[followup] Add/refactor JBUI.JBIcon/ScalableJBIcon/ValidatingScalableJBIcon

platform/core-api/src/com/intellij/ui/LayeredIcon.java

@@ -54,8 +54,8 @@ public class LayeredIcon extends JBUI.AuxScalableJBIcon {
   }
 
   @Override
-  public LayeredIcon withPreScaled(boolean preScaled) {
-    super.withPreScaled(preScaled);
+  public LayeredIcon withJBUIPreScaled(boolean preScaled) {
+    super.withJBUIPreScaled(preScaled);
     for (int i = 0; i < myIcons.length; i++) {
       myHShifts[i] = scaleVal(myHShifts[i], Scale.JBUI);
       myVShifts[i] = scaleVal(myVShifts[i], Scale.JBUI);
@@ -271,11 +271,10 @@ public class LayeredIcon extends JBUI.AuxScalableJBIcon {
 
   @Override
   public Icon scale(float scale) {
-    if (getScale() != scale) {
-      super.scale(scale);
-      if (myScaledIcons!= null) Arrays.fill(myScaledIcons, null);
-      updateSize();
-    }
+    if (scale == 1f) return this;
+
+    setScale(scaleVal(scale, Scale.ARBITRARY));
+    if (myScaledIcons != null) Arrays.fill(myScaledIcons, null);
     return this;
   }
 }

platform/core-api/src/com/intellij/ui/RowIcon.java

@@ -57,10 +57,10 @@ public class RowIcon extends JBUI.AuxScalableJBIcon {
 
   @Override
   public Icon scale(float scale) {
-    if (getScale() != scale || (getScale() != 1f && myScaledIcons == null)) {
-      super.scale(scale);
-      rescale();
-    }
+    if (scale == 1f) return this;
+
+    setScale(scaleVal(scale, Scale.ARBITRARY));
+    rescale();
     return this;
   }
 

platform/platform-api/src/com/intellij/ui/SizedIcon.java

@@ -58,9 +58,12 @@ public class SizedIcon extends JBUI.ScalableJBIcon {
 
   @Override
   public Icon scale(float scale) {
+    if (scale == 1f) return this;
+
     if (myDelegate instanceof ScalableIcon) {
-      myScaledDelegate = ((ScalableIcon)myDelegate).scale(scale);
+      setScale(scaleVal(scale, Scale.ARBITRARY));
+      myScaledDelegate = ((ScalableIcon)myDelegate).scale(getScale());
     }
-    return super.scale(scale);
+    return this;
   }
 }

platform/util/src/com/intellij/openapi/util/IconLoader.java

@@ -457,6 +457,8 @@ public final class IconLoader {
 
     @Override
     public Icon scale(float scale) {
+      if (scale == 1f) return this;
+
       if (!isValid()) getRealIcon(); // force state update & cache reset
 
       Icon icon = myScaledIconsCache.getScaledIcon(scale);
@@ -578,10 +580,12 @@ public final class IconLoader {
 
     @Override
     public Icon scale(float scale) {
+      if (scale == 1f) return this;
+
       getOrComputeIcon();
       if (myIcon instanceof ScalableIcon) {
-        myIcon = ((ScalableIcon)myIcon).scale(scale);
-        return super.scale(scale);
+        setScale(scaleVal(scale, Scale.ARBITRARY));
+        myIcon = ((ScalableIcon)myIcon).scale(getScale());
       }
       return this;
     }

platform/util/src/com/intellij/openapi/util/ScalableIcon.java

@@ -23,6 +23,11 @@ import javax.swing.*;
  */
 public interface ScalableIcon extends Icon {
   /**
+   * The method does either of the following:
+   * - creates/retrieves a scaled version of this icon and returns it.
+   * - scales this icon and returns it.
+   * The exact behavior is implementation dependant.
+   *
    * @param scaleFactor scale
    * @return scaled icon with width getIconWidth() * scaleFactor and height getIconHeight() * scaleFactor
    */

