diff --git a/src/header.rs b/src/header.rs
index 3508a5f..a38c420 100644
--- a/src/header.rs
+++ b/src/header.rs
@@ -98,7 +98,7 @@ pub enum ColorFormat {
impl ColorFormat {
/// Bits per color channel.
///
- /// Ex. Rgba32 has `8bpc`
+ /// Ex. `Rgba8` has `8bpc`
pub fn bpc(&self) -> u8 {
match self {
ColorFormat::Rgba8 => 8,
@@ -108,7 +108,7 @@ impl ColorFormat {
/// Bits per pixel.
///
- /// Ex. Rgba32 has `32bpp`
+ /// Ex. `Rgba8` has `32bpp`
pub fn bpp(&self) -> u16 {
match self {
ColorFormat::Rgba8 => 32,
@@ -118,13 +118,27 @@ impl ColorFormat {
/// Number of color channels.
///
- /// Ex. Rgba32 has `4` channels
- pub fn channels(self) -> u16 {
+ /// Ex. `Rgba8` has `4` channels
+ pub fn channels(&self) -> u16 {
match self {
ColorFormat::Rgba8 => 4,
ColorFormat::Rgb8 => 3,
}
}
+
+ /// The channel in which alpha is contained, or [`None`] if there is none.
+ ///
+ /// Ex. `Rgba8`'s 3rd channel is alpha
+ pub fn alpha_channel(&self) -> Option<u8> {
+ match self {
+ ColorFormat::Rgba8 => Some(4),
+ ColorFormat::Rgb8 => None,
+ }
+ }
+
+ pub fn pixel_byte_count(&self) -> u16 {
+ self.bpp() / 8
+ }
}
impl TryFrom<u8> for ColorFormat {
diff --git a/src/operations.rs b/src/operations.rs
index 602ecfb..8be04dd 100644
--- a/src/operations.rs
+++ b/src/operations.rs
@@ -1,19 +1,72 @@
-pub fn line_diff(width: u32, height: u32, data: &[u8]) -> Vec<u8> {
- let mut output_buf = Vec::with_capacity((width * height * 4) as usize);
+use crate::ColorFormat;
+use rayon::prelude::*;
+
+pub fn sub_rows(width: u32, height: u32, color_format: ColorFormat, input: &[u8]) -> Vec<u8> {
+ let mut data = Vec::with_capacity(width as usize * (color_format.bpp() / 8) as usize);
+
+ let block_height = f32::ceil(height as f32 / 3.0) as u32;
+ let line_byte_count = (width * color_format.pixel_byte_count() as u32) as usize;
+
+ let mut curr_line: Vec<u8>;
+ let mut prev_line: Vec<u8> = Vec::new();
+
+ let mut i = 0;
+ for y in 0..height {
+ curr_line = input[i..i + line_byte_count].to_vec();
+
+ if y % block_height != 0 {
+ curr_line.iter_mut()
+ .zip(prev_line.iter_mut())
+ .for_each(|(curr, prev)| {
+ *curr = curr.wrapping_sub(*prev);
+ *prev = prev.wrapping_add(*curr);
+ });
+ } else {
+ prev_line.clone_from(&curr_line);
+ }
+
+ data.extend_from_slice(&curr_line);
+ i += line_byte_count;
+ }
+
+ if color_format.alpha_channel().is_some() {
+ let (pixels, alpha): (Vec<[u8; 3]>, Vec<u8>) =
+ data.chunks(4)
+ .map(|i| (
+ [i[0], i[1], i[2]],
+ i[3]
+ ))
+ .unzip();
+
+ pixels.into_iter().flatten().chain(alpha).collect()
+ } else {
+ data
+ }
+}
+
+pub fn add_rows(width: u32, height: u32, color_format: ColorFormat, data: &[u8]) -> Vec<u8> {
+ let mut output_buf = Vec::with_capacity((width * height * color_format.channels() as u32) as usize);
let block_height = f32::ceil(height as f32 / 3.0) as u32;
- let mut curr_line;
- let mut prev_line = Vec::with_capacity(width as usize * 3);
-
- let mut curr_alpha;
- let mut prev_alpha = Vec::with_capacity(width as usize);
+ let mut curr_line: Vec<u8>;
+ let mut prev_line = Vec::new();
let mut rgb_index = 0;
- let mut alpha_index = (width * height * 3) as usize;
+ let mut alpha_index = (width * height * (color_format.channels() as u32 - 1)) as usize;
for y in 0..height {
- curr_line = data[rgb_index..rgb_index + width as usize * 3].to_vec();
- curr_alpha = data[alpha_index..alpha_index + width as usize].to_vec();
+ curr_line = if color_format.alpha_channel().is_some() {
+ data[rgb_index..rgb_index + width as usize * 3]
+ .chunks(3)
