From 3f081efd76b492f3ccd1d53022103f1b8cdfe6ba Mon Sep 17 00:00:00 2001
From: Pacien TRAN-GIRARD
Date: Sat, 10 Oct 2015 17:04:33 +0200
Subject: Implement color coding functions

---
 src/main/java/Color.java | 82 ++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 65 insertions(+), 17 deletions(-)

diff --git a/src/main/java/Color.java b/src/main/java/Color.java
index 9e05039..49a6618 100644
--- a/src/main/java/Color.java
+++ b/src/main/java/Color.java
@@ -4,6 +4,40 @@
  */
 public final class Color {
 
+    public static final int BYTE_MASK = 0b11111111;
+    public static final float DECIMAL_NORMALIZER = 255.0f;
+
+    public static final int RED_SHIFT = 16;
+    public static final int GREEN_SHIFT = 8;
+    public static final int BLUE_SHIFT = 0;
+
+    /**
+     * Returns shifted component from given packed color.
+     *
+     * @param rgb   32-bits RGB color
+     * @param shift binary shift
+     * @return a float between 0.0 and 1.0
+     * @see #getRGBValue
+     */
+    private static float getNormalizedRGBComponent(int rgb, int shift) {
+        return ((float) (rgb >> shift & BYTE_MASK)) / DECIMAL_NORMALIZER;
+    }
+
+    /**
+     * Returns RGB binary value from given component and color shift.
+     *
+     * @param component a float between 0.0 and 1.0
+     * @param shift     binary shift
+     * @return 32-bits RGB color
+     * @see #getNormalizedRGBComponent
+     */
+    private static int getRGBValue(float component, int shift) {
+        if (component < 0.0f) component = 0.0f;
+        if (component > 1.0f) component = 1.0f;
+
+        return ((int) (component * DECIMAL_NORMALIZER) & BYTE_MASK) << shift;
+    }
+
     /**
      * Returns red component from given packed color.
      *
@@ -14,8 +48,7 @@ public final class Color {
      * @see #getRGB(float, float, float)
      */
     public static float getRed(int rgb) {
-        // TODO getRed
-        return 0.0f;
+        return Color.getNormalizedRGBComponent(rgb, RED_SHIFT);
     }
 
     /**
@@ -28,8 +61,7 @@ public final class Color {
      * @see #getRGB(float, float, float)
      */
     public static float getGreen(int rgb) {
-        // TODO getGreen
-        return 0.0f;
+        return Color.getNormalizedRGBComponent(rgb, GREEN_SHIFT);
     }
 
     /**
@@ -42,8 +74,7 @@ public final class Color {
      * @see #getRGB(float, float, float)
      */
     public static float getBlue(int rgb) {
-        // TODO getBlue
-        return 0.0f;
+        return Color.getNormalizedRGBComponent(rgb, BLUE_SHIFT);
     }
 
     /**
@@ -57,8 +88,7 @@ public final class Color {
      * @see #getRGB(float)
      */
     public static float getGray(int rgb) {
-        // TODO getGray
-        return 0.0f;
+        return (Color.getRed(rgb) + Color.getGreen(rgb) + Color.getBlue(rgb)) / 3.0f;
     }
 
     /**
@@ -73,20 +103,22 @@ public final class Color {
      * @see #getBlue
      */
     public static int getRGB(float red, float green, float blue) {
-        // TODO getRGB
-        return 0;
+        int rgbValue = 0b0;
+        rgbValue |= Color.getRGBValue(red, RED_SHIFT);
+        rgbValue |= Color.getRGBValue(green, GREEN_SHIFT);
+        rgbValue |= Color.getRGBValue(blue, BLUE_SHIFT);
+        return rgbValue;
     }
 
     /**
      * Returns packed RGB components from given grayscale value.
      *
-     * @param gray   a float between 0.0 and 1.0
+     * @param gray a float between 0.0 and 1.0
      * @return 32-bits RGB color
      * @see #getGray
      */
     public static int getRGB(float gray) {
-        // TODO getRGB
-        return 0;
+        return Color.getRGB(gray, gray, gray);
     }
 
     /**
@@ -98,8 +130,16 @@ public final class Color {
      * @see #getGray
      */
     public static float[][] toGray(int[][] image) {
-        // TODO toGray
-        return null;
+        int width = image[0].length;
+        int height = image.length;
+
+        float[][] floatImage = new float[height][width];
+
+        for (int row = 0; row < height; ++row)
+            for (int col = 0; col < width; ++col)
+                floatImage[row][col] = Color.getGray(image[row][col]);
+
+        return floatImage;
     }
 
     /**
@@ -111,8 +151,16 @@ public final class Color {
      * @see #getRGB(float)
      */
     public static int[][] toRGB(float[][] gray) {
-        // TODO toRGB
-        return null;
+        int width = gray[0].length;
+        int height = gray.length;
+
+        int[][] rgbImage = new int[height][width];
+
+        for (int row = 0; row < height; ++row)
+            for (int col = 0; col < width; ++col)
+                rgbImage[row][col] = Color.getRGB(gray[row][col]);
+
+        return rgbImage;
     }
 
 }
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