Add debug logging to windows API calls

monitorcontrol/vcp/vcp_windows.py

@@ -35,10 +35,12 @@ def __init__(self, hmonitor: HMONITOR):
             Args:
                 hmonitor: logical monitor handle
             """
+            self.logger = logging.getLogger(__name__)
             self.hmonitor = hmonitor
 
         def __enter__(self):
             num_physical = DWORD()
+            self.logger.debug("GetNumberOfPhysicalMonitorsFromHMONITOR")
             try:
                 if not ctypes.windll.dxva2.GetNumberOfPhysicalMonitorsFromHMONITOR(
                     self.hmonitor, ctypes.byref(num_physical)
@@ -61,6 +63,7 @@ def __enter__(self):
                 raise VCPError("more than one physical monitor per hmonitor")
 
             physical_monitors = (PhysicalMonitor * num_physical.value)()
+            self.logger.debug("GetPhysicalMonitorsFromHMONITOR")
             try:
                 if not ctypes.windll.dxva2.GetPhysicalMonitorsFromHMONITOR(
                     self.hmonitor, num_physical.value, physical_monitors
@@ -81,6 +84,7 @@ def __exit__(
             exception_value: Optional[BaseException],
             exception_traceback: Optional[TracebackType],
         ) -> Optional[bool]:
+            self.logger.debug("DestroyPhysicalMonitor")
             try:
                 if not ctypes.windll.dxva2.DestroyPhysicalMonitor(self.handle):
                     raise VCPError(
@@ -101,6 +105,7 @@ def set_vcp_feature(self, code: int, value: int):
             Raises:
                 VCPError: Failed to set VCP feature.
             """
+            self.logger.debug(f"SetVCPFeature(_, {code=}, {value=})")
             try:
                 if not ctypes.windll.dxva2.SetVCPFeature(
                     HANDLE(self.handle), BYTE(code), DWORD(value)
@@ -124,6 +129,9 @@ def get_vcp_feature(self, code: int) -> Tuple[int, int]:
             """
             feature_current = DWORD()
             feature_max = DWORD()
+            self.logger.debug(
+                f"GetVCPFeatureAndVCPFeatureReply(_, {code=}, None, _, _)"
+            )
             try:
                 if not ctypes.windll.dxva2.GetVCPFeatureAndVCPFeatureReply(
                     HANDLE(self.handle),
@@ -135,6 +143,9 @@ def get_vcp_feature(self, code: int) -> Tuple[int, int]:
                     raise VCPError("failed to get VCP feature: " + ctypes.FormatError())
             except OSError as e:
                 raise VCPError("failed to get VCP feature") from e
+            self.logger.debug(
+                f"GetVCPFeatureAndVCPFeatureReply -> ({feature_current.value}, {feature_max.value})"
+            )
             return feature_current.value, feature_max.value
 
         def get_vcp_capabilities(self):
@@ -153,7 +164,7 @@ def get_vcp_capabilities(self):
             """
 
             cap_length = DWORD()
-
+            self.logger.debug("GetCapabilitiesStringLength")
             try:
                 if not ctypes.windll.dxva2.GetCapabilitiesStringLength(
                     HANDLE(self.handle), ctypes.byref(cap_length)
@@ -162,6 +173,7 @@ def get_vcp_capabilities(self):
                         "failed to get VCP capabilities: " + ctypes.FormatError()
                     )
                 cap_string = (ctypes.c_char * cap_length.value)()
+                self.logger.debug("CapabilitiesRequestAndCapabilitiesReply")
                 if not ctypes.windll.dxva2.CapabilitiesRequestAndCapabilitiesReply(
                     HANDLE(self.handle), cap_string, cap_length
                 ):
@@ -196,6 +208,8 @@ def _callback(hmonitor, hdc, lprect, lparam):
                 BOOL, HMONITOR, HDC, ctypes.POINTER(RECT), LPARAM
             )
             callback = MONITORENUMPROC(_callback)
+
+            self.logger.debug("EnumDisplayMonitors")
             if not ctypes.windll.user32.EnumDisplayMonitors(0, 0, callback, 0):
                 raise VCPError("Call to EnumDisplayMonitors failed")
         except OSError as e: