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Rust
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190//! albedo-render: a highlighted range of a source file as PNG pages.//!//! albedo-render FILE --start N --end N --out DIR [--columns 79]//! [--tab-width 4] [--language NAME] [--max-rows 80] [--max-images 4]//! [--no-line-numbers]//!//! Writes DIR/view-1.png onward and prints one line per fact, for the caller//! to parse from text output://!//! language rust (or: language plain [reason])//! image DIR/view-1.png FIRST LAST WIDTHxHEIGHT//! remaining FIRST LAST (lines left for another call, if any)//!//! A line split across pages appears in both. Errors go to stderr, exit 1.
mod highlight;mod layout;mod raster;
use highlight::{Colors, Language};use std::path::PathBuf;use std::process::ExitCode;
const MAX_FILE_BYTES: u64 = 8 * 1024 * 1024;
struct Request { file: PathBuf, start: usize, end: usize, out: PathBuf, columns: usize, tab_width: usize, language: Option<String>, max_rows: usize, max_images: usize, line_numbers: bool,}
fn main() -> ExitCode { match parse(std::env::args().skip(1)).and_then(|request| run(&request)) { Ok(report) => { print!("{report}"); ExitCode::SUCCESS } Err(message) => { eprintln!("albedo-render: {message}"); ExitCode::FAILURE } }}
fn parse(mut args: impl Iterator<Item = String>) -> Result<Request, String> { let mut file = None; let mut request = Request { file: PathBuf::new(), start: 0, end: 0, out: PathBuf::new(), columns: 79, tab_width: 4, language: None, max_rows: 80, max_images: 4, line_numbers: true, }; let mut out = None; while let Some(arg) = args.next() { let mut value = || args.next().ok_or(format!("{arg} needs a value")); let mut number = |low: usize, high: usize| -> Result<usize, String> { let text = value()?; match text.parse::<usize>() { Ok(n) if (low..=high).contains(&n) => Ok(n), _ => Err(format!( "{arg} must be an integer from {low} to {high}, not {text:?}" )), } }; match arg.as_str() { "--start" => request.start = number(1, usize::MAX)?, "--end" => request.end = number(1, usize::MAX)?, "--columns" => request.columns = number(20, 400)?, "--tab-width" => request.tab_width = number(1, 16)?, "--max-rows" => request.max_rows = number(1, 1000)?, "--max-images" => request.max_images = number(1, 64)?, "--language" => request.language = Some(value()?), "--no-line-numbers" => request.line_numbers = false, "--out" => out = Some(PathBuf::from(value()?)), flag if flag.starts_with("--") => return Err(format!("unknown option {flag}")), _ if file.is_none() => file = Some(PathBuf::from(arg)), _ => return Err(format!("unexpected argument {arg:?}")), } } request.file = file.ok_or("a file to render is required")?; request.out = out.ok_or("--out DIR is required")?; if request.start == 0 || request.end == 0 { return Err("--start and --end are required".into()); } if request.end < request.start { return Err(format!( "--end {} is before --start {}", request.end, request.start )); } Ok(request)}
fn run(request: &Request) -> Result<String, String> { let shown = request.file.display(); let size = std::fs::metadata(&request.file) .map_err(|e| format!("{shown}: {e}"))? .len(); if size > MAX_FILE_BYTES { return Err(format!( "{shown} is {size} bytes; at most {MAX_FILE_BYTES} can be rendered" )); } let bytes = std::fs::read(&request.file).map_err(|e| format!("{shown}: {e}"))?; if bytes[..bytes.len().min(8192)].contains(&0) { return Err(format!("{shown} looks binary (it contains NUL bytes)")); } let source = String::from_utf8_lossy(&bytes); let lines = layout::lines(&source); if request.start > lines.len() { return Err(format!( "{shown} has {} lines; --start {} is past the end", lines.len(), request.start )); } let end = request.end.min(lines.len());
let language = request .language .clone() .or_else(|| arborium::detect_language(&request.file.to_string_lossy()).map(String::from)); let colors = Colors::new( &source, language.as_deref(), &arborium_theme::theme::builtin::github_light(), ); let selected = &lines[request.start - 1..end]; let rows = layout::rows( selected, request.start, &colors, request.columns, request.tab_width, ); let pages = layout::pages(&rows, request.max_rows);
let mut report = match &colors.language { Language::Highlighted(name) => format!("language {name}\n"), Language::Unsupported(name) => format!("language plain no grammar for {name}\n"), Language::Failed(message) => format!("language plain {message}\n"), Language::Unknown => "language plain unknown file type\n".to_string(), }; let mut painter = raster::Painter::new(); let gutter = match request.line_numbers { true => end.to_string().len(), false => 1, }; for (index, range) in pages.iter().take(request.max_images).enumerate() { let page = &rows[range.clone()]; let path = request.out.join(format!("view-{}.png", index + 1)); let png = painter.png(&raster::Page { rows: page, gutter, numbers: request.line_numbers, columns: request.columns, foreground: colors.foreground, background: colors.background, }); std::fs::write(&path, &png).map_err(|e| format!("{}: {e}", path.display()))?; let (width, height) = dimensions(&png); let first = page.first().map_or(request.start, |row| row.line); let last = page.last().map_or(end, |row| row.line); report += &format!("image {} {first} {last} {width}x{height}\n", path.display()); } if let Some(rest) = pages.get(request.max_images) { report += &format!("remaining {} {end}\n", rows[rest.start].line); } Ok(report)}
/// Width and height from the IHDR chunk the encoder just wrote.fn dimensions(png: &[u8]) -> (u32, u32) { let field = |at: usize| u32::from_be_bytes(png[at..at + 4].try_into().unwrap()); (field(16), field(20))}