- 1 year ago
Cannot get program to process WM_POWERBROADCAST message
To process the WM_POWERBROADCAST
message in a Windows application, you need to add the appropriate message handler in your code. This message is sent to the application when the system's power status changes, such as when the computer is going into sleep mode, waking up from sleep, or shutting down.
Here's a step-by-step guide to process the WM_POWERBROADCAST
message in a Windows application:
- Include the necessary header files in your code:
cpp#include <Windows.h>
- Add a message handler in your Window Procedure (WndProc) function to handle the
WM_POWERBROADCAST
message:
cppLRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_POWERBROADCAST:
{
switch (wParam)
{
case PBT_APMQUERYSUSPEND:
// The system is asking if it can go into sleep mode
// Add your code to handle the query
break;
case PBT_APMRESUMESUSPEND:
// The system is waking up from sleep mode
// Add your code to handle the resume event
break;
case PBT_APMSUSPEND:
// The system is going into sleep mode
// Add your code to handle the suspend event
break;
case PBT_APMRESUMEAUTOMATIC:
// The system is waking up from an automatic sleep
// Add your code to handle the resume event
break;
case PBT_APMPOWERSTATUSCHANGE:
// The power status of the system has changed
// Add your code to handle the power status change
break;
case PBT_APMBATTERYLOW:
// The battery is running low
// Add your code to handle the low battery event
break;
case PBT_APMOEMEVENT:
// An OEM-defined event has occurred
// Add your code to handle the OEM event
break;
default:
// Handle other power-related events if needed
break;
}
}
break;
// Handle other messages if needed
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
Register your window class and create the window as usual. Make sure to use the
WndProc
function you defined above for the window procedure.Run your application and observe the
WM_POWERBROADCAST
messages being processed when power-related events occur on the system.
Keep in mind that the WM_POWERBROADCAST
message is sent to the top-level window in the application. If you have multiple windows, ensure that the message reaches the appropriate window by forwarding it as needed. Also, handle any other power-related events based on your application's requirements.
Additionally, if you are processing power events for a console application, you can use SetConsoleCtrlHandler
to handle CTRL_C_EVENT
, CTRL_BREAK_EVENT
, and other console-related events. The WM_POWERBROADCAST
message is primarily used for GUI applications.