Feature/manpage (#596)

This PR adds a build script to generate a man page using clap_mangen, as
per this example:
https://github.com/sondr3/clap-man-example/blob/main/build.rs

I'm not sure what to actually do with the man file from here, I guess
it's up to the packaging process to do something with it?
See
https://github.com/shssoichiro/oxipng/issues/69#issuecomment-1963352536

Note I couldn't see a way to include the `DISPLAY` chunk names from the
constant as we did before. They're now just hardcoded into the help and
will require manually updating if the list changes.

Closes #526

---------

Co-authored-by: Alejandro González <me@alegon.dev>

.gitignore

@@ -4,3 +4,4 @@ target
 *.out.png
 /.idea
 /node_modules
+/generated

Cargo.lock

@@ -134,6 +134,16 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2da6da31387c7e4ef160ffab6d5e7f00c42626fe39aea70a7b0f1773f7dd6c1b"
 
+[[package]]
+name = "clap_mangen"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f2e32b579dae093c2424a8b7e2bea09c89da01e1ce5065eb2f0a6f1cc15cc1f"
+dependencies = [
+ "clap",
+ "roff",
+]
+
 [[package]]
 name = "color_quant"
 version = "1.1.0"
@@ -455,6 +465,7 @@ version = "9.0.0"
 dependencies = [
  "bitvec",
  "clap",
+ "clap_mangen",
  "crossbeam-channel",
  "env_logger",
  "filetime",
@@ -529,6 +540,12 @@ dependencies = [
  "bytemuck",
 ]
 
+[[package]]
+name = "roff"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b833d8d034ea094b1ea68aa6d5c740e0d04bad9d16568d08ba6f76823a114316"
+
 [[package]]
 name = "rustc-hash"
 version = "1.1.0"

Cargo.toml

@@ -78,6 +78,8 @@ features = ["png"]
 version = "0.24.6"
 
 [build-dependencies]
+clap = "4.3.8"
+clap_mangen = "0.2.12"
 rustc_version = "0.4.0"
 
 [features]
@@ -98,3 +100,11 @@ opt-level = 2
 lto = "fat"
 strip = "symbols"
 panic = "abort"
+
+[package.metadata.deb]
+assets = [
+    ["target/release/oxipng", "usr/bin/", "755"],
+    ["generated/assets/oxipng.1", "usr/share/man/man1/", "644"],
+    ["README.md", "usr/share/doc/oxipng/", "644"],
+    ["CHANGELOG.md", "usr/share/doc/oxipng/", "644"],
+]

build.rs

@@ -0,0 +1,34 @@
+use std::{
+    env,
+    fs::File,
+    io::{BufWriter, Error},
+    path::Path,
+};
+
+use clap_mangen::Man;
+
+include!("src/cli.rs");
+
+fn build_manpages(outdir: &Path) -> Result<(), Error> {
+    let app = build_command();
+
+    let file = Path::new(&outdir).join("oxipng.1");
+    let mut file = BufWriter::new(File::create(file)?);
+
+    Man::new(app).render(&mut file)?;
+
+    Ok(())
+}
+
+fn main() -> Result<(), Error> {
+    println!("cargo:rerun-if-changed=src/cli.rs");
+    println!("cargo:rerun-if-changed=src/display_chunks.rs");
+
+    // Create `generated/assets/` folder.
+    let path = env::current_dir()?.join("generated").join("assets");
+    std::fs::create_dir_all(&path).unwrap();
+
+    build_manpages(&path)?;
+
+    Ok(())
+}

src/cli.rs

@@ -0,0 +1,357 @@
+use std::path::PathBuf;
+
+use clap::{value_parser, Arg, ArgAction, Command};
+
+include!("display_chunks.rs");
+
+pub fn build_command() -> Command {
+    // Note: clap 'wrap_help' is enabled to automatically wrap lines according to terminal width.
+    // To keep things tidy though, short help descriptions should be no more than 54 characters,
+    // so that they can fit on a single line in an 80 character terminal.
+    // Long help descriptions are soft wrapped here at 90 characters (column 91) but this does not
+    // affect output, it simply matches what is rendered when help is output to a file.
+    Command::new("oxipng")
+        .version(env!("CARGO_PKG_VERSION"))
+        .author("Joshua Holmer <jholmer.in@gmail.com>")
+        .about("Losslessly improve compression of PNG files")
+        .arg(
+            Arg::new("files")
+                .help("File(s) to compress (use '-' for stdin)")
+                .index(1)
+                .num_args(1..)
+                .use_value_delimiter(false)
+                .required(true)
+                .value_parser(value_parser!(PathBuf)),
+        )
+        .arg(
+            Arg::new("optimization")
+                .help("Optimization level (0-6, or max)")
+                .long_help("\
+Set the optimization level preset. The default level 2 is quite fast and provides good \
+compression. Lower levels are faster, higher levels provide better compression, though \
+with increasingly diminishing returns.
+
+    0   => --zc 5 --fast               (1 trial, determined heuristically)
+    1   => --zc 10 --fast              (1 trial, determined heuristically)
+    2   => --zc 11 -f 0,1,6,7 --fast   (4 fast trials, 1 main trial)
+    3   => --zc 11 -f 0,7,8,9          (4 trials)
+    4   => --zc 12 -f 0,7,8,9          (4 trials)
+    5   => --zc 12 -f 0,1,2,5,6,7,8,9  (8 trials)
+    6   => --zc 12 -f 0-9              (10 trials)
+    max =>                             (stable alias for the max level)
+
+Manually specifying a compression option (zc, f, etc.) will override the optimization \
+preset, regardless of the order you write the arguments.")
+                .short('o')
+                .long("opt")
+                .value_name("level")
+                .default_value("2")
+                .value_parser(["0", "1", "2", "3", "4", "5", "6", "max"])
+                .hide_possible_values(true),
+        )
+        .arg(
+            Arg::new("backup")
+                .help("Back up modified files")
+                .short('b')
+                .long("backup")
+                .hide(true)
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("recursive")
+                .help("Recurse input directories, optimizing all PNG files")
+                .long_help("\
+When directories are given as input, traverse the directory trees and optimize all PNG \
+files found (files with “.png” or “.apng” extension).")
+                .short('r')
+                .long("recursive")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("output_dir")
+                .help("Write output file(s) to <directory>")
+                .long_help("\
+Write output file(s) to <directory>. If the directory does not exist, it will be created. \
+Note that this will not preserve the directory structure of the input files when used with \
+'--recursive'.")
+                .long("dir")
+                .value_name("directory")
+                .value_parser(value_parser!(PathBuf))
+                .conflicts_with("output_file")
+                .conflicts_with("stdout"),
+        )
+        .arg(
+            Arg::new("output_file")
+                .help("Write output file to <file>")
+                .long("out")
+                .value_name("file")
+                .value_parser(value_parser!(PathBuf))
+                .conflicts_with("output_dir")
+                .conflicts_with("stdout"),
+        )
+        .arg(
+            Arg::new("stdout")
+                .help("Write output to stdout")
+                .long("stdout")
+                .action(ArgAction::SetTrue)
+                .conflicts_with("output_dir")
+                .conflicts_with("output_file"),
+        )
+        .arg(
+            Arg::new("preserve")
+                .help("Preserve file permissions and timestamps if possible")
+                .short('p')
+                .long("preserve")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("pretend")
+                .help("Do not write any files, only show compression results")
+                .short('P')
+                .long("pretend")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("strip-safe")
+                .help("Strip safely-removable chunks, same as '--strip safe'")
+                .short('s')
+                .action(ArgAction::SetTrue)
+                .conflicts_with("strip"),
+        )
+        .arg(
+            Arg::new("strip")
+                .help("Strip metadata (safe, all, or comma-separated list)\nCAUTION: 'all' will convert APNGs to standard PNGs")
+                .long_help(format!("\
+Strip metadata chunks, where <mode> is one of:
+
+    safe    =>  Strip all non-critical chunks, except for the following:
+                    {}
+    all     =>  Strip all non-critical chunks
+    <list>  =>  Strip chunks in the comma-separated list, e.g. 'bKGD,cHRM'
+
+CAUTION: 'all' will convert APNGs to standard PNGs.
+
+Note that 'bKGD', 'sBIT' and 'hIST' will be forcibly stripped if the color type or bit \
+depth is changed, regardless of any options set.",
+                       DISPLAY_CHUNKS
+                           .iter()
+                           .map(|c| String::from_utf8_lossy(c))
+                           .collect::<Vec<_>>()
+                           .join(", ")))
+                .long("strip")
+                .value_name("mode")
+                .conflicts_with("strip-safe"),
+        )
+        .arg(
+            Arg::new("keep")
+                .help("Strip all metadata except in the comma-separated list")
+                .long_help("\
+Strip all metadata chunks except those in the comma-separated list. The special value \
+'display' includes chunks that affect the image appearance, equivalent to '--strip safe'.
+
+E.g. '--keep eXIf,display' will strip chunks, keeping only eXIf and those that affect the \
+image appearance.")
+                .long("keep")
+                .value_name("list")
+                .conflicts_with("strip")
+                .conflicts_with("strip-safe"),
+        )
+        .arg(
+            Arg::new("alpha")
+                .help("Perform additional alpha channel optimization")
+                .long_help("\
+Perform additional optimization on images with an alpha channel, by altering the color \
+values of fully transparent pixels. This is generally recommended for better compression, \
+but take care as while this is “visually lossless”, it is technically a lossy \
+transformation and may be unsuitable for some applications.")
+                .short('a')
