Fix "hidpi" property

- When disabled, it should suppress JRE-HiDPI mode
- New test
- New run config for a standalone (fork) test run mode

platform/platform-impl/src/com/intellij/idea/StartupUtil.java

@@ -27,6 +27,7 @@ import com.intellij.ui.AppUIUtil;
 import com.intellij.util.Consumer;
 import com.intellij.util.EnvironmentUtil;
 import com.intellij.util.PlatformUtils;
+import com.intellij.util.SystemProperties;
 import com.intellij.util.ui.UIUtil;
 import org.apache.log4j.ConsoleAppender;
 import org.apache.log4j.Level;
@@ -82,6 +83,8 @@ public class StartupUtil {
     IdeaForkJoinWorkerThreadFactory.setupForkJoinCommonPool(Main.isHeadless(args));
     boolean newConfigFolder = false;
 
+    checkHiDPISettings();
+
     if (!Main.isHeadless()) {
       AppUIUtil.updateFrameClass();
       newConfigFolder = !new File(PathManager.getConfigPath()).exists();
@@ -180,6 +183,14 @@ public class StartupUtil {
     return true;
   }
 
+  // called via reflection from com.intellij.util.ui.HidpiPropTest
+  private static void checkHiDPISettings() {
+    if (SystemProperties.has("hidpi") && !SystemProperties.is("hidpi")) {
+      // suppress JRE-HiDPI mode
+      System.setProperty("sun.java2d.uiScale.enabled", "false");
+    }
+  }
+
   private static synchronized boolean checkSystemFolders() {
     String configPath = PathManager.getConfigPath();
     PathManager.ensureConfigFolderExists();

platform/platform-tests/testSrc/com/intellij/util/IconsLoadTimeTest.java

@@ -8,6 +8,7 @@ import com.intellij.internal.IconsLoadTime.StatData;
 import com.intellij.openapi.util.registry.Registry;
 import com.intellij.openapi.util.registry.RegistryValue;
 import com.intellij.testFramework.PlatformTestUtil;
+import com.intellij.util.ui.TestScaleHelper;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -32,13 +33,11 @@ public class IconsLoadTimeTest {
   // a list of icons for which we have SVG versions
   private static final String ICONS_LIST_PATH = PlatformTestUtil.getPlatformTestDataPath() + "icons/icons_list.txt";
 
-  private static String initialInternalProp;
   private static boolean initialSvgProp;
 
   @Before
   public void setState() {
-    initialInternalProp = System.getProperty("idea.is.internal");
-    System.setProperty("idea.is.internal", "true");
+    TestScaleHelper.setProperty("idea.is.internal", "true");
     RegistryValue rv = Registry.get("ide.svg.icon");
     initialSvgProp = rv.asBoolean();
     rv.setValue(true);
@@ -68,12 +67,7 @@ public class IconsLoadTimeTest {
 
   @After
   public void restoreState() {
-    if (initialInternalProp == null) {
-      System.clearProperty("idea.is.internal");
-    }
-    else {
-      System.setProperty("idea.is.internal", initialInternalProp);
-    }
+    TestScaleHelper.restoreProperties();
     Registry.get("ide.svg.icon").setValue(initialSvgProp);
   }
 }

platform/platform-tests/testSrc/com/intellij/util/ui/HidpiPropTest.java

@@ -0,0 +1,49 @@
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.util.ui;
+
+import com.intellij.idea.StartupUtil;
+import com.intellij.util.MethodInvocator;
+import com.intellij.util.ReflectionUtil;
+import com.intellij.util.SystemProperties;
+import org.junit.*;
+
+import javax.swing.*;
+import java.awt.*;
+
+/**
+ * Tests "hidpi" system property.
+ *
+ * @author tav
+ */
+public class HidpiPropTest {
+  static final String HIDPI_PROP = "hidpi";
+  static final String UI_SCALE_PROP = "sun.java2d.uiScale.enabled";
+  static final String STANDALONE_PROP = "intellij.test.standalone";
+
+  @Before
+  public void checkStandalone() {
+    Assume.assumeTrue("not in " + STANDALONE_PROP + " mode", SystemProperties.is(STANDALONE_PROP));
+  }
+
+  @Before
+  public void setState() {
+    TestScaleHelper.setProperty(HIDPI_PROP, "false");
+    MethodInvocator m = new MethodInvocator(StartupUtil.class, "checkHiDPISettings");
+    Assume.assumeTrue("StartupUtil.checkHiDPISettings method not available", m.isAvailable());
+    m.invoke(null);
+  }
+
+  @After
+  public void restoreState() {
+    TestScaleHelper.restoreProperties();
+  }
+
+  @Test
+  public void test() {
+    Graphics2D g = TestScaleHelper.createGraphics(2);
+
+    Assert.assertFalse(UI_SCALE_PROP + " should be disabled", SystemProperties.is(UI_SCALE_PROP));
+    Assert.assertFalse("hidpi should be disabled", UIUtil.isJreHiDPI());
+    Assert.assertFalse("hidpi should be disabled", UIUtil.isJreHiDPI(g));
+  }
+}

platform/platform-tests/testSrc/com/intellij/util/ui/TestScaleHelper.java

@@ -2,14 +2,26 @@
 package com.intellij.util.ui;
 
 import com.intellij.util.FieldAccessor;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.junit.After;
 import org.junit.Before;
 
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
+
 /**
  * @author tav
  */
+@SuppressWarnings("JUnitTestCaseWithNoTests")
 public class TestScaleHelper {
-  private static final FieldAccessor<UIUtil, Boolean> JRE_HIDPI_ACCESSOR = new FieldAccessor<>(UIUtil.class, "jreHiDPI");
+  private static final FieldAccessor<UIUtil, AtomicReference<Boolean>> JRE_HIDPI_ACCESSOR =
+    new FieldAccessor<>(UIUtil.class, "jreHiDPI");
+
+  private static final Map<String, String> origProps = new HashMap<>();
 
   private float originalUserScale;
   private boolean originalJreHiDPIEnabled;
@@ -24,9 +36,37 @@ public class TestScaleHelper {
   public void restoreState() {
     JBUI.setUserScaleFactor(originalUserScale);
     overrideJreHiDPIEnabled(originalJreHiDPIEnabled);
+    restoreProperties();
+  }
+
+  public static void setProperty(@NotNull String name, @Nullable String value) {
+    origProps.put(name, System.getProperty(name));
+    _setProperty(name, value);
+  }
+
+  private static void _setProperty(String name, String value) {
+    if (value != null) {
+      System.setProperty(name, value);
+    }
+    else {
+      System.clearProperty(name);
+    }
+  }
+
+  public static void restoreProperties() {
+    for (Map.Entry<String, String> entry : origProps.entrySet()) {
+      _setProperty(entry.getKey(), entry.getValue());
+    }
   }
 
   public static void overrideJreHiDPIEnabled(boolean enabled) {
-    JRE_HIDPI_ACCESSOR.set(null, enabled);
+    JRE_HIDPI_ACCESSOR.get(null).set(enabled);
+  }
+
+  public static Graphics2D createGraphics(double scale) {
+    //noinspection UndesirableClassUsage
+    Graphics2D g = new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB).createGraphics();
+    g.scale(scale, scale);
+    return g;
   }
 }

platform/util/src/com/intellij/util/ui/UIUtil.java

@@ -78,6 +78,7 @@ import java.util.List;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.regex.Pattern;
 
 /**
@@ -387,9 +388,9 @@ public class UIUtil {
     return isJreHiDPIEnabled() && JBUI.isHiDPI(JBUI.sysScale(ctx));
   }
 
-  // accessed from com.intellij.util.ui.paint.AbstractPainter2D via reflect
-  private static Boolean jreHiDPI;
-  private static boolean jreHiDPI_earlierVersion;
+  // accessed from com.intellij.util.ui.TestScaleHelper via reflect
+  private static final AtomicReference<Boolean> jreHiDPI = new AtomicReference<Boolean>();
+  private static volatile boolean jreHiDPI_earlierVersion;
 
   /**
    * Returns whether the JRE-managed HiDPI mode is enabled.
@@ -398,30 +399,36 @@ public class UIUtil {
    * @see JBUI.ScaleType
    */
   public static boolean isJreHiDPIEnabled() {
-    if (jreHiDPI != null) {
-      return jreHiDPI;
-    }
-    jreHiDPI = false;
-    jreHiDPI_earlierVersion = true;
-    if (SystemInfo.isLinux) {
-      return false; // pending support
-    }
-    if (SystemInfo.isJetBrainsJvm) {
-      try {
-        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
-        if (ge instanceof SunGraphicsEnvironment) {
-          Method m = ReflectionUtil.getDeclaredMethod(SunGraphicsEnvironment.class, "isUIScaleOn");
-          jreHiDPI = (Boolean)m.invoke(ge);
-          jreHiDPI_earlierVersion = false;
+    if (jreHiDPI.get() != null) return jreHiDPI.get();
+
+    synchronized (jreHiDPI) {
+      if (jreHiDPI.get() != null) return jreHiDPI.get();
+
+      jreHiDPI.set(false);
+      if (SystemProperties.has("hidpi") && !SystemProperties.is("hidpi")) {
+        return false;
+      }
+      jreHiDPI_earlierVersion = true;
+      if (SystemInfo.isLinux) {
+        return false; // pending support
+      }
+      if (SystemInfo.isJetBrainsJvm) {
+        try {
+          GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
+          if (ge instanceof SunGraphicsEnvironment) {
+            Method m = ReflectionUtil.getDeclaredMethod(SunGraphicsEnvironment.class, "isUIScaleOn");
+            jreHiDPI.set(m != null && (Boolean)m.invoke(ge));
+            jreHiDPI_earlierVersion = false;
+          }
+        }
+        catch (Throwable ignore) {
         }
       }
-      catch (Throwable ignore) {
+      if (SystemInfo.isMac) {
+        jreHiDPI.set(true);
       }
+      return jreHiDPI.get();
     }
-    if (SystemInfo.isMac) {
-      jreHiDPI = true;
-    }
-    return jreHiDPI;
   }
 
   /**