Change cursor when hovering over draggable artists

daniilS · QuLogic · daniilS · commit a8d1677de1c1 · 2023-07-28T13:24:54.000+01:00
Co-Authored-By: Elliott Sales de Andrade &lt;quantum.analyst@gmail.com&gt;
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -1298,6 +1298,9 @@ def __clear(self):
         self.child_axes = []
         self._current_image = None  # strictly for pyplot via _sci, _gci
         self._projection_init = None  # strictly for pyplot.subplot
+
+        if hasattr(self, "legend_") and self.legend_ is not None:
+            self.legend_.axes = self.legend_.figure = None
         self.legend_ = None
         self.containers = []
 
diff --git a/lib/matplotlib/offsetbox.py b/lib/matplotlib/offsetbox.py
@@ -32,6 +32,7 @@
 import matplotlib.path as mpath
 import matplotlib.text as mtext
 import matplotlib.transforms as mtransforms
+from matplotlib.backend_tools import Cursors
 from matplotlib.font_manager import FontProperties
 from matplotlib.image import BboxImage
 from matplotlib.patches import (
@@ -1489,6 +1490,7 @@ def __init__(self, ref_artist, use_blit=False):
         if not ref_artist.pickable():
             ref_artist.set_picker(True)
         self.got_artist = False
+        self._hover = False
         self._use_blit = use_blit and self.canvas.supports_blit
         callbacks = ref_artist.figure._canvas_callbacks
         self._disconnectors = [
@@ -1508,7 +1510,33 @@ def __init__(self, ref_artist, use_blit=False):
         disconnect.args[0] for disconnect in self._disconnectors[:2]])
 
     def on_motion(self, evt):
-        if self._check_still_parented() and self.got_artist:
+        # Only check if the widget lock is available, setting it would prevent
+        # picking.
+        if not (
+            self._check_still_parented()
+            and self.canvas.widgetlock.available(self)
+            and self.ref_artist.pickable()
+        ):
+            return
+
+        picker = self.ref_artist.get_picker()
+        if callable(picker):
+            inside, _ = picker(self, evt)
+        else:
+            inside, _ = self.ref_artist.contains(evt)
+
+        # If the mouse is moving quickly while dragging, it may leave the artist,
+        # but should still use the move cursor.
+        if inside or self.got_artist:
+            self._hover = True
+            self.canvas.set_cursor(Cursors.MOVE)
+        elif self._hover:
+            # Only change the cursor back if this is the widget that set it, to
+            # avoid multiple draggable widgets fighting over the cursor.
+            self._hover = False
+            self.canvas.set_cursor(Cursors.POINTER)
+
+        if self.got_artist:
             dx = evt.x - self.mouse_x
             dy = evt.y - self.mouse_y
             self.update_offset(dx, dy)
@@ -1554,6 +1582,10 @@ def disconnect(self):
         for disconnector in self._disconnectors:
             disconnector()
 
+        if self._hover:
+            self._hover = False
+            self.canvas.set_cursor(Cursors.POINTER)
+
     def save_offset(self):
         pass
 
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -8644,13 +8644,19 @@ def test_extent_units():
 
 def test_cla_clears_children_axes_and_fig():
     fig, ax = plt.subplots()
-    lines = ax.plot([], [], [], [])
+
+    lines = ax.plot([], [], [], [], label="line")
     img = ax.imshow([[1]])
-    for art in lines + [img]:
+    legend = ax.legend()
+
+    children = [*lines, img, legend]
+
+    for art in children:
         assert art.axes is ax
         assert art.figure is fig
+
     ax.clear()
-    for art in lines + [img]:
+    for art in children:
         assert art.axes is None
         assert art.figure is None
 