+                .long("alpha")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("interlace")
+                .help("Set PNG interlacing type (0, 1, keep)")
+                .long_help("\
+Set the PNG interlacing type, where <type> is one of:
+
+    0     =>  Remove interlacing from all images that are processed
+    1     =>  Apply Adam7 interlacing on all images that are processed
+    keep  =>  Keep the existing interlacing type of each image
+
+Note that interlacing can add 25-50% to the size of an optimized image. Only use it if you \
+believe the benefits outweigh the costs for your use case.")
+                .short('i')
+                .long("interlace")
+                .value_name("type")
+                .default_value("0")
+                .value_parser(["0", "1", "keep"])
+                .hide_possible_values(true),
+        )
+        .arg(
+            Arg::new("scale16")
+                .help("Forcibly reduce 16-bit images to 8-bit (lossy)")
+                .long_help("\
+Forcibly reduce images with 16 bits per channel to 8 bits per channel. This is a lossy \
+operation but can provide significant savings when you have no need for higher depth. \
+Reduction is performed by scaling the values such that, e.g. 0x00FF is reduced to 0x01 \
+rather than 0x00.
+
+Without this flag, 16-bit images will only be reduced in depth if it can be done \
+losslessly.")
+                .long("scale16")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("verbose")
+                .help("Run in verbose mode (use twice to increase verbosity)")
+                .short('v')
+                .long("verbose")
+                .action(ArgAction::Count)
+                .conflicts_with("quiet"),
+        )
+        .arg(
+            Arg::new("quiet")
+                .help("Run in quiet mode")
+                .short('q')
+                .long("quiet")
+                .action(ArgAction::SetTrue)
+                .conflicts_with("verbose"),
+        )
+        .arg(
+            Arg::new("filters")
+                .help("Filters to try (0-9; see '--help' for details)")
+                .long_help("\
+Perform compression trials with each of the given filter types. You can specify a \
+comma-separated list, or a range of values. E.g. '-f 0-3' is the same as '-f 0,1,2,3'.
+
+PNG delta filters (apply the same filter to every line)
+    0  =>  None      (recommended to always include this filter)
+    1  =>  Sub
+    2  =>  Up
+    3  =>  Average
+    4  =>  Paeth
+
+Heuristic strategies (try to find the best delta filter for each line)
+    5  =>  MinSum    Minimum sum of absolute differences
+    6  =>  Entropy   Highest Shannon entropy
+    7  =>  Bigrams   Lowest count of distinct bigrams
+    8  =>  BigEnt    Highest Shannon entropy of bigrams
+    9  =>  Brute     Smallest compressed size (slow)
+
+The default value depends on the optimization level preset.")
+                .short('f')
+                .long("filters")
+                .value_name("list"),
+        )
+        .arg(
+            Arg::new("fast")
+                .help("Use fast filter evaluation")
+                .long_help("\
+Perform a fast compression evaluation of each enabled filter, followed by a single main \
+compression trial of the best result. Recommended if you have more filters enabled than \
+CPU cores.")
+                .long("fast")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("compression")
+                .help("Deflate compression level (1-12)")
+                .long_help("\
+Deflate compression level (1-12) for main compression trials. The levels here are defined \
+by the libdeflate compression library.
+
+The default value depends on the optimization level preset.")
+                .long("zc")
+                .value_name("level")
+                .value_parser(1..=12)
+                .conflicts_with("zopfli"),
+        )
+        .arg(
+            Arg::new("no-bit-reduction")
+                .help("Do not change bit depth")
+                .long("nb")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("no-color-reduction")
+                .help("Do not change color type")
+                .long("nc")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("no-palette-reduction")
+                .help("Do not change color palette")
+                .long("np")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("no-grayscale-reduction")
+                .help("Do not change to or from grayscale")
+                .long("ng")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("no-reductions")
+                .help("Do not perform any transformations")
+                .long_help("\
+Do not perform any transformations and do not deinterlace by default.")
+                .long("nx")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("no-recoding")
+                .help("Do not recompress unless transformations occur")
+                .long_help("\
+Do not recompress IDAT unless required due to transformations. Recompression of other \
+compressed chunks (such as iCCP) will also be disabled. Note that the combination of \
+'--nx' and '--nz' will fully disable all optimization.")
+                .long("nz")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("fix")
+                .help("Disable checksum validation")
+                .long_help("\
+Do not perform checksum validation of PNG chunks. This may allow some files with errors to \
+be processed successfully.")
+                .long("fix")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("force")
+                .help("Write the output even if it is larger than the input")
+                .long("force")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("zopfli")
+                .help("Use the much slower but stronger Zopfli compressor")
+                .long_help("\
+Use the much slower but stronger Zopfli compressor for main compression trials. \
+Recommended use is with '-o max' and '--fast'.")
+                .short('Z')
+                .long("zopfli")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("timeout")
+                .help("Maximum amount of time to spend on optimizations")
+                .long_help("\
+Maximum amount of time, in seconds, to spend on optimizations. Oxipng will check the \
+timeout before each transformation or compression trial, and will stop trying to optimize \
+the file if the timeout is exceeded. Note that this does not cut short any operations that \
+are already in progress, so it is currently of limited effectiveness for large files with \
+high compression levels.")
+                .value_name("secs")
+                .long("timeout")
+                .value_parser(value_parser!(u64)),
+        )
+        .arg(
+            Arg::new("threads")
+                .help("Set number of threads to use [default: num CPU cores]")
+                .long("threads")
+                .short('t')
+                .value_name("num")
+                .value_parser(value_parser!(usize)),
+        )
+}

