我正在尝试建立一个小程序,以根据当前房间的亮度调整显示器的亮度。
我按照MSDN的说明进行了设置:
cout << "Legen Sie das Fenster bitte auf den zu steuernden Monitor.\n";
system("PAUSE");
HMONITOR hMon = NULL;
char OldConsoleTitle[1024];
char NewConsoleTitle[1024];
GetConsoleTitle(OldConsoleTitle, 1024);
SetConsoleTitle("CMDWindow7355608");
Sleep(40);
HWND hWnd = FindWindow(NULL, "CMDWindow7355608");
SetConsoleTitle(OldConsoleTitle);
hMon = MonitorFromWindow(hWnd, MONITOR_DEFAULTTOPRIMARY);
DWORD cPhysicalMonitors;
LPPHYSICAL_MONITOR pPhysicalMonitors = NULL;
BOOL bSuccess = GetNumberOfPhysicalMonitorsFromHMONITOR(
hMon,
&cPhysicalMonitors
);
if(bSuccess)
{
pPhysicalMonitors = (LPPHYSICAL_MONITOR)malloc(
cPhysicalMonitors* sizeof(PHYSICAL_MONITOR));
if(pPhysicalMonitors!=NULL)
{
LPDWORD min = NULL, max = NULL, current = NULL;
GetPhysicalMonitorsFromHMONITOR(hMon, cPhysicalMonitors, pPhysicalMonitors);
HANDLE pmh = pPhysicalMonitors[0].hPhysicalMonitor;
if(!GetMonitorBrightness(pmh, min, current, max))
{
cout << "Fehler: " << GetLastError() << endl;
system("PAUSE");
return 0;
}
//cout << "Minimum: " << min << endl << "Aktuell: " << current << endl << "Maximum: " << max << endl;
system("PAUSE");
}
}
但是问题是:每次我尝试使用GetMonitorBrightness()时,该程序都会因
Access Violation while writing at Position 0x00000000
而崩溃(我将此错误翻译为德语)在尝试调试时,我看到pPhysicalMonitors实际上包含我要使用的监视器,但是
pPhysicalMonitors[0].hPhysicalMonitor
仅包含0x0000000。这可能是问题的一部分吗? 最佳答案
您正在将NULL指针传递给GetMonitorBrightness()
,因此在尝试将其输出值写入无效内存时会崩溃。
就像GetNumberOfPhysicalMonitorsFromHMONITOR()
一样,GetMonitorBrightness()
希望您传递实际变量的地址,例如:
DWORD min, max, current;
if (!GetMonitorBrightness(pmh, &min, ¤t, &max))
不会。但是,您没有检查以确保
cPhysicalMonitors
> 0,并且您忽略了GetPhysicalMonitorsFromHMONITOR()
的返回值以确保它实际上是用数据填充PHYSICAL_MONITOR
数组。