Handle bounding boxes for use tags

Fix #2332.

tests/draw/svg/test_opacity.py

@@ -145,3 +145,19 @@ def test_translate_opacity(assert_same_renderings):
                   fill="blue" opacity="50%" />
         ''',
     )
+
+
+@assert_no_logs
+def test_translate_use_opacity(assert_same_renderings):
+    # Regression test for https://github.com/Kozea/WeasyPrint/issues/1976
+    assert_same_renderings(
+        opacity_source % '''
+            <defs>
+              <rect id="rect" x="-10" y="-10" width="5" height="5" fill="blue" />
+            </defs>
+            <use href="#rect" transform="translate(12, 12)" opacity="0.5" />
+        ''',
+        opacity_source % '''
+            <rect x="2" y="2" width="5" height="5" fill="blue" opacity="50%" />
+        ''',
+    )

weasyprint/svg/bounding_box.py

@@ -222,6 +222,16 @@ def bounding_box_g(svg, node, font_size):
     return bounding_box
 
 
+def bounding_box_use(svg, node, font_size):
+    """Bounding box for use node."""
+    from .defs import get_use_tree
+
+    if (tree := get_use_tree(svg, node, font_size)) is None:
+        return EMPTY_BOUNDING_BOX
+    else:
+        return bounding_box(svg, tree, font_size, True)
+
+
 def _bounding_box_elliptical_arc(x1, y1, rx, ry, phi, large, sweep, x, y):
     """Bounding box of an elliptical arc in path node."""
     rx, ry = abs(rx), abs(ry)
@@ -349,6 +359,7 @@ BOUNDING_BOX_METHODS = {
     'polygon': bounding_box_polyline,
     'path': bounding_box_path,
     'g': bounding_box_g,
+    'use': bounding_box_use,
     'marker': bounding_box_g,
     'text': bounding_box_text,
     'tspan': bounding_box_text,

weasyprint/svg/defs.py

@@ -8,16 +8,9 @@ from .bounding_box import bounding_box, is_valid_bounding_box
 from .utils import alpha_value, color, parse_url, size, transform
 
 
-def use(svg, node, font_size):
-    """Draw use tags."""
+def get_use_tree(svg, node, font_size):
     from . import SVG
 
-    x, y = svg.point(node.get('x'), node.get('y'), font_size)
-
-    for attribute in ('x', 'y', 'viewBox', 'mask'):
-        if attribute in node.attrib:
-            del node.attrib[attribute]
-
     parsed_url = parse_url(node.get_href(svg.url))
     svg_url = parse_url(svg.url)
     if svg_url.scheme == 'data':
@@ -46,6 +39,20 @@ def use(svg, node, font_size):
             use_svg.get_intrinsic_size(font_size)
             tree = use_svg.tree
 
+    return tree
+
+
+def use(svg, node, font_size):
+    """Draw use tags."""
+    x, y = svg.point(node.get('x'), node.get('y'), font_size)
+
+    for attribute in ('x', 'y', 'viewBox', 'mask'):
+        if attribute in node.attrib:
+            del node.attrib[attribute]
+
+    if (tree := get_use_tree(svg, node, font_size)) is None:
+        return
+
     if tree.tag in ('svg', 'symbol'):
         # Explicitely specified
         # https://www.w3.org/TR/SVG11/struct.html#UseElement