src/display_chunks.rs

@@ -0,0 +1,4 @@
+/// List of chunks that affect image display and will be kept when using the `Safe` chunk strip option
+pub const DISPLAY_CHUNKS: [[u8; 4]; 7] = [
+    *b"cICP", *b"iCCP", *b"sRGB", *b"pHYs", *b"acTL", *b"fcTL", *b"fdAT",
+];

src/headers.rs

@@ -5,6 +5,7 @@ use rgb::{RGB16, RGBA8};
 use crate::{
     colors::{BitDepth, ColorType},
     deflate::{crc32, inflate},
+    display_chunks::DISPLAY_CHUNKS,
     error::PngError,
     interlace::Interlacing,
     AtomicMin, Deflaters, PngResult,
@@ -86,17 +87,12 @@ pub enum StripChunks {
 }
 
 impl StripChunks {
-    /// List of chunks that affect image display and will be kept when using the `Safe` option
-    pub const DISPLAY: [[u8; 4]; 7] = [
-        *b"cICP", *b"iCCP", *b"sRGB", *b"pHYs", *b"acTL", *b"fcTL", *b"fdAT",
-    ];
-
     pub(crate) fn keep(&self, name: &[u8; 4]) -> bool {
         match &self {
             StripChunks::None => true,
             StripChunks::Keep(names) => names.contains(name),
             StripChunks::Strip(names) => !names.contains(name),
-            StripChunks::Safe => Self::DISPLAY.contains(name),
+            StripChunks::Safe => DISPLAY_CHUNKS.contains(name),
             StripChunks::All => false,
         }
     }

src/lib.rs

@@ -62,6 +62,7 @@ pub use crate::{
 mod atomicmin;
 mod colors;
 mod deflate;
+mod display_chunks;
 mod error;
 mod evaluate;
 mod filters;

src/main.rs

@@ -20,365 +20,24 @@ mod rayon;
 use std::num::NonZeroU8;
 use std::{ffi::OsString, fs::DirBuilder, io::Write, path::PathBuf, process::exit, time::Duration};
 
