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use crate::colors::ColorType;
use crate::deflate;
use crate::error::PngError;
use crate::filters::*;
use crate::headers::*;
use crate::interlace::{deinterlace_image, interlace_image, Interlacing};
use bitvec::bitarr;
use indexmap::IndexMap;
use libdeflater::{CompressionLvl, Compressor};
use rgb::ComponentSlice;
use rgb::RGBA8;
use rustc_hash::FxHashMap;
use std::fs::File;
use std::io::{BufReader, Read, Write};
use std::iter::Iterator;
use std::path::Path;
use std::sync::Arc;
pub(crate) mod scan_lines;
use self::scan_lines::ScanLines;
const BRUTE_LEVEL: i32 = 1; const BRUTE_LINES: usize = 4; #[derive(Debug, Clone)]
pub struct PngImage {
pub ihdr: IhdrData,
pub data: Vec<u8>,
pub palette: Option<Vec<RGBA8>>,
pub transparency_pixel: Option<Vec<u8>>,
pub aux_headers: IndexMap<[u8; 4], Vec<u8>>,
}
#[derive(Debug, Clone)]
pub struct PngData {
pub raw: Arc<PngImage>,
pub idat_data: Vec<u8>,
pub filtered: Vec<u8>,
}
type PaletteWithTrns = (Option<Vec<RGBA8>>, Option<Vec<u8>>);
impl PngData {
#[inline]
pub fn new(filepath: &Path, fix_errors: bool) -> Result<Self, PngError> {
let byte_data = Self::read_file(filepath)?;
Self::from_slice(&byte_data, fix_errors)
}
pub fn read_file(filepath: &Path) -> Result<Vec<u8>, PngError> {
let file = match File::open(filepath) {
Ok(f) => f,
Err(_) => return Err(PngError::new("Failed to open file for reading")),
};
let file_len = file.metadata().map(|m| m.len() as usize).unwrap_or(0);
let mut reader = BufReader::new(file);
let mut header = [0; 8];
if reader.read_exact(&mut header).is_err() {
return Err(PngError::new("Not a PNG file: too small"));
}
if !file_header_is_valid(&header) {
return Err(PngError::new("Invalid PNG header detected"));
}
let mut byte_data: Vec<u8> = Vec::with_capacity(file_len);
byte_data.extend_from_slice(&header);
match reader.read_to_end(&mut byte_data) {
Ok(_) => (),
Err(_) => return Err(PngError::new("Failed to read from file")),
}
Ok(byte_data)
}
pub fn from_slice(byte_data: &[u8], fix_errors: bool) -> Result<Self, PngError> {
let mut byte_offset: usize = 0;
let header = byte_data.get(0..8).ok_or(PngError::TruncatedData)?;
if !file_header_is_valid(header) {
return Err(PngError::NotPNG);
}
byte_offset += 8;
let mut aux_headers: IndexMap<[u8; 4], Vec<u8>> = IndexMap::new();
let mut idat_headers: Vec<u8> = Vec::new();
while let Some(header) = parse_next_header(byte_data, &mut byte_offset, fix_errors)? {
match &header.name {
b"IDAT" => idat_headers.extend_from_slice(header.data),
b"acTL" => return Err(PngError::APNGNotSupported),
_ => {
aux_headers.insert(header.name, header.data.to_owned());
}
}
}
if idat_headers.is_empty() {
return Err(PngError::ChunkMissing("IDAT"));
}
let ihdr = match aux_headers.remove(b"IHDR") {
Some(ihdr) => ihdr,
None => return Err(PngError::ChunkMissing("IHDR")),
};
let ihdr_header = parse_ihdr_header(&ihdr)?;
let raw_data = deflate::inflate(idat_headers.as_ref(), ihdr_header.raw_data_size())?;
if raw_data.len() != ihdr_header.raw_data_size() {
return Err(PngError::TruncatedData);
}
let (palette, transparency_pixel) = Self::palette_to_rgba(
ihdr_header.color_type,
aux_headers.remove(b"PLTE"),
aux_headers.remove(b"tRNS"),
)?;
let mut raw = PngImage {
ihdr: ihdr_header,
data: raw_data,
palette,
transparency_pixel,
aux_headers,
};
let unfiltered = raw.unfilter_image()?;
Ok(Self {
idat_data: idat_headers,
filtered: std::mem::replace(&mut raw.data, unfiltered),
raw: Arc::new(raw),
})
}
fn palette_to_rgba(
color_type: ColorType,
palette_data: Option<Vec<u8>>,
trns_data: Option<Vec<u8>>,
) -> Result<PaletteWithTrns, PngError> {
if color_type == ColorType::Indexed {
let palette_data =
palette_data.ok_or_else(|| PngError::new("no palette in indexed image"))?;
let mut palette: Vec<_> = palette_data
.chunks(3)
.map(|color| RGBA8::new(color[0], color[1], color[2], 255))
.collect();
if let Some(trns_data) = trns_data {
