Refactor filters

src/main/python/ttconv/filters/doc/lcd.py

@@ -23,8 +23,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-"""Least common denominator filter. Merges regions and removes all text
-formatting but color."""
+"""Defines the Least common denominator (LCD) filter."""
 
 from __future__ import annotations
 import logging
@@ -63,8 +62,8 @@ def _safe_area_decoder(s):
   return safe_area
 
 @dataclass
-class LCDFilterConfig(ModuleConfiguration):
-  """Configuration class for the Simplify Regions filter"""
+class LCDDocFilterConfig(ModuleConfiguration):
+  """Configuration class for the Least common denominator (LCD) filter"""
 
   @classmethod
   def name(cls):
@@ -82,14 +81,15 @@ def name(cls):
   # specifies the paragraph background color
   bg_color: typing.Optional[ColorType] = field(default=NamedColors.black.value, metadata={"decoder": ttconv.utils.parse_color})
 
-class LCDFilter(DocumentFilter):
-  """Filter that simplifies regions"""
+class LCDDocFilter(DocumentFilter):
+  """Merges regions and removes all text formatting with the exception of color
+  and text alignment."""
 
   @classmethod
   def get_config_class(cls) -> ModuleConfiguration:
-    return LCDFilterConfig
+    return LCDDocFilterConfig
 
-  def __init__(self, config: LCDFilterConfig):
+  def __init__(self, config: LCDDocFilterConfig):
     super().__init__(config)
 
   def process(self, doc: ContentDocument) -> ContentDocument:

src/main/python/ttconv/filters/isd/__init__.py

@@ -25,12 +25,5 @@
 
 """Data model filter"""
 
-from ttconv.isd import ISD
 
 
-class Filter:
-  """Abstract base class for filters"""
-
-  def process(self, isd: ISD):
-    """Process the specified ISD and returns it."""
-    raise NotImplementedError

src/main/python/ttconv/filters/isd/default_style_properties.py

@@ -28,15 +28,15 @@
 import logging
 from typing import Dict, Type, Any
 
-from ttconv.filters.isd import Filter
+from ttconv.filters.isd_filter import ISDFilter
 from ttconv.isd import ISD
 from ttconv.model import ContentElement
 from ttconv.style_properties import StyleProperty
 
 LOGGER = logging.getLogger(__name__)
 
 
-class DefaultStylePropertyValuesFilter(Filter):
+class DefaultStylePropertyValuesISDFilter(ISDFilter):
   """Filter that remove default style properties"""
 
   def __init__(self, style_property_default_values: Dict[Type[StyleProperty], Any]):

src/main/python/ttconv/filters/isd/merge_paragraphs.py

@@ -27,14 +27,14 @@
 
 import logging
 
-from ttconv.filters.isd import Filter
+from ttconv.filters.isd_filter import ISDFilter
 from ttconv.isd import ISD
 from ttconv.model import Div, P, Br, ContentElement
 
 LOGGER = logging.getLogger(__name__)
 
 
-class ParagraphsMergingFilter(Filter):
+class ParagraphsMergingISDFilter(ISDFilter):
   """Filter for merging ISD document paragraphs per region into a single paragraph"""
 
   def _get_paragraphs(self, element: ContentElement):

src/main/python/ttconv/filters/isd/merge_regions.py

@@ -27,14 +27,14 @@
 
 import logging
 
-from ttconv.filters.isd import Filter
+from ttconv.filters.isd_filter import ISDFilter
 from ttconv.isd import ISD
 from ttconv.model import Body
 
 LOGGER = logging.getLogger(__name__)
 
 
-class RegionsMergingFilter(Filter):
+class RegionsMergingISDFilter(ISDFilter):
   """Filter for merging ISD document regions into a single region"""
 
   def process(self, isd: ISD):

src/main/python/ttconv/filters/isd/supported_style_properties.py

@@ -28,41 +28,24 @@
 import logging
 from typing import Dict, List, Type
 
-from ttconv.filters.isd import Filter
+from ttconv.filters.isd_filter import ISDFilter
 from ttconv.isd import ISD
 from ttconv.model import ContentElement
 from ttconv.style_properties import StyleProperty
+import ttconv.filters.supported_style_properties
 
