[jdk9] HiDPI scale is not detected on some linux desktops

(cherry picked from commit 9279d80110)

src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKEngine.java

@@ -40,6 +40,7 @@ import com.sun.java.swing.plaf.gtk.GTKConstants.TextDirection;
 
 import sun.awt.image.SunWritableRaster;
 import sun.swing.ImageCache;
+import sun.awt.X11GraphicsDevice;
 
 /**
  * GTKEngine delegates all painting job to native GTK libraries.
@@ -271,6 +272,18 @@ class GTKEngine {
         regionToWidgetTypeMap.put(Region.TREE, WidgetType.TREE);
         regionToWidgetTypeMap.put(Region.TREE_CELL, WidgetType.TREE_CELL);
         regionToWidgetTypeMap.put(Region.VIEWPORT, WidgetType.VIEWPORT);
+
+        Object value = INSTANCE.getSetting(Settings.GTK_XFT_DPI);
+        if (value instanceof Integer) {
+            int dpi = ((Integer)value).intValue() / 1024;
+            if (dpi == -1) {
+                dpi = 96;
+            }
+            if (dpi < 50) {
+                dpi = 50;
+            }
+            X11GraphicsDevice.setGlobalScale(Math.round(dpi / 96f));
+        }
     }
 
     /** Translate Region and JComponent into WidgetType ordinals */

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

@@ -72,6 +72,8 @@ public final class X11GraphicsDevice extends GraphicsDevice
     private volatile Insets insets;
     private boolean shutdownHookRegistered;
     private int scale;
+    private volatile boolean isNativeScaleDefault;
+    private static int globalScale; // derived from Xft.dpi
 
     public X11GraphicsDevice(int screennum) {
         this.screen = screennum;
@@ -570,6 +572,17 @@ public final class X11GraphicsDevice extends GraphicsDevice
         return (int)Math.round(getNativeScaleFactor(screen));
     }
 
+    public static void setGlobalScale(int scale) {
+        globalScale = scale;
+        for (GraphicsDevice gd : GraphicsEnvironment.getLocalGraphicsEnvironment().getScreenDevices()) {
+            X11GraphicsDevice x11gd = (X11GraphicsDevice)gd;
+            if (x11gd.isNativeScaleDefault) {
+                x11gd.scale = globalScale;
+                x11gd.isNativeScaleDefault = false;
+            }
+        }
+    }
+
     private int initScaleFactor() {
 
         if (SunGraphicsEnvironment.isUIScaleEnabled()) {
@@ -580,7 +593,10 @@ public final class X11GraphicsDevice extends GraphicsDevice
                 return (int) debugScale;
             }
             int nativeScale = getNativeScale();
-            return nativeScale >= 1 ? nativeScale : 1;
+            if (nativeScale > 0) return nativeScale;
+            if (globalScale > 0) return globalScale;
+            isNativeScaleDefault = true;
+            return 1;
         }
 
         return 1;

src/java.desktop/unix/native/common/awt/systemscale/systemScale.c

@@ -170,6 +170,7 @@ static double getDesktopScale(char *output_name) {
             }
             fp_g_variant_unref(value);
         }
+        /* [tav]
         if (result > 0) {
             value = get_schema_value("com.canonical.Unity.Interface",
                                                            "text-scale-factor");
@@ -177,7 +178,7 @@ static double getDesktopScale(char *output_name) {
                 result *= fp_g_variant_get_double(value);
                 fp_g_variant_unref(value);
             }
-        }
+        }*/
     }
 
     if (result <= 0) {
@@ -189,6 +190,7 @@ static double getDesktopScale(char *output_name) {
         }
     }
 
+    /* [tav]
     if (result <= 0) {
         void *value = get_schema_value("org.gnome.desktop.interface",
                                                          "text-scaling-factor");
@@ -196,7 +198,7 @@ static double getDesktopScale(char *output_name) {
             result = fp_g_variant_get_double(value);
             fp_g_variant_unref(value);
         }
-    }
+    }*/
 
     return result;
 
@@ -214,7 +216,7 @@ static int getScale(const char *name) {
     return -1;
 }
 
-double getNativeScaleFactor(char *output_name) {
+double getNativeScaleFactor(char *output_name, double default_value) {
     static int scale = -2.0;
     double native_scale = 0;
     int gdk_scale = 0;
@@ -230,10 +232,10 @@ double getNativeScaleFactor(char *output_name) {
     native_scale = getDesktopScale(output_name);
 
     if (native_scale <= 0) {
-        native_scale = 1;
+        native_scale = default_value;
     }
 
     gdk_scale = getScale("GDK_SCALE");
 
-    return gdk_scale > 0 ? native_scale * gdk_scale : native_scale;
+    return gdk_scale > 0 ? (native_scale <= 0 ? 1 : native_scale) * gdk_scale : native_scale;
 }

src/java.desktop/unix/native/common/awt/systemscale/systemScale.h

@@ -28,7 +28,7 @@
 #include <signal.h>
 #include <stdlib.h>
 
-double getNativeScaleFactor(char *output_name);
+double getNativeScaleFactor(char *output_name, double default_value);
 
 #endif
 

src/java.desktop/unix/native/libawt_xawt/awt/awt_GraphicsEnv.c

@@ -2075,7 +2075,7 @@ Java_sun_awt_X11GraphicsDevice_getNativeScaleFactor
     (JNIEnv *env, jobject this, jint screen) {
     // in case of Xinerama individual screen scales are not supported
     char *name = get_output_screen_name(env, usingXinerama ? 0 : screen);
-    double scale = getNativeScaleFactor(name);
+    double scale = getNativeScaleFactor(name, -1);
     if (name) {
         free(name);
     }

src/java.desktop/unix/native/libsplashscreen/splashscreen_sys.c

@@ -813,7 +813,7 @@ SplashGetScaledImageName(const char* jarName, const char* fileName,
 #ifndef __linux__
     return JNI_FALSE;
 #endif
-    *scaleFactor = (float)getNativeScaleFactor(NULL);
+    *scaleFactor = (float)getNativeScaleFactor(NULL, 1);
     return GetScaledImageName(fileName, scaledImgName, scaleFactor, scaledImageNameLength);
 }