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

@@ -43,6 +43,18 @@ public class ColorIcon extends EmptyIcon {
     this(size, color, false);
   }
 
+  protected ColorIcon(ColorIcon icon) {
+    super(icon);
+    myColor = icon.myColor;
+    myBorder = icon.myBorder;
+    myColorSize = icon.myColorSize;
+  }
+
+  @Override
+  protected ColorIcon copy() {
+    return new ColorIcon(this);
+  }
+
   public Color getIconColor() {
     return myColor;
   }

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

@@ -16,7 +16,6 @@
 
 package com.intellij.util.ui;
 
-import com.intellij.openapi.util.Pair;
 import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
@@ -32,9 +31,8 @@ import java.util.Map;
  *
  * @see ColorIcon
  */
-public class EmptyIcon extends JBUI.ScalableJBIcon {
-  private static final Map<Pair<Integer, Boolean>, EmptyIcon> cache =
-    new HashMap<Pair<Integer, Boolean>, EmptyIcon>(); // (size, preScaled) -> (icon)
+public class EmptyIcon extends JBUI.CachingScalableJBIcon<EmptyIcon> {
+  private static final Map<Integer, EmptyIcon> cache = new HashMap<Integer, EmptyIcon>();
 
   public static final Icon ICON_16 = JBUI.scale(create(16));
   public static final Icon ICON_18 = JBUI.scale(create(18));
@@ -43,13 +41,12 @@ public class EmptyIcon extends JBUI.ScalableJBIcon {
 
   protected final int width;
   protected final int height;
-  private EmptyIcon myScaledCache;
   private boolean myUseCache;
 
   /**
    * Creates an icon of the provided size.
    *
-   * Use {@link JBUI#scale(EmptyIcon)} to meet HiDPI.
+   * Use {@link JBUI#scale(JBUI.JBIcon)} to meet HiDPI.
    */
   public static EmptyIcon create(int size) {
     return create(size, size);
@@ -58,7 +55,7 @@ public class EmptyIcon extends JBUI.ScalableJBIcon {
   /**
    * Creates an icon of the provided size.
    *
-   * Use {@link JBUI#scale(EmptyIcon)} to meet HiDPI.
+   * Use {@link JBUI#scale(JBUI.JBIcon)} to meet HiDPI.
    */
   public static EmptyIcon create(int width, int height) {
     return create(width, height, true);
@@ -98,39 +95,34 @@ public class EmptyIcon extends JBUI.ScalableJBIcon {
     myUseCache = icon.myUseCache;
   }
 
+  @Override
   protected EmptyIcon copy() {
     return new EmptyIcon(this);
   }
 
   @Override
-  public EmptyIcon withPreScaled(boolean preScaled) {
-    if (myUseCache && isPreScaled() != preScaled) {
-      Pair<Integer, Boolean> key = key(width, height, preScaled);
+  public EmptyIcon withJBUIPreScaled(boolean preScaled) {
+    if (myUseCache && isJBUIPreScaled() != preScaled) {
+      Integer key = key(width, height, isJBUIPreScaled());
       if (key != null) cache.remove(key); // rather useless to keep it in cache
       return create(width, height, preScaled);
     }
-    return (EmptyIcon)super.withPreScaled(preScaled);
+    return (EmptyIcon)super.withJBUIPreScaled(preScaled);
   }
 
   private static EmptyIcon create(int width, int height, boolean preScaled) {
-    Pair<Integer, Boolean> key = key(width, height, preScaled);
+    Integer key = key(width, height, preScaled);
     EmptyIcon icon = (key != null) ? cache.get(key) : null;
     if (icon == null) {
       icon = new EmptyIcon(width, height, true);
-      icon.setPreScaled(preScaled);
+      icon.setJBUIPreScaled(preScaled);
       if (key != null) cache.put(key, icon);
     }
     return icon;
   }
 
