From ac038474ceeee9b3fef9fe777c2d34def563d19e Mon Sep 17 00:00:00 2001
From: hexyoungs <chuxdesign@hotmail.com>
Date: Fri, 25 Sep 2020 10:40:53 +0800
Subject: [PATCH] feat: using luminance to determine text color

of circlecounttool
---
 src/tools/circlecount/circlecounttool.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/tools/circlecount/circlecounttool.cpp b/src/tools/circlecount/circlecounttool.cpp
index 3b9ca65c..9a53a994 100644
--- a/src/tools/circlecount/circlecounttool.cpp
+++ b/src/tools/circlecount/circlecounttool.cpp
@@ -89,8 +89,11 @@ void CircleCountTool::process(QPainter& painter,
           textRect, Qt::AlignCenter, QString::number(m_count));
     }
 
-    // Lightness value ranges from 0-255, we split at 75 as this looks best
-    if (m_color.lightness() <= 75) {
+    // Calculate the perceptive luminance - human eye favors green color
+    double luma = ((0.299 * m_color.red()) + (0.587 * m_color.green()) +
+                   (0.114 * m_color.blue())) /
+                  255;
+    if (luma <= 0.5) {
         painter.setPen(Qt::white);
     } else {
         painter.setPen(Qt::black);