Issue #23: Raise error if can't set resolution to desired values

sksurgeryimage/acquire/video_source.py

@@ -52,8 +52,9 @@ def __init__(self, source_num_or_file, dims=None):
             if height < 1:
                 raise ValueError("Height must be >= 1")
 
-            self.source.set(cv2.CAP_PROP_FRAME_WIDTH, width)
-            self.source.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
+            self.set_resolution(width, height)
+
+
 
         else:
             width = int(self.source.get(cv2.CAP_PROP_FRAME_WIDTH))
@@ -64,6 +65,25 @@ def __init__(self, source_num_or_file, dims=None):
         self.frame = np.empty((height, width, 3), dtype=np.uint8)
         self.ret = None
 
+    def set_resolution(self, width: int, height: int):
+        """Set the resolution of the input source.
+
+        :param width: Width
+        :type width: int
+        :param height: Height
+        :type height: int
+        :raises ValueError: If resolution is not supported.
+        """
+        self.source.set(cv2.CAP_PROP_FRAME_WIDTH, width)
+        self.source.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
+
+        set_w = self.source.get(cv2.CAP_PROP_FRAME_WIDTH)
+        set_h = self.source.get(cv2.CAP_PROP_FRAME_HEIGHT)
+
+        if set_w != width or set_h != height:
+            raise ValueError(f"Tried to set width/height to {width} x {height} \
+                 but failed. Width and height set to {set_w} x {set_h}")
+
     def grab(self):
         """
         Call the cv2.VideoCapture grab function and get a timestamp.

tests/acquire/video_source/test_video_source.py

@@ -92,8 +92,21 @@ def test_add_source_from_camera_custom_dimensions(video_source_wrapper):
     except IndexError:
         return
 
+def test_add_source_from_camera_invalid_dimensions(video_source_wrapper):
+    """
+    Add a camera and pass in custom dimensions to cv2.VideoCapture.
+    """
+    try:
+        camera_input = 0
+        custom_dims = [100, 24]  # default is 640 x 480
+
+        with pytest.raises(ValueError):
+            video_source_wrapper.add_camera(camera_input, custom_dims)
+
+    except IndexError:
+        return
 
-def test_add_source_from_camera_invalid_dims(video_source_wrapper):
+def test_add_source_from_file_invalid_dims(video_source_wrapper):
     camera_input = 'tests/data/acquire/100x50_100_frames.avi'
 
     custom_dims = ["happy", "birthday"]