Change cursor when hovering over draggable artists

daniilS · daniilS · commit 407f4b719d90 · 2023-06-22T18:32:57.000+01:00
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 (
@@ -1485,6 +1486,7 @@ 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 = [
@@ -1504,6 +1506,33 @@ def __init__(self, ref_artist, use_blit=False):
         disconnect.args[0] for disconnect in self._disconnectors[:2]])
 
     def on_motion(self, evt):
+        # 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)
+        ):
+            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:
+            # Ideally, this should use an open hand cursor on hover, and a closed
+            # hand when dragging, but those cursors are not natively provided by
+            # all platforms.
+            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._check_still_parented() and self.got_artist:
             dx = evt.x - self.mouse_x
             dy = evt.y - self.mouse_y
@@ -1550,6 +1579,9 @@ def disconnect(self):
         for disconnector in self._disconnectors:
             disconnector()
 
+        if self._hover:
+            self.canvas.set_cursor(Cursors.POINTER)
+
     def save_offset(self):
         pass
 
