This commit is contained in:
Henrik Jess Nielsen
218
crates/kreuzberg-tesseract/src/lib.rs
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218
crates/kreuzberg-tesseract/src/lib.rs
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#![cfg_attr(
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not(any(feature = "build-tesseract", feature = "build-tesseract-wasm")),
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allow(unused_variables, dead_code)
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)]
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#![allow(clippy::arc_with_non_send_sync)]
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#![allow(clippy::missing_transmute_annotations)]
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#![allow(clippy::type_complexity)]
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#![allow(clippy::new_without_default)]
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#![allow(clippy::not_unsafe_ptr_arg_deref)]
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#![allow(clippy::cmp_null)]
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//! # kreuzberg-tesseract
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//!
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//! `kreuzberg-tesseract` provides safe Rust bindings for Tesseract OCR with built-in compilation
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//! of Tesseract and Leptonica libraries. This crate aims to make OCR functionality
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//! easily accessible in Rust projects while handling the complexity of interfacing
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//! with the underlying C++ libraries.
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//!
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//! ## Usage
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//!
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//! Here's a basic example of how to use `kreuzberg-tesseract`:
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//!
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//! ```rust
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//! use std::path::PathBuf;
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//! use std::error::Error;
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//! use kreuzberg_tesseract::TesseractAPI;
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//!
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//! fn get_default_tessdata_dir() -> PathBuf {
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//! if cfg!(target_os = "macos") {
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//! let home_dir = std::env::var("HOME").expect("HOME environment variable not set");
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//! PathBuf::from(home_dir)
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//! .join("Library")
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//! .join("Application Support")
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//! .join("kreuzberg-tesseract")
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//! .join("tessdata")
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//! } else if cfg!(target_os = "linux") {
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//! let home_dir = std::env::var("HOME").expect("HOME environment variable not set");
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//! PathBuf::from(home_dir)
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//! .join(".kreuzberg-tesseract")
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//! .join("tessdata")
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//! } else if cfg!(target_os = "windows") {
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//! PathBuf::from(std::env::var("APPDATA").expect("APPDATA environment variable not set"))
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//! .join("kreuzberg-tesseract")
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//! .join("tessdata")
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//! } else {
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//! panic!("Unsupported operating system");
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//! }
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//! }
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//!
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//! fn get_tessdata_dir() -> PathBuf {
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//! match std::env::var("TESSDATA_PREFIX") {
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//! Ok(dir) => {
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//! let path = PathBuf::from(dir);
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//! let path = if path.ends_with("tessdata") { path } else { path.join("tessdata") };
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//! println!("Using TESSDATA_PREFIX directory: {:?}", path);
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//! path
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//! }
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//! Err(_) => {
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//! let default_dir = get_default_tessdata_dir();
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//! println!(
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//! "TESSDATA_PREFIX not set, using default directory: {:?}",
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//! default_dir
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//! );
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//! default_dir
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//! }
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//! }
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//! }
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//!
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//! fn main() -> Result<(), Box<dyn Error>> {
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//! let api = TesseractAPI::new()?;
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//!
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//! // Get tessdata directory (uses default location or TESSDATA_PREFIX if set)
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//! let tessdata_dir = get_tessdata_dir();
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//! api.init(tessdata_dir.to_str().unwrap(), "eng")?;
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//!
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//! let width = 24;
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//! let height = 24;
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//! let bytes_per_pixel = 1;
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//! let bytes_per_line = width * bytes_per_pixel;
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//!
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//! // Initialize image data with all white pixels
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//! let mut image_data = vec![255u8; width * height];
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//!
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//! // Draw number 9 with clearer distinction
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//! for y in 4..19 {
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//! for x in 7..17 {
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//! // Top bar
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//! if y == 4 && x >= 8 && x <= 15 {
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//! image_data[y * width + x] = 0;
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//! }
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//! // Top curve left side
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//! if y >= 4 && y <= 10 && x == 7 {
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//! image_data[y * width + x] = 0;
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//! }
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//! // Top curve right side
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//! if y >= 4 && y <= 11 && x == 16 {
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//! image_data[y * width + x] = 0;
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//! }
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//! // Middle bar
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//! if y == 11 && x >= 8 && x <= 15 {
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//! image_data[y * width + x] = 0;
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//! }
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//! // Bottom right vertical line
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//! if y >= 11 && y <= 18 && x == 16 {
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//! image_data[y * width + x] = 0;
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//! }
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//! // Bottom bar
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//! if y == 18 && x >= 8 && x <= 15 {
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//! image_data[y * width + x] = 0;
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//! }
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//! }
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//! }
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//!
