file io might be done, untested

Cargo.lock

@@ -2,6 +2,87 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "justerror"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "befab2078d3ff679889e32730a1e9107b06a60a18ed7dfa3384f66ebe5e1062a"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.101"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "89ae43fd86e4158d6db51ad8e2b80f313af9cc74f5c0e03ccb87de09998732de"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.106"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ede7c438028d4436d71104916910f5bb611972c5cfd7f89b8300a8186e6fada6"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "thiserror"
+version = "2.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3467d614147380f2e4e374161426ff399c91084acd2363eaf549172b3d5e60c0"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "2.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c5e1be1c48b9172ee610da68fd9cd2770e7a4056cb3fc98710ee6906f0c7960"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.106",
+]
+
 [[package]]
 name = "tinyrender"
 version = "0.1.0"
+dependencies = [
+ "justerror",
+ "thiserror",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"

Cargo.toml

@@ -4,3 +4,5 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+justerror = "1.1.0"
+thiserror = "2.0.16"

src/main.rs

@@ -1,3 +1,6 @@
-fn main() {
-    println!("Hello, world!");
-}
+#[macro_use]
+extern crate justerror;
+
+mod tga;
+
+fn main() {}

src/tga.rs

@@ -1,9 +1,11 @@
 use std::{
     fs::File,
-    io::Read,
+    io::{Read, Write},
     ops::{Deref, DerefMut},
 };
 
+const HEADER_SIZE: usize = 18;
+
 #[derive(Debug, Default, Clone, PartialEq, Eq)]
 #[repr(C, packed)]
 pub struct TGAHeader {
@@ -63,24 +65,70 @@ impl DerefMut for TGAColor {
     }
 }
 
+impl From<[u8; 4]> for TGAColor {
+    fn from(value: [u8; 4]) -> Self {
+        Self { bgra: value }
+    }
+}
+
 impl TGAColor {
     pub fn new() -> Self {
         Self { bgra: [0; 4] }
     }
+
+    pub fn b(&mut self) -> &mut u8 {
+        &mut self[0]
+    }
+
+    pub fn g(&mut self) -> &mut u8 {
+        &mut self[1]
+    }
+
+    pub fn r(&mut self) -> &mut u8 {
+        &mut self[2]
+    }
+
+    pub fn a(&mut self) -> &mut u8 {
+        &mut self[3]
+    }
 }
 
 #[derive(Debug, Default, Clone, PartialEq, Eq)]
 struct TGAImage {
     pub format: Format,
-    pub width: u32,
-    pub height: u32,
+    pub width: u16,
+    pub height: u16,
     data: Vec<u8>,
 }
 
-pub type IoResult = std::io::Result<()>;
+pub type IoResult = std::result::Result<(), TGAError>;
+
+#[Error]
+pub enum TGAError {
+    IoError(std::io::Error),
+    Other(String),
+}
+
+impl From<String> for TGAError {
+    fn from(value: String) -> Self {
+        Self::Other(value)
+    }
+}
+
+impl From<&str> for TGAError {
+    fn from(value: &str) -> Self {
+        Self::Other(value.to_string())
+    }
+}
+
+impl From<std::io::Error> for TGAError {
+    fn from(value: std::io::Error) -> Self {
+        Self::IoError(value)
+    }
+}
 
 impl TGAImage {
-    pub fn new(width: u32, height: u32, format: Format) -> Self {
+    pub fn new(width: u16, height: u16, format: Format) -> Self {
         Self {
             format,
             width,
@@ -89,20 +137,20 @@ impl TGAImage {
         }
     }
 
-    pub fn bytes_per_pixel(&self) -> u8 {
-        self.format as u8
+    pub fn from_file(file: &str) -> Result<Self, TGAError> {
+        let mut img = TGAImage::default();
+        img.read_file(file)?;
+        Ok(img)
     }
 
     pub fn read_file(&mut self, file: &str) -> IoResult {
         let mut file = std::fs::File::open(file)?;
-        let header_size = size_of::<TGAHeader>();
-        assert_eq!(header_size, 18);
-        let mut bytes = [0u8; header_size];
-        file.read_exact(&mut bytes)?;
-        let header: TGAHeader = unsafe { std::mem::transmute(bytes) };
+        let mut header_bytes = [0u8; HEADER_SIZE];
+        file.read_exact(&mut header_bytes)?;
+        let header: TGAHeader = unsafe { std::mem::transmute(header_bytes) };
 
         if header.width < 1 || header.height < 1 {
-            return Err("bad image metadata".into());
+            return Err("bad image metadata".to_string().into());
         }
         self.format = (header.bits_per_pixel >> 3).try_into()?;
 
@@ -123,10 +171,53 @@ impl TGAImage {
                 return Err("invalid TGA file".into());
             }
         }
+        Ok(())
     }
 
