Fix issue for interlacing images smaller than 4px

Fixes #42

CHANGELOG.md

@@ -1,3 +1,6 @@
+**Version 0.8.2**
+ - Fix issue where images smaller than 4px width would crash on interlacing ([#42](https://github.com/shssoichiro/oxipng/issues/42))
+
 **Version 0.8.1**
  - Minor optimizations
  - Fix issue where interlaced images with certain widths would fail to optimize

Cargo.lock

@@ -1,6 +1,6 @@
 [root]
 name = "oxipng"
-version = "0.8.0"
+version = "0.8.2"
 dependencies = [
  "bit-vec 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "oxipng"
-version = "0.8.1"
+version = "0.8.2"
 authors = ["Joshua Holmer <jholmer.in@gmail.com>"]
 description = "A lossless PNG compression optimizer"
 license = "MIT"

src/lib.rs

@@ -388,11 +388,8 @@ fn optimize_png(mut png: &mut png::PngData, file_original_size: usize, opts: &Op
                 let filtered = filters.get(&trial.0).unwrap();
                 let best = best.clone();
                 scope.execute(move || {
-                    let new_idat = deflate::deflate::deflate(filtered,
-                                                             trial.1,
-                                                             trial.2,
-                                                             trial.3,
-                                                             opts.window)
+                    let new_idat =
+                        deflate::deflate::deflate(filtered, trial.1, trial.2, trial.3, opts.window)
                             .unwrap();
 
                     if opts.verbosity == Some(1) {

src/main.rs

@@ -10,11 +10,10 @@ use std::fs::DirBuilder;
 use std::io::{Write, stderr};
 use std::path::PathBuf;
 
-const VERSION_STRING: &'static str = "0.8.1";
+const VERSION_STRING: &'static str = "0.8.2";
 
 fn main() {
-    let matches =
-        App::new("oxipng")
+    let matches = App::new("oxipng")
         .version(VERSION_STRING)
         .author("Joshua Holmer <jholmer.in@gmail.com>")
         .about("Losslessly improves compression of PNG files")

src/png.rs

@@ -416,9 +416,9 @@ impl PngData {
         ihdr_data.write_u8(self.ihdr_data.interlaced).ok();
         write_png_block(b"IHDR", &ihdr_data, &mut output);
         // Ancillary headers
-        for (key, header) in self.aux_headers.iter().filter(|&(ref key, _)| {
-            !(**key == "bKGD" || **key == "hIST" || **key == "tRNS")
-        }) {
+        for (key, header) in self.aux_headers
+            .iter()
+            .filter(|&(ref key, _)| !(**key == "bKGD" || **key == "hIST" || **key == "tRNS")) {
             write_png_block(key.as_bytes(), header, &mut output);
         }
         // Palette
@@ -433,9 +433,9 @@ impl PngData {
             write_png_block(b"tRNS", &transparency_pixel, &mut output);
         }
         // Special ancillary headers that need to come after PLTE but before IDAT
-        for (key, header) in self.aux_headers.iter().filter(|&(ref key, _)| {
-            **key == "bKGD" || **key == "hIST" || **key == "tRNS"
-        }) {
+        for (key, header) in self.aux_headers
+            .iter()
+            .filter(|&(ref key, _)| **key == "bKGD" || **key == "hIST" || **key == "tRNS") {
             write_png_block(key.as_bytes(), header, &mut output);
         }
         // IDAT data
@@ -548,10 +548,10 @@ impl PngData {
         }
 
         // Reduce from 16 to 8 bits per channel per pixel
-        let mut reduced =
-            Vec::with_capacity((self.ihdr_data.width * self.ihdr_data.height *
+        let mut reduced = Vec::with_capacity((self.ihdr_data.width * self.ihdr_data.height *
                                               self.channels_per_pixel() as u32 +
-                                self.ihdr_data.height) as usize);
+                                              self.ihdr_data
+            .height) as usize);
         let mut high_byte = 0;
 
