Add initial OCR support in document_writer (#141)

Author: ginnyTheCat

.github/workflows/CI.yml

@@ -42,6 +42,9 @@ jobs:
       - run: sudo apt-get -y install libfontconfig1-dev
         if: matrix.os == 'ubuntu-latest'
 
+      - name: Download tesseract training data
+        run: curl -LO https://github.com/tesseract-ocr/tessdata/raw/main/eng.traineddata
+
       - run: cargo test --features serde
 
       - name: Test package mupdf-sys
@@ -90,9 +93,14 @@ jobs:
         with:
           submodules: "recursive"
           fetch-depth: 500
-      - run: |
-          rustc --version --verbose
-          cargo test --features serde
+
+      - name: Download tesseract training data
+        run: curl -LO https://github.com/tesseract-ocr/tessdata/raw/main/eng.traineddata
+
+      - run: rustc --version --verbose
+      - run: cargo test --features serde
+        env:
+          CARGO_TERM_COLOR: always
 
   asan:
     name: Address Sanitizer
@@ -105,10 +113,14 @@ jobs:
       - uses: dtolnay/rust-toolchain@nightly
         with:
           components: rust-src
+
       - run: sudo apt-get -y install libfontconfig1-dev llvm
+
+      - name: Download tesseract training data
+        run: curl -LO https://github.com/tesseract-ocr/tessdata/raw/main/eng.traineddata
+
       - name: cargo test --features serde
-        run: |
-          cargo test -Zbuild-std --target x86_64-unknown-linux-gnu --features serde
+        run: cargo test -Zbuild-std --target x86_64-unknown-linux-gnu --features serde
         env:
           RUSTFLAGS: -Zsanitizer=address
           LSAN_OPTIONS: report_objects=1:suppressions=lsan_suppressions.txt
@@ -123,7 +135,12 @@ jobs:
           fetch-depth: 500
       - uses: dtolnay/rust-toolchain@stable
       - uses: taiki-e/install-action@valgrind
+
       - run: sudo apt-get -y install libfontconfig1-dev
+
+      - name: Download tesseract training data
+        run: curl -LO https://github.com/tesseract-ocr/tessdata/raw/main/eng.traineddata
+
       - run: cargo test --features serde
         env:
           CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER: "valgrind --error-exitcode=1 --track-origins=yes"

.gitignore

@@ -2,4 +2,4 @@ target
 Cargo.lock
 **/*.rs.bk
 /build
-tests/output/*.png
+tests/output/*

mupdf-sys/wrapper.c

@@ -3227,6 +3227,20 @@ fz_document_writer *mupdf_new_document_writer(fz_context *ctx, const char *filen
     return writer;
 }
 
+fz_document_writer *mupdf_new_pdfocr_writer(fz_context *ctx, const char *path, const char *options, mupdf_error_t **errptr)
+{
+    fz_document_writer *writer = NULL;
+    fz_try(ctx)
+    {
+        writer = fz_new_pdfocr_writer(ctx, path, options);
+    }
+    fz_catch(ctx)
+    {
+        mupdf_save_error(ctx, errptr);
+    }
+    return writer;
+}
+
 fz_device *mupdf_document_writer_begin_page(fz_context *ctx, fz_document_writer *writer, fz_rect mediabox, mupdf_error_t **errptr)
 {
     fz_device *device = NULL;

src/document_writer.rs

@@ -3,16 +3,20 @@ use std::ptr;
 
 use mupdf_sys::*;
 
-use crate::{context, Device, Error, Rect};
+use crate::{context, Device, Error, FilePath, Rect};
 
 #[derive(Debug)]
 pub struct DocumentWriter {
     inner: *mut fz_document_writer,
 }
 
 impl DocumentWriter {
-    pub fn new(filename: &str, format: &str, options: &str) -> Result<Self, Error> {
-        let c_filename = CString::new(filename)?;
+    pub fn new<P: AsRef<FilePath> + ?Sized>(
+        filename: &P,
+        format: &str,
+        options: &str,
+    ) -> Result<Self, Error> {
+        let c_filename = CString::new(filename.as_ref().as_bytes())?;
         let c_format = CString::new(format)?;
         let c_options = CString::new(options)?;
         unsafe {
@@ -26,6 +30,21 @@ impl DocumentWriter {
         .map(|inner| Self { inner })
     }
 
+    #[cfg(feature = "tesseract")]
+    pub fn with_ocr<P: AsRef<FilePath> + ?Sized>(path: &P, options: &str) -> Result<Self, Error> {
+        let c_path = CString::new(path.as_ref().as_bytes())?;
+        let c_options = CString::new(options)?;
+
+        unsafe {
+            ffi_try!(mupdf_new_pdfocr_writer(
+                context(),
+                c_path.as_ptr(),
+                c_options.as_ptr()
+            ))
+        }
+        .map(|inner| Self { inner })
+    }
+
     pub fn begin_page(&mut self, media_box: Rect) -> Result<Device, Error> {
         unsafe {
             ffi_try!(mupdf_document_writer_begin_page(
@@ -57,3 +76,47 @@ impl Drop for DocumentWriter {
         }
     }
 }
+
+#[cfg(not(target_arch = "wasm32"))]
+#[cfg(test)]
+mod test {
+    use crate::{pdf::PdfDocument, ColorParams, Image, Matrix, Rect};
+
+    use super::DocumentWriter;
+
+    #[test]
+    fn test_writer_ocr() {
+        let output = "tests/output/ocr.pdf";
+
+        {
+            let mut writer = DocumentWriter::with_ocr(output, "").unwrap();
+
+            let image = Image::from_file("tests/files/ocr.png").unwrap();
+            let width = image.width() as f32;
+            let height = image.height() as f32;
+
+            let device = writer
+                .begin_page(Rect {
+                    x0: 0.0,
+                    y0: 0.0,
+                    x1: width,
+                    y1: height,
+                })
+                .unwrap();
+            device
+                .fill_image(
+                    &image,
+                    &Matrix::new_scale(width, height),
+                    1.0,
+                    ColorParams::default(),
+                )
+                .unwrap();
+            writer.end_page(device).unwrap();
+        }
+
+        let doc = PdfDocument::open(output).unwrap();
+        let page = doc.load_page(0).unwrap();
+        let res = page.search("A short OCR test", 0).unwrap();
+        assert_eq!(res.len(), 1);
+    }
+}

tests/files/i32-box.pdf

@@ -36,15 +36,6 @@ fn test_issue_27_flatten() {
 #[cfg(not(target_arch = "wasm32"))]
 #[test]
 fn test_issue_43_malloc() {
-    const IDENTITY: mupdf::Matrix = mupdf::Matrix {
-        a: 1.0,
-        b: 0.0,
-        c: 0.0,
-        d: 1.0,
-        e: 0.0,
-        f: 0.0,
-    };
-
     let density = 300;
     let height = 1500;
     let options = format!("resolution={},height={}", density, height);
@@ -57,7 +48,7 @@ fn test_issue_43_malloc() {
         let page0 = doc.load_page(0).unwrap();
         let mediabox = page0.bounds().unwrap();
         let device = writer.begin_page(mediabox).unwrap();
-        page0.run(&device, &IDENTITY).unwrap();
+        page0.run(&device, &mupdf::Matrix::IDENTITY).unwrap();
         writer.end_page(device).unwrap();
     }
 }