src/java.desktop/unix/classes/sun/awt/X11GraphicsDevice.java

*** 42,51 ****
--- 42,52 ----
  import sun.java2d.xr.XRGraphicsConfig;
  import sun.java2d.loops.SurfaceType;
  
  import sun.awt.util.ThreadGroupUtils;
  import sun.misc.ManagedLocalsThread;
+ import sun.security.action.GetPropertyAction;
  
  /**
   * This is an implementation of a GraphicsDevice object for a single
   * X11 screen.
   *
*** 61,73 ****
--- 62,76 ----
      private static Boolean xrandrExtSupported;
      private final Object configLock = new Object();
      private SunDisplayChanger topLevels = new SunDisplayChanger();
      private DisplayMode origDisplayMode;
      private boolean shutdownHookRegistered;
+     private int scale;
  
      public X11GraphicsDevice(int screennum) {
          this.screen = screennum;
+         this.scale = initScaleFactor();
      }
  
      /*
       * Initialize JNI field and method IDs for fields that may be
       * accessed from C.
*** 277,286 ****
--- 280,290 ----
                                                  ArrayList<DisplayMode> modes);
      private static native void configDisplayMode(int screen,
                                                   int width, int height,
                                                   int displayMode);
      private static native void resetNativeData(int screen);
+     private static native int getNativeScaleFactor(int screen);
  
      /**
       * Returns true only if:
       *   - the Xrandr extension is present
       *   - the necessary Xrandr functions were loaded successfully
*** 507,516 ****
--- 511,547 ----
       */
      public void addDisplayChangedListener(DisplayChangedListener client) {
          topLevels.add(client);
      }
  
+     public int getScaleFactor(){
+         return scale;
+     }
+ 
+     private int initScaleFactor() {
+ 
+         boolean hidpiEnabled = "true".equals(AccessController.doPrivileged(
+                 new GetPropertyAction("sun.java2d.uiScale.enabled", "true")));
+ 
+         if (!hidpiEnabled) {
+             return 1;
+         }
+ 
+         String hidpiScale = AccessController.doPrivileged(
+                 new GetPropertyAction("sun.java2d.uiScale", "-1"));
+         try {
+             int scale = Integer.parseInt(hidpiScale);
+             if (scale >= 1) {
+                 return scale;
+             }
+         } catch (NumberFormatException ignore) {
+         }
+ 
+         int scale = getNativeScaleFactor(screen);
+         return scale >= 1 ? scale : 1;
+     }
+     
      /**
       * Remove a DisplayChangeListener from this X11GraphicsDevice.
       */
      public void removeDisplayChangedListener(DisplayChangedListener client) {
          topLevels.remove(client);