matplotlib · wuyao1997 · Mar 21, 2026 · Mar 21, 2026 · Mar 21, 2026 · Mar 21, 2026
diff --git a/lib/matplotlib/backends/backend_svg.py b/lib/matplotlib/backends/backend_svg.py
@@ -338,8 +338,20 @@ def __init__(self, width, height, svgwriter, basename=None, image_dpi=72,
             id=mpl.rcParams['svg.id'],
             attrib={'xmlns:xlink': "http://www.w3.org/1999/xlink"})
         self._write_metadata(metadata)
+        self._write_highlight_gradient()
         self._write_default_style()
 
+    def _write_highlight_gradient(self):
+        # Add highlight gradient (id="_m_overlayGradient")
+        highlightGradient = """
+            <radialGradient id="_m_overlayGradient" cx="40%" cy="40%" r="70%">
+                    <stop offset="10%" stop-color="#ffffff" stop-opacity="0.8"/>
+                    <stop offset="40%" stop-color="#ffffff" stop-opacity="0"/>
+                    <stop offset="100%" stop-color="#ffffff" stop-opacity="0"/>
+            </radialGradient>"""
+        self.writer._XMLWriter__write(f"<defs>\n{highlightGradient}\n</defs>")
+        return
+
     def _get_clippath_id(self, clippath):
         """
         Returns a stable and unique identifier for the *clippath* argument
@@ -704,7 +716,8 @@ def draw_path(self, gc, path, transform, rgbFace=None):
             self.writer.end('a')
 
     def draw_markers(
-            self, gc, marker_path, marker_trans, path, trans, rgbFace=None):
+            self, gc, marker_path, marker_trans, path,
+            trans, rgbFace=None, highlight=False):
         # docstring inherited
 
         if not len(path.vertices):
@@ -742,6 +755,11 @@ def draw_markers(
                 attrib['y'] = _short_float_fmt(y)
                 attrib['style'] = self._get_style(gc, rgbFace)
                 writer.element('use', attrib=attrib)
+                if highlight:
+                    mask_attrib = attrib.copy()
+                    del mask_attrib['style']
+                    mask_attrib['fill'] = "url(#_m_overlayGradient)"
+                    writer.element('use', attrib=mask_attrib)
         if gc.get_url() is not None:
             self.writer.end('a')
         writer.end('g')

diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -416,9 +416,17 @@ def draw(self, renderer):
             gc.set_dashes(*self._linestyles[0])
             gc.set_antialiased(self._antialiaseds[0])
             gc.set_url(self._urls[0])
+
+            kwargs = {}
+            from .backends.backend_svg import RendererSVG
+            svg_func = getattr(RendererSVG.draw_markers, "__qualname__", None)
+            local_func = getattr(renderer.draw_markers, "__qualname__", None)
+            if hasattr(self, "_highlight_svg") and svg_func == local_func:
+                kwargs["highlight"] = self._highlight_svg
+
             renderer.draw_markers(
                 gc, paths[0], combined_transform.frozen(),
-                mpath.Path(offsets), offset_trf, tuple(facecolors[0]))
+                mpath.Path(offsets), offset_trf, tuple(facecolors[0]), **kwargs)
         else:
             # The current new API of draw_path_collection() is provisional
             # and will be changed in a future PR.

diff --git a/lib/matplotlib/legend_handler.py b/lib/matplotlib/legend_handler.py
@@ -308,6 +308,9 @@ def create_artists(self, legend, orig_handle,
 
         legline.set_transform(trans)
 
+        if hasattr(orig_handle, "_highlight_svg"):
+            legline._highlight_svg = orig_handle._highlight_svg
+
         return [legline]
 
 
@@ -504,10 +507,13 @@ class HandlerPathCollection(HandlerRegularPolyCollection):
     r"""Handler for `.PathCollection`\s, which are used by `~.Axes.scatter`."""
 
     def create_collection(self, orig_handle, sizes, offsets, offset_transform):
-        return type(orig_handle)(
+        leg_handle = type(orig_handle)(
             [orig_handle.get_paths()[0]], sizes=sizes,
             offsets=offsets, offset_transform=offset_transform,
         )
+        if hasattr(orig_handle, "_highlight_svg"):
+            leg_handle._highlight_svg = orig_handle._highlight_svg
+        return leg_handle
 
 
 class HandlerCircleCollection(HandlerRegularPolyCollection):

diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
@@ -885,17 +885,24 @@ def draw(self, renderer):
                 else:
                     # Don't scale for pixels, and don't stroke them
                     marker_trans = marker_trans.scale(w)
+
+                kwargs = {}
+                from .backends.backend_svg import RendererSVG
+                svg_func = getattr(RendererSVG.draw_markers, "__qualname__", None)
+                local_func = getattr(renderer.draw_markers, "__qualname__", None)
+                if hasattr(self, "_highlight_svg") and svg_func == local_func:
+                    kwargs["highlight"] = self._highlight_svg
                 renderer.draw_markers(gc, marker_path, marker_trans,
                                       subsampled, affine.frozen(),
-                                      fc_rgba)
+                                      fc_rgba, **kwargs)
 
                 alt_marker_path = marker.get_alt_path()
                 if alt_marker_path:
                     alt_marker_trans = marker.get_alt_transform()
                     alt_marker_trans = alt_marker_trans.scale(w)
                     renderer.draw_markers(
                             gc, alt_marker_path, alt_marker_trans, subsampled,
-                            affine.frozen(), fcalt_rgba)
+                            affine.frozen(), fcalt_rgba, **kwargs)
 
             gc.restore()