Hello Hart,
Thank you so much for your prompt reply!
My problem is actually that I would just like to list all active monitors and somehow identify them uniquely between system restarts or system sleep states. I don't need to enable or disable any monitors or generally change anything about the current configuration.
Maybe my mistake was using QDC_DATABASE_CURRENT instead of QDC_ONLY_ACTIVE_PATHS, although I was already filtering for DISPLAYCONFIG_PATH_ACTIVE anyway.
A few of my users have reported that QueryDisplayConfig (with QDC_DATABASE_CURRENT) does not return the source mode of the monitor from the iGPU even though it is active already. Using EnumDisplayMonitors in this case does work, however. I believe the affected
users are all using Windows 10, so I have looked around and found the (undocumented?) flag QDC_VIRTUAL_MODE_AWARE which I am now using for Windows 10 and handle sourceModeInfoIdx accordingly. Although I don't have an understanding yet of what this virtual
mode is about (virtual resolution perhaps?).
Just for additional information:
I would be happy with EnumDisplayMonitors, but yet another subset of my customers report their monitor names being swapped after sleeping or restarting this way (same when I use the GDI source name from QueryDisplayConfig). Checking Google, the issue of names
being swapped seems to have been reported by other developers in the past, so likely EnumDisplayMonitors is not intended to be used with these expectations.
Please let me know if there is anything else I could further clarify about my issue. I have also not been able to reproduce this problem on my own machine, but I presume I must be doing something wrong or missing something in my implementation.
(Confusingly enough, some users reported the source mode containing the wrong position or size without QDC_VIRTUAL_MODE_AWARE. Which makes me think I am referencing the source mode incorrectly. Only one has reported back so far, but their issue got
fixed when I added QDC_VIRTUAL_MODE_AWARE.)
This is a condensed version of what I am currently doing:
uint32 pathInfoCount = 0;
uint32 modeInfoCount = 0;
uint32 queryMode = IsWindows10OrGreater() ? QDC_ONLY_ACTIVE_PATHS | QDC_VIRTUAL_MODE_AWARE : QDC_ONLY_ACTIVE_PATHS;
result = GetDisplayConfigBufferSizes(queryMode, &pathInfoCount, &modeInfoCount);
if (result != ERROR_SUCCESS)
{
return false;
}
pathInfoCount = MAX(1, pathInfoCount + 16);
modeInfoCount = MAX(1, modeInfoCount + 16);
DISPLAYCONFIG_PATH_INFO *pathInfo = new DISPLAYCONFIG_PATH_INFO[pathInfoCount];
DISPLAYCONFIG_MODE_INFO *modeInfo = new DISPLAYCONFIG_MODE_INFO[modeInfoCount];
result = QueryDisplayConfig(queryMode, &pathInfoCount, pathInfo, &modeInfoCount, modeInfo, nullptr);
if (result != ERROR_SUCCESS)
{
delete[] pathInfo;
delete[] modeInfo;
return false;
}
unordered_set<uint32> knownSourceIndices;
for (int p = 0; p < pathInfoCount; ++p)
{
DISPLAYCONFIG_PATH_INFO &path = pathInfo[p];
if ((path.flags & DISPLAYCONFIG_PATH_ACTIVE) == 0)
{
continue;
}
DISPLAYCONFIG_SOURCE_DEVICE_NAME sourceDeviceName;
sourceDeviceName.header.adapterId = path.sourceInfo.adapterId;
sourceDeviceName.header.size = sizeof(DISPLAYCONFIG_SOURCE_DEVICE_NAME);
sourceDeviceName.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME;
sourceDeviceName.header.id = path.sourceInfo.id;
result = DisplayConfigGetDeviceInfo((DISPLAYCONFIG_DEVICE_INFO_HEADER*) &sourceDeviceName);
if (result != ERROR_SUCCESS)
{
continue;
}
DISPLAYCONFIG_TARGET_DEVICE_NAME deviceName;
deviceName.header.adapterId = path.targetInfo.adapterId;
deviceName.header.size = sizeof(DISPLAYCONFIG_TARGET_DEVICE_NAME);
deviceName.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_TARGET_NAME;
deviceName.header.id = path.targetInfo.id;
result = DisplayConfigGetDeviceInfo((DISPLAYCONFIG_DEVICE_INFO_HEADER*) &deviceName);
if (result != ERROR_SUCCESS)
{
*deviceName.monitorDevicePath = 0;
*deviceName.monitorFriendlyDeviceName = 0;
}
const bool usingVirtualMode = (path.flags & DISPLAYCONFIG_PATH_SUPPORT_VIRTUAL_MODE) != 0;
const uint32 sourceModeIndex = usingVirtualMode ? path.sourceInfo.sourceModeInfoIdx : path.sourceInfo.modeInfoIdx;
if (usingVirtualMode ?
path.sourceInfo.sourceModeInfoIdx == DISPLAYCONFIG_PATH_SOURCE_MODE_IDX_INVALID :
path.sourceInfo.modeInfoIdx == DISPLAYCONFIG_PATH_MODE_IDX_INVALID)
{
continue;
}
// Ignore cloned sources
if (knownSourceIndices.find(sourceModeIndex) != knownSourceIndices.end())
{
continue;
}
knownSourceIndices.insert(sourceModeIndex);
MonitorInfo::Monitor monitor;
monitor.friendlyName = UTF8CONVERT().to_bytes(deviceName.monitorFriendlyDeviceName);
monitor.deviceName = UTF8CONVERT().to_bytes(sourceDeviceName.viewGdiDeviceName);
const DISPLAYCONFIG_SOURCE_MODE &srcMode = modeInfo[sourceModeIndex].sourceMode;
const DISPLAYCONFIG_ROTATION rotation = path.targetInfo.rotation;
if (rotation == DISPLAYCONFIG_ROTATION_IDENTITY || rotation == DISPLAYCONFIG_ROTATION_ROTATE180)
{
monitor.w = srcMode.width;
monitor.h = srcMode.height;
}
else
{
monitor.w = srcMode.height;
monitor.h = srcMode.width;
}
monitor.x = srcMode.position.x;
monitor.y = srcMode.position.y;
RECT monitorRect;
monitorRect.left = monitor.x;
monitorRect.right = monitor.x + monitor.w;
monitorRect.top = monitor.y;
monitorRect.bottom = monitor.y + monitor.h;
monitor.handle = MonitorFromRect(&monitorRect, MONITOR_DEFAULTTONEAREST);
if (monitor.handle == nullptr)
{
continue;
}
data.monitors->push_back(monitor);
}
delete[] pathInfo;
delete[] modeInfo;
