Handle svg tags with no size

tests/draw/svg/test_bounding_box.py

@@ -309,3 +309,22 @@ def test_bounding_box_path_s(assert_pixels):
         </g>
       </svg>
     ''')
+
+
+@assert_no_logs
+def test_svg_empty_size(assert_pixels):
+    assert_pixels('''
+        BBB__
+        BBB__
+        BBB__
+        BBB__
+        _____
+    ''', '''
+      <style>
+        @page { size: 5px }
+        svg { display: block }
+      </style>
+      <svg xmlns="http://www.w3.org/2000/svg">
+        <rect x="0" y="0" width="3" height="4" fill="blue" />
+      </svg>
+    ''')

weasyprint/svg/__init__.py

@@ -81,6 +81,7 @@
     'mask',
     'path',
     'pattern',
+    'symbol',
 ))
 
 
@@ -306,6 +307,19 @@ def override_iter(self, iterator):
         self.__class__ = type(
             'Node', (Node,), {'__iter__': lambda _: iterator})
 
+    def set_svg_size(self, svg, concrete_width, concrete_height):
+        """"Set SVG concrete and inner widths and heights from svg node."""
+        svg.concrete_width = concrete_width
+        svg.concrete_height = concrete_height
+        svg.normalized_diagonal = hypot(concrete_width, concrete_height) / sqrt(2)
+
+        if viewbox := self.get_viewbox():
+            svg.inner_width, svg.inner_height = viewbox[2], viewbox[3]
+        else:
+            svg.inner_width, svg.inner_height = svg.concrete_width, svg.concrete_height
+        svg.inner_diagonal = hypot(svg.inner_width, svg.inner_height) / sqrt(2)
+
+
 
 class SVG:
     """An SVG document."""
@@ -368,19 +382,7 @@ def draw(self, stream, concrete_width, concrete_height, base_url,
         """Draw image on a stream."""
         self.stream = stream
 
-        self.concrete_width = concrete_width
-        self.concrete_height = concrete_height
-        self.normalized_diagonal = (
-            hypot(concrete_width, concrete_height) / sqrt(2))
-
-        viewbox = self.get_viewbox()
-        if viewbox:
-            self.inner_width, self.inner_height = viewbox[2], viewbox[3]
-        else:
-            self.inner_width = self.concrete_width
-            self.inner_height = self.concrete_height
-        self.inner_diagonal = (
-            hypot(self.inner_width, self.inner_height) / sqrt(2))
+        self.tree.set_svg_size(self, concrete_width, concrete_height)
 
         self.base_url = base_url
         self.url_fetcher = url_fetcher
@@ -390,7 +392,7 @@ def draw(self, stream, concrete_width, concrete_height, base_url,
 
     def draw_node(self, node, font_size, fill_stroke=True):
         """Draw a node."""
-        if node.tag in ('defs', 'symbol'):
+        if node.tag == 'defs':
             return
 
         # Update font size
@@ -456,6 +458,11 @@ def draw_node(self, node, font_size, fill_stroke=True):
         if node.display and TAGS.get(node.tag) == text:
             node.text_bounding_box = EMPTY_BOUNDING_BOX
 
+        # Save concrete size of root svg tag
+        if node.tag == 'svg':
+            concrete_width = self.concrete_width
+            concrete_height = self.concrete_height
+
         # Draw node
         if node.visible and node.tag in TAGS:
             with suppress(PointError):
@@ -478,6 +485,10 @@ def draw_node(self, node, font_size, fill_stroke=True):
                     node.text_bounding_box = extend_bounding_box(
                         node.text_bounding_box, ((x1, y1), (x2, y2)))
 
+        # Restore concrete and inner size of root svg tag
+        if node.tag == 'svg':
+            self.tree.set_svg_size(svg, concrete_width, concrete_height)
+
         # Handle text anchor
         if node.tag == 'text' and text_anchor in ('middle', 'end'):
             group_id = self.stream.id

weasyprint/svg/images.py

@@ -1,5 +1,6 @@
 """Draw image and svg tags."""
 
+from .bounding_box import bounding_box, is_valid_bounding_box
 from .utils import preserve_ratio
 
 
@@ -10,8 +11,19 @@ def svg(svg, node, font_size):
     if svg.tree == node:
         width, height = svg.concrete_width, svg.concrete_height
     else:
-        width, height = svg.point(
-            node.get('width'), node.get('height'), font_size)
+        width, height = node.get('width'), node.get('height')
+        if None in (width, height):
+            node._etree_node.tag = 'g'
+            box = bounding_box(svg, node, font_size, stroke=True)
+            if is_valid_bounding_box(box):
+                width = box[0] + box[2]
+                height = box[1] + box[3]
+            else:
+                width = height = 0
+            node._etree_node.tag = 'svg'
+        else:
+            width, height = svg.point(width, height, font_size)
+    node.set_svg_size(svg, width, height)
     scale_x, scale_y, translate_x, translate_y = preserve_ratio(
         svg, node, font_size, width, height)
     if svg.tree != node and node.get('overflow', 'hidden') == 'hidden':