-use clap::{value_parser, Arg, ArgAction, ArgMatches, Command};
+use clap::ArgMatches;
+mod cli;
 use indexmap::IndexSet;
 use log::{error, warn, Level, LevelFilter};
 use oxipng::{Deflaters, InFile, Options, OutFile, RowFilter, StripChunks};
 use rayon::prelude::*;
 
+use crate::cli::DISPLAY_CHUNKS;
+
 fn main() {
-    // Note: clap 'wrap_help' is enabled to automatically wrap lines according to terminal width.
+    let matches = cli::build_command()
-    // To keep things tidy though, short help descriptions should be no more than 54 characters,
+        // Set the value parser for filters which isn't appropriate to do in the build_command function
-    // so that they can fit on a single line in an 80 character terminal.
+        .mut_arg("filters", |arg| {
-    // Long help descriptions are soft wrapped here at 90 characters (column 91) but this does not
+            arg.value_parser(|x: &str| {
-    // affect output, it simply matches what is rendered when help is output to a file.
+                parse_numeric_range_opts(x, 0, RowFilter::LAST)
-    let matches = Command::new("oxipng")
+                    .map_err(|_| "Invalid option for filters")
-        .version(env!("CARGO_PKG_VERSION"))
+            })
-        .author("Joshua Holmer <jholmer.in@gmail.com>")
+        })
-        .about("Losslessly improve compression of PNG files")
-        .arg(
-            Arg::new("files")
-                .help("File(s) to compress (use '-' for stdin)")
-                .index(1)
-                .num_args(1..)
-                .use_value_delimiter(false)
-                .required(true)
-                .value_parser(value_parser!(PathBuf)),
-        )
-        .arg(
-            Arg::new("optimization")
-                .help("Optimization level (0-6, or max)")
-                .long_help("\
-Set the optimization level preset. The default level 2 is quite fast and provides good \
-compression. Lower levels are faster, higher levels provide better compression, though \
-with increasingly diminishing returns.
-
-0   => --zc 5 --fast               (1 trial, determined heuristically)
-1   => --zc 10 --fast              (1 trial, determined heuristically)
-2   => --zc 11 -f 0,1,6,7 --fast   (4 fast trials, 1 main trial)
-3   => --zc 11 -f 0,7,8,9          (4 trials)
-4   => --zc 12 -f 0,7,8,9          (4 trials)
-5   => --zc 12 -f 0,1,2,5,6,7,8,9  (8 trials)
-6   => --zc 12 -f 0-9              (10 trials)
-max =>                             (stable alias for the max level)
-
-Manually specifying a compression option (zc, f, etc.) will override the optimization \
-preset, regardless of the order you write the arguments.")
-                .short('o')
-                .long("opt")
-                .value_name("level")
-                .default_value("2")
-                .value_parser(["0", "1", "2", "3", "4", "5", "6", "max"])
-                .hide_possible_values(true),
-        )
-        .arg(
-            Arg::new("backup")
-                .help("Back up modified files")
-                .short('b')
-                .long("backup")
-                .hide(true)
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("recursive")
-                .help("Recurse input directories, optimizing all PNG files")
-                .long_help("\
-When directories are given as input, traverse the directory trees and optimize all PNG \
-files found (files with “.png” or “.apng” extension).")
-                .short('r')
-                .long("recursive")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("output_dir")
-                .help("Write output file(s) to <directory>")
-                .long_help("\
-Write output file(s) to <directory>. If the directory does not exist, it will be created. \
-Note that this will not preserve the directory structure of the input files when used with \
-'--recursive'.")
-                .long("dir")
-                .value_name("directory")
-                .value_parser(value_parser!(PathBuf))
-                .conflicts_with("output_file")
-                .conflicts_with("stdout"),
-        )
-        .arg(
-            Arg::new("output_file")
-                .help("Write output file to <file>")
-                .long("out")
-                .value_name("file")
-                .value_parser(value_parser!(PathBuf))
-                .conflicts_with("output_dir")
-                .conflicts_with("stdout"),
-        )
-        .arg(
-            Arg::new("stdout")
-                .help("Write output to stdout")
-                .long("stdout")
-                .action(ArgAction::SetTrue)
-                .conflicts_with("output_dir")
-                .conflicts_with("output_file"),
-        )
-        .arg(
-            Arg::new("preserve")
-                .help("Preserve file permissions and timestamps if possible")
-                .short('p')
-                .long("preserve")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("pretend")
-                .help("Do not write any files, only show compression results")
-                .short('P')
