Initial commit of the converter image transformation refactor

apps/converter/backends/python/base.py

@@ -0,0 +1,80 @@
+from PIL import Image
+
+from django.utils.translation import ugettext_lazy as _
+
+from converter.literals import QUALITY_DEFAULT, QUALITY_SETTINGS
+from converter.exceptions import ConvertError, UnknownFormat, IdentifyError
+from converter.backends import ConverterBase
+from converter.literals import TRANSFORMATION_RESIZE, \
+    TRANSFORMATION_ROTATE
+
+class ConverterClass(ConverterBase):
+    def identify_file(self, input_filepath, arguments=None):
+        pass
+
+
+    def get_page_count(self, input_filepath):
+        page_count = 1
+        im = Image.open(input_filepath)
+
+        try:
+            while 1:
+                im.seek(im.tell()+1)
+                page_count += 1
+                # do something to im
+        except EOFError:
+            pass # end of sequence
+            
+        return page_count
+        
+            
+    def convert_file(self, input_filepath, output_filepath, quality=QUALITY_DEFAULT, arguments=None):
+        im = Image.open(input_filepath)
+        outfile, format = output_filepath.split(u':')
+        im.save(outfile, format)
+        '''
+        command = []
+        command.append(unicode(GM_PATH))
+        command.append(u'convert')
+        command.extend(unicode(QUALITY_SETTINGS[quality]).split())
+        command.extend(unicode(GM_SETTINGS).split())
+        command.append(unicode(input_filepath))
+        if arguments:
+            command.extend(unicode(arguments).split())
+        command.append(unicode(output_filepath))
+        proc = subprocess.Popen(command, close_fds=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
+        return_code = proc.wait()
+        if return_code != 0:
+            #Got an error from convert program
+            error_line = proc.stderr.readline()
+            if (CONVERTER_ERROR_STRING_NO_DECODER in error_line) or (CONVERTER_ERROR_STARTS_WITH in error_line):
+                #Try to determine from error message which class of error is it
+                raise UnknownFormat
+            else:
+                raise ConvertError(error_line)
+        '''
+
+    def get_format_list(self):
+        """
+        Introspect PIL's internal registry to obtain a list of the
+        supported file types
+        """
+        formats = []
+        for format_name in Image.ID:
+            formats.append((format_name, u''))
+        
+        return formats
+
+
+    def get_available_transformations(self):
+        return [
+            TRANSFORMATION_RESIZE, TRANSFORMATION_ROTATE
+        ]
+
+
+    def get_page_count(self, input_filepath):
+        try:
+            return len(self.identify_file(unicode(input_filepath)).splitlines())
+        except:
+            #TODO: send to other page number identifying program
+            return 1