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Hi,
i can turn the Monitor( Display ) off and on programaticly with SendMessage and SC_MONITORPOWER. But in some cases, other applications may prevent that.
My question is : how can i detect the Monitor state( On/Off-Standby ) ? And Can i detect if the system supports Power-Saving features?
Thanks in advance.
>> how can i detect the Monitor state
>> Can i detect if the system supports Power-Saving features?Code:#include <windows.h>
#include <setupapi.h>
#ifdef _MSC_VER
#pragma comment(lib, "Setupapi.lib")
#endif
#include <list>
#include <vector>
#include <string>
using namespace std;
// my StlPort configured w/o iostreams at the moment
#include <stdio.h>
//------------------------------------------------------------------------------
struct DevData
{
std::wstring Description; // SPDRP_DEVICEDESC
CM_POWER_DATA PowerData; // SPDRP_DEVICE_POWER_DATA
DevData()
{
PowerData.PD_Size = sizeof(PowerData);
}//constructor
};//DevData
//------------------------------------------------------------------------------
bool GetDeviceRegString(HDEVINFO infoSet, SP_DEVINFO_DATA *pinfoData,
DWORD prop, wstring &val)
{
DWORD req_sz = 0;
BOOL res = SetupDiGetDeviceRegistryPropertyW(infoSet, pinfoData, prop,
0, 0, 0, &req_sz);
if (!res && (GetLastError() != ERROR_INSUFFICIENT_BUFFER))
{
if (GetLastError() != ERROR_INVALID_DATA)
{
printf("SetupDiGetDeviceRegistryPropertyW() failed, le = %u",
GetLastError());
}//if
return false;
}//if
vector<wchar_t> vec_buff; // in case we have to go to the heap
wchar_t auto_buff[512];
DWORD buff_sz;
wchar_t *buff;
if (req_sz > sizeof(auto_buff))
{
vec_buff.reserve(req_sz/2 + 2);
buff = &vec_buff[0];
buff_sz = req_sz;
}//if
else
{
buff = auto_buff;
buff_sz = sizeof(auto_buff);
}//else
res = SetupDiGetDeviceRegistryPropertyW(infoSet, pinfoData, prop,
0, (PBYTE)buff, buff_sz, 0);
if (!res)
{
DWORD le = GetLastError();
if (le != ERROR_INVALID_DATA)
{
printf("SetupDiGetDeviceRegistryPropertyW(%d) "
"failed, le = %u",
prop, le);
return false;
}//if
// return empty string on ERROR_INVALID_DATA
val.erase(val.begin(), val.end());
return true;
}//else
val.assign(buff, req_sz);
return true;
}//GetDeviceRegString
//------------------------------------------------------------------------------
template <typename T>
bool GetDeviceRegData(HDEVINFO infoSet, SP_DEVINFO_DATA *pinfoData,
DWORD prop, T &val)
{
SetLastError(0);
BOOL res = SetupDiGetDeviceRegistryPropertyW(infoSet, pinfoData, prop,
0, (PBYTE)&val,
sizeof(val), 0);
DWORD le = GetLastError();
if (!res || (le == ERROR_INVALID_DATA))
{
if (le != ERROR_INVALID_DATA)
printf("GetDeviceRegData() failed, le = %u", le);
return false;
}//if
return true;
}//GetDeviceRegData
//------------------------------------------------------------------------------
void ListDeviceClassData(const GUID *classGuid, std::list<DevData> &devList)
{
devList.clear();
const DWORD flags = DIGCF_PRESENT;
HDEVINFO infoSet = SetupDiGetClassDevsW(classGuid, 0, 0, flags);
if (infoSet == INVALID_HANDLE_VALUE)
{
printf("SetupDiGetClassDevs() failed, le = %u",
GetLastError());
return;
}//if
SP_DEVINFO_DATA infoData;
infoData.cbSize = sizeof(SP_DEVINFO_DATA);
DWORD n;
for (n = 0; SetupDiEnumDeviceInfo(infoSet, n, &infoData); ++n)
{
DevData dd;
if (GetDeviceRegString(infoSet, &infoData, SPDRP_DEVICEDESC,
dd.Description) &&
GetDeviceRegData(infoSet, &infoData, SPDRP_DEVICE_POWER_DATA,
dd.PowerData))
{
devList.push_back(dd);
}//if
}//for
if (GetLastError() != ERROR_NO_MORE_ITEMS)
{
printf("Last call to SetupDiEnumDeviceInfo(%d) failed, le = %u",
n, GetLastError());
}//if
SetupDiDestroyDeviceInfoList(infoSet);
}//ListDeviceClassData
//------------------------------------------------------------------------------
void print_monitor_info()
{
const GUID MonitorClassGuid =
{0x4d36e96e, 0xe325, 0x11ce,
{0xbf, 0xc1, 0x08, 0x00, 0x2b, 0xe1, 0x03, 0x18}};
list<DevData> monitors;
ListDeviceClassData(&MonitorClassGuid, monitors);
printf("# Monitors = %d\n", monitors.size());
list<DevData>::iterator it = monitors.begin(),
it_end = monitors.end();
for (; it != it_end; ++it)
{
const char *off_msg = "";
if (it->PowerData.PD_MostRecentPowerState > PowerDeviceD0)
off_msg = ", *** Sleeping State ***";
printf("[%ls]\n"
" PowerState = %d%s\n",
it->Description.c_str(),
it->PowerData.PD_MostRecentPowerState,
off_msg);
}//for
putchar('\n');
}//print_monitor_info
//------------------------------------------------------------------------------
int main()
{
printf("*** Current Status of Monitor(s) ***\n\n");
print_monitor_info();
printf("*** Turning OFF Monitor(s) ***\n\n");
fflush(stdout);
Sleep(500); // don't use mouse or keyboard
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM)2);
print_monitor_info();
printf("*** Turning ON Monitor(s) ***\n\n");
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM)-1);
print_monitor_info();
return 0;
}//main
//------------------------------------------------------------------------------
Like what?
