Merge pull request #29585 from Thebinary110/expose-window-parameters-to-python

highgui: expose saveWindowParameters and loadWindowParameters to Python

modules/highgui/include/opencv2/highgui.hpp

@@ -739,7 +739,7 @@ location of the window windowName.
 
 @param windowName Name of the window.
  */
-CV_EXPORTS void saveWindowParameters(const String& windowName);
+CV_EXPORTS_W void saveWindowParameters(const String& windowName);
 
 /** @brief Loads parameters of the specified window.
 
@@ -748,7 +748,7 @@ location of the window windowName.
 
 @param windowName Name of the window.
  */
-CV_EXPORTS void loadWindowParameters(const String& windowName);
+CV_EXPORTS_W void loadWindowParameters(const String& windowName);
 
 CV_EXPORTS  int startLoop(int (*pt2Func)(int argc, char *argv[]), int argc, char* argv[]);
 

modules/highgui/misc/python/test/test_window_parameters.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+from __future__ import print_function
+
+import os
+
+# Force Qt's headless-safe platform plugin when nothing else is already
+# configured. Without this, namedWindow() on a Qt-enabled build with no
+# display server available (e.g. CI workers, which do not run the Python
+# test suite under a virtual framebuffer) aborts the whole process instead
+# of raising a catchable exception -- so this must be set *before* the
+# first GUI call, and a plain try/except around namedWindow is not enough.
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+import cv2 as cv
+
+from tests_common import NewOpenCVTests
+
+
+class window_parameters_test(NewOpenCVTests):
+
+    def test_save_load_window_parameters(self):
+        window_name = "test_save_load_window_parameters"
+        try:
+            cv.namedWindow(window_name, cv.WINDOW_NORMAL)
+        except cv.error:
+            self.skipTest("No GUI backend available in this build/environment")
+
+        try:
+            # Should not raise when the library is built with a backend that
+            # supports persisting window state (currently: Qt).
+            cv.saveWindowParameters(window_name)
+            cv.loadWindowParameters(window_name)
+        except cv.error as e:
+            # Expected on builds without Qt support (see NO_QT_ERR_MSG in window.cpp)
+            self.skipTest("saveWindowParameters/loadWindowParameters require the Qt "
+                           "highgui backend: " + str(e))
+        finally:
+            cv.destroyWindow(window_name)
+
+
+if __name__ == '__main__':
+    NewOpenCVTests.bootstrap()