Allow APNG with reductions disabled

src/lib.rs

@@ -32,6 +32,7 @@ use crate::png::PngImage;
 use crate::reduction::*;
 use log::{debug, info, trace, warn};
 use rayon::prelude::*;
+use std::borrow::Cow;
 use std::fmt;
 use std::fs::{copy, File, Metadata};
 use std::io::{stdin, stdout, BufWriter, Read, Write};
@@ -559,17 +560,30 @@ fn optimize_png(
  debug!(" IDAT size = {} bytes", idat_original_size);
  debug!(" File size = {} bytes", file_original_size);
 
+ // Check for APNG by presence of acTL chunk
+ let opts = if png.aux_chunks.iter().any(|c| &c.name == b"acTL") {
+ warn!("APNG detected, disabling all reductions");
+ let mut opts = opts.to_owned();
+ opts.interlace = None;
+ opts.bit_depth_reduction = false;
+ opts.color_type_reduction = false;
+ opts.palette_reduction = false;
+ opts.grayscale_reduction = false;
+ Cow::Owned(opts)
+ } else {
+ Cow::Borrowed(opts)
+ };
  let max_size = if opts.force {
  None
  } else {
  Some(png.estimated_output_size())
  };
- if let Some(new_png) = optimize_raw(raw.clone(), opts, deadline, max_size) {
+ if let Some(new_png) = optimize_raw(raw.clone(), &opts, deadline, max_size) {
  png.raw = new_png.raw;
  png.idat_data = new_png.idat_data;
  }
 
- postprocess_chunks(png, opts, &raw.ihdr);
+ postprocess_chunks(png, &opts, &raw.ihdr);
 
  let output = png.output();
 

src/png/mod.rs

@@ -93,8 +93,16 @@ impl PngData {
  let mut aux_chunks: Vec<Chunk> = Vec::new();
  while let Some(chunk) = parse_next_chunk(byte_data, &mut byte_offset, opts.fix_errors)? {
  match &chunk.name {
- b"IDAT" => idat_data.extend_from_slice(chunk.data),
- b"acTL" => return Err(PngError::APNGNotSupported),
+ b"IDAT" => {
+ if idat_data.is_empty() {
+ // Keep track of where the first IDAT sits relative to other chunks
+ aux_chunks.push(Chunk {
+ name: chunk.name,
+ data: Vec::new(),
+ })
+ }
+ idat_data.extend_from_slice(chunk.data);
+ }
  b"IHDR" | b"PLTE" | b"tRNS" => {
  key_chunks.insert(chunk.name, chunk.data.to_owned());
  }
@@ -165,9 +173,10 @@ impl PngData {
  ihdr_data.write_all(&[0]).ok(); // Filter method -- 5-way adaptive filtering
  ihdr_data.write_all(&[self.raw.ihdr.interlaced as u8]).ok();
  write_png_block(b"IHDR", &ihdr_data, &mut output);
- // Ancillary chunks
- for chunk in self
- .aux_chunks
+ // Ancillary chunks - split into those that come before IDAT and those that come after
+ let mut aux_split = self.aux_chunks.split(|c| &c.name == b"IDAT");
+ let aux_pre = aux_split.next().unwrap();
+ for chunk in aux_pre
  .iter()
  .filter(|c| !(&c.name == b"bKGD" || &c.name == b"hIST" || &c.name == b"tRNS"))
  {
@@ -202,15 +211,20 @@ impl PngData {
  _ => {}
  }
  // Special ancillary chunks that need to come after PLTE but before IDAT
- for chunk in self
- .aux_chunks
+ for chunk in aux_pre
  .iter()
  .filter(|c| &c.name == b"bKGD" || &c.name == b"hIST" || &c.name == b"tRNS")
  {
  write_png_block(&chunk.name, &chunk.data, &mut output);
  }
  // IDAT data
  write_png_block(b"IDAT", &self.idat_data, &mut output);
+ // Ancillary chunks that come after IDAT
+ for aux_post in aux_split {
+ for chunk in aux_post {
+ write_png_block(&chunk.name, &chunk.data, &mut output);
+ }
+ }
  // Stream end
  write_png_block(b"IEND", &[], &mut output);
 

tests/lib.rs

@@ -30,7 +30,7 @@ fn optimize_from_memory_apng() {
  in_file.read_to_end(&mut in_file_buf).unwrap();
 
  let result = oxipng::optimize_from_memory(&in_file_buf, &Options::default());
- assert!(result.is_err());
+ assert!(result.is_ok());
 }
 
 #[test]
@@ -58,9 +58,9 @@ fn optimize_apng() {
  let result = oxipng::optimize(
  &"tests/files/apng_file.png".into(),
  &OutFile::Path(None),
- &Options::default(),
+ &Options::from_preset(0),
  );
- assert!(result.is_err());
+ assert!(result.is_ok());
 }
 
 #[test]