From 6f3c30a9ce28a7596f1b552d23bca3863557878f Mon Sep 17 00:00:00 2001 From: Steve Kondik Date: Fri, 26 Feb 2016 11:44:29 +0100 Subject: [PATCH] cmsdk: Factoring out color temperature to RGB conversion algorithm * We need this for other things besides LiveDisplay. Change-Id: I14c80b059beded80c7cee369a9b40f71d6e905e8 --- src/java/cyanogenmod/util/ColorUtils.java | 224 +++++++++++++++++++++- 1 file changed, 223 insertions(+), 1 deletion(-) diff --git a/src/java/cyanogenmod/util/ColorUtils.java b/src/java/cyanogenmod/util/ColorUtils.java index 37b4e5d..0142396 100644 --- a/src/java/cyanogenmod/util/ColorUtils.java +++ b/src/java/cyanogenmod/util/ColorUtils.java @@ -1,5 +1,5 @@ /* - * Copyright (c) 2011-2015 CyanogenMod Project + * Copyright (c) 2011-2016 The CyanogenMod Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -19,6 +19,7 @@ import android.graphics.Bitmap; import android.graphics.Color; import android.graphics.drawable.BitmapDrawable; import android.graphics.drawable.Drawable; +import android.util.MathUtils; import com.android.internal.util.cm.palette.Palette; @@ -301,4 +302,225 @@ public class ColorUtils { return alertColor; } + + /** + * Convert a color temperature value (in Kelvin) to a RGB units as floats. + * This can be used in a transform matrix or hardware gamma control. + * + * @param tempK + * @return + */ + public static float[] temperatureToRGB(int degreesK) { + int k = MathUtils.constrain(degreesK, 1000, 20000); + float a = (k % 100) / 100.0f; + int i = ((k - 1000)/ 100) * 3; + + return new float[] { interp(i, a), interp(i+1, a), interp(i+2, a) }; + } + + private static float interp(int i, float a) { + return MathUtils.lerp((float)sColorTable[i], (float)sColorTable[i+3], a); + } + + /** + * This table is a modified version of the original blackbody chart, found here: + * http://www.vendian.org/mncharity/dir3/blackbody/UnstableURLs/bbr_color.html + * + * Created by Ingo Thiel. + */ + private static final double[] sColorTable = new double[] { + 1.00000000, 0.18172716, 0.00000000, + 1.00000000, 0.25503671, 0.00000000, + 1.00000000, 0.30942099, 0.00000000, + 1.00000000, 0.35357379, 0.00000000, + 1.00000000, 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