+ .zip(data[alpha_index..alpha_index + width as usize].into_iter())
+ .flat_map(|(a, b)| {
+ a.into_iter().chain(vec![b])
+ })
+ .copied()
+ .collect()
+ } else {
+ data[rgb_index..rgb_index + width as usize * 3].to_vec()
+ };
if y % block_height != 0 {
curr_line
@@ -22,81 +75,15 @@ pub fn line_diff(width: u32, height: u32, data: &[u8]) -> Vec<u8> {
.for_each(|(curr_p, prev_p)| {
*curr_p = curr_p.wrapping_add(*prev_p);
});
- curr_alpha
- .iter_mut()
- .zip(&prev_alpha)
- .for_each(|(curr_a, prev_a)| {
- *curr_a = curr_a.wrapping_add(*prev_a);
- });
}
// Write the decoded RGBA data to the final buffer
- curr_line
- .windows(3)
- .step_by(3)
- .zip(&curr_alpha)
- .for_each(|(curr_p, alpha_p)| {
- output_buf.extend_from_slice(&[curr_p[0], curr_p[1], curr_p[2], *alpha_p]);
- });
+ output_buf.extend_from_slice(&curr_line);
prev_line.clone_from(&curr_line);
- prev_alpha.clone_from(&curr_alpha);
-
rgb_index += width as usize * 3;
alpha_index += width as usize;
}
output_buf
}
-
-pub fn diff_line(width: u32, height: u32, input: &[u8]) -> Vec<u8> {
- let mut data = Vec::with_capacity(width as usize * 3);
- let mut alpha_data = Vec::with_capacity(width as usize);
-
- let block_height = f32::ceil(height as f32 / 3.0) as u32;
- let pixel_byte_count = 4;
- let line_byte_count = (width * pixel_byte_count as u32) as usize;
-
- let mut curr_line: Vec<u8>;
- let mut prev_line: Vec<u8> = Vec::with_capacity(width as usize * 3);
-
- let mut curr_alpha: Vec<u8>;
- let mut prev_alpha: Vec<u8> = Vec::with_capacity(width as usize);
-
- let mut i = 0;
- for y in 0..height {
- curr_line = input[i..i + line_byte_count]
- .windows(4)
- .step_by(4)
- .flat_map(|r| [r[0], r[1], r[2]])
- .collect();
- curr_alpha = input[i..i + line_byte_count]
- .iter()
- .skip(3)
- .step_by(4)
- .copied()
- .collect();
-
- if y % block_height != 0 {
- for x in 0..width as usize * 3 {
- curr_line[x] = curr_line[x].wrapping_sub(prev_line[x]);
- prev_line[x] = prev_line[x].wrapping_add(curr_line[x]);
- }
- for x in 0..width as usize {
- curr_alpha[x] = curr_alpha[x].wrapping_sub(prev_alpha[x]);
- prev_alpha[x] = prev_alpha[x].wrapping_add(curr_alpha[x]);
- }
- } else {
- prev_line.clone_from(&curr_line);
- prev_alpha.clone_from(&curr_alpha);
- }
-
- data.extend_from_slice(&curr_line);
- alpha_data.extend_from_slice(&curr_alpha);
- i += line_byte_count;
- }
-
- data.extend_from_slice(&alpha_data);
-
- data
-}
diff --git a/src/picture.rs b/src/picture.rs
index 4f952d9..2b0d357 100644
--- a/src/picture.rs
+++ b/src/picture.rs
@@ -10,7 +10,7 @@ use crate::{
compression::{dct::{dct_compress, dct_decompress, DctParameters},
lossless::{compress, decompress, CompressionError, CompressionInfo}},
header::{ColorFormat, CompressionType, Header},
- operations::{diff_line, line_diff},
+ operations::{add_rows, sub_rows},
};
#[derive(Error, Debug)]
@@ -132,7 +132,12 @@ impl SquishyPicture {
let modified_data = match self.header.compression_type {
CompressionType::None => &self.bitmap,
CompressionType::Lossless => {
- &diff_line(self.header.width, self.header.height, &self.bitmap)
+ &sub_rows(
+ self.header.width,
+ self.header.height,
+ self.header.color_format,
+ &self.bitmap
+ )
},
CompressionType::LossyDct => {
&dct_compress(
@@ -187,7 +192,7 @@ impl SquishyPicture {
let bitmap = match header.compression_type {
CompressionType::None => pre_bitmap,
CompressionType::Lossless => {
- line_diff(header.width, header.height, &pre_bitmap)
+ add_rows(header.width, header.height, header.color_format, &pre_bitmap)
},
CompressionType::LossyDct => {
dct_decompress(