gg
Wow :cool:.
Many thanks Codeplug, i appreciate your answer.
Like:Quote:
Originally Posted by Codeplug
- Go to standby
- Wake-Up from standby
Getting power capabilities:
S-states defined: http://msdn.microsoft.com/en-us/library/ms798270.aspxCode:#include <ntstatus.h> // for STATUS_SUCCESS
#define WIN32_NO_STATUS
#include <windows.h>
#include <powrprof.h>
#pragma comment(lib, "PowrProf.lib")
typedef DWORD NTSTATUS; // from DDK
#include <iostream> // I have iostreams now :)
using namespace std;
int main()
{
SYSTEM_POWER_CAPABILITIES spc = {0};
NTSTATUS res = CallNtPowerInformation(SystemPowerCapabilities, 0, 0,
(PVOID)&spc, sizeof(spc));
if (res != STATUS_SUCCESS)
{
cerr << "CallNtPowerInformation() failed, status = "
<< res << ", le = " << GetLastError() << endl;
return 1;
}//if
cout << "SystemS3 = ";
if (spc.SystemS3 != FALSE)
cout << "TRUE" << endl;
else
cout << "FALSE" << endl;
return 0;
}//main
SYSTEM_POWER_CAPABILITIES: http://msdn.microsoft.com/en-us/libr...15(VS.85).aspx
gg
Awful code.
Use the monitor power state api which has been given many times on Usenet (~10 lines of code)
>> Awful code.
:( I'm sorry you don't like it. Just for my own self-improvement, would elaborate a bit more? Does it not work for you? Is it just the choice of API's used?
>> Use the monitor power state api which has been given many times
That sounds cool - I'm always willing to learn a new API! Could you post a link or something - you know - something useful?
gg
@Codeplug:
Your code is working great. :)
I have 2 more questions:
1.Where are the display properties stored in Win9x ? Under WinXp they are stored in :
2.Is it possible to detect the monitor state under Win9x ?Code:"HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\DISPLAY"
Thanks in advance.
@Alex31:
I do not understand you :mad:
If you know the solution, then post it here and do not send me any Private Messages more saying that i can ask on professional win32 newsgroup:
Quote:
You can ask on professional win32 api newsgroup :
news://194.177.96.26/comp.os.ms-wind...ogrammer.win32
where it has already been discussed
>> 1.Where are the display properties stored in Win9x ?
Event Win2K isn't supported by MS anymore ;) I don't know, but you could the Win32 API for this, with GetSystemMetrics() etc...
>> 2.Is it possible to detect the monitor state under Win9x ?
Wish I could help. A "Win9x not supported" comment in your code solves things nicely though ;)
>> news: ... /comp.os.ms-windows.programmer.win32
I use Google as my newsgroup reader. Here's the link for comp.os.ms-windows.programmer.win32.
So if you search just that group with "Monitor Power", Google returns 18 hits. Sadly, no "monitor power state api" was revealed :( There was actually only one useful posting out of all those hits:
But why limit your search just to that group:Quote:
Originally Posted by jim clark
- microsoft.public.vb.general.discussion
I'll go ahead and summarize all the other suggestions in the newsgroups that don't work:
* "It can't be done"
You'll find a few "[MSFT]", "[MS]", and "[MSMVP]" people making this claim.
* "Use SPI_GETLOWPOWERACTIVE and/or SPI_GETPOWEROFFACTIVE"
Doesn't work, I confirmed.
* "Use Win32_DesktopMonitor WMI object"
Doesn't work, I confirmed. I even tried Win32_PnPEntity, no go. (ask if you'd like the code). Also confirmed in the newsgroups.
* "Use the undocumented NtGetDevicePowerState()"
May work, don't know. But since the documented GetDevicePowerState() says "This function cannot be used to query the power state of a display device." - the I doubt that it's undocumented (assumed) helper-function would work. Similar conclusion reached in newsgroups.
>> That sounds cool - I'm always willing to learn a new API! Could you post a link or something
@Alex31> I was giving you a chance to admit your mistake - in the hopes that you would actually search for a link to post - and discover that no such link, and no such API exists.
Check your facts before posting, especially in one of my subscribed threads.
gg