我用的是notbook 灌的是win7系统，想要通过API控制monitor的背光亮度。
下面的代码中，调用GetNumberOfPhysicalMonitorsFromHMONITOR函数返回值0，cPhysicalMonitors中有physical monitor的描述，但physical handle 一直是NULL .
看起来是执行过了，但handle去哪儿了呢？为什么没能传回来？


[code cpp]
void __fastcall TForm1::Button2Click(TObject *Sender)
{
BOOL bReturnValue = false;
HMONITOR hMonitor = NULL;
HWND hwnd = NULL;
DWORD cPhysicalMonitors;
LPPHYSICAL_MONITOR pPhysicalMonitors = NULL;
LPDWORD pdwMonitorCapabilities;
LPDWORD pdwSupportedColorTemperatures;
// Get the monitor handle.
hMonitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTOPRIMARY);
// Get the number of physical monitors.
BOOL bSuccess = GetNumberOfPhysicalMonitorsFromHMONITOR( hMonitor, &cPhysicalMonitors ); //error
if (bSuccess)
{
// Allocate the array of PHYSICAL_MONITOR structures.
pPhysicalMonitors = (LPPHYSICAL_MONITOR)malloc(cPhysicalMonitors * sizeof(PHYSICAL_MONITOR));
if (pPhysicalMonitors != NULL)
{
// Get the array.
bSuccess = GetPhysicalMonitorsFromHMONITOR(hMonitor, cPhysicalMonitors, pPhysicalMonitors);
bSuccess = GetMonitorCapabilities(hMonitor,pdwMonitorCapabilities,pdwSupportedColorTemperatures);
// Use the monitor handles (not shown).
DWORD nMin = 0, nCur = 0, nMax = 0;
bSuccess = GetMonitorBrightness(hMonitor, &nMin, &nCur, &nMax);
LightTrackBar->Max =nMax;
LightTrackBar->Min =nMin;
LightTrackBar->Position = nCur;
// Close the monitor handles.
bSuccess = DestroyPhysicalMonitors(cPhysicalMonitors, pPhysicalMonitors);
// Free the array.
free(pPhysicalMonitors);
}
}
}
[/code]

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Gaia

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