fix(gamma): prevent crash and avoid flooding niri/smithay that is slow af to refresh

src/system/gamma_service.cpp

@@ -15,14 +15,13 @@
 #include <string>
 #include <sys/mman.h>
 #include <unistd.h>
-#include <vector>
 
 namespace {
 
   constexpr Logger kLog("gamma");
 
   constexpr float kTransitionDurationMs = 1500.0f;
-  constexpr int kTransitionIntervalMs = 33;
+  constexpr int kTransitionIntervalMs = 100;
 
   int timeToMinutes(std::string_view hhmm) {
     return (hhmm[0] - '0') * 600 + (hhmm[1] - '0') * 60 + (hhmm[3] - '0') * 10 + (hhmm[4] - '0');
@@ -510,18 +509,25 @@ void GammaService::startTransition(int fromKelvin, int toKelvin) {
   m_transitionFromKelvin = fromKelvin;
   m_targetKelvin = toKelvin;
   m_transitionProgress = 0.0f;
+  m_transitionStart = std::chrono::steady_clock::now();
   m_transitionTimer.startRepeating(std::chrono::milliseconds(kTransitionIntervalMs), [this]() { tickTransition(); });
 }
 
 void GammaService::tickTransition() {
-  m_transitionProgress =
-      std::min(1.0f, m_transitionProgress + static_cast<float>(kTransitionIntervalMs) / kTransitionDurationMs);
+  const auto elapsed = std::chrono::steady_clock::now() - m_transitionStart;
+  m_transitionProgress = std::min(1.0f, static_cast<float>(std::chrono::duration<double, std::milli>(elapsed).count()) /
+                                            kTransitionDurationMs);
   const int interpolated = static_cast<int>(
       std::lerp(static_cast<float>(m_transitionFromKelvin), static_cast<float>(m_targetKelvin), m_transitionProgress));
-  applyGammaToAll(interpolated);
-  m_currentKelvin = interpolated;
+  if (interpolated != m_currentKelvin) {
+    applyGammaToAll(interpolated);
+    m_currentKelvin = interpolated;
+  }
   if (m_transitionProgress >= 1.0f) {
     m_transitionTimer.stop();
+    if (m_currentKelvin != m_targetKelvin) {
+      applyGammaToAll(m_targetKelvin);
+    }
     m_currentKelvin = m_targetKelvin;
     if (m_restoreAfterTransition) {
       restoreAll();

src/system/gamma_service.h

@@ -6,10 +6,10 @@
 #include <chrono>
 #include <cstdint>
 #include <functional>
+#include <list>
 #include <optional>
 #include <string>
 #include <string_view>
-#include <vector>
 
 class IpcService;
 class WaylandConnection;
@@ -102,12 +102,13 @@ private:
   std::optional<double> m_weatherLongitude;
   ChangeCallback m_changeCallback;
 
-  std::vector<OutputGamma> m_outputs;
+  std::list<OutputGamma> m_outputs;
 
   int m_currentKelvin = -1;
   int m_targetKelvin = -1;
   int m_transitionFromKelvin = -1;
   float m_transitionProgress = 0.0f;
+  std::chrono::steady_clock::time_point m_transitionStart{};
   Timer m_transitionTimer;
 
   bool m_restoreAfterTransition = false;