Use Exponential Moving Average (EMA) to achieve this. The way it works
is to take the previous values in consideration by giving more weight to
the more recent ones. This makes the level bar appear more smooth and
less jittery.
We met an Input Device level_bar display issue on a machine which has
no internal mic. At first there is no external mic plugged, so the
Input Device list is empty and level_bar is gray color, after we plug
an external mic, the level_bar has red color ripples, then we unplug
the external mic, the Input Device list changes to empty and we
expect the level_bar changes back to gray color, but some bars are
still red color.
Here clear the self->value to 0 if the stream is empty, then the
level_bar will change back to gray color when Input/Output device
list is empty.
Signed-off-by: Hui Wang <hui.wang@canonical.com>
The current code does not differenciate between input and
output, and thus it shows the same icon for muting outputs
and inputs. As per design suggesion [1], the input row
should use the "microphone-sensitivity-muted-symbolic" icon.
In order to achieve that, move the CcLevelBarStreamType enum
to a separate header, and rename it to CcStreamType. And also
pass the stream type to the volume slider.
In CcVolumeSlider, update the code to switch to the correct
mute icon depending on the stream type.
[1] https://gitlab.gnome.org/GNOME/gnome-control-center/issues/539
Fixes https://gitlab.gnome.org/GNOME/gnome-control-center/issues/539
