size method should rescale dimension objects

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2015 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@ import org.jetbrains.annotations.Nullable;
 import javax.swing.*;
 import javax.swing.border.Border;
 import javax.swing.border.CompoundBorder;
+import javax.swing.plaf.UIResource;
 import java.awt.*;
 
 /**
@@ -36,35 +37,61 @@ import java.awt.*;
 public class JBUI {
   private static final Logger LOG = Logger.getInstance("#com.intellij.util.ui.JBUI");
 
-  private static float scaleFactor = 1.0f;
+  private static float SCALE_FACTOR = calculateScaleFactor();
 
-  static {
-    calculateScaleFactor();
-  }
-
-  private static void calculateScaleFactor() {
+  private static float calculateScaleFactor() {
     if (SystemInfo.isMac) {
       LOG.info("UI scale factor: 1.0");
-      scaleFactor = 1.0f;
-      return;
+      return 1.0f;
     }
 
     if (SystemProperties.has("hidpi") && !SystemProperties.is("hidpi")) {
       LOG.info("UI scale factor: 1.0");
-      scaleFactor = 1.0f;
-      return;
+      return 1.0f;
     }
 
-    UIUtil.initSystemFontData();
-    Pair<String, Integer> fdata = UIUtil.getSystemFontData();
+    float s = 1f;
 
-    int size;
-    if (fdata != null) {
-      size = fdata.getSecond();
-    } else {
+    // On Linux: rely on DPI
+    if (SystemInfo.isLinux) {
+      final int dpi = getSystemDPI();
+      if (dpi < 120) s = 1f;
+      else if (dpi < 144) s = 1.25f;
+      else if (dpi < 168) s = 1.5f;
+      else if (dpi < 192) s = 1.75f;
+      else s = 2f;
+
+      LOG.info("UI scale factor: " + s);
+      return s;
+    }
+
+    int size = -1;
+
+    // On Windows: rely on default system font
+    if (SystemInfo.isWindows) {
+      UIUtil.initSystemFontData();
+      Pair<String, Integer> fdata = UIUtil.getSystemFontData();
+      if (fdata != null) size = fdata.getSecond();
+    }
+    if (size == -1) {
       size = Fonts.label().getSize();
     }
-    setScaleFactor(size/UIUtil.DEF_SYSTEM_FONT_SIZE);
+    if (size <= 13) s = 1.0f;
+    else if (size <= 16) s = 1.25f;
+    else if (size <= 18) s = 1.5f;
+    else if (size < 24)  s = 1.75f;
+    else s = 2.0f;
+
+    LOG.info("UI scale factor: " + s);
+    return s;
+  }
+
+  private static int getSystemDPI() {
+    try {
+      return Toolkit.getDefaultToolkit().getScreenResolution();
+    } catch (HeadlessException e) {
+      return 96;
+    }
   }
 
   public static void setScaleFactor(float scale) {
@@ -82,22 +109,19 @@ public class JBUI {
       //Default UI font size for Unity and Gnome is 15. Scaling factor 1.25f works badly on Linux
       scale = 1f;
     }
-    if (scaleFactor == scale) {
-      return;
-    }
-    LOG.info("UI scale factor: " + scale);
+    LOG.info("UI scale factor changed: " + scale);
 
-    scaleFactor = scale;
+    SCALE_FACTOR = scale;
     IconLoader.setScale(scale);
   }
 
   public static int scale(int i) {
-    return Math.round(scaleFactor * i);
+    return Math.round(SCALE_FACTOR * i);
   }
 
   public static int scaleFontSize(int fontSize) {
-    if (scaleFactor == 1.25f) return (int)(fontSize * 1.34f);
-    if (scaleFactor == 1.75f) return (int)(fontSize * 1.67f);
+    if (SCALE_FACTOR == 1.25f) return (int)(fontSize * 1.34f);
+    if (SCALE_FACTOR == 1.75f) return (int)(fontSize * 1.67f);
     return scale(fontSize);
   }
 
@@ -110,7 +134,15 @@ public class JBUI {
   }
 
   public static JBDimension size(Dimension size) {
-    return size instanceof JBDimension ? ((JBDimension)size) : new JBDimension(size.width, size.height);
+    if (size instanceof JBDimension) {
+      final JBDimension jbSize = (JBDimension)size;
+      if (jbSize.originalScale == scale(1f)) {
+        return jbSize;
+      }
+      final JBDimension newSize = new JBDimension((int)(jbSize.width / jbSize.originalScale), (int)(jbSize.height / jbSize.originalScale));
+      return size instanceof UIResource ? newSize.asUIResource() : newSize;
+    }
+    return new JBDimension(size.width, size.height);
   }
 
   public static JBInsets insets(int top, int left, int bottom, int right) {
@@ -154,7 +186,7 @@ public class JBUI {
   }
 
   public static float scale(float f) {
-    return f * scaleFactor;
+    return f * SCALE_FACTOR;
   }
 
   public static JBInsets insets(Insets insets) {
@@ -162,7 +194,7 @@ public class JBUI {
   }
 
   public static boolean isHiDPI() {
-    return scaleFactor > 1.0f;
+    return SCALE_FACTOR > 1.0f;
   }
 
   public static class Fonts {