Merge branch 4.x

samples/python/_coverage.py

@@ -18,7 +18,7 @@ if __name__ == '__main__':
     for fn in glob('*.py'):
         print(' --- ', fn)
         code = open(fn).read()
-        found |= set(re.findall('cv2?\.\w+', code))
+        found |= set(re.findall(r'cv2?\.\w+', code))
 
     cv2_used = found & cv2_callable
     cv2_unused = cv2_callable - cv2_used

samples/python/audio_spectrogram.py

@@ -330,6 +330,10 @@ class AudioDrawing:
         """
 
         time_step = self.windLen - self.overlap
+        if time_step <= 0:
+            raise ValueError(
+                "Invalid STFT parameters: overlap must be smaller than window length"
+            )
         stft = []
 
         if self.windowType == "Hann":
@@ -801,4 +805,4 @@ if __name__ == "__main__":
 
     args = parser.parse_args()
 
-    AudioDrawing(args).Draw()
+    AudioDrawing(args).Draw()

samples/python/demo.py

@@ -105,7 +105,11 @@ class App:
         webbrowser.open(url)
 
     def on_demo_select(self, evt):
-        name = self.demos_lb.get( self.demos_lb.curselection()[0] )
+        selection = self.demos_lb.curselection()
+        if not selection:
+            return
+
+        name = self.demos_lb.get(selection[0])
         fn = self.samples[name]
 
         descr = ""

samples/python/stitching_detailed.py

@@ -97,10 +97,8 @@ parser.add_argument(
 )
 parser.add_argument(
     '--try_cuda',
-    action='store',
-    default=False,
+    action='store_true',
     help="Try to use CUDA. The default value is no. All default values are for CPU mode.",
-    type=bool, dest='try_cuda'
 )
 parser.add_argument(
     '--work_megapix', action='store', default=0.6,