Add --ziwi option

src/cli.rs

@@ -340,6 +340,17 @@ speed up compression for large files. This option requires '--zopfli' to be set.
                 .value_parser(value_parser!(NonZeroU64))
                 .requires("zopfli"),
         )
+        .arg(
+            Arg::new("iterations-without-improvement")
+                .hide_short_help(true)
+                .long_help("\
+Stop Zopfli compression after this number of iterations without improvement. Use this in \
+conjunction with a high value for '--zi' to achieve better compression in reasonable time.")
+                .long("ziwi")
+                .value_name("iterations")
+                .value_parser(value_parser!(NonZeroU64))
+                .requires("zopfli"),
+        )
         .arg(
             Arg::new("timeout")
                 .help("Maximum amount of time to spend on optimizations")

src/main.rs

@@ -334,8 +334,12 @@ fn parse_opts_into_struct(
     #[cfg(feature = "zopfli")]
     if matches.get_flag("zopfli") {
         let iteration_count = *matches.get_one::<NonZeroU64>("iterations").unwrap();
+        let iterations_without_improvement = *matches
+            .get_one::<NonZeroU64>("iterations-without-improvement")
+            .unwrap_or(&NonZeroU64::MAX);
         opts.deflater = Deflater::Zopfli(ZopfliOptions {
             iteration_count,
+            iterations_without_improvement,
             ..Default::default()
         });
     }