bendns' repos / pnm
pnm decoding and encoding
Diffstat (limited to 'src/pgm.rs')
-rw-r--r--src/pgm.rs180
1 files changed, 180 insertions, 0 deletions
diff --git a/src/pgm.rs b/src/pgm.rs
new file mode 100644
index 0000000..0b844d8
--- /dev/null
+++ b/src/pgm.rs
@@ -0,0 +1,180 @@
+//! [Portable GreyMap Format](https://en.wikipedia.org/wiki/Netpbm#PGM_example) grey image encoding and decoding.
+pub(crate) const CHANNELS: usize = 1;
+pub type Input<'a> = Image<&'a [u8], 1>;
+pub type Output = Image<Vec<u8>, 1>;
+pub type Uninit = fimg::uninit::Image<u8, 1>;
+use crate::encode::{encodeu32, P};
+use atools::prelude::*;
+use fimg::Image;
+
+#[cfg(test)]
+fn tdata() -> &'static [u8] {
+ include_bytes!("../tdata/fimg-gray.imgbuf")
+}
+
+/// Module for handling plain ascii (human readable) [PGM](https://en.wikipedia.org/wiki/Netpbm#PGM_example) (Y) images.
+pub mod plain {
+
+ use crate::encode::encode_;
+
+ use super::*;
+ pub const MAGIC: u8 = 2;
+
+ /// Encode an <code>[Image]<[u8], 1></code> into a [PBM](https://en.wikipedia.org/wiki/Netpbm#PBM_example) ASCII Image.
+ pub fn encode<T: AsRef<[u8]>>(x: Image<T, 1>) -> String {
+ let mut y = Vec::with_capacity(size(x.as_ref()));
+ let n = unsafe { encode_into(x.as_ref(), y.as_mut_ptr()) };
+ unsafe { y.set_len(n) };
+ unsafe { String::from_utf8_unchecked(y) }
+ }
+
+ crate::decode::dec_fn! {
+ max "Decode an ASCII [PGM](https://en.wikipedia.org/wiki/Netpbm#PGM_example) image into an <code>[Image]<[Box]<[u8]>, 1></code>"
+ }
+
+ #[doc = include_str!("decode_body_into.md")]
+ pub fn decode_body_into(x: &[u8], mut into: Uninit, max: u8) -> Result<Output> {
+ let mut out = into.buf().as_mut_ptr() as *mut u8;
+ let pixels = into.width() * into.height();
+ for b in x
+ .split(u8::is_ascii_whitespace)
+ .filter(|x| !x.is_empty() && x.len() <= 3)
+ .filter(|x| x.iter().all(u8::is_ascii_digit))
+ .map(|x| x.iter().fold(0, |acc, &x| acc * 10 + (x - b'0')))
+ .map(|x| {
+ if max == 255 {
+ x
+ } else {
+ ((x as f32 / max as f32) * 255.) as u8
+ }
+ })
+ .take(pixels as usize)
+ {
+ // SAFETY: iterator over `pixels` elements.
+ unsafe { out.push(b) };
+ }
+ if unsafe { out.sub_ptr(into.buf().as_mut_ptr().cast()) < pixels as usize } {
+ return Err(Error::MissingData);
+ }
+ // SAFETY: checked that the pixels have been initialized.
+ Ok(unsafe { into.assume_init() })
+ }
+
+ #[doc = include_str!("encode_into.md")]
+ pub unsafe fn encode_into(x: Input, out: *mut u8) -> usize {
+ let mut o = out;
+ o.put(b'P'.join(MAGIC + b'0'));
+ o.push(b' ');
+ encodeu32(x.width(), &mut o);
+ o.push(b' ');
+ encodeu32(x.height(), &mut o);
+ o.put(*b" 255\n");
+ for row in x.buffer().chunks_exact(x.width() as _) {
+ for &on in row {
+ o.put(encode_(on));
+ }
+ // cosmetic
+ o.push(b'\n');
+ }
+ o.sub_ptr(out)
+ }
+
+ #[doc = include_str!("est.md")]
+ pub fn size(x: Input) -> usize {
+ 2 // P1
+ + 23 // \n4294967295 4294967295\n
+ + x.height() as usize // \n
+ + x.len() * 4 // '255 '
+ }
+
+ #[test]
+ fn test_encode() {
+ assert_eq!(
+ encode(Image::build(20, 15).buf(tdata())),
+ include_str!("../tdata/fimgA.pgm")
+ );
+ }
+
+ #[test]
+ fn test_decode() {
+ assert_eq!(
+ &**decode(include_bytes!("../tdata/fimgA.pgm"))
+ .unwrap()
+ .buffer(),
+ tdata()
+ )
+ }
+}
+
+/// Module for handling raw (binary) [PGM](https://en.wikipedia.org/wiki/Netpbm#PGM_example) (gray) images.
+pub mod raw {
+ use super::*;
+ pub const MAGIC: u8 = 5;
+ /// Encode an <code>[Image]<[u8], 1></code> [PBM](https://en.wikipedia.org/wiki/Netpbm#PGM_example) Raw (binary) Image.
+ pub fn encode<T: AsRef<[u8]>>(x: Image<T, 1>) -> Vec<u8> {
+ let mut y = Vec::with_capacity(size(x.as_ref()));
+ let n = unsafe { encode_into(x.as_ref(), y.as_mut_ptr()) };
+ unsafe { y.set_len(n) };
+ y
+ }
+
+ crate::decode::dec_fn! {
+ "Decode a raw binary [PGM](https://en.wikipedia.org/wiki/Netpbm#PGM_example) image into an <code>[Image]<[Box]<[u8]>, 1></code>"
+ }
+
+ #[doc = include_str!("encode_into.md")]
+ pub unsafe fn encode_into(x: Input, out: *mut u8) -> usize {
+ let mut o = out;
+ o.put(b'P'.join(MAGIC + b'0'));
+ o.push(b' ');
+ encodeu32(x.width(), &mut o);
+ o.push(b' ');
+ encodeu32(x.height(), &mut o);
+ o.put(*b" 255\n");
+ for &x in *x.buffer() {
+ o.push(x)
+ }
+
+ o.sub_ptr(out)
+ }
+
+ #[doc = include_str!("decode_body_into.md")]
+ pub fn decode_body_into(x: &[u8], mut into: Uninit) -> Result<Output> {
+ let mut out = into.buf().as_mut_ptr() as *mut u8;
+ let pixels = into.width() * into.height();
+ for b in x.iter().copied().take(pixels as _) {
+ // SAFETY: took `pixels` pixels.
+ unsafe { out.push(b) };
+ }
+ if unsafe { out.sub_ptr(into.buf().as_mut_ptr().cast()) < pixels as usize } {
+ return Err(Error::MissingData);
+ }
+ // SAFETY: checked that the pixels have been initialized.
+ Ok(unsafe { into.assume_init() })
+ }
+
+ #[doc = include_str!("est.md")]
+ pub fn size(x: Input) -> usize {
+ 2 // magic
+ + 23 // w h
+ + x.len() // data
+ }
+
+ #[test]
+ fn test_decode() {
+ assert_eq!(
+ &**decode(include_bytes!("../tdata/fimgR.pgm"))
+ .unwrap()
+ .buffer(),
+ tdata()
+ )
+ }
+
+ #[test]
+ fn test_encode() {
+ assert_eq!(
+ encode(Image::build(20, 15).buf(tdata())),
+ include_bytes!("../tdata/fimgR.pgm")
+ );
+ }
+}