Merge pull request #38580 from mantidproject/restore-lost-legend

Restore lost legend when dragged out of figure

Author: peterfpeterson

docs/source/release/v6.12.0/Workbench/Bugfixes/38580.rst

@@ -0,0 +1 @@
+- Legends now automatically snap back to the default position if dragged off-screen.

qt/applications/workbench/workbench/plotting/figureinteraction.py

@@ -29,7 +29,7 @@
 
 # mantid imports
 from mantid.api import AnalysisDataService as ads
-from mantid.plots import datafunctions, MantidAxes, axesfunctions, MantidAxes3D
+from mantid.plots import datafunctions, MantidAxes, axesfunctions, MantidAxes3D, LegendProperties
 from mantid.plots.utility import zoom, MantidAxType, legend_set_draggable
 from mantidqt.plotting.figuretype import FigureType, figure_type
 from mantidqt.plotting.markers import SingleMarker
@@ -254,6 +254,30 @@ def on_mouse_button_release(self, event):
             self.marker_selected_in_double_click_event = None
             self.double_click_event = None
 
+        self.legend_bounds_check(event)
+
+    @staticmethod
+    def legend_bounds_check(event):
+        fig = event.canvas.figure
+
+        for ax in fig.get_axes():
+            legend1 = ax.get_legend()
+            if legend1 is None:
+                continue
+
+            bbox_fig = fig.get_window_extent()
+            bbox_legend = legend1.get_window_extent()
+
+            outside_window = (
+                bbox_legend.x1 < bbox_fig.x0 or bbox_legend.x0 > bbox_fig.x1 or bbox_legend.y1 < bbox_fig.y0 or bbox_legend.y0 > bbox_fig.y1
+            )
+
+            # Snap back legend
+            if outside_window:
+                props = LegendProperties.from_legend(legend1)
+                LegendProperties.create_legend(props, legend1.axes)
+                fig.canvas.draw_idle()
+
     def on_leave(self, event):
         """
         When leaving the axis or canvas, restore cursor to default one