img: add Image.scaled_dimensions()

Steve Canny · Steve Canny · commit 4008ab22ccfb · 2015-02-16T13:41:54.000-08:00
diff --git a/docx/image/image.py b/docx/image/image.py
@@ -12,7 +12,7 @@
 
 from ..compat import BytesIO, is_string
 from .exceptions import UnrecognizedImageError
-from ..shared import Inches, lazyproperty
+from ..shared import Emu, Inches, lazyproperty
 
 
 class Image(object):
@@ -133,7 +133,7 @@ def height(self):
         """
         return Inches(self.px_height / self.vert_dpi)
 
-    def scaled_dimensions(self, width, height):
+    def scaled_dimensions(self, width=None, height=None):
         """
         Return a (cx, cy) 2-tuple representing the native dimensions of this
         image scaled by applying the following rules to *width* and *height*.
@@ -147,7 +147,18 @@ def scaled_dimensions(self, width, height):
         dpi if no value is specified, as is often the case. The returned
         values are both |Length| objects.
         """
-        raise NotImplementedError
+        if width is None and height is None:
+            return self.width, self.height
+
+        if width is None:
+            scaling_factor = float(height) / float(self.height)
+            width = round(self.width * scaling_factor)
+
+        if height is None:
+            scaling_factor = float(width) / float(self.width)
+            height = round(self.height * scaling_factor)
+
+        return Emu(width), Emu(height)
 
     @lazyproperty
     def sha1(self):
diff --git a/features/doc-add-picture.feature b/features/doc-add-picture.feature
@@ -4,30 +4,26 @@ Feature: Append an inline picture in its own paragraph
   I need a way to add a picture in its own paragraph
 
 
-  @wip
   Scenario: Add a picture at native size
     Given a blank document
      When I add a picture specifying only the image file
      Then the document contains the inline picture
       And the picture has its native width and height
 
 
-  @wip
   Scenario: Add a picture specifying both width and height
     Given a blank document
      When I add a picture specifying 1.75" width and 2.5" height
      Then picture.width is 1.75 inches
       And picture.height is 2.5 inches
 
 
-  @wip
   Scenario: Add a picture specifying only width
     Given a blank document
      When I add a picture specifying a width of 1.5 inches
      Then picture.height is 2.14 inches
 
 
-  @wip
   Scenario: Add a picture specifying only height
     Given a blank document
      When I add a picture specifying a height of 1.5 inches
diff --git a/features/run-add-picture.feature b/features/run-add-picture.feature
@@ -4,15 +4,13 @@ Feature: Add picture to a run
   I need a way to add a picture to a run
 
 
-  @wip
   Scenario: Add a picture to a body paragraph run
     Given a run
      When I add a picture to the run
      Then the picture appears at the end of the run
       And the document contains the inline picture
 
 
-  @wip
   Scenario Outline: Add a picture to a run in a table cell
     Given a run inside a table cell retrieved from <cell-source>
      When I add a picture to the run
diff --git a/tests/image/test_image.py b/tests/image/test_image.py
@@ -17,11 +17,12 @@
 from docx.image.png import Png
 from docx.image.tiff import Tiff
 from docx.opc.constants import CONTENT_TYPE as CT
-from docx.shared import Length
+from docx.shared import Emu, Length
 
 from ..unitutil.file import test_file
 from ..unitutil.mock import (
-    function_mock, class_mock, initializer_mock, instance_mock, method_mock
+    function_mock, class_mock, initializer_mock, instance_mock, method_mock,
+    property_mock
 )
 
 
@@ -90,6 +91,15 @@ def it_knows_the_image_native_size(self, size_fixture):
         assert isinstance(image.width, Length)
         assert isinstance(image.height, Length)
 
+    def it_can_scale_its_dimensions(self, scale_fixture):
+        image, width, height, expected_value = scale_fixture
+
+        scaled_width, scaled_height = image.scaled_dimensions(width, height)
+
+        assert (scaled_width, scaled_height) == expected_value
+        assert isinstance(scaled_width, Length)
+        assert isinstance(scaled_height, Length)
+
     def it_knows_the_image_filename(self):
         filename = 'foobar.png'
         image = Image(None, filename, None)
@@ -189,6 +199,19 @@ def known_image_fixture(self, request):
         image_filename, characteristics = cases[request.param]
         return image_filename, characteristics
 
+    @pytest.fixture(params=[
+        (None, None, 1000, 2000),
+        (100,  None,  100,  200),
+        (None,  500,  250,  500),
+        (1500, 1500, 1500, 1500),
+    ])
+    def scale_fixture(self, request, width_prop_, height_prop_):
+        width, height, scaled_width, scaled_height = request.param
+        width_prop_.return_value = Emu(1000)
+        height_prop_.return_value = Emu(2000)
+        image = Image(None, None, None)
+        return image, width, height, (scaled_width, scaled_height)
+
     @pytest.fixture
     def size_fixture(self, image_header_):
         image_header_.px_width, image_header_.px_height = 150, 75
@@ -218,6 +241,10 @@ def _from_stream_(self, request, image_):
             request, Image, '_from_stream', return_value=image_
         )
 
+    @pytest.fixture
+    def height_prop_(self, request):
+        return property_mock(request, Image, 'height')
+
     @pytest.fixture
     def image_(self, request):
         return instance_mock(request, Image)
@@ -241,6 +268,10 @@ def Image__init_(self, request):
     def stream_(self, request):
         return instance_mock(request, BytesIO)
 
+    @pytest.fixture
+    def width_prop_(self, request):
+        return property_mock(request, Image, 'width')
+
 
 class Describe_ImageHeaderFactory(object):
 
