Use X11 or go to the screen width to determine the resolution

debian/control

@@ -12,7 +12,8 @@ Build-Depends: debhelper-compat (= 12),
                qtbase5-dev-tools,
                libqt5x11extras5-dev,
                libgsettings-qt-dev,
-               libkf5windowsystem-dev
+               libkf5windowsystem-dev,
+               libx11-dev,
 Standards-Version: 4.5.0
 Rules-Requires-Root: no
 Homepage: https://github.com/ukui/kylin-nm

kylin-nm.pro

@@ -18,7 +18,7 @@ CONFIG += release
 
 # CONFIG += link_pkgconfig
 # PKGCONFIG += gsettings-qt
-LIBS    +=  -L/usr/lib/ -lgsettings-qt
+LIBS    +=  -L/usr/lib/ -lgsettings-qt -lX11
 
 target.path = /usr/bin
 target.source += $$TARGET

src/main.cpp

@@ -26,6 +26,7 @@
 #include <QApplication>
 #include <QDebug>
 #include <QDesktopWidget>
+#include <X11/Xlib.h>
 
 #define LOG_IDENT "ukui_kylin_nm"
 
@@ -33,11 +34,19 @@
 int main(int argc, char *argv[])
 {
     //QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+    Display *disp = XOpenDisplay(NULL);
+    Screen *scrn = DefaultScreenOfDisplay(disp);
+    if (NULL == scrn) {
+        return 0;
+    }
+    int width = scrn->width;
 
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
-        QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
-        QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
-#endif
+    if (width > 2560) {
+        #if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
+                QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+                QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
+        #endif
+    }
 
     QApplication a(argc, argv);