for (color, trns) in palette.iter_mut().zip(trns_data) {
color.a = trns;
}
}
Ok((Some(palette), None))
} else {
Ok((None, trns_data))
}
}
pub fn output(&self) -> Vec<u8> {
let mut output = vec![0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A];
let mut ihdr_data = Vec::with_capacity(13);
ihdr_data.write_all(&self.raw.ihdr.width.to_be_bytes()).ok();
ihdr_data
.write_all(&self.raw.ihdr.height.to_be_bytes())
.ok();
ihdr_data.write_all(&[self.raw.ihdr.bit_depth.as_u8()]).ok();
ihdr_data
.write_all(&[self.raw.ihdr.color_type.png_header_code()])
.ok();
ihdr_data.write_all(&[0]).ok(); ihdr_data.write_all(&[0]).ok(); ihdr_data.write_all(&[self.raw.ihdr.interlaced as u8]).ok();
write_png_block(b"IHDR", &ihdr_data, &mut output);
for (key, header) in self
.raw
.aux_headers
.iter()
.filter(|&(key, _)| !(key == b"bKGD" || key == b"hIST" || key == b"tRNS"))
{
write_png_block(key, header, &mut output);
}
if let Some(ref palette) = self.raw.palette {
let mut palette_data = Vec::with_capacity(palette.len() * 3);
let mut max_palette_size = 1 << (self.raw.ihdr.bit_depth.as_u8() as usize);
if let Some(&idx) = self.raw.aux_headers.get(b"bKGD").and_then(|b| b.first()) {
max_palette_size = max_palette_size.max(idx as usize + 1);
}
for px in palette.iter().take(max_palette_size) {
palette_data.extend_from_slice(px.rgb().as_slice());
}
write_png_block(b"PLTE", &palette_data, &mut output);
let num_transparent =
palette
.iter()
.take(max_palette_size)
.enumerate()
.fold(
0,
|prev, (index, px)| {
if px.a == 255 {
prev
} else {
index + 1
}
},
);
if num_transparent > 0 {
let trns_data: Vec<_> = palette[0..num_transparent].iter().map(|px| px.a).collect();
write_png_block(b"tRNS", &trns_data, &mut output);
}
} else if let Some(ref transparency_pixel) = self.raw.transparency_pixel {
write_png_block(b"tRNS", transparency_pixel, &mut output);
}
for (key, header) in self
.raw
.aux_headers
.iter()
.filter(|&(key, _)| key == b"bKGD" || key == b"hIST" || key == b"tRNS")
{
write_png_block(key, header, &mut output);
}
write_png_block(b"IDAT", &self.idat_data, &mut output);
write_png_block(b"IEND", &[], &mut output);
output
}
}
impl PngImage {
#[inline]
#[must_use]
pub fn change_interlacing(&self, interlace: Interlacing) -> Option<PngImage> {
if interlace == self.ihdr.interlaced {
return None;
}
Some(if interlace == Interlacing::Adam7 {
interlace_image(self)
} else {
deinterlace_image(self)
})
}
#[inline]
pub fn channels_per_pixel(&self) -> u8 {
self.ihdr.color_type.channels_per_pixel()
}
#[inline]
pub fn scan_lines(&self, has_filter: bool) -> ScanLines<'_> {
ScanLines::new(self, has_filter)
}
fn unfilter_image(&self) -> Result<Vec<u8>, PngError> {
let mut unfiltered = Vec::with_capacity(self.data.len());
let bpp = ((self.ihdr.bit_depth.as_u8() * self.channels_per_pixel() + 7) / 8) as usize;
let mut last_line: Vec<u8> = Vec::new();
let mut last_pass = None;
let mut unfiltered_buf = Vec::new();
for line in self.scan_lines(true) {
if last_pass != line.pass {
last_line.clear();
last_pass = line.pass;
}
last_line.resize(line.data.len(), 0);
let filter = RowFilter::try_from(line.filter).map_err(|_| PngError::InvalidData)?;
filter.unfilter_line(bpp, line.data, &last_line, &mut unfiltered_buf)?;
unfiltered.extend_from_slice(&unfiltered_buf);
std::mem::swap(&mut last_line, &mut unfiltered_buf);
unfiltered_buf.clear();
}
Ok(unfiltered)
}
pub fn filter_image(&self, filter: RowFilter, optimize_alpha: bool) -> Vec<u8> {
let mut filtered = Vec::with_capacity(self.data.len());
let bpp = ((self.ihdr.bit_depth.as_u8() * self.channels_per_pixel() + 7) / 8) as usize;
let alpha_bytes = match self.ihdr.color_type {
ColorType::RGBA | ColorType::GrayscaleAlpha if optimize_alpha => {
(self.ihdr.bit_depth.as_u8() / 8) as usize
}
_ => 0,
};
let mut prev_line = Vec::new();
let mut prev_pass: Option<u8> = None;
let mut f_buf = Vec::new();
for line in self.scan_lines(false) {
