Add displayinfo_win.cpp — Windows display enumeration using Win32 API

src/wg/displayinfo_win.cpp

@@ -0,0 +1,63 @@
+// src/wg/displayinfo_win.cpp — Windows implementation of display enumeration.
+//
+// Uses Win32 API: EnumDisplayMonitors, GetMonitorInfoW, EnumDisplayDevicesW, WideCharToMultiByte.
+
+#include "displayinfo.h"
+
+#ifdef _WIN32
+
+#include <windows.h>
+#include <string>
+#include <vector>
+
+namespace wg {
+
+// UTF-16 to UTF-8 conversion helper.
+static std::string wideToUtf8(const wchar_t *wide) {
+    if (!wide) return "";
+    int len = WideCharToMultiByte(CP_UTF8, 0, wide, -1, nullptr, 0, nullptr, nullptr);
+    if (len <= 0) return "";
+    std::string utf8(len - 1, '\0');
+    WideCharToMultiByte(CP_UTF8, 0, wide, -1, &utf8[0], len, nullptr, nullptr);
+    return utf8;
+}
+
+// Monitor enumeration callback.
+static BOOL CALLBACK monitorEnumProc(HMONITOR hmon, HDC, LPRECT, LPARAM lParam) {
+    auto *displays = static_cast<std::vector<DisplayInfo> *>(reinterpret_cast<void *>(lParam));
+
+    MONITORINFOEX mi = {};
+    mi.cbSize = sizeof(mi);
+    if (!GetMonitorInfoW(hmon, &mi)) {
+        return TRUE; // Continue enumeration
+    }
+
+    // Get friendly device name via EnumDisplayDevicesW.
+    DISPLAY_DEVICEW dd = {};
+    dd.cb = sizeof(dd);
+    EnumDisplayDevicesW(mi.szDevice, 0, &dd, 0);
+
+    DisplayInfo info;
+    info.name = wideToUtf8(mi.szDevice);
+    info.friendlyName = wideToUtf8(dd.DeviceString);
+    if (info.friendlyName.empty()) {
+        info.friendlyName = info.name;
+    }
+    info.width = mi.rcMonitor.right - mi.rcMonitor.left;
+    info.height = mi.rcMonitor.bottom - mi.rcMonitor.top;
+    info.isPrimary = (mi.dwFlags & MONITORINFOF_PRIMARY) != 0;
+
+    displays->push_back(info);
+    return TRUE;
+}
+
+std::vector<DisplayInfo> enumerateDisplays() {
+    std::vector<DisplayInfo> displays;
+    EnumDisplayMonitors(nullptr, nullptr, monitorEnumProc,
+                        reinterpret_cast<LPARAM>(&displays));
+    return displays;
+}
+
+} // namespace wg
+
+#endif // _WIN32