-                .long("pretend")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("strip-safe")
-                .help("Strip safely-removable chunks, same as '--strip safe'")
-                .short('s')
-                .action(ArgAction::SetTrue)
-                .conflicts_with("strip"),
-        )
-        .arg(
-            Arg::new("strip")
-                .help("Strip metadata (safe, all, or comma-separated list)\nCAUTION: 'all' will convert APNGs to standard PNGs")
-                .long_help(format!("\
-Strip metadata chunks, where <mode> is one of:
-
-safe    =>  Strip all non-critical chunks, except for the following:
-                {}
-all     =>  Strip all non-critical chunks
-<list>  =>  Strip chunks in the comma-separated list, e.g. 'bKGD,cHRM'
-
-CAUTION: 'all' will convert APNGs to standard PNGs.
-
-Note that 'bKGD', 'sBIT' and 'hIST' will be forcibly stripped if the color type or bit \
-depth is changed, regardless of any options set.",
-                    StripChunks::DISPLAY
-                        .iter()
-                        .map(|c| String::from_utf8_lossy(c))
-                        .collect::<Vec<_>>()
-                        .join(", ")))
-                .long("strip")
-                .value_name("mode")
-                .conflicts_with("strip-safe"),
-        )
-        .arg(
-            Arg::new("keep")
-                .help("Strip all metadata except in the comma-separated list")
-                .long_help("\
-Strip all metadata chunks except those in the comma-separated list. The special value \
-'display' includes chunks that affect the image appearance, equivalent to '--strip safe'.
-
-E.g. '--keep eXIf,display' will strip chunks, keeping only eXIf and those that affect the \
-image appearance.")
-                .long("keep")
-                .value_name("list")
-                .conflicts_with("strip")
-                .conflicts_with("strip-safe"),
-        )
-        .arg(
-            Arg::new("alpha")
-                .help("Perform additional alpha channel optimization")
-                .long_help("\
-Perform additional optimization on images with an alpha channel, by altering the color \
-values of fully transparent pixels. This is generally recommended for better compression, \
-but take care as while this is “visually lossless”, it is technically a lossy \
-transformation and may be unsuitable for some applications.")
-                .short('a')
-                .long("alpha")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("interlace")
-                .help("Set PNG interlacing type (0, 1, keep)")
-                .long_help("\
-Set the PNG interlacing type, where <type> is one of:
-
-0     =>  Remove interlacing from all images that are processed
-1     =>  Apply Adam7 interlacing on all images that are processed
-keep  =>  Keep the existing interlacing type of each image
-
-Note that interlacing can add 25-50% to the size of an optimized image. Only use it if you \
-believe the benefits outweigh the costs for your use case.")
-                .short('i')
-                .long("interlace")
-                .value_name("type")
-                .default_value("0")
-                .value_parser(["0", "1", "keep"])
-                .hide_possible_values(true),
-        )
-        .arg(
-            Arg::new("scale16")
-                .help("Forcibly reduce 16-bit images to 8-bit (lossy)")
-                .long_help("\
-Forcibly reduce images with 16 bits per channel to 8 bits per channel. This is a lossy \
-operation but can provide significant savings when you have no need for higher depth. \
-Reduction is performed by scaling the values such that, e.g. 0x00FF is reduced to 0x01 \
-rather than 0x00.
-
-Without this flag, 16-bit images will only be reduced in depth if it can be done \
-losslessly.")
-                .long("scale16")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("verbose")
-                .help("Run in verbose mode (use twice to increase verbosity)")
-                .short('v')
-                .long("verbose")
-                .action(ArgAction::Count)
-                .conflicts_with("quiet"),
-        )
-        .arg(
-            Arg::new("quiet")
-                .help("Run in quiet mode")
-                .short('q')
-                .long("quiet")
-                .action(ArgAction::SetTrue)
-                .conflicts_with("verbose"),
-        )
-        .arg(
-            Arg::new("filters")
-                .help(format!("Filters to try (0-{}; see '--help' for details)", RowFilter::LAST))
-                .long_help("\
-Perform compression trials with each of the given filter types. You can specify a \
-comma-separated list, or a range of values. E.g. '-f 0-3' is the same as '-f 0,1,2,3'.
-
-PNG delta filters (apply the same filter to every line)
-    0  =>  None      (recommended to always include this filter)
-    1  =>  Sub
-    2  =>  Up
-    3  =>  Average
-    4  =>  Paeth
-Heuristic strategies (try to find the best delta filter for each line)
-    5  =>  MinSum    Minimum sum of absolute differences
-    6  =>  Entropy   Highest Shannon entropy
