Merge pull request #198 from ptomulik/use-bbox

Add Use.bbox()

svgelements/svgelements.py

@@ -7690,6 +7690,47 @@ def select(self, conditional=None):
                     for s in subitem.select(conditional):
                         yield s
 
+    @staticmethod
+    def union_bbox(elements, transformed=True, with_stroke=False):
+        """
+        Returns the union of the bounding boxes for the elements within the iterator.
+
+        :param transformed: Should the children of this object be properly transformed.
+        :param with_stroke: should the stroke-width be included in the bounds of the elements
+        :return: union of all bounding boxes of elements within the iterable.
+        """
+        boxes = []
+        for e in elements:
+            if not hasattr(e, "bbox") or isinstance(e, (Group, Use)):
+                continue
+            box = e.bbox(transformed=transformed, with_stroke=with_stroke)
+            if box is None:
+                continue
+            boxes.append(box)
+        if len(boxes) == 0:
+            return None
+        (xmins, ymins, xmaxs, ymaxs) = zip(*boxes)
+        return (min(xmins), min(ymins), max(xmaxs), max(ymaxs))
+
+    def bbox(self, transformed=True, with_stroke=False):
+        """
+        Returns the bounding box of the given object.
+
+        In the case of groups this is the union of all the bounding boxes of all bound children.
+
+        Setting transformed to false, may yield unexpected results if subitems are transformed in non-uniform
+        ways.
+
+        :param transformed: bounding box of the properly transformed children.
+        :param with_stroke: should the stroke-width be included in the bounds.
+        :return: bounding box of the given element
+        """
+        return Use.union_bbox(
+            self.select(),
+            transformed=transformed,
+            with_stroke=with_stroke,
+        )
+
 
 class ClipPath(SVGElement, list):
     """

test/test_use.py

@@ -6,6 +6,22 @@
 
 class TestElementUse(unittest.TestCase):
 
+    def test_use_bbox_method(self):
+        q = io.StringIO(u'''<?xml version="1.0" encoding="utf-8" ?>
+                        <svg viewBox="0, 0, 100, 100" height="100" width="100"
+                             xmlns:xlink="http://www.w3.org/1999/xlink">
+                            <use x="0" y="0" xlink:href="#rect1234"/>
+                            <use x="20" y="20" xlink:href="#rect1234"/>
+                            <defs>
+                                <rect id="rect1234" x="0" y="20" width="50" height="50"/>
+                            </defs>
+                        </svg>''')
+        svg = SVG.parse(q)
+        use = list(svg.select(lambda e: isinstance(e, Use)))
+        self.assertEqual(2, len(use))
+        self.assertEqual((0.0, 20.0, (0.0 + 50.0), (20.0 + 50.0)), use[0].bbox())
+        self.assertEqual((20.0 + 0.0, 20.0 + 20.0, (20.0 + 50.0), (20.0 + 20.0 + 50.0)), use[1].bbox())
+
     def test_issue_156(self):
         q1 = io.StringIO(u'''<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <svg