 LOGGER = logging.getLogger(__name__)
 
 
-class SupportedStylePropertiesFilter(Filter):
+class SupportedStylePropertiesISDFilter(ISDFilter):
   """Filter that remove unsupported style properties"""
 
   def __init__(self, supported_style_properties: Dict[Type[StyleProperty], List]):
-    self.supported_style_properties = supported_style_properties
-
-  def _process_element(self, element: ContentElement):
-    """Filter ISD element style properties"""
-
-    element_styles = list(element.iter_styles())
-    for style_prop in element_styles:
-
-      if style_prop in self.supported_style_properties.keys():
-        value = element.get_style(style_prop)
-        supported_values = self.supported_style_properties[style_prop]
-
-        if len(supported_values) == 0 or value in supported_values:
-          continue
-
-      element.set_style(style_prop, None)
-
-    for child in element:
-      self._process_element(child)
+    self.filter = ttconv.filters.supported_style_properties.SupportedStylePropertiesFilter(supported_style_properties)
 
   def process(self, isd: ISD):
     """Filter ISD document style properties"""
     LOGGER.debug("Filter default style properties from ISD.")
 
     for region in isd.iter_regions():
-      self._process_element(region)
+      self.filter.process_element(region)

src/main/python/ttconv/filters/isd_filter.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+# -*- coding: UTF-8 -*-
+
+# Copyright (c) 2020, Sandflow Consulting LLC
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice, this
+#    list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright notice,
+#    this list of conditions and the following disclaimer in the documentation
+#    and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Data model filter"""
+
+from ttconv.isd import ISD
+
+class ISDFilter:
+  """Abstract base class for filters"""
+
+  def process(self, isd: ISD):
+    """Process the specified ISD and returns it."""
+    raise NotImplementedError

src/main/python/ttconv/filters/remove_animations.py

@@ -31,9 +31,6 @@
 from ttconv.model import ContentDocument, ContentElement
 from ttconv.style_properties import StyleProperty
 
-LOGGER = logging.getLogger(__name__)
-
-
 class RemoveAnimationFilter:
   """Filter that remove animations"""
 

src/main/python/ttconv/filters/supported_style_properties.py

@@ -31,9 +31,6 @@
 from ttconv.model import ContentDocument, ContentElement
 from ttconv.style_properties import StyleProperty
 
-LOGGER = logging.getLogger(__name__)
-
-
 class SupportedStylePropertiesFilter:
   """Filter that remove unsupported style properties"""
 

src/main/python/ttconv/srt/writer.py

@@ -31,11 +31,11 @@
 
 import ttconv.model as model
 import ttconv.srt.style as style
-from ttconv.filters.isd import Filter
-from ttconv.filters.isd.default_style_properties import DefaultStylePropertyValuesFilter
-from ttconv.filters.isd.merge_paragraphs import ParagraphsMergingFilter
-from ttconv.filters.isd.merge_regions import RegionsMergingFilter
-from ttconv.filters.isd.supported_style_properties import SupportedStylePropertiesFilter
+from ttconv.filters.isd_filter import ISDFilter
+from ttconv.filters.isd.default_style_properties import DefaultStylePropertyValuesISDFilter
+from ttconv.filters.isd.merge_paragraphs import ParagraphsMergingISDFilter
+from ttconv.filters.isd.merge_regions import RegionsMergingISDFilter
+from ttconv.filters.isd.supported_style_properties import SupportedStylePropertiesISDFilter
 from ttconv.isd import ISD
 from ttconv.srt.paragraph import SrtParagraph
 from ttconv.srt.config import SRTWriterConfiguration
@@ -47,10 +47,10 @@
 class SrtContext:
   """SRT writer context"""
 
