Enhance the support of SVG images

docs/install.rst

@@ -12,7 +12,7 @@ WeasyPrint |version| depends on:
 * cairocffi_ ≥ 0.3
 * tinycss_ = 0.3
 * cssselect_ ≥ 0.6
-* CairoSVG_ ≥ 0.5
+* CairoSVG_ ≥ 1.0.20
 * Pyphen_ ≥ 0.8
 * Optional: GDK-PixBuf_ [#]_
 

setup.py

@@ -30,7 +30,7 @@
     'html5lib>=0.999',
     'tinycss==0.3',
     'cssselect>=0.6',
-    'CairoSVG>=0.4.1',
+    'CairoSVG>=1.0.20',
     'cffi>=0.6',
     'cairocffi>=0.5',
     'Pyphen>=0.8'

weasyprint/images.py

@@ -13,6 +13,7 @@
 from __future__ import division, unicode_literals
 
 from io import BytesIO
+from xml.etree import ElementTree
 import math
 
 import cairocffi
@@ -67,7 +68,7 @@ def __init__(self, image_surface):
             self._intrinsic_width / self._intrinsic_height
             if self._intrinsic_height != 0 else float('inf'))
 
-    def get_intrinsic_size(self, image_resolution):
+    def get_intrinsic_size(self, image_resolution, _font_size):
         # Raster images are affected by the 'image-resolution' property.
         return (self._intrinsic_width / image_resolution,
                 self._intrinsic_height / image_resolution)
@@ -96,6 +97,14 @@ def device_units_per_user_units(self):
         return scale / 0.75
 
 
+class FakeSurface(object):
+    """Fake CairoSVG surface used to get SVG attributes."""
+    context_height = 0
+    context_width = 0
+    font_size = 12
+    dpi = 96
+
+
 class SVGImage(object):
     def __init__(self, svg_data, base_url):
         # Don’t pass data URIs to CairoSVG.
@@ -104,41 +113,57 @@ def __init__(self, svg_data, base_url):
             base_url if not base_url.lower().startswith('data:') else None)
         self._svg_data = svg_data
 
-        # TODO: find a way of not doing twice the whole rendering.
         try:
-            svg = self._render()
+            self._tree = ElementTree.fromstring(self._svg_data)
         except Exception as e:
             raise ImageLoadingError.from_exception(e)
-        # TODO: support SVG images with none or only one of intrinsic
-        #       width, height and ratio.
-        if not (svg.width > 0 and svg.height > 0):
-            raise ImageLoadingError(
-                'SVG images without an intrinsic size are not supported.')
-        self._intrinsic_width = svg.width
-        self._intrinsic_height = svg.height
-        self.intrinsic_ratio = self._intrinsic_width / self._intrinsic_height
-
-    def get_intrinsic_size(self, _image_resolution):
-        # Vector images are affected by the 'image-resolution' property.
-        return self._intrinsic_width, self._intrinsic_height
 
-    def _render(self):
-        # Draw to a cairo surface but do not write to a file.
-        # This is a CairoSVG surface, not a cairo surface.
-        return ScaledSVGSurface(
-            cairosvg.parser.Tree(
-                bytestring=self._svg_data, url=self._base_url),
-            output=None, dpi=96)
+    def get_intrinsic_size(self, _image_resolution, font_size):
+        # Vector images may be affected by the font size.
+        fake_surface = FakeSurface()
+        fake_surface.font_size = font_size
+        # Percentages don't provide an intrinsic size, we transform percentages
+        # into 0 using a (0, 0) context size:
+        # http://www.w3.org/TR/SVG/coords.html#IntrinsicSizing
+        self._width = cairosvg.surface.size(
+            fake_surface, self._tree.get('width'))
+        self._height = cairosvg.surface.size(
+            fake_surface, self._tree.get('height'))
+        _, _, viewbox = cairosvg.surface.node_format(fake_surface, self._tree)
+        self._intrinsic_width = self._width or None
+        self._intrinsic_height = self._height or None
+        self.intrinsic_ratio = None
+        if viewbox:
+            if self._width and self._height:
+                self.intrinsic_ratio = self._width / self._height
+            else:
+                if viewbox[2] and viewbox[3]:
+                    self.intrinsic_ratio = viewbox[2] / viewbox[3]
+                    if self._width:
+                        self._intrinsic_height = (
+                            self._width / self.intrinsic_ratio)
+                    elif self._height:
+                        self._intrinsic_width = (
+                            self._height * self.intrinsic_ratio)
+        elif self._width and self._height:
+            self.intrinsic_ratio = self._width / self._height
+        return self._intrinsic_width, self._intrinsic_height
 
