Add OCREngine class.

pixelocr/gui/ocrengine.py

@@ -0,0 +1,78 @@
+# Copyright (C) 2014  Andrey Golovizin
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+from queue import Queue
+
+from PyQt4.QtCore import (
+    signal,
+    slot,
+    QThread, 
+)
+
+from ..image import Image
+from ..page import Page, Letter, Space
+
+
+class OCREngine(QThread):
+    unknownLetter = signal([Letter])
+    pageChanged = signal([Page])
+
+    def __init__(self, filenames):
+        super().__init__()
+        self.filenames = filenames
+        self.chardb = {}
+        self.help_queue = Queue()
+
+    def load_page(self, filename):
+        return Page(Image.fromfile(filename).unframe(10))
+
+    def run(self):
+        for page_text in self.recognize():
+            print(page_text)
+
+    def recognize(self):
+        for filename in self.filenames:
+            page = self.load_page(filename)
+            self.pageChanged.emit(page)
+            yield '\n'.join(self.recognize_page(page))
+
+    def recognize_page(self, page):
+        for line in page.lines:
+            yield ''.join(self.recognize_line(line))
+
+    def recognize_line(self, line):
+        for letter in line.letters:
+            yield self.recognize_letter(letter)
+
+    def recognize_letter(self, letter):
+        if isinstance(letter, Space):
+            return ' '
+        try:
+            return self.chardb[letter.key]
+        except KeyError:
+            text = self.ask_for_help(letter)
+            self.chardb[letter.key] = text
+            return text
+
+    def ask_for_help(self, unknown_letter):
+        self.unknownLetter.emit(unknown_letter)
+        return self.receive_help()
+
+    def give_help(self, text):
+        self.help_queue.put(text)
+
+    def receive_help(self):
+        return self.help_queue.get()