Simplify tracking of reduction_occurred

src/evaluate.rs

@@ -25,7 +25,6 @@ pub struct Candidate {
     pub idat_data: Vec<u8>,
     pub filtered: Vec<u8>,
     pub filter: RowFilter,
-    pub is_reduction: bool,
     // first wins tie-breaker
     nth: usize,
 }
@@ -95,11 +94,6 @@ impl Evaluator {
         self.eval_best_candidate.into_inner()
     }
 
-    /// Set baseline image. It will be used only to measure minimum compression level required
-    pub fn set_baseline(&self, image: Arc<PngImage>) {
-        self.try_image_inner(image, false)
-    }
-
     /// Set best size, if known in advance
     pub fn set_best_size(&self, size: usize) {
         self.best_candidate_size.set_min(size);
@@ -107,10 +101,6 @@ impl Evaluator {
 
     /// Check if the image is smaller than others
     pub fn try_image(&self, image: Arc<PngImage>) {
-        self.try_image_inner(image, true)
-    }
-
-    fn try_image_inner(&self, image: Arc<PngImage>, is_reduction: bool) {
         let nth = self.nth.fetch_add(1, SeqCst);
         // These clones are only cheap refcounts
         let deadline = self.deadline.clone();
@@ -150,7 +140,6 @@ impl Evaluator {
                         idat_data,
                         filtered,
                         filter,
-                        is_reduction,
                         nth,
                     };
 

src/lib.rs

@@ -615,7 +615,7 @@ fn optimize_png(
 
 /// Perform optimization on the input image data using the options provided
 fn optimize_raw(
-    mut png: Arc<PngImage>,
+    image: Arc<PngImage>,
     opts: &Options,
     deadline: Arc<Deadline>,
     max_size: Option<usize>,
@@ -631,16 +631,14 @@ fn optimize_raw(
         eval_compression,
         false,
     );
-    let (baseline, mut reduction_occurred) =
-        perform_reductions(png.clone(), opts, &deadline, &eval);
-    png = baseline;
+    let mut png = perform_reductions(image.clone(), opts, &deadline, &eval);
     let mut eval_result = eval.get_best_candidate();
     if let Some(ref result) = eval_result {
-        if result.is_reduction {
-            png = result.image.clone();
-            reduction_occurred = true;
-        }
+        png = result.image.clone();
     }
+    let reduction_occurred = png.ihdr.color_type != image.ihdr.color_type
+        || png.ihdr.bit_depth != image.ihdr.bit_depth
+        || png.ihdr.interlaced != image.ihdr.interlaced;
 
     if reduction_occurred {
         report_format("Reducing image to ", &png);

src/reduction/mod.rs

@@ -18,15 +18,13 @@ pub(crate) fn perform_reductions(
     opts: &Options,
     deadline: &Deadline,
     eval: &Evaluator,
-) -> (Arc<PngImage>, bool) {
-    let mut reduction_occurred = false;
+) -> Arc<PngImage> {
     let mut evaluation_added = false;
 
     // Interlacing must be processed first in order to evaluate the rest correctly
     if let Some(interlacing) = opts.interlace {
         if let Some(reduced) = png.change_interlacing(interlacing) {
             png = Arc::new(reduced);
-            reduction_occurred = true;
         }
     }
 
@@ -35,7 +33,6 @@ pub(crate) fn perform_reductions(
     if opts.optimize_alpha && !deadline.passed() {
         if let Some(reduced) = cleaned_alpha_channel(&png) {
             png = Arc::new(reduced);
-            // This does not count as a reduction
         }
     }
 
@@ -44,7 +41,6 @@ pub(crate) fn perform_reductions(
     if opts.bit_depth_reduction && !deadline.passed() {
         if let Some(reduced) = reduced_bit_depth_16_to_8(&png, opts.scale_16) {
             png = Arc::new(reduced);
-            reduction_occurred = true;
         }
     }
 
@@ -53,7 +49,6 @@ pub(crate) fn perform_reductions(
     if opts.color_type_reduction && opts.grayscale_reduction && !deadline.passed() {
         if let Some(reduced) = reduced_rgb_to_grayscale(&png) {
             png = Arc::new(reduced);
-            reduction_occurred = true;
         }
     }
 
@@ -62,7 +57,6 @@ pub(crate) fn perform_reductions(
     if opts.bit_depth_reduction && !deadline.passed() {
         if let Some(reduced) = expanded_bit_depth_to_8(&png) {
             png = Arc::new(reduced);
-            reduction_occurred = true;
         }
     }
 
@@ -71,7 +65,6 @@ pub(crate) fn perform_reductions(
     if opts.palette_reduction && !deadline.passed() {
         if let Some(reduced) = reduced_palette(&png, opts.optimize_alpha) {
             png = Arc::new(reduced);
-            reduction_occurred = true;
         }
     }
 
@@ -90,7 +83,6 @@ pub(crate) fn perform_reductions(
                 evaluation_added = true;
             } else {
                 baseline = png.clone();
-                reduction_occurred = true;
             }
         }
     }
@@ -127,7 +119,6 @@ pub(crate) fn perform_reductions(
                 evaluation_added = true;
             } else {
                 baseline = new.clone();
-                reduction_occurred = true;
             }
             indexed = Some(new);
         }
@@ -146,7 +137,7 @@ pub(crate) fn perform_reductions(
     }
 
     if evaluation_added {
-        eval.set_baseline(baseline.clone());
+        eval.try_image(baseline.clone());
     }
-    (baseline, reduction_occurred)
+    baseline
 }