This is part 2 of an ongoing series, in which we build in public an Online Manga Reader (OMR) with unique features such as instant loading, thumbnail preview, rotation, dual page and cinema mode using Rust and Yew.
You can grab the repo here.
Read all of the posts here.
The Problem:
As I'm currently reading the chapters from the file system, I need a way to automatically count the available chapters and the number of pages each chapter has.
Unfortunately, you can't read from the filesystem in Yew.
Solution:
We need to generate a rust file that can be consumed.
We can achieve that using Rust's built-in build scripts.
Full Code below:
//<root>/build.rs (NOT <root>/src/build.rs) use std::{collections::HashMap, fs}; /** * Recreates a HashMap<i16, i8> that from the directory structure of the manga * that is consumed by the state.rs */ fn main() { println!("cargo:rerun-if-changed=build.rs"); let out_dir = "./src/"; let mut chapter_state: HashMap<i16, i8> = HashMap::new(); let dir_path = "./src/assets/manga/one_piece"; // replace with your directory path let manga_folders = fs::read_dir(dir_path).expect("Failed to read directory"); for read in manga_folders { let entry = match read { Err(_) => continue, Ok(e) => e, }; if !entry.path().is_dir() { continue; } if let Some(folder_name) = entry.path().file_name().and_then(|n| n.to_str()) { if let Ok(folder_num) = folder_name.parse::<i16>() { let count = fs::read_dir(entry.path()) .expect("Failed to read directory") .count() as i8; chapter_state.insert(folder_num, count); } } } let mut sorted_manga_folders: Vec<(i16, i8)> = chapter_state.into_iter().collect(); sorted_manga_folders.sort_by_key(|&(chapter, _)| -chapter); let mut chapter_concat: String = "[".to_owned(); for (index, (chapter, page)) in sorted_manga_folders.iter().enumerate() { let comma_suffix = if index == sorted_manga_folders.len() - 1 { "" } else { "," }; chapter_concat.push_str(&format!("({}, {}){}", chapter, page, comma_suffix)); } chapter_concat.push_str("]"); println!("cargo:warning={:?}", &chapter_concat); let chapter_map_rs = format!( " // Automatically generated - see build.rs // Do not modify manually! use std::collections::HashMap; pub fn get_chapters() -> HashMap<i16, i8> {{ let chapter_state: HashMap<i16, i8> = HashMap::from({}); chapter_state }} ", chapter_concat ); let dest_path = format!("{}/chapter_map.rs", out_dir); fs::write(&dest_path, chapter_map_rs).unwrap(); } -
We create a
build.rsfile in the root directory. -
We use a special
println!macro that instructs rust to only runbuild.rsif the file has changed. -
The
out_dirvariable instructs Rust to send our file to thesrcfolder so we can consume it later. -
We then iterate over the
/src/assets/one_piecefolder to create a HashMap with the number of the chapter as the key and the number of pages as the value. -
We then create a string that will serve as the content of the rust file. This is then generated to /src/chapter_map.rs with the following contents:
// Automatically generated - see build.rs // Do not modify manually! use std::collections::HashMap; pub fn get_chapters() -> HashMap<i16, i8> { let chapter_state: HashMap<i16, i8> = HashMap::from([(1047, 20),(1046, 17),(1045, 20),(1044, 17),(1043, 17),(1042, 17)]); chapter_state } Note, that this content will depend on whether you have your assets placed inside.
- You then need to make the
chapter_map.rsfile available inmain.rsfile in order for you to import it on your file.
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