MPL backend check

proxtoolbox/Problems/OrbitalTomog/Graphics/stack_viewer.py

 import matplotlib.pyplot as plt
+from matplotlib import get_backend
 from numpy import max, min
 from matplotlib.widgets import Slider
+from warnings import warn
 
+good_backends = ['Qt5Agg','TkAgg','Qt4Agg']
 
 class SingleStackViewer:
     def __init__(self, volume):
@@ -11,6 +14,8 @@ class SingleStackViewer:
 
         :param volume: real-valued np.ndarray (3D)
         """
+        if get_backend() not in good_backends:
+            warn(Warning('Current matplotlib backend may not allow for optimal funcionality! Use, e.g., Qt'))
         fig, ax = plt.subplots()
         ax.volume = volume
         ax.index = volume.shape[0] // 2
@@ -53,8 +58,12 @@ class XYZStackViewer:
         :param cmap: color map to use (e.g. 'seismic' or 'viridis'). For 'seismic, will center on 0, else'
         :param clim: tuple with the min-max values of the colorscale
         """
-        self.volume = volume
+        if get_backend() not in good_backends:
+            warn(Warning('Current matplotlib backend may not allow for optimal funcionality! Use, e.g., Qt'))
 
+        self.volume = volume
+        self.indices = [s // 2 for s in volume.shape]
+        self.shape = self.volume.shape
         if clim[0] is not None:
             self.minval, self.maxval = clim
         elif cmap == 'seismic':
@@ -63,14 +72,11 @@ class XYZStackViewer:
         else:
             self.maxval = max(volume)
             self.minval = min([0, min(volume)])
-        self.indices = [s // 2 for s in volume.shape]
-        self.shape = self.volume.shape
 
         self.fig, self.ax = plt.subplots(1, 3, figsize=(10, 4))
-
-        im = self.ax[0].imshow(volume[self.indices[0], :, :], cmap=cmap, vmin=-self.minval, vmax=self.maxval)
-        im = self.ax[1].imshow(volume[:, self.indices[0], :], cmap=cmap, vmin=-self.minval, vmax=self.maxval)
-        im = self.ax[2].imshow(volume[:, :, self.indices[0]], cmap=cmap, vmin=-self.minval, vmax=self.maxval)
+        im = self.ax[0].imshow(volume[self.indices[0], :, :], cmap=cmap, vmin=self.minval, vmax=self.maxval)
+        im = self.ax[1].imshow(volume[:, self.indices[0], :], cmap=cmap, vmin=self.minval, vmax=self.maxval)
+        im = self.ax[2].imshow(volume[:, :, self.indices[0]], cmap=cmap, vmin=self.minval, vmax=self.maxval)
         self.ax[1].set_yticks([])
         self.ax[2].set_yticks([])
 
@@ -116,3 +122,20 @@ class XYZStackViewer:
         self.ax[2].images[0].set_array(self.volume[:, :, int(n)])
         self.fig.canvas.draw_idle()
 
+    # def process_key(self, event):
+    #     """Look for special events captured by mpl_connect, send to correct function """
+    #     fig = event.canvas.figure
+    #     ax = fig.axes[0]
+    #     if event.key == 'j':
+    #         self.previous_slice(ax)
+    #     elif event.key == 'k':
+    #         self.next_slice(ax)
+    #     fig.canvas.draw()
+    #
+    # def previous_slice(self, ax):
+    #     """Go to the previous slice on all plots."""
+    #     # do stuff: set_array for all, set self.indices, set_val for sliders
+    #
+    # def next_slice(self, ax):
+    #     """Go to the next slice."""
+    #     # do something