-    pub fn write_file(&self, file: &str) -> IoResult {
-        todo!()
+    pub fn write_file(&mut self, file: &str, do_vflip: bool, do_rle: bool) -> IoResult {
+        let mut developer_area = [0u8; 4];
+        let mut extension_area = [0u8; 4];
+        let mut footer: Vec<u8> = vec![
+            'T', 'R', 'U', 'E', 'V', 'I', 'S', 'I', 'O', 'N', '-', 'X', 'F', 'I', 'L', 'E', '.',
+            '\0',
+        ]
+        .into_iter()
+        .map(|b| b as u8)
+        .collect();
+
+        let mut file = std::fs::File::create(file)?;
+
+        let mut header = TGAHeader::default();
+        header.bits_per_pixel = self.bytes_per_pixel() << 3;
+        header.width = self.width;
+        header.height = self.height;
+
+        header.datatype_code = match self.format {
+            Format::Grayscale if do_rle => 11,
+            Format::Grayscale => 3,
+            _ if do_rle => 10,
+            _ => 2,
+        };
+
+        header.image_descriptor = if do_vflip { 0x00 } else { 0x20 };
+
+        let mut header: [u8; HEADER_SIZE] = unsafe { std::mem::transmute(header) };
+
+        file.write_all(&mut header)?;
+
+        if do_rle {
+            self.write_rle_file(&mut file)?;
+        } else {
+            file.write_all(&mut self.data)?;
+        }
+
+        file.write_all(&mut developer_area)?;
+        file.write_all(&mut extension_area)?;
+        file.write_all(&mut footer)?;
+
+        file.flush()?;
+
+        Ok(())
     }
 
     pub fn flip_horizontal(&mut self) {
@@ -145,7 +236,100 @@ impl TGAImage {
         todo!()
     }
 
+    pub fn bytes_per_pixel(&self) -> u8 {
+        self.format as u8
+    }
+
     fn read_rle_file(&mut self, file: &mut File) -> IoResult {
-        todo!()
+        let num_pixels = (self.width * self.height) as usize;
+        let bpp = self.bytes_per_pixel() as usize;
+        self.data.resize(num_pixels * bpp, 0);
+
+        let mut current_pixel = 0;
+        let mut current_byte = 0;
+        let mut buffer = vec![0u8; bpp];
+        while current_pixel < num_pixels {
+            let mut chunk_header = [0u8; 1];
+            file.read_exact(&mut chunk_header)?;
+            let [mut chunk_header] = chunk_header;
+            if chunk_header < 128 {
+                chunk_header += 1;
+                for _ in 0..chunk_header {
+                    file.read_exact(&mut buffer)?;
+                    for &b in buffer.iter() {
+                        self.data[current_byte] = b;
+                        current_byte += 1;
+                    }
+                    current_pixel += 1;
+                    if current_pixel > num_pixels {
+                        return Err("too many pixels read".into());
+                    }
+                }
+            } else {
+                chunk_header -= 127;
+                file.read_exact(&mut buffer)?;
+                for _ in 0..chunk_header {
+                    for &b in buffer.iter() {
+                        self.data[current_byte] = b;
+                        current_byte += 1;
+                    }
+                    current_pixel += 1;
+                    if current_pixel > num_pixels {
+                        return Err("too many pixels read".into());
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    fn write_rle_file(&mut self, file: &mut File) -> IoResult {
+        let max_chunk_len = 128;
+        let num_pixels = (self.width * self.height) as usize;
+        let mut current_pixel = 0;
+
+        let bpp = self.bytes_per_pixel() as usize;
+
+        while current_pixel < num_pixels {
+            let chunk_start = current_pixel * bpp;
+            let mut current_byte = current_pixel * bpp;
+
+            let mut run_length = 1;
+            let mut raw = true;
+
+            while (current_pixel + run_length) < num_pixels && run_length < max_chunk_len {
+                let mut succ_eq = true;
+                let mut t = 0;
+                while succ_eq && t < bpp {
+                    succ_eq = self.data[current_byte + t] == self.data[current_byte + t + bpp];
+                    t += 1;
+                }
+                current_byte += bpp;
+                if 1 == run_length {
+                    raw = !succ_eq;
+                }
+                if raw && succ_eq {
+                    run_length -= 1;
+                    break;
+                }
+                if !(raw || succ_eq) {
+                    break;
+                }
+                run_length += 1;
+            }
+            current_pixel += run_length;
+            let mut out = if raw {
+                [run_length as u8 - 1]
+            } else {
+                [run_length as u8 + 127]
+            };
+
+            file.write_all(&mut out)?;
+            let chunk_end = if raw { run_length * bpp } else { bpp };
+            file.write_all(&mut self.data[chunk_start..chunk_end])?;
+        }
+
+        Ok(())
     }
 }