-  private static Pair<Integer, Boolean> key(int width, int height, boolean preScaled) {
-    return (width == height && width < 129) ? Pair.create(width, preScaled) : null;
-  }
-
-  private boolean isCached() {
-    if (!myUseCache) return false;
-    Pair<Integer, Boolean> key = key(width, height, isPreScaled());
-    return key != null && cache.containsKey(key);
+  private static Integer key(int width, int height, boolean preScaled) {
+    return (width == height && width < 129) ? preScaled ? width : JBUI.scale(width) : null;
   }
 
   @Override
@@ -154,20 +146,18 @@ public class EmptyIcon extends JBUI.ScalableJBIcon {
 
     final EmptyIcon icon = (EmptyIcon)o;
 
-    if (height != icon.height) return false;
-    if (width != icon.width) return false;
+    if (scaleVal(height, Scale.JBUI) != icon.scaleVal(height, Scale.JBUI)) return false;
+    if (scaleVal(width, Scale.JBUI) != icon.scaleVal(width, Scale.JBUI)) return false;
     if (getScale() != icon.getScale()) return false;
-    if (isPreScaled() != icon.isPreScaled()) return false;
 
     return true;
   }
 
   @Override
   public int hashCode() {
-    int result = width;
-    result = 31 * result + height;
+    int result = scaleVal(width, Scale.JBUI);
+    result = 31 * result + scaleVal(height, Scale.JBUI);
     result = 31 * result + (getScale() != +0.0f ? Float.floatToIntBits(getScale()) : 0);
-    result = 31 * result + Boolean.valueOf(isPreScaled()).hashCode();
     return result;
   }
 
@@ -175,17 +165,6 @@ public class EmptyIcon extends JBUI.ScalableJBIcon {
     return new EmptyIconUIResource(this);
   }
 
-  @Override
-  public EmptyIcon scale(float scale) {
-    if (getScale() == scale || !isCached()) {
-      return (EmptyIcon)super.scale(scale);
-    }
-    if (myScaledCache == null || myScaledCache.getScale() != scale) {
-      myScaledCache = copy(); // never cached
-    }
-    return myScaledCache.scale(scale);
-  }
-
   public static class EmptyIconUIResource extends EmptyIcon implements UIResource {
     protected EmptyIconUIResource(EmptyIcon icon) {
       super(icon);

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

@@ -166,7 +166,7 @@ public class JBUI {
   }
 
   public static <T extends JBIcon> T scale(T icon) {
-    return (T)icon.withPreScaled(false);
+    return (T)icon.withJBUIPreScaled(false);
   }
 
   public static JBDimension emptySize() {
@@ -309,14 +309,14 @@ public class JBUI {
     /**
      * @return whether the icon size metrics are pre-scaled or not
      */
-    protected boolean isPreScaled() {
+    protected boolean isJBUIPreScaled() {
       return myInitialJBUIScale != 1f;
     }
 
     /**
      * Sets the icon size metrics to {@code preScaled}
      */
-    protected void setPreScaled(boolean preScaled) {
+    protected void setJBUIPreScaled(boolean preScaled) {
       myInitialJBUIScale = preScaled ? scale(1f) : 1f;
     }
 
@@ -325,8 +325,8 @@ public class JBUI {
      *
      * @return the icon (this or new instance) with size metrics set to {@code preScaled}
      */
-    public JBIcon withPreScaled(boolean preScaled) {
-      setPreScaled(preScaled);
+    public JBIcon withJBUIPreScaled(boolean preScaled) {
+      setJBUIPreScaled(preScaled);
       return this;
     }
 
@@ -399,12 +399,44 @@ public class JBUI {
           return super.scaleVal(value * myScale);
       }
     }
+  }
 
