From 6310160c4ee85f1d1b7935c82b29e9589247981d Mon Sep 17 00:00:00 2001
From: Daniel Solomon <solomondaniel@google.com>
Date: Tue, 27 Nov 2018 13:15:10 -0800
Subject: [PATCH] Add a public chromatic adaptation API to ColorSpace

This change adds a public version of ColorSpace.chromaticAdaptation(),
so that chromatic adaptation can be done on independent CIE xyY or XYZ
coordinates without the involvement of ColorSpace.Rgb.

Test: cts-tradefed run singleCommand cts-dev --module CtsGraphicsTestCases --test android.graphics.cts.ColorSpaceTest
Bug 116516917

Change-Id: I73c33750c343301bed4bb018c351d87c5043b59b
---
 api/current.txt                               |  1 +
 .../java/android/graphics/ColorSpace.java     | 34 +++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/api/current.txt b/api/current.txt
index abd3c312e7e6e..6bb899d04bf4f 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -13687,6 +13687,7 @@ package android.graphics {
   public abstract class ColorSpace {
     method public static android.graphics.ColorSpace adapt(android.graphics.ColorSpace, float[]);
     method public static android.graphics.ColorSpace adapt(android.graphics.ColorSpace, float[], android.graphics.ColorSpace.Adaptation);
+    method public static float[] chromaticAdaptation(android.graphics.ColorSpace.Adaptation, float[], float[]);
     method public static android.graphics.ColorSpace.Connector connect(android.graphics.ColorSpace, android.graphics.ColorSpace);
     method public static android.graphics.ColorSpace.Connector connect(android.graphics.ColorSpace, android.graphics.ColorSpace, android.graphics.ColorSpace.RenderIntent);
     method public static android.graphics.ColorSpace.Connector connect(android.graphics.ColorSpace);
diff --git a/graphics/java/android/graphics/ColorSpace.java b/graphics/java/android/graphics/ColorSpace.java
index 2e1d81a294e9a..bf114b969b674 100644
--- a/graphics/java/android/graphics/ColorSpace.java
+++ b/graphics/java/android/graphics/ColorSpace.java
@@ -1778,6 +1778,40 @@ public abstract class ColorSpace {
         return mul3x3(inverse3x3(matrix), mul3x3Diag(LMS, matrix));
     }
 
+    /**
+     * <p>Computes the chromatic adaptation transform from the specified
+     * source white point to the specified destination white point.</p>
+     *
+     * <p>The transform is computed using the von Kries method, described
+     * in more details in the documentation of {@link Adaptation}. The
+     * {@link Adaptation} enum provides different matrices that can be
+     * used to perform the adaptation.</p>
+     *
+     * @param adaptation The adaptation method
+     * @param srcWhitePoint The white point to adapt from
+     * @param dstWhitePoint The white point to adapt to
+     * @return A 3x3 matrix as a non-null array of 9 floats
+     */
+    @NonNull
+    @Size(9)
+    public static float[] chromaticAdaptation(@NonNull Adaptation adaptation,
+            @NonNull @Size(min = 2, max = 3) float[] srcWhitePoint,
+            @NonNull @Size(min = 2, max = 3) float[] dstWhitePoint) {
+        float[] srcXyz = srcWhitePoint.length == 3 ?
+            Arrays.copyOf(srcWhitePoint, 3) : xyYToXyz(srcWhitePoint);
+        float[] dstXyz = dstWhitePoint.length == 3 ?
+            Arrays.copyOf(dstWhitePoint, 3) : xyYToXyz(dstWhitePoint);
+
+        if (compare(srcXyz, dstXyz)) {
+            return new float[] {
+                1.0f, 0.0f, 0.0f,
+                0.0f, 1.0f, 0.0f,
+                0.0f, 0.0f, 1.0f
+            };
+        }
+        return chromaticAdaptation(adaptation.mTransform, srcXyz, dstXyz);
+    }
+
     /**
      * Implementation of the CIE XYZ color space. Assumes the white point is D50.
      */