6 +59,8 @@ All image format decoders implement the ```ImageDecoder``` trait which provides
 ```image``` provides the following pixel types:
 + **Rgb**: RGB pixel
 + **Rgba**: RGBA pixel
++ **Bgr**: BGR pixel
++ **Bgra**: BGRA pixel
 + **Luma**: Grayscale pixel
 + **LumaA**: Grayscale with alpha
 

src/buffer.rs

@@ -6,7 +6,7 @@ use std::io;
 use num_traits::Zero;
 
 use traits::Primitive;
-use color::{ Rgb, Rgba, Luma, LumaA, FromColor, ColorType };
+use color::{ Bgr, Bgra, Rgb, Rgba, Luma, LumaA, FromColor, ColorType };
 use image::GenericImage;
 use dynimage::save_buffer;
 use utils::expand_packed;
@@ -64,6 +64,12 @@ pub trait Pixel: Copy + Clone {
     /// Convert this pixel to RGB with an alpha channel
     fn to_rgba(&self) -> Rgba<Self::Subpixel>;
 
+    /// Convert this pixel to BGR
+    fn to_bgr(&self) -> Bgr<Self::Subpixel>;
+
+    /// Convert this pixel to BGRA with an alpha channel
+    fn to_bgra(&self) -> Bgra<Self::Subpixel>;
+
     /// Convert this pixel to luma
     fn to_luma(&self) -> Luma<Self::Subpixel>;
 
@@ -609,11 +615,15 @@ pub type RgbaImage = ImageBuffer<Rgba<u8>, Vec<u8>>;
 pub type GrayImage = ImageBuffer<Luma<u8>, Vec<u8>>;
 /// Sendable grayscale + alpha channel image buffer
 pub type GrayAlphaImage = ImageBuffer<LumaA<u8>, Vec<u8>>;
+/// Sendable Bgr image buffer
+pub type BgrImage = ImageBuffer<Bgr<u8>, Vec<u8>>;
+/// Sendable Bgr + alpha channel image buffer
+pub type BgraImage = ImageBuffer<Bgra<u8>, Vec<u8>>;
 
 #[cfg(test)]
 mod test {
 
-    use super::{ImageBuffer, RgbImage};
+    use super::{ImageBuffer, RgbImage, ConvertBuffer, Pixel, GrayImage};
     use color;
     #[cfg(feature = "benchmarks")]
     use test;