Added OCR capabilites

apps/ocr/api.py

@@ -0,0 +1,66 @@
+#Some code from http://wiki.github.com/hoffstaetter/python-tesseract
+
+import os
+
+import subprocess
+import tempfile
+
+from django.utils.translation import ugettext as _
+
+from documents.models import DocumentPage
+from documents.conf.settings import TEMPORARY_DIRECTORY
+from converter.api import convert_document_for_ocr
+
+from ocr.conf.settings import TESSERACT_PATH
+
+
+def cleanup(filename):
+    ''' tries to remove the given filename. Ignores non-existent files '''
+    try:
+        os.remove(filename)
+    except OSError:
+        pass
+
+class TesseractError(Exception):
+    def __init__(self, status, message):
+        self.status = status
+        self.message = message
+
+
+def run_tesseract(input_filename, output_filename_base, lang=None):
+    command = [TESSERACT_PATH, input_filename, output_filename_base]
+    if lang is not None:
+        command += ['-l', lang]
+
+    proc = subprocess.Popen(command, stderr=subprocess.PIPE)
+    return (proc.wait(), proc.stderr.read())
+
+
+def ocr_document(document):
+    total_pages = 1
+    page = 0
+    while page < total_pages:
+        imagefile = convert_document_for_ocr(document, page=page)
+        desc, filepath = tempfile.mkstemp()
+        try:
+            status, error_string = run_tesseract(imagefile, filepath)
+            if status:
+                errors = get_errors(error_string)
+                raise TesseractError(status, errors)
+        finally:
+            ocr_output = os.extsep.join([filepath, 'txt'])
+            f = file(ocr_output)
+            try:
+                document_page, created = DocumentPage.objects.get_or_create(document=document,
+                    page_number=page)
+                document_page.content = f.read().strip()
+                document_page.page_label = _(u'Text from OCR')
+                document_page.save()
+            finally:
+                f.close()
+                cleanup(filepath)
+                cleanup(ocr_output)
+                cleanup(imagefile)
+            
+        page += 1
+