From eb1092c9f8f7c3497178007a3572637d94e3d367 Mon Sep 17 00:00:00 2001
From: Andreas Schildbach <andreas@schildbach.de>
Date: Mon, 23 Feb 2015 11:54:01 +0100
Subject: [PATCH] Add method to determine the perceived brightness of a color.

---
 enabler/src/de/schildbach/pte/dto/Style.java | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/enabler/src/de/schildbach/pte/dto/Style.java b/enabler/src/de/schildbach/pte/dto/Style.java
index a7107b1b..8c61c80c 100644
--- a/enabler/src/de/schildbach/pte/dto/Style.java
+++ b/enabler/src/de/schildbach/pte/dto/Style.java
@@ -128,13 +128,16 @@ public class Style implements Serializable
 		return color & 0xff;
 	}
 
-	public static int deriveForegroundColor(final int backgroundColor)
+	public static float perceivedBrightness(final int color)
 	{
 		// formula for perceived brightness computation: http://www.w3.org/TR/AERT#color-contrast
-		final double a = 1 - (0.299 * Style.red(backgroundColor) + 0.587 * Style.green(backgroundColor) + 0.114 * Style.blue(backgroundColor)) / 255;
+		return (0.299f * Style.red(color) + 0.587f * Style.green(color) + 0.114f * Style.blue(color)) / 256;
+	}
 
+	public static int deriveForegroundColor(final int backgroundColor)
+	{
 		// dark colors, white font. Or light colors, black font
-		if (a >= 0.5)
+		if (perceivedBrightness(backgroundColor) < 0.5)
 			return WHITE;
 		else
 			return BLACK;