         for line in self.scan_lines() {
@@ -888,24 +888,34 @@ fn interlace_image(png: &mut PngData) {
     let bits_per_pixel = png.ihdr_data.bit_depth.as_u8() * png.channels_per_pixel();
     for (index, line) in png.scan_lines().enumerate() {
         match index % 8 {
-            // Add filter bytes to appropriate lines
+            // Add filter bytes to passes that will be in the output image
             0 => {
                 passes[0].extend(BitVec::from_elem(8, false));
-                passes[3].extend(BitVec::from_elem(8, false));
-                passes[5].extend(BitVec::from_elem(8, false));
-                if png.ihdr_data.width > 4 {
+                if png.ihdr_data.width >= 5 {
                     passes[1].extend(BitVec::from_elem(8, false));
                 }
+                if png.ihdr_data.width >= 3 {
+                    passes[3].extend(BitVec::from_elem(8, false));
+                }
+                if png.ihdr_data.width >= 2 {
+                    passes[5].extend(BitVec::from_elem(8, false));
+                }
             }
             4 => {
-                passes[3].extend(BitVec::from_elem(8, false));
-                passes[5].extend(BitVec::from_elem(8, false));
                 passes[2].extend(BitVec::from_elem(8, false));
+                if png.ihdr_data.width >= 3 {
+                    passes[3].extend(BitVec::from_elem(8, false));
+                }
+                if png.ihdr_data.width >= 2 {
+                    passes[5].extend(BitVec::from_elem(8, false));
+                }
             }
             2 | 6 => {
                 passes[4].extend(BitVec::from_elem(8, false));
+                if png.ihdr_data.width >= 2 {
                     passes[5].extend(BitVec::from_elem(8, false));
                 }
+            }
             _ => {
                 passes[6].extend(BitVec::from_elem(8, false));
             }
@@ -975,8 +985,7 @@ fn deinterlace_image(png: &mut PngData) {
         let bit_vec = BitVec::from_bytes(&line.data);
         let bits_in_line = ((png.ihdr_data.width - pass_constants.x_shift as u32) as f32 /
                             pass_constants.x_step as f32)
-                               .ceil() as usize *
-                           bits_per_pixel as usize;
+            .ceil() as usize * bits_per_pixel as usize;
         for (i, bit) in bit_vec.iter().enumerate() {
             // Avoid moving padded 0's into new image
             if i >= bits_in_line {

tests/flags.rs

@@ -486,3 +486,44 @@ fn fix_errors() {
     // Cannot check if pixels are equal because image crate cannot read corrupt (input) PNGs
     remove_file(output).ok();
 }
+
+#[test]
+fn issue_42() {
+    let input = PathBuf::from("tests/files/issue_42.png");
+    let mut opts = get_opts(&input);
+    opts.interlace = Some(1);
+    let output = opts.out_file.clone();
+
+    let png = png::PngData::new(&input, opts.fix_errors).unwrap();
+
+    assert_eq!(png.ihdr_data.interlaced, 0);
+    assert_eq!(png.ihdr_data.color_type, png::ColorType::GrayscaleAlpha);
+    assert_eq!(png.ihdr_data.bit_depth, png::BitDepth::Eight);
+
+    match oxipng::optimize(&input, &opts) {
+        Ok(_) => (),
+        Err(x) => panic!(x.to_owned()),
+    };
+    assert!(output.exists());
+
+    let png = match png::PngData::new(&output, opts.fix_errors) {
+        Ok(x) => x,
+        Err(x) => {
+            remove_file(output).ok();
+            panic!(x.to_owned())
+        }
+    };
+
+    assert_eq!(png.ihdr_data.interlaced, 1);
+    assert_eq!(png.ihdr_data.color_type, png::ColorType::GrayscaleAlpha);
+    assert_eq!(png.ihdr_data.bit_depth, png::BitDepth::Eight);
+
+    let old_png = image::open(&input).unwrap();
+    let new_png = image::open(&output).unwrap();
+
+    // Conversion should be lossless
+    assert_eq!(old_png.pixels().map(|x| x.2.channels().to_owned()).collect::<Vec<Vec<u8>>>(),
+               new_png.pixels().map(|x| x.2.channels().to_owned()).collect::<Vec<Vec<u8>>>());
+
+    remove_file(output).ok();
+}