Basic Brightness control.

power_console.fluid

@@ -50,5 +50,10 @@ Function {make_window()} {open
       label AC
       xywh {129 49 34 24} type Normal box PLASTIC_ROUND_DOWN_BOX when 0
     }
+    Fl_Slider brightness {
+      label Brightness
+      callback adjustBrightness selected
+      xywh {129 81 20 52} labelsize 12
+    }
   }
 }

power_console_main.cc

@@ -77,6 +77,18 @@ scheduledUpdate( void * )
 	acButton->value( ac );
 	if( C::debugUpdate ) std::cerr << "AC state read as: " << ac << std::endl;
 
+
+	std::ifstream i_max{ "/sys/class/backlight/intel_backlight/max_brightness" };
+
+	int max;
+	i_max >> max;
+
+
+	std::ifstream inf{ "/sys/class/backlight/intel_backlight/brightness" };
+	int in;
+	inf >> in;
+
+	brightness->value( 101 - 100 * in / max );
 }
 
 // Since this requires launching bg processes, we only do it at startup and then every 30s.
@@ -103,6 +115,10 @@ main( const int argcnt, char **argvec )
 	level->value( 0 );
 	level->label( battLevelString.c_str() );
 
+	brightness->minimum( 1 );
+	brightness->maximum( 100 );
+	brightness->step( 1 );
+
 
 	w->hotspot( w );
 	w->show( argcnt, argvec );
@@ -155,3 +171,41 @@ perfChosen()
 {
 	setPowerMode( "performance" );
 }
+
+namespace
+{
+	void
+	changeBrightness( int pct )
+	{
+		std::ifstream i_max{ "/sys/class/backlight/intel_backlight/max_brightness" };
+
+		int max;
+		i_max >> max;
+
+		int adj= max * pct / 100;
+		std::cerr << "Adjustment computed: " << adj << std::endl;
+
+		std::ofstream out{ "/sys/class/backlight/intel_backlight/brightness" };
+		out << adj;
+	}
+
+	void
+	increaseBrightness( int pct )
+	{
+		changeBrightness( pct );
+	}
+
+	void
+	decreaseBrightness( int pct )
+	{
+		changeBrightness( -pct );
+	}
+}
+
+void
+adjustBrightness( Fl_Slider *, void * )
+{
+	const int amount= 101 - brightness->value();
+	std::cerr << "Adjusting brightness by " << amount << std::endl;
+	changeBrightness( amount );
+}