-    7  =>  Bigrams   Lowest count of distinct bigrams
-    8  =>  BigEnt    Highest Shannon entropy of bigrams
-    9  =>  Brute     Smallest compressed size (slow)
-
-The default value depends on the optimization level preset.")
-                .short('f')
-                .long("filters")
-                .value_name("list")
-                .value_parser(|x: &str| {
-                    parse_numeric_range_opts(x, 0, RowFilter::LAST)
-                        .map_err(|_| "Invalid option for filters")
-                }),
-        )
-        .arg(
-            Arg::new("fast")
-                .help("Use fast filter evaluation")
-                .long_help("\
-Perform a fast compression evaluation of each enabled filter, followed by a single main \
-compression trial of the best result. Recommended if you have more filters enabled than \
-CPU cores.")
-                .long("fast")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("compression")
-                .help("Deflate compression level (1-12)")
-                .long_help("\
-Deflate compression level (1-12) for main compression trials. The levels here are defined \
-by the libdeflate compression library.
-
-The default value depends on the optimization level preset.")
-                .long("zc")
-                .value_name("level")
-                .value_parser(1..=12)
-                .conflicts_with("zopfli"),
-        )
-        .arg(
-            Arg::new("no-bit-reduction")
-                .help("Do not change bit depth")
-                .long("nb")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("no-color-reduction")
-                .help("Do not change color type")
-                .long("nc")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("no-palette-reduction")
-                .help("Do not change color palette")
-                .long("np")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("no-grayscale-reduction")
-                .help("Do not change to or from grayscale")
-                .long("ng")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("no-reductions")
-                .help("Do not perform any transformations")
-                .long_help("\
-Do not perform any transformations and do not deinterlace by default.")
-                .long("nx")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("no-recoding")
-                .help("Do not recompress unless transformations occur")
-                .long_help("\
-Do not recompress IDAT unless required due to transformations. Recompression of other \
-compressed chunks (such as iCCP) will also be disabled. Note that the combination of \
-'--nx' and '--nz' will fully disable all optimization.")
-                .long("nz")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("fix")
-                .help("Disable checksum validation")
-                .long_help("\
-Do not perform checksum validation of PNG chunks. This may allow some files with errors to \
-be processed successfully.")
-                .long("fix")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("force")
-                .help("Write the output even if it is larger than the input")
-                .long("force")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("zopfli")
-                .help("Use the much slower but stronger Zopfli compressor")
-                .long_help("\
-Use the much slower but stronger Zopfli compressor for main compression trials. \
-Recommended use is with '-o max' and '--fast'.")
-                .short('Z')
-                .long("zopfli")
-                .action(ArgAction::SetTrue),
-        )
-        .arg(
-            Arg::new("timeout")
-                .help("Maximum amount of time to spend on optimizations")
-                .long_help("\
-Maximum amount of time, in seconds, to spend on optimizations. Oxipng will check the \
-timeout before each transformation or compression trial, and will stop trying to optimize \
-the file if the timeout is exceeded. Note that this does not cut short any operations that \
-are already in progress, so it is currently of limited effectiveness for large files with \
-high compression levels.")
-                .value_name("secs")
-                .long("timeout")
-                .value_parser(value_parser!(u64)),
-        )
-        .arg(
-            Arg::new("threads")
-                .help("Set number of threads to use [default: num CPU cores]")
-                .long("threads")
-                .short('t')
-                .value_name("num")
-                .value_parser(value_parser!(usize)),
-        )
         .after_help("Run `oxipng --help` to see full details of all options")
         .after_long_help("")
         .get_matches_from(std::env::args());
@@ -624,7 +283,7 @@ fn parse_opts_into_struct(
             })
             .collect::<Result<IndexSet<_>, _>>()?;
         if keep_display {
-            names.extend(StripChunks::DISPLAY.iter().cloned());
+            names.extend(DISPLAY_CHUNKS.iter().cloned());
         }
         opts.strip = StripChunks::Keep(names)
     }