pngquant for lossy compression

Cargo.toml

@@ -31,6 +31,7 @@ infer = "0.8"
 image = { version = "0.24", default-features = false, features = ["jpeg", "png", "webp", "gif"] }
 img-parts = "0.2"
 bytes = "1.1"
+imagequant = "4.0.0"
 
 [dev-dependencies]
 dssim = "3.2.0"

README.md

@@ -51,12 +51,12 @@ pub struct Parameters {
 ```Rust
 pub struct Parameters {
     pub oxipng: oxipng::Options,
-    pub level: u32,
+    pub quality: u32,
     pub force_zopfli: bool
 }
 ```
 - `oxipng`: oxipng options. Should be left as default unless you want to do something advanced. Refer to [oxipng](https://github.com/shssoichiro/oxipng) for documentation.
-- `level`: level of optimization, from 1 to 7. Increasing the level will result in a smaller file, at the cost of computation time. If the optimization flag is `true`, the level is set to `6`. Default: `3`.
+- `quality`: in a range from 1 to 100, the quality of the resulting image. Default `80`.
 - `force_zopfli`: if `optimization` is `true` and this option is also `true`, will use zopfli algorithm for compression, resulting in a smaller image, but it may take minutes to finish the process. Default `false`.
 
 #### gif

src/jpeg.rs

@@ -18,7 +18,6 @@ pub fn compress(input_path: String, output_path: String, parameters: CSParameter
 {
     let mut in_file = fs::read(input_path)?;
 
-
     if parameters.width > 0 || parameters.height > 0 {
         if parameters.keep_metadata {
             let metadata = extract_metadata(in_file.clone());

src/lib.rs

@@ -14,7 +14,7 @@ use std::os::raw::c_char;
 pub struct CCSParameters {
     pub keep_metadata: bool,
     pub jpeg_quality: u32,
-    pub png_level: u32,
+    pub png_quality: u32,
     pub png_force_zopfli: bool,
     pub gif_quality: u32,
     pub webp_quality: u32,
@@ -48,7 +48,7 @@ pub fn initialize_parameters() -> CSParameters
 
     let png = png::Parameters {
         oxipng: oxipng::Options::default(),
-        level: 3,
+        quality: 80,
         force_zopfli: false,
     };
 
@@ -78,7 +78,7 @@ pub unsafe extern fn c_compress(input_path: *const c_char, output_path: *const c
     let mut parameters = initialize_parameters();
 
     parameters.jpeg.quality = params.jpeg_quality;
-    parameters.png.level = params.png_level;
+    parameters.png.quality = params.png_quality;
     parameters.optimize = params.optimize;
     parameters.keep_metadata = params.keep_metadata;
     parameters.png.force_zopfli = params.png_force_zopfli;
@@ -140,7 +140,7 @@ fn validate_parameters(parameters: &CSParameters) -> Result<(), Box<dyn Error>>
         return Err("Invalid JPEG quality value".into());
     }
 
-    if parameters.png.level == 0 || parameters.png.level > 7 {
+    if parameters.png.quality > 100 {
         return Err("Invalid PNG quality value".into());
     }
 

src/png.rs

@@ -7,20 +7,35 @@ use crate::resize::resize;
 
 pub struct Parameters {
     pub oxipng: oxipng::Options,
-    pub level: u32,
+    pub quality: u32,
     pub force_zopfli: bool,
 }
 
-pub fn compress(input_path: String, output_path: String, parameters: CSParameters) -> Result<(), io::Error> {
+pub fn compress (input_path: String, output_path: String, parameters: CSParameters) -> Result<(), io::Error> {
     let mut in_file = fs::read(input_path)?;
 
     if parameters.width > 0 || parameters.height > 0 {
         in_file = resize(in_file, parameters.width, parameters.height, Png)?;
     }
 
-    let mut oxipng_options = parameters.png.oxipng;
-    oxipng_options.deflate = oxipng::Deflaters::Libdeflater;
+    let optimized_png: Vec<u8> = if parameters.optimize {
+        lossless(in_file, parameters)?
+    } else {
+        lossy(in_file, parameters)?
+    };
 
+    let mut output_file_buffer = File::create(output_path)?;
+    output_file_buffer.write_all(optimized_png.as_slice())?;
+
+    Ok(())
+}
+
+pub fn lossy (in_file: Vec<u8>, parameters: CSParameters) -> Result<Vec<u8>, io::Error> {
+    lossless(in_file, parameters)
+}
+
+pub fn lossless(in_file: Vec<u8>, parameters: CSParameters) -> Result<Vec<u8>, io::Error> {
+    let mut oxipng_options = parameters.png.oxipng;
     if !parameters.keep_metadata {
         oxipng_options.strip = oxipng::Headers::Safe;
     }
@@ -28,11 +43,7 @@ pub fn compress(input_path: String, output_path: String, parameters: CSParameter
     if parameters.optimize && parameters.png.force_zopfli {
         oxipng_options.deflate = oxipng::Deflaters::Zopfli;
     } else {
-        let mut preset = parameters.png.level - 1;
-        if parameters.optimize {
-            preset = 6;
-        }
-        oxipng_options = oxipng::Options::from_preset(preset as u8);
+        oxipng_options = oxipng::Options::from_preset(6);
     }
 
     let optimized_png = match oxipng::optimize_from_memory(in_file.as_slice(), &oxipng_options) {
@@ -40,8 +51,5 @@ pub fn compress(input_path: String, output_path: String, parameters: CSParameter
         Err(e) => return Err(io::Error::new(io::ErrorKind::Other, e))
     };
 
-    let mut output_file_buffer = File::create(output_path)?;
-    output_file_buffer.write_all(optimized_png.as_slice())?;
-
-    Ok(())
+    Ok(optimized_png)
 }

tests/png.rs

@@ -107,7 +107,7 @@ fn downscale_zopfli_compress_png() {
     let mut params = caesium::initialize_parameters();
     params.width = 150;
     params.height = 150;
-    params.png.level = 3;
+    params.png.quality = 80;
     params.optimize = true;
     params.png.force_zopfli = true;
     caesium::compress(String::from("tests/samples/uncompressed_드림캐쳐.png"),