     def draw(self, context, concrete_width, concrete_height, _image_rendering):
-        # Do not re-use the rendered Surface object,
-        # but regenerate it as needed.
-        # If a surface for a SVG image is still alive by the time we call
-        # show_page(), cairo will rasterize the image instead writing vectors.
-        svg = self._render()
-        context.scale(concrete_width / svg.width, concrete_height / svg.height)
-        context.set_source_surface(svg.cairo)
-        context.paint()
+        try:
+            svg = ScaledSVGSurface(
+                cairosvg.parser.Tree(
+                    bytestring=self._svg_data, url=self._base_url),
+                output=None, dpi=96, parent_width=concrete_width,
+                parent_height=concrete_height)
+            if svg.width and svg.height:
+                context.scale(
+                    concrete_width / svg.width, concrete_height / svg.height)
+                context.set_source_surface(svg.cairo)
+                context.paint()
+        except Exception as e:
+            LOGGER.warning(
+                'Failed to draw an SVG image at %s : %s', self._base_url, e)
 
 
 def get_image_from_uri(cache, url_fetcher, url, forced_mime_type=None):
@@ -291,8 +316,8 @@ def __init__(self, color_stops, repeating):
         #: bool
         self.repeating = repeating
 
-    def get_intrinsic_size(self, _image_resolution):
-        # Raster images are affected by the 'image-resolution' property.
+    def get_intrinsic_size(self, _image_resolution, _font_size):
+        # Gradients are not affected by image resolution, parent or font size.
         return None, None
 
     intrinsic_ratio = None

weasyprint/layout/backgrounds.py

@@ -147,7 +147,7 @@ def layout_background_layer(box, page, resolution, image, size, clip, repeat,
             assert clip == 'content-box', clip
             clipped_boxes = [box.rounded_content_box()]
 
-    if image is None or 0 in image.get_intrinsic_size(1):
+    if image is None or 0 in image.get_intrinsic_size(1, 1):
         return BackgroundLayer(
             image=None, unbounded=(box is page), painting_area=painting_area,
             size='unused', position='unused', repeat='unused',
@@ -172,7 +172,8 @@ def layout_background_layer(box, page, resolution, image, size, clip, repeat,
             positioning_width, positioning_height, image.intrinsic_ratio)
     else:
         size_width, size_height = size
-        iwidth, iheight = image.get_intrinsic_size(resolution)
+        iwidth, iheight = image.get_intrinsic_size(
+            resolution, box.style.font_size)
         image_width, image_height = replaced.default_image_sizing(
             iwidth, iheight, image.intrinsic_ratio,
             percentage(size_width, positioning_width),

weasyprint/layout/inlines.py

@@ -248,47 +248,42 @@ def replaced_box_width(box, device_size):
     """
     Compute and set the used width for replaced boxes (inline- or block-level)
     """
-    # http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-width
     intrinsic_width, intrinsic_height = box.replacement.get_intrinsic_size(
-        box.style.image_resolution)
-    # TODO: update this when we have replaced elements that do not
-    # always have an intrinsic width. (See commented code below.)
-    assert intrinsic_width is not None
-    assert intrinsic_height is not None
+        box.style.image_resolution, box.style.font_size)
+
+    # This algorithm simply follows the different points of the specification:
+    # http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-width
+    if box.height == 'auto' and box.width == 'auto':
+        if intrinsic_width is not None:
+            # Point #1
+            box.width = intrinsic_width
+        elif box.replacement.intrinsic_ratio is not None:
+            if intrinsic_height is not None:
+                # Point #2 first part
+                box.width = intrinsic_height * box.replacement.intrinsic_ratio
+            else:
+                # Point #3
+                # " It is suggested that, if the containing block's width does
+                #   not itself depend on the replaced element's width, then the
+                #   used value of 'width' is calculated from the constraint
+                #   equation used for block-level, non-replaced elements in
+                #   normal flow. "
+                # Whaaaaat? Let's not do this and use a value that may work
+                # well at least with inline blocks.
+                box.width = (
+                    box.style.font_size * box.replacement.intrinsic_ratio)
 
     if box.width == 'auto':
-        if box.height == 'auto':
+        if box.replacement.intrinsic_ratio is not None:
+            # Point #2 second part
+            box.width = box.height * box.replacement.intrinsic_ratio
+        elif intrinsic_width is not None:
+            # Point #4
             box.width = intrinsic_width
         else:
-            intrinsic_ratio = intrinsic_width / intrinsic_height
-            box.width = box.height * intrinsic_ratio
-
-    # Untested code for when we do not always have an intrinsic width.
-#    if box.height == 'auto' and box.width == 'auto':
-#        if intrinsic_width is not None:
-#            box.width = intrinsic_width
-#        elif intrinsic_height is not None and intrinsic_ratio is not None:
-#            box.width = intrinsic_ratio * intrinsic_height
-#        elif box.height != 'auto' and intrinsic_ratio is not None:
-#            box.width = intrinsic_ratio * box.height
-#        elif intrinsic_ratio is not None:
-#            pass
-#            # TODO: Intrinsic ratio only: undefined in CSS 2.1.
-#            # " It is suggested that, if the containing block's width does not
-#            #   itself depend on the replaced element's width, then the used
-#            #   value of 'width' is calculated from the constraint equation
-#            #   used for block-level, non-replaced elements in normal flow. "
-
-#    # Still no value
-#    if box.width == 'auto':
-#        if intrinsic_width is not None:
-#            box.width = intrinsic_width
-#        else:
-#            # Then the used value of 'width' becomes 300px. If 300px is too
-#            # wide to fit the device, UAs should use the width of the largest
-#            # rectangle that has a 2:1 ratio and fits the device instead.
-#            device_width, _device_height = device_size
-#            box.width = min(300, device_width)
+            # Point #5
+            device_width, _device_height = device_size
+            box.width = min(300, device_width)
 
