Audio: Change how volume works

Across the entire audio system, audio now works in 0-1 terms instead of
0-100 as before. Therefore, volume is now a double instead of an int.
The master volume of the AudioServer changes smoothly through a
FadingProperty, preventing clicks. Finally, volume computations are done
with logarithmic scaling, which is more natural for the human ear.

Note that this could be 4-5 different commits, but as they change each
other's code all the time, it makes no sense to split them up.

1 files changed, 9 insertions, 10 deletions

diff --git a/Userland/Applets/Audio/main.cpp b/Userland/Applets/Audio/main.cpp
index be6247078f..0e1e736942 100644
--- a/Userland/Applets/Audio/main.cpp
+++ b/Userland/Applets/Audio/main.cpp
@@ -38,8 +38,8 @@ public:
             update();
         };
 
-        m_audio_client->on_main_mix_volume_change = [this](int volume) {
-            m_audio_volume = volume;
+        m_audio_client->on_main_mix_volume_change = [this](double volume) {
+            m_audio_volume = static_cast<int>(volume * 100);
             if (!m_audio_muted)
                 update();
         };
@@ -87,14 +87,14 @@ public:
         };
 
         m_slider = m_root_container->add<GUI::VerticalSlider>();
-        m_slider->set_max(20);
-        int non_log_volume = sqrt(100 * m_audio_volume);
-        m_slider->set_value(-(non_log_volume / 5.0f) + 20);
+        m_slider->set_max(100);
+        m_slider->set_page_step(5);
+        m_slider->set_step(5);
+        m_slider->set_value(m_slider->max() - m_audio_volume);
         m_slider->set_knob_size_mode(GUI::Slider::KnobSizeMode::Proportional);
         m_slider->on_change = [&](int value) {
-            int volume = clamp((20 - value) * 5, 0, 100);
-            double volume_log = ((volume / 100.0) * (volume / 100.0)) * 100.0;
-            m_audio_client->set_main_mix_volume(static_cast<i32>(volume_log));
+            double volume = clamp(static_cast<double>(m_slider->max() - value) / m_slider->max(), 0.0, 1.0);
+            m_audio_client->set_main_mix_volume(volume);
             update();
         };
 
@@ -131,8 +131,7 @@ private:
     {
         if (m_audio_muted)
             return;
-        int new_slider_value = m_slider->value() + event.wheel_delta() / 4;
-        m_slider->set_value(new_slider_value);
+        m_slider->dispatch_event(event);
         update();
     }