Separate PartialInfo from Info

src/common.rs

@@ -77,6 +77,16 @@ impl ColorType {
                 || self == ColorType::Rgba))
             || (bit_depth == BitDepth::Sixteen && self == ColorType::Indexed)
     }
+
+    pub(crate) fn bits_per_pixel(&self, bit_depth: BitDepth) -> usize {
+        self.samples() * bit_depth as usize
+    }
+
+    pub(crate) fn bytes_per_pixel(&self, bit_depth: BitDepth) -> usize {
+        // If adjusting this for expansion or other transformation passes, remember to keep the old
+        // implementation for bpp_in_prediction, which is internal to the png specification.
+        self.samples() * ((bit_depth as usize + 7) >> 3)
+    }
 }
 
 /// Bit depth of the PNG file.
@@ -683,14 +693,14 @@ impl Info<'_> {
 
     /// Returns the number of bits per pixel.
     pub fn bits_per_pixel(&self) -> usize {
-        self.color_type.samples() * self.bit_depth as usize
+        self.color_type.bits_per_pixel(self.bit_depth)
     }
 
     /// Returns the number of bytes per pixel.
     pub fn bytes_per_pixel(&self) -> usize {
         // If adjusting this for expansion or other transformation passes, remember to keep the old
         // implementation for bpp_in_prediction, which is internal to the png specification.
-        self.color_type.samples() * ((self.bit_depth as usize + 7) >> 3)
+        self.color_type.bytes_per_pixel(self.bit_depth)
     }
 
     /// Return the number of bytes for this pixel used in prediction.

src/encoder.rs

@@ -514,33 +514,20 @@ impl PartialInfo {
     }
 
     fn bpp_in_prediction(&self) -> BytesPerPixel {
-        // Passthrough
-        self.to_info().bpp_in_prediction()
+        BytesPerPixel::from_usize(self.bytes_per_pixel())
+    }
+
+    fn bytes_per_pixel(&self) -> usize {
+        self.color_type.bytes_per_pixel(self.bit_depth)
     }
 
     fn raw_row_length(&self) -> usize {
-        // Passthrough
-        self.to_info().raw_row_length()
+        self.raw_row_length_from_width(self.width)
     }
 
     fn raw_row_length_from_width(&self, width: u32) -> usize {
-        // Passthrough
-        self.to_info().raw_row_length_from_width(width)
-    }
-
-    /// Converts this partial info to an owned Info struct,
-    /// setting missing values to their defaults
-    fn to_info(&self) -> Info<'static> {
-        Info {
-            width: self.width,
-            height: self.height,
-            bit_depth: self.bit_depth,
-            color_type: self.color_type,
-            frame_control: self.frame_control,
-            animation_control: self.animation_control,
-            compression: self.compression,
-            ..Default::default()
-        }
+        self.color_type
+            .raw_row_length_from_width(self.bit_depth, width)
     }
 }