Langauge checking

src/ocrmypdf.py

@@ -28,7 +28,7 @@ import ruffus.cmdline as cmdline
 from .hocrtransform import HocrTransform
 from .pageinfo import pdf_get_all_pageinfo
 from .pdfa import generate_pdfa_def
-from .tesseract import TESS_VERSION
+from . import tesseract
 
 
 warnings.simplefilter('ignore', pypdf.utils.PdfReadWarning)
@@ -51,11 +51,11 @@ EXIT_OTHER_ERROR=15
 
 MINIMUM_TESS_VERSION = '3.02.02'
 
-if TESS_VERSION < MINIMUM_TESS_VERSION:
+if tesseract.VERSION < MINIMUM_TESS_VERSION:
     print(
         "Please install tesseract {0} or newer "
         "(currently installed version is {1})".format(
-            MINIMUM_TESS_VERSION, TESS_VERSION),
+            MINIMUM_TESS_VERSION, tesseract.VERSION),
         file=sys.stderr)
     sys.exit(EXIT_MISSING_DEPENDENCY)
 
@@ -74,7 +74,7 @@ parser.add_argument(
     'output_file',
     help="output searchable PDF file")
 parser.add_argument(
-    '-l', '--language', nargs='*', default=['eng'],
+    '-l', '--language', action='append',
     help="language of the file to be OCRed")
 
 preprocessing = parser.add_argument_group(
@@ -135,6 +135,26 @@ debugging.add_argument(
 
 options = parser.parse_args()
 
+# ----------
+# Languages
+
+if not options.language:
+    options.language = ['eng']  # Enforce English hegemony
+
+# Support v2.x "eng+deu" language syntax
+if '+' in options.language[0]:
+    options.language = options.language[0].split('+')
+
+if not set(options.language).issubset(tesseract.LANGUAGES):
+    print(
+        "The installed version of tesseract does not have language "
+        "data for the following requested languages: ",
+        file=sys.stderr)
+    for lang in (set(options.language) - tesseract.LANGUAGES):
+        print(lang, file=sys.stderr)
+    sys.exit(EXIT_BAD_ARGS)
+
+
 # ----------
 # Logging
 

src/tesseract.py

@@ -1,21 +1,40 @@
 #!/usr/bin/env python3
 
-from cffi import FFI
-from ctypes.util import find_library
+from subprocess import Popen, PIPE, CalledProcessError
 import sys
+import os
+import re
+
+
+def _version():
+    args_tess = [
+        'tesseract',
+        '--version'
+    ]
+    p_tess = Popen(args_tess, close_fds=True, universal_newlines=True,
+                   stdout=PIPE, stderr=PIPE)
+    _, versions = p_tess.communicate(timeout=5)
+
+    tesseract_version = re.match(r'tesseract\s(.+)', versions).group(1)
+    return tesseract_version
+
+
+def _languages():
+    args_tess = [
+        'tesseract',
+        '--list-langs'
+    ]
+    p_tess = Popen(args_tess, close_fds=True, universal_newlines=True,
+                   stdout=PIPE, stderr=PIPE)
+    _, langs = p_tess.communicate(timeout=5)
+
+    return set(lang.strip() for lang in langs.splitlines()[1:])
 
-ffi = FFI()
 try:
-    libtess = ffi.dlopen(find_library('libtesseract'))
-except Exception:
-    print("Could not find Tesseract 3.02.02", file=sys.stderr)
+    VERSION = _version()
+    LANGUAGES = _languages()
+except Exception as e:
+    print(e)
+    print("Could not find tesseract executable", file=sys.stderr)
+
     sys.exit(1)
-
-ffi.cdef('''
-    const char* TessVersion();
-''')
-
-cstr_version = libtess.TessVersion()
-TESS_VERSION = ffi.string(cstr_version).decode('ascii')
-
-__all__ = ['TESS_VERSION']