+  /**
+   * A ScalableJBIcon providing an immutable caching implementation of the {@link #scale(float)} method.
+   *
+   * @author tav
+   * @author Aleksey Pivovarov
+   */
+  public static abstract class CachingScalableJBIcon<T extends CachingScalableJBIcon> extends ScalableJBIcon {
+    private CachingScalableJBIcon myScaledIconCache;
+
+    protected CachingScalableJBIcon() {}
+
+    protected CachingScalableJBIcon(CachingScalableJBIcon icon) {
+      super(icon);
+      myScaledIconCache = null;
+    }
+
+    /**
+     * @return a new scaled copy of this icon, or the cached instance of the provided scale
+     */
     @Override
     public Icon scale(float scale) {
-      if (getScale() != scale) setScale(scale);
-      return this;
+      if (scale == 1f)  return this;
+
+      scale = scaleVal(scale, Scale.ARBITRARY); // accumulate scale
+      if (myScaledIconCache == null || myScaledIconCache.getScale() != scale) {
+        myScaledIconCache = copy();
+        myScaledIconCache.setScale(scale);
+      }
+      return myScaledIconCache;
     }
+
+    /**
+     * @return a deep copy of this icon instance
+     */
+    @NotNull
+    protected abstract T copy();
   }
 
   public interface AuxJBUIScale {

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

@@ -51,6 +51,16 @@ public class TwoColorsIcon extends ColorIcon {
     mySecondColor = secondColor != null ? secondColor : Gray.TRANSPARENT;
   }
 
+  protected TwoColorsIcon(TwoColorsIcon icon) {
+    super(icon);
+    mySecondColor = icon.mySecondColor;
+  }
+
+  @Override
+  protected TwoColorsIcon copy() {
+    return new TwoColorsIcon(this);
+  }
+
   @Override
   public void paintIcon(final Component component, Graphics g, int x, int y) {
     Graphics2D g2d = (Graphics2D)g.create();

platform/vcs-log/impl/src/com/intellij/vcs/log/ui/filter/StructureFilterPopupComponent.java

@@ -331,9 +331,9 @@ class StructureFilterPopupComponent extends FilterPopupComponent<VcsLogFileFilte
     }
 
     @Override
-    public CheckboxColorIcon withPreScaled(boolean preScaled) {
-      mySizedIcon = JBUI.scale(mySizedIcon);
-      return (CheckboxColorIcon)super.withPreScaled(preScaled);
+    public CheckboxColorIcon withJBUIPreScaled(boolean preScaled) {
+      mySizedIcon = (SizedIcon)mySizedIcon.withJBUIPreScaled(preScaled);
+      return (CheckboxColorIcon)super.withJBUIPreScaled(preScaled);
     }
 
     @Override

plugins/ui-designer-core/src/com/intellij/designer/propertyTable/renderers/ColorIcon.java

@@ -34,6 +34,18 @@ public final class ColorIcon extends EmptyIcon {
     myColorSize = colorSize;
   }
 
+  protected ColorIcon(ColorIcon icon) {
+    super(icon);
+    myColorSize = icon.myColorSize;
+    myColor = icon.myColor;
+    myShowRedLine = icon.myShowRedLine;
+  }
+
+  @Override
+  protected ColorIcon copy() {
+    return new ColorIcon(this);
+  }
+
   public Color getColor() {
     return myShowRedLine ? null : myColor;
   }

xml/xml-psi-impl/src/com/intellij/xml/util/ColorIconCache.java

@@ -22,6 +22,7 @@ import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
 import java.awt.*;
+import java.util.Arrays;
 import java.util.Map;
 
 /**
@@ -67,6 +68,17 @@ public class ColorIconCache {
       myColours = colours;
     }
 
+    protected ColorIcon(ColorIcon icon) {
+      super(icon);
+      myColor = icon.myColor;
+      if (icon.myColours != null) myColours = Arrays.copyOf(icon.myColours, icon.myColours.length);
+    }
+
+    @Override
+    protected ColorIcon copy() {
+      return new ColorIcon(this);
+    }
+
     @Override
     public void paintIcon(final Component component, final Graphics g, final int i, final int j) {
       final int iconWidth = getIconWidth();