From 729e50ff2e3bd15a1ab9353db30fdf2a3f67f80f Mon Sep 17 00:00:00 2001
From: Alberto Griggio <agriggio@users.noreply.github.com>
Date: Fri, 8 Dec 2017 15:54:05 +0100
Subject: [PATCH] color toning: properly draw hue and strength gradients for
 the highlights and shadows sliders

Fixes #4209
---
 rtgui/colortoning.cc       | 22 ++++++++++------------
 rtgui/thresholdselector.cc |  3 +++
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/rtgui/colortoning.cc b/rtgui/colortoning.cc
index c5d9252cd..b53f7e5db 100644
--- a/rtgui/colortoning.cc
+++ b/rtgui/colortoning.cc
@@ -954,36 +954,34 @@ void ColorToning::colorForValue (double valX, double valY, enum ColorCaller::Ele
     if (callerId == 1) {         // ch - main curve
         Color::hsv2rgb01(float(valY), 1.0f, 0.5f, R, G, B);
     } else if (callerId == 2) {  // Slider 1 background
-        if (valY > 0.5)
+        if (valY <= 0.5)
             // the hue range
         {
             Color::hsv2rgb01(float(valX), 1.0f, 0.5f, R, G, B);
         } else {
             // the strength applied to the current hue
             double strength, hue;
-            float r_, g_, b_;
             hlColSat->getValue(strength, hue);
-            Color::hsv2rgb01(valY * 2.f, 1.f, 1.f, r_, g_, b_);
             Color::hsv2rgb01(hue / 360.f, 1.f, 1.f, R, G, B);
-            R = r_ + (R - r_) * valX;
-            G = g_ + (G - g_) * valX;
-            B = b_ + (B - b_) * valX;
+            const double gray = 0.46;
+            R = (gray * (1.0 - valX)) + R * valX;
+            G = (gray * (1.0 - valX)) + G * valX;
+            B = (gray * (1.0 - valX)) + B * valX;
         }
     } else if (callerId == 3) {  // Slider 2 background
-        if (valY > 0.5)
+        if (valY <= 0.5)
             // the hue range
         {
             Color::hsv2rgb01(float(valX), 1.0f, 0.5f, R, G, B);
         } else {
             // the strength applied to the current hue
             double strength, hue;
-            float r_, g_, b_;
             shadowsColSat->getValue(strength, hue);
-            Color::hsv2rgb01(valY * 2.f, 1.f, 1.f, r_, g_, b_);
             Color::hsv2rgb01(hue / 360.f, 1.f, 1.f, R, G, B);
-            R = r_ + (R - r_) * valX;
-            G = g_ + (G - g_) * valX;
-            B = b_ + (B - b_) * valX;
+            const double gray = 0.46;
+            R = (gray * (1.0 - valX)) + R * valX;
+            G = (gray * (1.0 - valX)) + G * valX;
+            B = (gray * (1.0 - valX)) + B * valX;
         }
     }
 
diff --git a/rtgui/thresholdselector.cc b/rtgui/thresholdselector.cc
index 0f9b11cf2..891095e6f 100644
--- a/rtgui/thresholdselector.cc
+++ b/rtgui/thresholdselector.cc
@@ -284,6 +284,9 @@ void ThresholdSelector::updateBackBuffer()
     cr->set_line_cap(Cairo::LINE_CAP_BUTT);
 
     if (is_sensitive() && coloredBar.canGetColors()) {
+        if (updatePolicy == RTUP_DYNAMIC) {
+            coloredBar.setDirty(true);
+        }
         // this will eventually create/update the off-screen Surface for the gradient area only !
         coloredBar.setDrawRectangle(hb + hwslider, int(float(h) * 1.5f / 7.f + 0.5f), iw + 1, int(float(h) * 4.f / 7.f + 0.5f));
         // that we're displaying here