Better logic for updating cv2.VideoCapture resolution (#52)

* adding some better logic for updating resolution

* bumping version and refactoring function

* Automatically reformatting code with black and isort

* one more refactor

---------

Co-authored-by: Auto-format Bot <[email protected]>

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "framegrab"
-version = "0.6.3"
+version = "0.6.4"
 description = "Easily grab frames from cameras or streams"
 authors = ["Groundlight <[email protected]>"]
 license = "MIT"

src/framegrab/grabber.py

@@ -473,15 +473,26 @@ def _set_cv2_resolution(self) -> None:
         """Set the resolution of the cv2.VideoCapture object based on the FrameGrabber's config.
         If the FrameGrabber lacks both of these properties (height and width), this method
         will do nothing.
+
+        Similarly, if the specified resolution equals the existing resolution, this function will
+        do nothing. This is because setting the resolution of a cv2.VideoCapture object is non-trivial and
+        can take multiple seconds, so we should only do it when something has changed.
         """
-        resolution = self.config.get("options", {}).get("resolution", {})
-        height = resolution.get("height")
-        width = resolution.get("width")
-
-        if width:
-            self.capture.set(cv2.CAP_PROP_FRAME_WIDTH, width)
-        if height:
-            self.capture.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
+        resolution = self.config.get("options", {}).get("resolution")
+        if resolution is None:
+            return
+
+        new_height = resolution.get("height")
+        new_width = resolution.get("width")
+
+        if new_width:
+            current_width = int(self.capture.get(cv2.CAP_PROP_FRAME_WIDTH))
+            if new_width != current_width:
+                self.capture.set(cv2.CAP_PROP_FRAME_WIDTH, new_width)
+        if new_height:
+            current_height = int(self.capture.get(cv2.CAP_PROP_FRAME_HEIGHT))
+            if new_height != current_height:
+                self.capture.set(cv2.CAP_PROP_FRAME_HEIGHT, new_height)
 
     def apply_options(self, options: dict) -> None:
         """Update generic options such as crop and zoom as well as