Add carla_get_desktop_scale_factor utility function

Signed-off-by: falkTX <falktx@falktx.com>

source/backend/CarlaUtils.h

@@ -304,6 +304,8 @@ CARLA_EXPORT void carla_set_process_name(const char* name);
 /* --------------------------------------------------------------------------------------------------------------------
  * window control */
 
+CARLA_EXPORT double carla_get_desktop_scale_factor();
+
 CARLA_EXPORT int carla_cocoa_get_window(void* nsViewPtr);
 CARLA_EXPORT void carla_cocoa_set_transient_window_for(void* nsViewChild, void* nsViewParent);
 

source/backend/utils/Windows.cpp

@@ -31,6 +31,22 @@ namespace CB = CarlaBackend;
 
 // -------------------------------------------------------------------------------------------------------------------
 
+double carla_get_desktop_scale_factor()
+{
+    // allow custom scale for testing
+    if (const char* const scale = getenv("DPF_SCALE_FACTOR"))
+        return std::max(1.0, std::atof(scale));
+    // Qt env var for the same
+    if (const char* const scale = getenv("QT_SCALE_FACTOR"))
+        return std::max(1.0, std::atof(scale));
+
+#if defined(CARLA_OS_MAC) && !defined(CARLA_PLUGIN_EXPORT)
+    return [NSScreen mainScreen].backingScaleFactor;
+#endif
+
+    return 1.0;
+}
+
 int carla_cocoa_get_window(void* nsViewPtr)
 {
     CARLA_SAFE_ASSERT_RETURN(nsViewPtr != nullptr, 0);

source/frontend/carla_utils.py

@@ -327,6 +327,9 @@ class CarlaUtils():
         self.lib.carla_juce_cleanup.argtypes = None
         self.lib.carla_juce_cleanup.restype = None
 
+        self.lib.carla_get_desktop_scale_factor.argtypes = None
+        self.lib.carla_get_desktop_scale_factor.restype = c_double
+
         self.lib.carla_cocoa_get_window.argtypes = [c_uintptr]
         self.lib.carla_cocoa_get_window.restype = c_int
 
@@ -480,6 +483,9 @@ class CarlaUtils():
     def juce_cleanup(self):
         self.lib.carla_juce_cleanup()
 
+    def get_desktop_scale_factor(self):
+        return float(self.lib.carla_get_desktop_scale_factor())
+
     def cocoa_get_window(self, winId):
         return self.lib.carla_cocoa_get_window(winId)