 
 @handle_min_max_height
@@ -298,35 +293,33 @@ def replaced_box_height(box, device_size):
     """
     # http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-height
     intrinsic_width, intrinsic_height = box.replacement.get_intrinsic_size(
-        box.style.image_resolution)
-    # TODO: update this when we have replaced elements that do not
-    # always have intrinsic dimensions. (See commented code below.)
-    assert intrinsic_width is not None
-    assert intrinsic_height is not None
+        box.style.image_resolution, box.style.font_size)
+
     if intrinsic_height == 0:
         # Results in box.height == 0 if used, whatever the used width
         # or intrinsic width.
         intrinsic_ratio = float('inf')
-    else:
+    elif intrinsic_width and intrinsic_height:
         intrinsic_ratio = intrinsic_width / intrinsic_height
+    else:
+        intrinsic_ratio = None
 
     # Test 'auto' on the computed width, not the used width
     if box.style.height == 'auto' and box.style.width == 'auto':
         box.height = intrinsic_height
-    elif box.style.height == 'auto':
+    elif box.style.height == 'auto' and intrinsic_ratio:
         box.height = box.width / intrinsic_ratio
 
-    # Untested code for when we do not always have intrinsic dimensions.
-#    if box.style.height == 'auto' and box.style.width == 'auto':
-#        if intrinsic_height is not None:
-#            box.height = intrinsic_height
-#    elif intrinsic_ratio is not None and box.style.height == 'auto':
-#        box.height = box.width / intrinsic_ratio
-#    elif box.style.height == 'auto' and intrinsic_height is not None:
-#        box.height = intrinsic_height
-#    elif box.style.height == 'auto':
-#        device_width, _device_height = device_size
-#        box.height = min(150, device_width / 2)
+    if (box.style.height == 'auto' and box.style.width == 'auto' and
+            intrinsic_height is not None):
+        box.height = intrinsic_height
+    elif intrinsic_ratio is not None and box.style.height == 'auto':
+        box.height = box.width / intrinsic_ratio
+    elif box.style.height == 'auto' and intrinsic_height is not None:
+        box.height = intrinsic_height
+    elif box.style.height == 'auto':
+        device_width, _device_height = device_size
+        box.height = min(150, device_width / 2)
 
 
 def inline_replaced_box_layout(box, device_size):

weasyprint/layout/preferred.py

@@ -554,7 +554,8 @@ def replaced_min_content_width(box, outer=True):
             assert height.unit == 'px'
             height = height.value
         image = box.replacement
-        iwidth, iheight = image.get_intrinsic_size(box.style.image_resolution)
+        iwidth, iheight = image.get_intrinsic_size(
+            box.style.image_resolution, box.style.font_size)
         width, _ = default_image_sizing(
             iwidth, iheight, image.intrinsic_ratio, 'auto', height,
             default_width=300, default_height=150)

weasyprint/layout/replaced.py

@@ -23,7 +23,8 @@ def image_marker_layout(box):
     """
     image = box.replacement
     one_em = box.style.font_size
-    iwidth, iheight = image.get_intrinsic_size(box.style.image_resolution)
+    iwidth, iheight = image.get_intrinsic_size(
+        box.style.image_resolution, one_em)
     box.width, box.height = default_image_sizing(
         iwidth, iheight, image.intrinsic_ratio, box.width, box.height,
         default_width=one_em, default_height=one_em)
@@ -57,10 +58,14 @@ def default_image_sizing(intrinsic_width, intrinsic_height, intrinsic_ratio,
             else default_width
         ), specified_height
     else:
-        return (intrinsic_width if intrinsic_width is not None
-                else default_width,
-                intrinsic_height if intrinsic_height is not None
-                else default_height)
+        if intrinsic_width is not None or intrinsic_height is not None:
+            return default_image_sizing(
+                intrinsic_width, intrinsic_height, intrinsic_ratio,
+                intrinsic_width, intrinsic_height, default_width,
+                default_height)
+        else:
+            return contain_constraint_image_sizing(
+                default_width, default_height, intrinsic_ratio)
 
 
 def contain_constraint_image_sizing(

weasyprint/tests/test_draw.py

@@ -1328,11 +1328,9 @@ def test_images():
                             alt="Hello, world!">'''),
             ]
         ])
-    assert len(logs) == 2
+    assert len(logs) == 1
     assert 'WARNING: Failed to load image' in logs[0]
     assert 'inexistent2.png' in logs[0]
-    assert 'WARNING: Failed to load image at data:image/svg+xml' in logs[1]
-    assert 'intrinsic size' in logs[1]
 
     assert_pixels('image_0x1', 8, 8, no_image, '''
         <style>