JAL-98 refactor bleachColour() to ColorUtils

diff --git a/src/jalview/schemes/ResidueColourScheme.java b/src/jalview/schemes/ResidueColourScheme.java
index 56c573c..a15ca20 100755 (executable)
--- a/src/jalview/schemes/ResidueColourScheme.java
+++ b/src/jalview/schemes/ResidueColourScheme.java
@@ -25,6 +25,7 @@ import jalview.analysis.Profile;
 import jalview.datamodel.AnnotatedCollectionI;
 import jalview.datamodel.SequenceCollectionI;
 import jalview.datamodel.SequenceI;
+import jalview.util.ColorUtils;
 import jalview.util.Comparison;
 import jalview.util.MessageManager;
 
@@ -311,33 +312,13 @@ public class ResidueColourScheme implements ColourSchemeI
     float bleachFactor = (11 - (conservationScore - '0')) / 10f;
 
     /*
-     * scale this by the percentage slider / 20
-     */
-    bleachFactor *= (inc / 20f);
-
-    int red = currentColour.getRed();
-    int green = currentColour.getGreen();
-    int blue = currentColour.getBlue();
-
-    /*
-     * bleach colours towards white (255, 255, 255),
-     * depending on the consensus score and the conservation slider value
-     * scores of:                      0  1  2  3  4  5  6  7  8  9
+     * scale this up by 0-5 (percentage slider / 20)
+     * as a result, scores of:         0  1  2  3  4  5  6  7  8  9
      * fade to white at slider value: 18 20 22 25 29 33 40 50 67 100%
      */
-    red += (255 - red) * bleachFactor;
-    green += (255 - green) * bleachFactor;
-    blue += (255 - blue) * bleachFactor;
+    bleachFactor *= (inc / 20f);
 
-    if (red > 255 || green > 255 || blue > 255)
-    {
-      currentColour = Color.white;
-    }
-    else
-    {
-      currentColour = new Color(red, green, blue);
-    }
-    return currentColour;
+    return ColorUtils.bleachColour(currentColour, bleachFactor);
   }
 
   @Override

diff --git a/src/jalview/util/ColorUtils.java b/src/jalview/util/ColorUtils.java
index 31d1ded..525bfdb 100644 (file)
--- a/src/jalview/util/ColorUtils.java
+++ b/src/jalview/util/ColorUtils.java
@@ -142,4 +142,53 @@ public class ColorUtils
             * (maxColour.getBlue() - minColour.getBlue());
     return new Color(r / 255, g / 255, b / 255);
   }
+
+  /**
+   * 'Fades' the given colour towards white by the specified proportion. A
+   * factor of 1 or more results in White, a factor of 0 leaves the colour
+   * unchanged, and a factor between 0 and 1 results in a proportionate change
+   * of RGB values towards (255, 255, 255).
+   * <p>
+   * A negative bleachFactor can be specified to darken the colour towards Black
+   * (0, 0, 0).
+   * 
+   * @param colour
+   * @param bleachFactor
+   * @return
+   */
+  public static Color bleachColour(Color colour, float bleachFactor)
+  {
+    if (bleachFactor >= 1f)
+    {
+      return Color.WHITE;
+    }
+    if (bleachFactor <= -1f)
+    {
+      return Color.BLACK;
+    }
+    if (bleachFactor == 0f)
+    {
+      return colour;
+    }
+
+    int red = colour.getRed();
+    int green = colour.getGreen();
+    int blue = colour.getBlue();
+
+    if (bleachFactor > 0)
+    {
+      red += (255 - red) * bleachFactor;
+      green += (255 - green) * bleachFactor;
+      blue += (255 - blue) * bleachFactor;
+      return new Color(red, green, blue);
+    }
+    else
+    {
+      float factor = 1 + bleachFactor;
+      red *= factor;
+      green *= factor;
+      blue *= factor;
+      return new Color(red, green, blue);
+    }
+  }
 }

diff --git a/test/jalview/util/ColorUtilsTest.java b/test/jalview/util/ColorUtilsTest.java
index 69675f7..77a023f 100644 (file)
--- a/test/jalview/util/ColorUtilsTest.java
+++ b/test/jalview/util/ColorUtilsTest.java
@@ -22,6 +22,7 @@ package jalview.util;
 
 import static org.testng.AssertJUnit.assertEquals;
 import static org.testng.AssertJUnit.assertNull;
+import static org.testng.AssertJUnit.assertSame;
 
 import java.awt.Color;
 
@@ -132,4 +133,27 @@ public class ColorUtilsTest
             .getGraduatedColour(40f, 10f, minColour, 10f, maxColour);
     assertEquals(minColour, col);
   }
+
+  @Test(groups = { "Functional" })
+  public void testBleachColour()
+  {
+    Color colour = new Color(155, 105, 55);
+    assertSame(colour, ColorUtils.bleachColour(colour, 0));
+    assertEquals(Color.WHITE, ColorUtils.bleachColour(colour, 1));
+    assertEquals(Color.WHITE, ColorUtils.bleachColour(colour, 2));
+    assertEquals(new Color(175, 135, 95),
+            ColorUtils.bleachColour(colour, 0.2f));
+    assertEquals(new Color(225, 210, 195),
+            ColorUtils.bleachColour(colour, 0.7f));
+
+    /*
+     * and some 'negative fade'
+     */
+    assertEquals(Color.BLACK, ColorUtils.bleachColour(colour, -1));
+    assertEquals(Color.BLACK, ColorUtils.bleachColour(colour, -2));
+    assertEquals(new Color(124, 84, 44),
+            ColorUtils.bleachColour(colour, -0.2f));
+    assertEquals(new Color(46, 31, 16), // with rounding down
+            ColorUtils.bleachColour(colour, -0.7f));
+  }
 }