-  filters: List[Filter] = (
-    RegionsMergingFilter(),
-    ParagraphsMergingFilter(),
-    SupportedStylePropertiesFilter({
+  filters: List[ISDFilter] = (
+    RegionsMergingISDFilter(),
+    ParagraphsMergingISDFilter(),
+    SupportedStylePropertiesISDFilter({
       StyleProperties.FontWeight: [
         # Every values
       ],
@@ -65,7 +65,7 @@ class SrtContext:
         # Every values
       ],
     }),
-    DefaultStylePropertyValuesFilter({
+    DefaultStylePropertyValuesISDFilter({
       StyleProperties.Color: NamedColors.white.value,
       StyleProperties.FontWeight: FontWeightType.normal,
       StyleProperties.FontStyle: FontStyleType.normal,

src/main/python/ttconv/vtt/writer.py

@@ -32,10 +32,10 @@
 import ttconv.model as model
 from ttconv.vtt.config import VTTWriterConfiguration
 import ttconv.vtt.style as style
-from ttconv.filters.isd.default_style_properties import DefaultStylePropertyValuesFilter
-from ttconv.filters.isd.merge_paragraphs import ParagraphsMergingFilter
-from ttconv.filters.isd.merge_regions import RegionsMergingFilter
-from ttconv.filters.isd.supported_style_properties import SupportedStylePropertiesFilter
+from ttconv.filters.isd.default_style_properties import DefaultStylePropertyValuesISDFilter
+from ttconv.filters.isd.merge_paragraphs import ParagraphsMergingISDFilter
+from ttconv.filters.isd.merge_regions import RegionsMergingISDFilter
+from ttconv.filters.isd.supported_style_properties import SupportedStylePropertiesISDFilter
 from ttconv.isd import ISD
 from ttconv.vtt.cue import VttCue
 from ttconv.vtt.css_class import CssClass
@@ -61,9 +61,9 @@ def __init__(self, config: VTTWriterConfiguration):
     self._filters = []
 
     if not self._config.line_position:
-      self._filters.append(RegionsMergingFilter())
+      self._filters.append(RegionsMergingISDFilter())
 
-    self._filters.append(ParagraphsMergingFilter())
+    self._filters.append(ParagraphsMergingISDFilter())
 
     supported_styles = {
       StyleProperties.FontWeight: [],
@@ -92,10 +92,10 @@ def __init__(self, config: VTTWriterConfiguration):
         StyleProperties.Direction: [],
       })
 
-    self._filters.append(SupportedStylePropertiesFilter(supported_styles))
+    self._filters.append(SupportedStylePropertiesISDFilter(supported_styles))
 
     self._filters.append(
-      DefaultStylePropertyValuesFilter({
+      DefaultStylePropertyValuesISDFilter({
         StyleProperties.Color: NamedColors.white.value,
         StyleProperties.BackgroundColor: NamedColors.transparent.value,
         StyleProperties.FontWeight: FontWeightType.normal,

src/test/python/test_filter_default_style_properties.py

@@ -29,7 +29,7 @@
 from fractions import Fraction
 import unittest
 
-from ttconv.filters.isd.default_style_properties import DefaultStylePropertyValuesFilter
+from ttconv.filters.isd.default_style_properties import DefaultStylePropertyValuesISDFilter
 from ttconv.isd import ISD
 from ttconv.model import P, ContentDocument, Region, Body, Div, Span, Text
 from ttconv.style_properties import StyleProperties, NamedColors, FontStyleType, DirectionType
@@ -38,7 +38,7 @@
 class DefaultStylesFilterTest(unittest.TestCase):
 
   def test_process_element(self):
-    default_style_value_filter = DefaultStylePropertyValuesFilter({
+    default_style_value_filter = DefaultStylePropertyValuesISDFilter({
       StyleProperties.Color: StyleProperties.Color.make_initial_value()
     })
 
