Implement hysteresis for setting monitor brightness

AdaptiveBrightness/main_window.cpp

@@ -19,7 +19,7 @@
 #include "sensor_driver.hpp"
 #include "utils.hpp"
 
-MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent)
+MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent), m_mtx(QMutex::RecursionMode::Recursive)
 {
     qDebug(ltr("Creating main window"));
 
@@ -54,6 +54,8 @@ void MainWindow::closeEvent(QCloseEvent* event)
 
 void MainWindow::enumSensors()
 {
+    m_sensors.clear();
+
     auto sensors = enumerateSensors();
 
     for(auto& sensor: sensors) {
@@ -357,6 +359,12 @@ void MainWindow::updateState()
 
 bool MainWindow::setMonitorBrightness(float& brightness)
 {
+    constexpr auto hysteresis = [](const auto& lowThreshold, const auto& highThreshold, const auto& currentValue, const auto& newValue) {
+        if(newValue > highThreshold || newValue < lowThreshold)
+            return newValue;
+        return currentValue;
+    };
+
     if(m_monitors.empty()) {
         return false;
     }
@@ -365,6 +373,28 @@ bool MainWindow::setMonitorBrightness(float& brightness)
     bool allMonitorsSameBrightness = true;
 
     for(size_t i = 0; i < m_monitors.size(); ++i) {
+        const auto updateMonitorBrightness = [&] {
+            const auto brightnessRange = m_monitors[i].maxBrightness - m_monitors[i].minBrightness;
+            const auto hysteresisDelta = m_monitors[i].manualOverride ? 0.f : m_monitors[i].HYSTERESIS_THRESHOLD * brightnessRange;
+            const auto lowThreshold = std::clamp(m_monitors[i].prevBrightness - hysteresisDelta, m_monitors[i].minBrightness, m_monitors[i].maxBrightness);
+            const auto highThreshold = std::clamp(m_monitors[i].prevBrightness + hysteresisDelta, m_monitors[i].minBrightness, m_monitors[i].maxBrightness);
+            if(hysteresis(lowThreshold, highThreshold, m_monitors[i].prevBrightness, m_monitors[i].brightness) != m_monitors[i].prevBrightness) {
+                qDebug(ltr("Setting monitor %1 brightness from %2 to %3")
+                           .arg(i)
+                           .arg(m_monitors[i].prevBrightness, 0, 'f', 2)
+                           .arg(m_monitors[i].brightness, 0, 'f', 2));
+                m_monitors[i].prevBrightness = m_monitors[i].brightness;
+                return m_monitors[i].driver.setBrightness(m_monitors[i].brightness);
+            }
+            else {
+                qDebug(ltr("Hysteresis prevented setting monitor %1 brightness from %2 to %3")
+                           .arg(i)
+                           .arg(m_monitors[i].prevBrightness, 0, 'f', 2)
+                           .arg(m_monitors[i].brightness, 0, 'f', 2));
+            }
+            return true;
+        };
+
         if(!std::isnan(brightness) && !m_monitors[i].manualOverride) {
             m_monitors[i].brightness = brightness;
         }
@@ -375,7 +405,7 @@ bool MainWindow::setMonitorBrightness(float& brightness)
             allMonitorsSameBrightness = false;
         }
 
-        if(!m_monitors[i].driver.setBrightness(m_monitors[i].brightness)) {
+        if(!updateMonitorBrightness()) {
             errorOccurred = true;
         }
         else if(m_ui.monitorDropdown->currentIndex() == static_cast<int>(i)) {

AdaptiveBrightness/main_window.hpp

@@ -75,10 +75,13 @@ class MainWindow : public QMainWindow {
     };
 
     struct MonitorData {
+        static constexpr auto HYSTERESIS_THRESHOLD = 0.05f;
+
         Monitor driver;
         float minBrightness;
         float maxBrightness;
         float brightness;
+        float prevBrightness;
         bool manualOverride;
     };
 

firmware/README.md

@@ -56,7 +56,7 @@ Found DFU: [0483:df11] ver=2200, devnum=57, cfg=1, intf=0, path="2-13.2.2", alt=
 Found DFU: [0483:df11] ver=2200, devnum=57, cfg=1, intf=0, path="2-13.2.2", alt=0, name="@Internal Flash  /0x08000000/032*0001Kg", serial="FFFFFFFEFFFF"
 ```
 
-The firmware can then be flashing using:
+The firmware can then be flashed using:
 
 ```console
 $ dfu-util -a 0 -s 0x08000000 -D AdaptiveBrightnessFirmware.bin