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//! // Set the image data
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//! api.set_image(&image_data, width.try_into().unwrap(), height.try_into().unwrap(), bytes_per_pixel.try_into().unwrap(), bytes_per_line.try_into().unwrap())?;
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//!
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//! // Set whitelist for digits only
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//! api.set_variable("tessedit_char_whitelist", "0123456789")?;
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//!
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//! // Set PSM mode to single character
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//! api.set_variable("tessedit_pageseg_mode", "10")?;
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//!
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//! // Get the recognized text
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//! let text = api.get_utf8_text()?;
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//! println!("Recognized text: {}", text.trim());
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//!
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//! Ok(())
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//! }
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//! ```
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/// Declare FFI functions with `extern "C-unwind"` on native targets (to catch
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/// C++ exceptions from Tesseract/Leptonica) and `extern "C"` on WASM (where
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/// the LLVM backend does not support `cleanupret` / C++ unwinding).
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macro_rules! ffi_extern {
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(
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$(
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$(#[$meta:meta])*
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$vis:vis fn $name:ident($($arg:ident : $ty:ty),* $(,)?) $(-> $ret:ty)?;
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)*
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) => {
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#[cfg(not(target_arch = "wasm32"))]
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unsafe extern "C-unwind" {
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$(
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$(#[$meta])*
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$vis fn $name($($arg : $ty),*) $(-> $ret)?;
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)*
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}
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#[cfg(target_arch = "wasm32")]
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unsafe extern "C" {
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$(
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$(#[$meta])*
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$vis fn $name($($arg : $ty),*) $(-> $ret)?;
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)*
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}
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};
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}
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pub use error::{Result, TesseractError};
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mod error;
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// WASM: Override __cxa_atexit to be a no-op. WASI SDK's __cxa_atexit calls calloc during
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// C++ static initialization, which crashes because dlmalloc's heap isn't properly set up
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// for wasm32-unknown-unknown. Since WASM modules never exit normally, atexit handlers
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// are unnecessary.
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#[cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))]
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mod wasm_compat {
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#[unsafe(no_mangle)]
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pub unsafe extern "C" fn __cxa_atexit(
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_func: Option<unsafe extern "C" fn(*mut core::ffi::c_void)>,
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_arg: *mut core::ffi::c_void,
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_dso_handle: *mut core::ffi::c_void,
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) -> i32 {
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0 // Success, but don't actually register anything
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}
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}
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mod page_iterator;
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pub use page_iterator::{BlockInfo, PageIterator, ParaInfo};
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mod result_iterator;
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pub use result_iterator::{FontAttributes, ResultIterator, WordData};
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mod choice_iterator;
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pub use choice_iterator::ChoiceIterator;
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mod monitor;
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pub use monitor::TessMonitor;
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mod result_renderer;
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pub use result_renderer::TessResultRenderer;
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mod mutable_iterator;
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pub use mutable_iterator::MutableIterator;
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mod enums;
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pub use enums::{
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TessOrientation, TessPageIteratorLevel, TessPageSegMode, TessParagraphJustification, TessPolyBlockType,
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TessTextlineOrder, TessWritingDirection,
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};
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mod api;
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pub use api::{BoundingBoxArray, TesseractAPI};
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pub mod leptonica;
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#[cfg(any(feature = "build-tesseract", feature = "build-tesseract-wasm"))]
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pub use leptonica::Pix;
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/// Returns the compile-time-bundled English `eng.traineddata` blob when the
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/// `bundle-tessdata-eng` feature is enabled, otherwise `None`.
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///
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/// The bundled data is the `tessdata_fast` variant (~4 MB) downloaded by
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/// `build.rs` to `TESSDATA_PREFIX_BUNDLED/tessdata/eng.traineddata`. Embedding
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/// it lets WASM builds drive Tesseract OCR without filesystem access or
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/// runtime fetches.
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#[cfg(feature = "bundle-tessdata-eng")]
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pub fn bundled_eng_traineddata() -> Option<&'static [u8]> {
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Some(include_bytes!(concat!(
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env!("TESSDATA_PREFIX_BUNDLED"),
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"/tessdata/eng.traineddata"
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)))
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}
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/// Returns `None` when the `bundle-tessdata-eng` feature is disabled.
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#[cfg(not(feature = "bundle-tessdata-eng"))]
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pub fn bundled_eng_traineddata() -> Option<&'static [u8]> {
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None
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}
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