@@ -55,7 +55,7 @@ def test_process_element(self):
     self.assertEqual(len(StyleProperties.ALL) - 1, len(p._styles))
 
   def test_process_isd(self):
-    default_style_value_filter = DefaultStylePropertyValuesFilter({
+    default_style_value_filter = DefaultStylePropertyValuesISDFilter({
       StyleProperties.BackgroundColor: NamedColors.red.value,
       StyleProperties.Direction: DirectionType.ltr
     })

src/test/python/test_filter_merge_paragraphs.py

@@ -30,7 +30,7 @@
 from typing import List
 import unittest
 
-from ttconv.filters.isd.merge_paragraphs import ParagraphsMergingFilter
+from ttconv.filters.isd.merge_paragraphs import ParagraphsMergingISDFilter
 from ttconv.isd import ISD
 from ttconv.model import P, Body, Div, Span, Text, ContentElement, Br
 
@@ -66,7 +66,7 @@ def _get_text_from_children(element: ContentElement) -> str:
       return ParagraphsMergingFilterTest._get_text_from_children(child)
 
   def test_merging_regions(self):
-    paragraphs_merging_filter = ParagraphsMergingFilter()
+    paragraphs_merging_filter = ParagraphsMergingISDFilter()
 
     isd = ISD(None)
 

src/test/python/test_filter_merge_regions.py

@@ -29,7 +29,7 @@
 
 import unittest
 
-from ttconv.filters.isd.merge_regions import RegionsMergingFilter
+from ttconv.filters.isd.merge_regions import RegionsMergingISDFilter
 from ttconv.isd import ISD
 from ttconv.model import P, Body, Div, Span, Text, ContentElement
 
@@ -62,7 +62,7 @@ def _get_text_from_children(element: ContentElement) -> str:
       return RegionsMergingFilterTest._get_text_from_children(child)
 
   def test_merging_regions(self):
-    regions_merging_filter = RegionsMergingFilter()
+    regions_merging_filter = RegionsMergingISDFilter()
 
     isd = ISD(None)
 

src/test/python/test_filter_supported_style_properties.py

@@ -29,7 +29,8 @@
 from fractions import Fraction
 import unittest
 
-from ttconv.filters.isd.supported_style_properties import SupportedStylePropertiesFilter
+from ttconv.filters.supported_style_properties import SupportedStylePropertiesFilter
+from ttconv.filters.isd.supported_style_properties import SupportedStylePropertiesISDFilter as SupportedStylePropertiesFilterISD
 from ttconv.isd import ISD
 from ttconv.model import P, ContentDocument, Region, Body, Div, Span, Text
 from ttconv.style_properties import StyleProperties, NamedColors, FontStyleType, DirectionType, ExtentType, LengthType
@@ -53,22 +54,22 @@ def test_process_element(self):
     self.assertEqual(StyleProperties.Color.make_initial_value(), p.get_style(StyleProperties.Color))
     self.assertEqual(StyleProperties.Extent.make_initial_value(), p.get_style(StyleProperties.Extent))
 
-    supported_style_properties._process_element(p)
+    supported_style_properties.process_element(p)
 
     self.assertIsNone(p.get_style(StyleProperties.Color))
     self.assertEqual(StyleProperties.Extent.make_initial_value(), p.get_style(StyleProperties.Extent))
     self.assertEqual(1, len(p._styles))
 
     p.set_style(StyleProperties.Color, NamedColors.red.value)
 
-    supported_style_properties._process_element(p)
+    supported_style_properties.process_element(p)
 
     self.assertEqual(2, len(p._styles))
     self.assertEqual(NamedColors.red.value, p.get_style(StyleProperties.Color))
     self.assertEqual(StyleProperties.Extent.make_initial_value(), p.get_style(StyleProperties.Extent))
 
   def test_process_isd(self):
-    supported_style_properties = SupportedStylePropertiesFilter({
+    supported_style_properties = SupportedStylePropertiesFilterISD({
       StyleProperties.BackgroundColor: [
         NamedColors.red.value
       ],