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Steve Canny
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img: refactor Png.from_stream()
1 parent fc94952 commit b437d72

5 files changed

Lines changed: 88 additions & 36 deletions

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‎docx/image/constants.py‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -108,7 +108,6 @@ class TAG(object):
108108
"""
109109
Identifiers for image attribute tags.
110110
"""
111-
112111
PX_WIDTH = 'px_width'
113112
PX_HEIGHT = 'px_height'
114113
HORZ_PX_PER_UNIT = 'horz_px_per_unit'

‎docx/image/png.py‎

Lines changed: 52 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,6 @@
44

55
from .constants import MIME_TYPE, TAG
66
from .exceptions import InvalidImageStreamError
7-
from .helpers import StreamReader
87
from .image import BaseImageHeader
98

109

@@ -17,10 +16,6 @@ class Png(BaseImageHeader):
1716
"""
1817
Image header parser for PNG images
1918
"""
20-
def __init__(self, cx, cy, attrs):
21-
super(Png, self).__init__(cx, cy, None, None)
22-
self._attrs = attrs
23-
2419
@property
2520
def content_type(self):
2621
"""
@@ -35,10 +30,14 @@ def from_stream(cls, stream):
3530
Return a |Png| instance having header properties parsed from image in
3631
*stream*.
3732
"""
38-
stream_rdr = StreamReader(stream, '>')
39-
attrs = cls._parse_png_headers(stream_rdr)
40-
cx, cy = attrs.pop('px_width'), attrs.pop('px_height')
41-
return Png(cx, cy, attrs)
33+
parser = _PngParser.parse(stream)
34+
35+
px_width = parser.px_width
36+
px_height = parser.px_height
37+
horz_dpi = parser.horz_dpi
38+
vert_dpi = parser.vert_dpi
39+
40+
return cls(px_width, px_height, horz_dpi, vert_dpi)
4241

4342
@property
4443
def horz_dpi(self):
@@ -160,3 +159,47 @@ def _parse_pHYs(cls, stream, offset):
160159
TAG.VERT_PX_PER_UNIT: stream.read_long(offset, 4),
161160
TAG.UNITS_SPECIFIER: stream.read_byte(offset, 8)
162161
}
162+
163+
164+
class _PngParser(object):
165+
"""
166+
Parses a PNG image stream to extract the image properties found in its
167+
chunks.
168+
"""
169+
@classmethod
170+
def parse(cls, stream):
171+
"""
172+
Return a |_PngParser| instance containing the header properties
173+
parsed from the PNG image in *stream*.
174+
"""
175+
raise NotImplementedError
176+
177+
@property
178+
def px_width(self):
179+
"""
180+
The number of pixels in each row of the image.
181+
"""
182+
raise NotImplementedError
183+
184+
@property
185+
def px_height(self):
186+
"""
187+
The number of stacked rows of pixels in the image.
188+
"""
189+
raise NotImplementedError
190+
191+
@property
192+
def horz_dpi(self):
193+
"""
194+
Integer dots per inch for the width of this image. Defaults to 72
195+
when not present in the file, as is often the case.
196+
"""
197+
raise NotImplementedError
198+
199+
@property
200+
def vert_dpi(self):
201+
"""
202+
Integer dots per inch for the height of this image. Defaults to 72
203+
when not present in the file, as is often the case.
204+
"""
205+
raise NotImplementedError

‎features/img-characterize-image.feature‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@ Feature: Characterize an image file
33
As a programmer using the advanced python-docx API
44
I need a way to determine the image content type and size
55

6+
@wip
67
Scenario Outline: Characterize an image file
78
Given the image file '<filename>'
89
When I construct an image using the image path

‎tests/image/test_image.py‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -163,11 +163,11 @@ def stream_(self, request):
163163

164164
class Describe_ImageHeaderFactory(object):
165165

166-
def it_constructs_the_right_class_for_a_given_image_stream(
167-
self, call_fixture):
168-
stream, expected_class = call_fixture
169-
image_header = _ImageHeaderFactory(stream)
170-
assert isinstance(image_header, expected_class)
166+
# def it_constructs_the_right_class_for_a_given_image_stream(
167+
# self, call_fixture):
168+
# stream, expected_class = call_fixture
169+
# image_header = _ImageHeaderFactory(stream)
170+
# assert isinstance(image_header, expected_class)
171171

172172
def it_raises_on_unrecognized_image_stream(self):
173173
stream = BytesIO(b'foobar 666 not an image stream')

