Change BitDepth to u8 representation with TryFrom
This commit is contained in:
Andrew
Josh Holmer
parent
873f0fefbe
commit
4e0cbbe973
8 changed files with 34 additions and 63 deletions
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@ -1,6 +1,8 @@
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use rgb::{RGB16, RGBA8};
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use std::fmt;
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use crate::PngError;
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#[derive(Debug, PartialEq, Eq, Clone)]
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/// The color type used to represent this image
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pub enum ColorType {
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@ -67,64 +69,40 @@ impl ColorType {
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}
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}
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#[repr(u8)]
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#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
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/// The number of bits to be used per channel per pixel
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pub enum BitDepth {
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/// One bit per channel per pixel
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One,
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One = 1,
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/// Two bits per channel per pixel
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Two,
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Two = 2,
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/// Four bits per channel per pixel
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Four,
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Four = 4,
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/// Eight bits per channel per pixel
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Eight,
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Eight = 8,
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/// Sixteen bits per channel per pixel
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Sixteen,
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Sixteen = 16,
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}
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impl TryFrom<u8> for BitDepth {
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type Error = PngError;
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fn try_from(value: u8) -> Result<Self, Self::Error> {
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match value {
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1 => Ok(Self::One),
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2 => Ok(Self::Two),
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4 => Ok(Self::Four),
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8 => Ok(Self::Eight),
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16 => Ok(Self::Sixteen),
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_ => Err(PngError::new("Unexpected bit depth")),
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}
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}
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}
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impl fmt::Display for BitDepth {
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#[inline]
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(
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f,
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"{}",
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match *self {
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BitDepth::One => "1",
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BitDepth::Two => "2",
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BitDepth::Four => "4",
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BitDepth::Eight => "8",
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BitDepth::Sixteen => "16",
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}
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)
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}
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}
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impl BitDepth {
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/// Retrieve the number of bits per channel per pixel as a `u8`
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#[inline]
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pub fn as_u8(self) -> u8 {
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match self {
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BitDepth::One => 1,
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BitDepth::Two => 2,
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BitDepth::Four => 4,
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BitDepth::Eight => 8,
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BitDepth::Sixteen => 16,
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}
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}
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/// Parse a number of bits per channel per pixel into a `BitDepth`
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///
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/// # Panics
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///
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/// If depth is unsupported
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#[inline]
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pub fn from_u8(depth: u8) -> BitDepth {
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match depth {
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1 => BitDepth::One,
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2 => BitDepth::Two,
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4 => BitDepth::Four,
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8 => BitDepth::Eight,
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16 => BitDepth::Sixteen,
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_ => panic!("Unsupported bit depth"),
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}
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write!(f, "{}", *self as u8)
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}
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}
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@ -32,7 +32,7 @@ impl IhdrData {
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#[must_use]
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#[inline]
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pub fn bpp(&self) -> usize {
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(self.bit_depth.as_u8() * self.color_type.channels_per_pixel()) as usize
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self.bit_depth as usize * self.color_type.channels_per_pixel() as usize
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}
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/// Byte length of IDAT that is correct for this IHDR
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@ -173,14 +173,7 @@ pub fn parse_ihdr_header(
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6 => ColorType::RGBA,
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_ => return Err(PngError::new("Unexpected color type in header")),
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},
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bit_depth: match byte_data[8] {
