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Performance optimizations

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Interlacing performance increased by about 50%
Various other minor optimizations throughout the program
This commit is contained in:
Joshua Holmer 2016-04-05 12:08:47 -04:00
parent 9302caed59
commit 1d0ce6fca8
1 changed files with 13 additions and 8 deletions
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21
src/png.rs
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@ -681,7 +681,7 @@ fn interlace_image(png: &mut PngData) {
break;
}
// Copy pixels into interlaced passes
let pix_modulo = (((i / bits_per_pixel as usize) as f32).floor() as usize) % 8;
let pix_modulo = (i / bits_per_pixel as usize) % 8;
match index % 8 {
0 => {
match pix_modulo {
@ -1035,10 +1035,11 @@ fn reduce_rgba_to_rgb(png: &PngData) -> Option<Vec<u8>> {
let mut reduced = Vec::with_capacity(png.raw_data.len());
let byte_depth = png.ihdr_data.bit_depth.as_u8() >> 3;
let bpp: usize = 4 * byte_depth as usize;
let colored_bytes = bpp - byte_depth as usize;
for line in png.scan_lines() {
reduced.push(line.filter);
for (i, byte) in line.data.iter().enumerate() {
if i % bpp >= (bpp - byte_depth as usize) {
if i % bpp >= colored_bytes {
if *byte != 255 {
return None;
}
@ -1055,13 +1056,14 @@ fn reduce_rgba_to_grayscale_alpha(png: &PngData) -> Option<Vec<u8>> {
let mut reduced = Vec::with_capacity(png.raw_data.len());
let byte_depth = png.ihdr_data.bit_depth.as_u8() >> 3;
let bpp: usize = 4 * byte_depth as usize;
let colored_bytes = bpp - byte_depth as usize;
for line in png.scan_lines() {
reduced.push(line.filter);
let mut low_bytes = Vec::with_capacity(4);
let mut high_bytes = Vec::with_capacity(4);
let mut trans_bytes = Vec::with_capacity(byte_depth as usize);
for (i, byte) in line.data.iter().enumerate() {
if i % bpp < (bpp - byte_depth as usize) {
if i % bpp < colored_bytes {
if byte_depth == 1 || i % 2 == 1 {
low_bytes.push(*byte);
} else {
@ -1186,6 +1188,7 @@ fn reduce_grayscale_to_palette(png: &PngData) -> Option<(Vec<u8>, Vec<u8>)> {
// Only perform reduction if we can get to 4-bits or less
let mut palette = Vec::with_capacity(16);
let bpp: usize = png.ihdr_data.bit_depth.as_u8() as usize;
let bpp_inverse = 8 - bpp;
for line in png.scan_lines() {
reduced.extend(BitVec::from_bytes(&[line.filter]));
let bit_vec = BitVec::from_bytes(&line.data);
@ -1193,11 +1196,11 @@ fn reduce_grayscale_to_palette(png: &PngData) -> Option<(Vec<u8>, Vec<u8>)> {
for (i, bit) in bit_vec.iter().enumerate() {
cur_pixel.push(bit);
if i % bpp == bpp - 1 {
let pix_value = cur_pixel.to_bytes()[0] >> (8 - bpp);
let pix_value = cur_pixel.to_bytes()[0] >> bpp_inverse;
let pix_slice = vec![pix_value, pix_value, pix_value];
if palette.contains(&pix_slice) {
let index = palette.iter().enumerate().find(|&x| x.1 == &pix_slice).unwrap().0;
let idx = BitVec::from_bytes(&[(index as u8) << (8 - bpp)]);
let idx = BitVec::from_bytes(&[(index as u8) << bpp_inverse]);
for b in idx.iter().take(bpp) {
reduced.push(b);
}
@ -1207,7 +1210,7 @@ fn reduce_grayscale_to_palette(png: &PngData) -> Option<(Vec<u8>, Vec<u8>)> {
return None;
}
palette.push(pix_slice.clone());
let idx = BitVec::from_bytes(&[(len as u8) << (8 - bpp)]);
let idx = BitVec::from_bytes(&[(len as u8) << bpp_inverse]);
for b in idx.iter().take(bpp) {
reduced.push(b);
}
@ -1248,6 +1251,7 @@ fn reduce_palette_to_grayscale(png: &PngData) -> Option<Vec<u8>> {
// Iterate through scanlines and assign grayscale value to each pixel
let bit_depth: usize = png.ihdr_data.bit_depth.as_u8() as usize;
let bit_depth_inverse = 8 - bit_depth;
for line in png.scan_lines() {
reduced.extend(BitVec::from_bytes(&[line.filter]));
let bit_vec = BitVec::from_bytes(&line.data);
@ -1258,7 +1262,7 @@ fn reduce_palette_to_grayscale(png: &PngData) -> Option<Vec<u8>> {
cur_pixel.push(bit);
if cur_pixel.len() == bit_depth {
// `to_bytes` gives us e.g. 10000000 for a 1-bit pixel, when we would want 00000001
let padded_pixel = cur_pixel.to_bytes()[0] >> (8 - bit_depth);
let padded_pixel = cur_pixel.to_bytes()[0] >> bit_depth_inverse;
let palette_idx: usize = padded_pixel as usize * 3;
reduced.extend(BitVec::from_bytes(&[palette[palette_idx]]));
// BitVec's clear function doesn't set len to 0
@ -1321,10 +1325,11 @@ fn reduce_grayscale_alpha_to_grayscale(png: &PngData) -> Option<Vec<u8>> {
let mut reduced = Vec::with_capacity(png.raw_data.len());
let byte_depth = png.ihdr_data.bit_depth.as_u8() >> 3;
let bpp: usize = 2 * byte_depth as usize;
let colored_bytes = bpp - byte_depth as usize;
for line in png.scan_lines() {
reduced.push(line.filter);
for (i, byte) in line.data.iter().enumerate() {
if i % bpp >= (bpp - byte_depth as usize) {
if i % bpp >= colored_bytes {
if *byte != 255 {
return None;
}