if prev_pass != line.pass || line.data.len() != prev_line.len() {
prev_line = vec![0; line.data.len()];
}
let mut line_data = line.data.to_vec();
if filter <= RowFilter::Paeth {
let filter = if prev_pass == line.pass || filter <= RowFilter::Sub {
filter
} else {
RowFilter::None
};
filter.filter_line(bpp, &mut line_data, &prev_line, &mut f_buf, alpha_bytes);
filtered.extend_from_slice(&f_buf);
prev_line = line_data;
} else {
let mut best_line = Vec::new();
let mut best_line_raw = Vec::new();
let try_filters = if prev_pass == line.pass {
RowFilter::STANDARD.iter()
} else {
RowFilter::SINGLE_LINE.iter()
};
match filter {
RowFilter::MinSum => {
let mut best_size = usize::MAX;
for f in try_filters {
f.filter_line(bpp, &mut line_data, &prev_line, &mut f_buf, alpha_bytes);
let size = f_buf.iter().fold(0, |acc, &x| {
let signed = x as i8;
acc + signed.unsigned_abs() as usize
});
if size < best_size {
best_size = size;
std::mem::swap(&mut best_line, &mut f_buf);
best_line_raw = line_data.clone();
}
}
}
RowFilter::Entropy => {
let mut best_size = i32::MIN;
for f in try_filters {
f.filter_line(bpp, &mut line_data, &prev_line, &mut f_buf, alpha_bytes);
let mut counts = vec![0; 0x100];
for &i in f_buf.iter() {
counts[i as usize] += 1;
}
let size = counts.into_iter().fold(0, |acc, x| {
if x == 0 {
return acc;
}
acc + ilog2i(x)
}) as i32;
if size > best_size {
best_size = size;
std::mem::swap(&mut best_line, &mut f_buf);
best_line_raw = line_data.clone();
}
}
}
RowFilter::Bigrams => {
let mut best_size = usize::MAX;
for f in try_filters {
f.filter_line(bpp, &mut line_data, &prev_line, &mut f_buf, alpha_bytes);
let mut set = bitarr![0; 0x10000];
for pair in f_buf.windows(2) {
let bigram = (pair[0] as usize) << 8 | pair[1] as usize;
set.set(bigram, true);
}
let size = set.count_ones();
if size < best_size {
best_size = size;
std::mem::swap(&mut best_line, &mut f_buf);
best_line_raw = line_data.clone();
}
}
}
RowFilter::BigEnt => {
let mut best_size = i32::MIN;
let mut counts = FxHashMap::<u16, u32>::default();
for f in try_filters {
f.filter_line(bpp, &mut line_data, &prev_line, &mut f_buf, alpha_bytes);
counts.clear();
for pair in f_buf.windows(2) {
let bigram = (pair[0] as u16) << 8 | pair[1] as u16;
counts.entry(bigram).and_modify(|e| *e += 1).or_insert(1);
}
let size = counts.values().fold(0, |acc, &x| acc + ilog2i(x)) as i32;
if size > best_size {
best_size = size;
std::mem::swap(&mut best_line, &mut f_buf);
best_line_raw = line_data.clone();
}
}
}
RowFilter::Brute => {
let mut best_size = usize::MAX;
let line_start = filtered.len();
filtered.resize(filtered.len() + line.data.len() + 1, 0);
let mut compressor =
Compressor::new(CompressionLvl::new(BRUTE_LEVEL).unwrap());
let limit = filtered.len().min((line.data.len() + 1) * BRUTE_LINES);
let capacity = compressor.zlib_compress_bound(limit);
let mut dest = vec![0; capacity];
for f in try_filters {
f.filter_line(bpp, &mut line_data, &prev_line, &mut f_buf, alpha_bytes);
filtered[line_start..].copy_from_slice(&f_buf);
let size = compressor
.zlib_compress(&filtered[filtered.len() - limit..], &mut dest)
.unwrap_or(usize::MAX);
if size < best_size {
best_size = size;
std::mem::swap(&mut best_line, &mut f_buf);
best_line_raw = line_data.clone();
}
}
filtered.resize(line_start, 0);
}
_ => unreachable!(),
}
filtered.extend_from_slice(&best_line);
prev_line = best_line_raw;
}
prev_pass = line.pass;
}
filtered
}
}
fn write_png_block(key: &[u8], header: &[u8], output: &mut Vec<u8>) {
let mut header_data = Vec::with_capacity(header.len() + 4);
header_data.extend_from_slice(key);
header_data.extend_from_slice(header);
output.reserve(header_data.len() + 8);
output.extend_from_slice(&(header_data.len() as u32 - 4).to_be_bytes());
let crc = deflate::crc32(&header_data);
output.append(&mut header_data);
output.extend_from_slice(&crc.to_be_bytes());
}
fn ilog2i(i: u32) -> u32 {
let log = 32 - i.leading_zeros() - 1;
i * log + ((i - (1 << log)) << 1)
}