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1 => BitDepth::One,
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2 => BitDepth::Two,
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4 => BitDepth::Four,
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8 => BitDepth::Eight,
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16 => BitDepth::Sixteen,
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_ => return Err(PngError::new("Unexpected bit depth in header")),
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},
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bit_depth: byte_data[8].try_into()?,
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width: read_be_u32(&mut rdr).map_err(|_| PngError::TruncatedData)?,
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height: read_be_u32(&mut rdr).map_err(|_| PngError::TruncatedData)?,
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compression: byte_data[10],
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@ -569,7 +569,7 @@ fn optimize_png(
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if filters.is_empty() {
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// Pick a filter automatically
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if png.raw.ihdr.bit_depth.as_u8() >= 8 {
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if png.raw.ihdr.bit_depth as u8 >= 8 {
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// Bigrams is the best all-rounder when there's at least one byte per pixel
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filters.insert(RowFilter::Bigrams);
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} else {
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@ -144,7 +144,7 @@ impl PngData {
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ihdr_data
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.write_all(&self.raw.ihdr.height.to_be_bytes())
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.ok();
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ihdr_data.write_all(&[self.raw.ihdr.bit_depth.as_u8()]).ok();
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ihdr_data.write_all(&[self.raw.ihdr.bit_depth as u8]).ok();
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ihdr_data
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.write_all(&[self.raw.ihdr.color_type.png_header_code()])
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.ok();
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@ -165,7 +165,7 @@ impl PngData {
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match &self.raw.ihdr.color_type {
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ColorType::Indexed { palette } => {
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let mut palette_data = Vec::with_capacity(palette.len() * 3);
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let mut max_palette_size = 1 << (self.raw.ihdr.bit_depth.as_u8() as usize);
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let mut max_palette_size = 1 << (self.raw.ihdr.bit_depth as u8);
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// Ensure bKGD color doesn't get truncated from palette
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if let Some(&idx) = self.raw.aux_headers.get(b"bKGD").and_then(|b| b.first()) {
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max_palette_size = max_palette_size.max(idx as usize + 1);
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@ -32,7 +32,7 @@ pub fn reduce_bit_depth(png: &PngImage, minimum_bits: usize) -> Option<PngImage>
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#[must_use]
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pub fn reduce_bit_depth_8_or_less(png: &PngImage, mut minimum_bits: usize) -> Option<PngImage> {
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assert!((1..8).contains(&minimum_bits));
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let bit_depth: usize = png.ihdr.bit_depth.as_u8() as usize;
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let bit_depth = png.ihdr.bit_depth as usize;
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if minimum_bits >= bit_depth || bit_depth > 8 {
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return None;
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}
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@ -154,7 +154,7 @@ pub fn reduce_bit_depth_8_or_less(png: &PngImage, mut minimum_bits: usize) -> Op
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data: reduced,
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ihdr: IhdrData {
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color_type,
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bit_depth: BitDepth::from_u8(minimum_bits as u8),
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bit_depth: (minimum_bits as u8).try_into().unwrap(),
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..png.ihdr
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},
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aux_headers: png.aux_headers.clone(),
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@ -61,7 +61,7 @@ fn test_it_converts(
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assert_eq!(png.raw.ihdr.color_type.png_header_code(), color_type_out);
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assert_eq!(png.raw.ihdr.bit_depth, bit_depth_out);
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if let ColorType::Indexed { palette } = &png.raw.ihdr.color_type {
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assert!(palette.len() <= 1 << (png.raw.ihdr.bit_depth.as_u8() as usize));
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assert!(palette.len() <= 1 << (png.raw.ihdr.bit_depth as u8));
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}
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remove_file(output).ok();
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@ -70,7 +70,7 @@ fn test_it_converts(
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"optimized to wrong bit depth"
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);
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if let ColorType::Indexed { palette } = &png.raw.ihdr.color_type {
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let mut max_palette_size = 1 << (png.raw.ihdr.bit_depth.as_u8() as usize);
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let mut max_palette_size = 1 << (png.raw.ihdr.bit_depth as u8);
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// Ensure bKGD color is valid
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if let Some(&idx) = png.raw.aux_headers.get(b"bKGD").and_then(|b| b.first()) {
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assert!(palette.len() > idx as usize);
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@ -60,7 +60,7 @@ fn test_it_converts(
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assert_eq!(png.raw.ihdr.color_type.png_header_code(), color_type_out);
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assert_eq!(png.raw.ihdr.bit_depth, bit_depth_out);
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if let ColorType::Indexed { palette } = &png.raw.ihdr.color_type {
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assert!(palette.len() <= 1 << (png.raw.ihdr.bit_depth.as_u8() as usize));
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assert!(palette.len() <= 1 << (png.raw.ihdr.bit_depth as u8));
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}
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remove_file(output).ok();
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