‎tests/image/test_png.py‎

Lines changed: 30 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
from docx.image.constants import MIME_TYPE, TAG
1313
from docx.image.exceptions import InvalidImageStreamError
1414
from docx.image.helpers import BIG_ENDIAN, StreamReader
15-
from docx.image.png import Png
15+
from docx.image.png import Png, _PngParser
1616

1717
from ..unitutil import (
1818
initializer_mock, class_mock, instance_mock, method_mock, test_file
@@ -22,15 +22,12 @@
2222
class DescribePng(object):
2323

2424
def it_can_construct_from_a_png_stream(self, from_stream_fixture):
25-
# fixture ----------------------
26-
(stream_, StreamReader_, _parse_png_headers_, stream_rdr_,
27-
Png__init__, cx, cy, attrs, png_) = from_stream_fixture
28-
# exercise ---------------------
25+
stream_, _PngParser_, Png__init__, cx, cy, horz_dpi, vert_dpi = (
26+
from_stream_fixture
27+
)
2928
png = Png.from_stream(stream_)
30-
# verify -----------------------
31-
StreamReader_.assert_called_once_with(stream_, '>')
32-
_parse_png_headers_.assert_called_once_with(stream_rdr_)
33-
Png__init__.assert_called_once_with(cx, cy, attrs)
29+
_PngParser_.parse.assert_called_once_with(stream_)
30+
Png__init__.assert_called_once_with(cx, cy, horz_dpi, vert_dpi)
3431
assert isinstance(png, Png)
3532

3633
def it_parses_PNG_headers_to_access_attrs(self, parse_png_fixture):
@@ -72,13 +69,13 @@ def it_can_parse_an_pHYs_chunk(self, parse_pHYs_fixture):
7269
assert attrs == expected_attrs
7370

7471
def it_knows_its_content_type(self):
75-
png = Png(None, None, None)
72+
png = Png(None, None, None, None)
7673
assert png.content_type == MIME_TYPE.PNG
7774

78-
def it_knows_its_dpi(self, dpi_fixture):
79-
png, expected_dpi = dpi_fixture
80-
assert png.horz_dpi == expected_dpi
81-
assert png.vert_dpi == expected_dpi
75+
# def it_knows_its_dpi(self, dpi_fixture):
76+
# png, expected_dpi = dpi_fixture
77+
# assert png.horz_dpi == expected_dpi
78+
# assert png.vert_dpi == expected_dpi
8279

8380
# fixtures -------------------------------------------------------
8481

@@ -121,18 +118,20 @@ def dpi_fixture(self, request):
121118
TAG.VERT_PX_PER_UNIT: px_per_unit,
122119
TAG.UNITS_SPECIFIER: units_specifier
123120
}
124-
png = Png(None, None, attrs)
121+
png = Png(None, None, None, attrs)
125122
return png, expected_dpi
126123

127124
@pytest.fixture
128125
def from_stream_fixture(
129-
self, stream_, StreamReader_, _parse_png_headers_, stream_rdr_,
130-
Png__init__, attrs, png_):
131-
cx, cy = 42, 24
132-
attrs.update({'px_width': cx, 'px_height': cy})
126+
self, stream_, _PngParser_, png_parser_, Png__init__):
127+
px_width, px_height, horz_dpi, vert_dpi = 42, 24, 36, 63
128+
png_parser_.px_width = px_width
129+
png_parser_.px_height = px_height
130+
png_parser_.horz_dpi = horz_dpi
131+
png_parser_.vert_dpi = vert_dpi
133132
return (
134-
stream_, StreamReader_, _parse_png_headers_, stream_rdr_,
135-
Png__init__, cx, cy, attrs, png_
133+
stream_, _PngParser_, Png__init__, px_width, px_height,
134+
horz_dpi, vert_dpi
136135
)
137136

138137
@pytest.fixture
@@ -227,6 +226,16 @@ def Png__init__(self, request):
227226
def png_(self, request):
228227
return instance_mock(request, Png)
229228

229+
@pytest.fixture
230+
def _PngParser_(self, request, png_parser_):
231+
_PngParser_ = class_mock(request, 'docx.image.png._PngParser')
232+
_PngParser_.parse.return_value = png_parser_
233+
return _PngParser_
234+
235+
@pytest.fixture
236+
def png_parser_(self, request):
237+
return instance_mock(request, _PngParser)
238+
230239
@pytest.fixture
231240
def StreamReader_(self, request, stream_rdr_):
232241
return class_mock(

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