Save image with specified format

src/buffer.rs

@@ -7,8 +7,8 @@ use std::slice::{Chunks, ChunksMut};
 
 use color::{ColorType, FromColor, Luma, LumaA, Rgb, Rgba, Bgr, Bgra};
 use flat::{FlatSamples, SampleLayout};
-use dynimage::save_buffer;
-use image::{GenericImage, GenericImageView};
+use dynimage::{save_buffer, save_buffer_with_format};
+use image::{GenericImage, GenericImageView, ImageFormat};
 use traits::Primitive;
 use utils::expand_packed;
 
@@ -768,6 +768,29 @@ where
     }
 }
 
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel<Subpixel = u8> + 'static,
+    Container: Deref<Target = [u8]>,
+{
+    /// Saves the buffer to a file at the specified path in
+    /// the specified format.
+    pub fn save_with_format<Q>(&self, path: Q, format: ImageFormat) -> io::Result<()>
+    where
+        Q: AsRef<Path>,
+    {
+        // This is valid as the subpixel is u8.
+        save_buffer_with_format(
+            path,
+            self,
+            self.width(),
+            self.height(),
+            <P as Pixel>::COLOR_TYPE,
+            format,
+        )
+    }
+}
+
 impl<P, Container> Deref for ImageBuffer<P, Container>
 where
     P: Pixel + 'static,

src/dynimage.rs

@@ -564,6 +564,17 @@ impl DynamicImage {
             p.save(path)
         })
     }
+
+    /// Saves the buffer to a file at the specified path in
+    /// the specified format.
+    pub fn save_with_format<Q>(&self, path: Q, format: ImageFormat) -> io::Result<()>
+    where
+        Q: AsRef<Path>,
+    {
+        dynamic_map!(*self, ref p -> {
+            p.save_with_format(path, format)
+        })
+    }
 }
 
 #[allow(deprecated)]
@@ -881,6 +892,59 @@ fn save_buffer_impl(
     }
 }
 
+/// Saves the supplied buffer to a file at the path specified
+/// in the specified format.
+///
+/// The buffer is assumed to have the correct format according
+/// to the specified color type.
+/// This will lead to corrupted files if the buffer contains
+/// malformed data. Currently only jpeg, png, ico, pnm, bmp and
+/// tiff files are supported.
+pub fn save_buffer_with_format<P>(
+    path: P,
+    buf: &[u8],
+    width: u32,
+    height: u32,
+    color: color::ColorType,
+    format: ImageFormat,
+) -> io::Result<()>
+where
+    P: AsRef<Path>,
+{
+    // thin wrapper function to strip generics
+    save_buffer_with_format_impl(path.as_ref(), buf, width, height, color, format)
+}
+
+fn save_buffer_with_format_impl(
+    path: &Path,
+    buf: &[u8],
+    width: u32,
+    height: u32,
+    color: color::ColorType,
+    format: ImageFormat,
+) -> io::Result<()> {
+    let fout = &mut BufWriter::new(File::create(path)?);
+
+    match format {
+        #[cfg(feature = "ico")]
+        image::ImageFormat::ICO => ico::ICOEncoder::new(fout).encode(buf, width, height, color),
+        #[cfg(feature = "jpeg")]
+        image::ImageFormat::JPEG => jpeg::JPEGEncoder::new(fout).encode(buf, width, height, color),
+        #[cfg(feature = "png_codec")]
+        image::ImageFormat::PNG => png::PNGEncoder::new(fout).encode(buf, width, height, color),
+        #[cfg(feature = "bmp")]
+        image::ImageFormat::BMP => bmp::BMPEncoder::new(fout).encode(buf, width, height, color),
+        #[cfg(feature = "tiff")]
+        image::ImageFormat::TIFF => tiff::TiffEncoder::new(fout)
+            .encode(buf, width, height, color)
+            .map_err(|e| io::Error::new(io::ErrorKind::Other, Box::new(e))),
+        _ => Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            &format!("Unsupported image format image/{:?}", format)[..],
+        )),
+    }
+}
+
 /// Create a new image from a Reader
 pub fn load<R: BufRead + Seek>(r: R, format: ImageFormat) -> ImageResult<DynamicImage> {
     #[allow(deprecated, unreachable_patterns)]