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use std::fs::File;
use std::io::prelude::*;
#[derive(Clone)]
pub struct Ppm {
pub width: usize,
pub height: usize,
pub data: Vec<u8>,
}
impl Ppm {
pub fn new(width: usize, height: usize) -> Ppm {
Ppm {
width,
height,
data: vec![0; width * height * 3],
}
}
pub fn read(filename: String) -> Result<Ppm, std::io::Error> {
let file = File::open(filename)?;
let mut reader = std::io::BufReader::new(file);
let mut line = String::new();
let _ = reader.read_line(&mut line)?;
if line.len() < 2 || &line[0..2] != "P3" {
return Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid image header - only P3 is supported"));
}
line.clear();
while line.is_empty() {
let _ = reader.read_line(&mut line)?;
}
let dimensions = line.split_whitespace().collect::<Vec<&str>>();
if dimensions.len() < 2 {
return Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid image dimensions"));
}
let width: usize = dimensions[0].parse().unwrap_or(0);
let height: usize = dimensions[1].parse().unwrap_or(0);
if width == 0 || height == 0 {
return Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid image dimensions"));
}
line.clear();
while line.is_empty() {
let _ = reader.read_line(&mut line)?;
}
if line.len() < 3 || &line[0..3] != "255" {
return Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid pixel type, only '255' is supported"));
}
let mut ppm = Ppm::new(width, height);
let mut row : usize = 0;
loop {
line.clear();
let len = reader.read_line(&mut line)?;
if len == 0 { break; }
let bytes = line.split_whitespace().collect::<Vec<&str>>();
let mut index : usize = 0;
for byte in bytes {
ppm.data[(row * ppm.width * 3) + index] = byte.parse().unwrap_or(0);
index += 1;
}
row += 1;
}
Ok(ppm)
}
pub fn write(&self, filename: String) -> std::io::Result<()> {
let mut file = File::create(filename)?;
write!(&mut file, "P3\n")?;
write!(&mut file, "{} {}\n", self.width, self.height)?;
write!(&mut file, "255\n")?;
for y in 0..self.height {
for x in 0..self.width {
let offset = (y * self.width * 3) + x * 3;
write!(&mut file, "{} {} {} ",
self.data[offset + 0],
self.data[offset + 1],
self.data[offset + 2]
)?;
}
write!(&mut file, "\n")?;
}
Ok(())
}
pub fn set_pixel(&mut self, x: usize, y: usize, r: u8, g: u8, b: u8) {
let offset = (y * self.width * 3) + x * 3;
self.data[offset + 0] = r;
self.data[offset + 1] = g;
self.data[offset + 2] = b;
}
pub fn get_pixel(&self, x: usize, y: usize) -> (u8, u8, u8) {
let offset = (y * self.width * 3) + x * 3;
(
self.data[offset + 0],
self.data[offset + 1],
self.data[offset + 2],
)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn round_trip() {
let width = 10;
let height = 5;
let mut orig = Ppm::new(width, height);
for y in 0..height {
for x in 0..width {
orig.set_pixel(x, y, x as u8, y as u8, 0x22);
}
}
let filename = "/tmp/test.ppm";
orig.write(String::from(filename)).unwrap();
let read_back = Ppm::read(String::from(filename)).unwrap();
assert_eq!(read_back.width, width);
assert_eq!(read_back.height, height);
assert_eq!(read_back.data, orig.data);
for y in 0..height {
for x in 0..width {
let (r,g,b) = read_back.get_pixel(x, y);
assert_eq!(r, x as u8);
assert_eq!(g, y as u8);
assert_eq!(b, 0x22);
}
}
}
}