added crosshair option in mantid

docs/source/release/v6.12.0/Workbench/New_features/38186.rst

@@ -0,0 +1 @@
+- A crosshair toggle option has been added in mantidplots

qt/applications/workbench/workbench/plotting/figuremanager.py

@@ -232,10 +232,13 @@ def __init__(self, canvas, num):
             self.toolbar.sig_waterfall_conversion.connect(self.update_toolbar_waterfall_plot)
             self.toolbar.sig_change_line_collection_colour_triggered.connect(self.change_line_collection_colour)
             self.toolbar.sig_hide_plot_triggered.connect(self.hide_plot)
+            self.toolbar.sig_crosshair_toggle_triggered.connect(self.crosshair_toggle)
             self.toolbar.setFloatable(False)
             tbs_height = self.toolbar.sizeHint().height()
         else:
             tbs_height = 0
+        # canvas.mpl_connect("motion_notify_event", self.crosshair)
+        # self.crosshair_toggle(False)
 
         # resize the main window so it will display the canvas with the
         # requested size:
@@ -251,9 +254,7 @@ def __init__(self, canvas, num):
         self.window.addDockWidget(Qt.LeftDockWidgetArea, self.fit_browser)
 
         self.superplot = None
-
         self.fit_browser.hide()
-
         if matplotlib.is_interactive():
             self.window.show()
             canvas.draw_idle()
@@ -264,11 +265,9 @@ def notify_axes_change(fig):
                 self.toolbar.update()
 
         canvas.figure.add_axobserver(notify_axes_change)
-
         # Register canvas observers
         self._fig_interaction = FigureInteraction(self)
         self._ads_observer = FigureManagerADSObserver(self)
-
         self.window.raise_()
 
     def full_screen_toggle(self):
@@ -603,6 +602,41 @@ def _reverse_axis_lines(ax):
             line.remove()
             ax.add_line(line)
 
+    def crosshair_toggle(self, on):
+        cid = self.canvas.mpl_connect("motion_notify_event", self.crosshair)
+        if not on:
+            self.canvas.mpl_disconnect(cid)
+
+    def crosshair(self, event):
+        axes = self.canvas.figure.gca()
+
+        # create a crosshair made from horizontal and verticle lines.
+        self.horizontal_line = axes.axhline(color="r", lw=1.0, ls="-")
+        self.vertical_line = axes.axvline(color="r", lw=1.0, ls="-")
+
+        def set_cross_hair_visible(visible):
+            need_redraw = self.horizontal_line.get_visible() != visible
+            self.horizontal_line.set_visible(visible)
+            self.vertical_line.set_visible(visible)
+            return need_redraw
+
+        # if event is out-of-bound we update
+        if not event.inaxes:
+            need_redraw = set_cross_hair_visible(False)
+            if need_redraw:
+                axes.figure.canvas.draw()
+
+        else:
+            set_cross_hair_visible(True)
+            x, y = event.xdata, event.ydata
+            self.horizontal_line.set_ydata([y])
+            self.vertical_line.set_xdata([x])
+            self.canvas.draw()
+
+        # after update we remove
+        self.horizontal_line.remove()
+        self.vertical_line.remove()
+
 
 # -----------------------------------------------------------------------------
 # Figure control

qt/applications/workbench/workbench/plotting/test/test_toolbar.py

@@ -117,6 +117,15 @@ def test_button_checked_for_plot_with_grid(self, mock_qappthread):
         # Grid button should be ON because we enabled the grid.
         self.assertTrue(self._is_grid_button_checked(fig))
 
+    @patch("workbench.plotting.figuremanager.QAppThreadCall")
+    def test_button_checked_for_plot_with_no_crosshair(self, mock_qappthread):
+        mock_qappthread.return_value = mock_qappthread
+
+        fig, axes = plt.subplots(subplot_kw={"projection": "mantid"})
+        axes.plot([-10, 10], [1, 2])
+        # Grid button should be OFF because we have not enabled the crosshair.
+        self.assertFalse(self._is_crosshair_button_checked(fig))
+
     @patch("workbench.plotting.figuremanager.QAppThreadCall")
     def test_button_checked_for_plot_with_grid_using_kwargs(self, mock_qappthread):
         mock_qappthread.return_value = mock_qappthread
@@ -266,6 +275,19 @@ def _is_button_enabled(cls, fig, button):
         fig_manager.toolbar.set_buttons_visibility(fig)
         return fig_manager.toolbar._actions[button].isEnabled()
 
+    @classmethod
+    def _is_crosshair_button_checked(cls, fig):
+        """
+        Create the figure manager and check whether its toolbar is toggled on or off for the given figure.
+        We have to explicitly call set_button_visibility() here, which would otherwise be called within the show()
+        function.
+        """
+        canvas = MantidFigureCanvas(fig)
+        fig_manager = FigureManagerWorkbench(canvas, 1)
+        # This is only called when show() is called on the figure manager, so we have to manually call it here.
+        fig_manager.toolbar.set_buttons_visibility(fig)
+        return fig_manager.toolbar._actions["toggle_crosshair"].isChecked()
+
 
 if __name__ == "__main__":
     unittest.main()

qt/applications/workbench/workbench/plotting/toolbar.py

@@ -34,6 +34,7 @@ def _create_script_action(self, text, tooltip_text, mdi_icon, *args):
 class WorkbenchNavigationToolbar(MantidNavigationToolbar):
     sig_home_clicked = QtCore.Signal()
     sig_grid_toggle_triggered = QtCore.Signal(bool)
+    sig_crosshair_toggle_triggered = QtCore.Signal(bool)
     sig_active_triggered = QtCore.Signal()
     sig_hold_triggered = QtCore.Signal()
     sig_toggle_fit_triggered = QtCore.Signal()
@@ -83,6 +84,7 @@ class WorkbenchNavigationToolbar(MantidNavigationToolbar):
         MantidNavigationTool("Fill Area", "Fill area under curves", "mdi.format-color-fill", "waterfall_fill_area", None),
         MantidStandardNavigationTools.SEPARATOR,
         MantidNavigationTool("Help", "Open plotting help documentation", "mdi.help", "launch_plot_help", None),
+        MantidNavigationTool("Crosshair", "Toggle crosshair", "mdi.plus", "toggle_crosshair", False),
         MantidNavigationTool("Hide", "Hide the plot", "mdi.eye", "hide_plot", None),
     )
 
@@ -93,6 +95,13 @@ def __init__(self, canvas, parent, coordinates=True):
         dpi_ratio = QtWidgets.QApplication.instance().desktop().physicalDpiX() / 100
         self.setIconSize(QtCore.QSize(int(24 * dpi_ratio), int(24 * dpi_ratio)))
 
+    def toggle_crosshair(self, enable=None):
+        if enable is None:
+            enable = self._actions["toggle_crosshair"].isChecked()
+        else:
+            self._actions["toggle_crosshair"].setChecked(enable)
+        self.sig_crosshair_toggle_triggered.emit(enable)
+
     def hide_plot(self):
         self.sig_hide_plot_triggered.emit()