Fix problems changing HSV/HSL color sliders with mouse wheel

When we change HSV/HSL sliders, the RGB color is calculated and all
sliders are re-updated from that color. As HSV/HSL are floating point
values, there might be a small adjustment in the 0-100 conversion for
the sliders, so we have to lock the changed slider to keep its
original value set from the mouse wheel.

Fix: https://community.aseprite.org/t/1411

src/app/ui/color_sliders.cpp

@@ -230,6 +230,7 @@ ColorSliders::ColorSliders()
   , m_items(int(Channel::Channels))
   , m_grid(3, false)
   , m_mode(Mode::Absolute)
+  , m_lockSlider(-1)
   , m_lockEntry(-1)
   , m_color(app::Color::fromMask())
 {
@@ -389,12 +390,18 @@ void ColorSliders::addSlider(const Channel channel,
 
 void ColorSliders::setAbsSliderValue(const Channel i, int value)
 {
+  if (m_lockSlider == i)
+    return;
+
   m_items[i].absSlider->setValue(value);
   updateEntryText(i);
 }
 
 void ColorSliders::setRelSliderValue(const Channel i, int value)
 {
+  if (m_lockSlider == i)
+    return;
+
   m_items[i].relSlider->setValue(value);
   updateEntryText(i);
 }
@@ -427,6 +434,8 @@ void ColorSliders::syncRelHsvHslSliders()
 
 void ColorSliders::onSliderChange(const Channel i)
 {
+  base::ScopedValue<int> lock(m_lockSlider, i, m_lockSlider);
+
   updateEntryText(i);
   onControlChange(i);
 }

src/app/ui/color_sliders.h

@@ -85,6 +85,7 @@ namespace app {
     std::vector<Item> m_items;
     ui::Grid m_grid;
     Mode m_mode;
+    int m_lockSlider;
     int m_lockEntry;
     app::Color m_color;
   };