feat: optimize png encoding (#12)

Cargo.toml

@@ -25,6 +25,6 @@ cast_sign_loss = "allow"
 [dependencies]
 clap = { version = "4.5", features = ["derive"] }
 env_logger = "0.10"
-image = "0.25"
+image = { version = "0.25", features = ["png"] }
 log = "0.4"
 thiserror = "1.0"

src/image_util.rs

@@ -1,6 +1,8 @@
-use std::{fs, path::Path};
+use std::{fs, ops::Deref, path::Path};
 
-use image::RgbaImage;
+use image::{
+    codecs::png, EncodableLayout, ImageBuffer, ImageEncoder, Pixel, PixelWithColorType, RgbaImage,
+};
 
 #[derive(Debug, thiserror::Error)]
 pub enum ImgUtilError {
@@ -157,3 +159,33 @@ pub fn crop_images(images: &mut Vec<RgbaImage>) -> ImgUtilResult<(i32, i32)> {
 
     Ok((shift_x, shift_y))
 }
+
+pub trait ImageBufferExt<P, C> {
+    fn save_optimized_png(&self, path: impl AsRef<Path>) -> ImgUtilResult<()>;
+}
+
+impl<P, C> ImageBufferExt<P, C> for ImageBuffer<P, C>
+where
+    P: Pixel + PixelWithColorType,
+    [P::Subpixel]: EncodableLayout,
+    C: Deref<Target = [P::Subpixel]>,
+{
+    fn save_optimized_png(&self, path: impl AsRef<Path>) -> ImgUtilResult<()> {
+        let mut file = fs::File::create(path)?;
+
+        let (width, height) = self.dimensions();
+        png::PngEncoder::new_with_quality(
+            &mut file,
+            png::CompressionType::Best,
+            png::FilterType::default(),
+        )
+        .write_image(
+            self.as_bytes(),
+            width,
+            height,
+            <P as PixelWithColorType>::COLOR_TYPE,
+        )?;
+
+        Ok(())
+    }
+}

src/main.rs

@@ -6,6 +6,7 @@ use std::{
 
 use clap::{Args, Parser, Subcommand};
 use image::{ImageBuffer, RgbaImage};
+use image_util::ImageBufferExt;
 
 #[macro_use]
 extern crate log;
@@ -277,10 +278,7 @@ fn generate_mipmap_icon(args: &IconArgs) -> Result<(), CommandError> {
 
     image::imageops::crop_imm(&res, 0, 0, total_width, res.height())
         .to_image()
-        .save_with_format(
-            output_name(&args.source, &args.output, None, "png"),
-            image::ImageFormat::Png,
-        )?;
+        .save_optimized_png(output_name(&args.source, &args.output, None, "png"))?;
 
     Ok(())
 }
@@ -401,7 +399,7 @@ fn generate_spritesheet(
 
     // save sheets
     for (sheet, path) in sheets {
-        sheet.save_with_format(path, image::ImageFormat::Png)?;
+        sheet.save_optimized_png(path)?;
     }
 
     let name = output_name(source, &args.output, None, "");