Possible improvements on the Statistics graphs/plots of recorded tracks

[NiaJ3oE2LM]

Is your feature request related to a problem? Please describe.

The value of pace is difficult to read precisely from the graph as the y-axis limits are way to far from the average:

• it's not possible to zoom in the y-axis direction
• it's not possible to hide other signals (for example: elevation)

The green/blue color legend assigned to Elevation and Speed/pace is barely distinguishable with a light theme and eye protection (night filter) on.

Describe the solution you'd like

Plots of Elevation & pace from recorded tracks - either by time or by distance - could be improved in the following way:

• allow scaling and limit setting of the y-axis for better visualization
• make use of a dual y-axis for decoupling the scale of the two signals: for example you could plot the elevation on the left-hand y-axis and the pace on the right-hand y-axis, still using the same x-axis (time or distance)
• click on the legend entry toggle hide/show of the associated signal. A user may want to hide a signal if it does not display relevant information.
• would be super nice to have a light low-pass noise filter on speed/pace raw data.

Additional context

May be related to:

• Charts: allow to hide elevation #1297
• Something (scale?) wrong with elevation graphs #1241
• Hairline for graphs #1596
• Allow rounding elevation scale domain #795

App version v4.16.1 installed from f-droid on android 10 and used for tracking running sessions.

[dennisguse]

Any improvement of the diagrams would be nice.
Currently, no library is used (aka everything implemented in OpenTracks).