Clear all stored trend values when changing active trend.

[eidekrist]

Fixes #175 by removing all stored trend data when navigating to/from a plot.

If the user is looking at a lot of trend data (long time span, many variables etc), the whole application can slow down. By navigating away from the plot the application will become snappy again.

Consequence: When navigating to a plot, it can take 3-4 seconds before any data appears. Before the fix, old data was shown in the mean time. Update; I have created a little shortcut such that when navigating to a plot, the initial data is generated much faster than before.

[ljamt]

Clearing data for the inactive plots really made a difference 👍
Fix looks good.
Tested with CI artifact.

[cesarcarc]

Nice improvement! Now, the application becomes more responsive when not in the trend view. Whenever entering the trend view, we first see the empty plot for a few seconds (here, time will vary depending on how many variables and which time span is selected).

[cesarcarc]

I believe I might have found a small issue:

Setup:
House configuration loaded
2 plots configured:

• Plot 1 (only one signal, clock.clock), time span; 10s
• Plot 2 (3 signals, OuterWall1.h_wall, Room1.T_room, Room2.T_room): time span: 20m

Action 1:

• Navigate to plot 2 (ws messages around 6.5MB), click on timespan 20m
• Navigate to plot 1

Result 1:

• (ws messages around 4.3MB)

Action 2:

• Navigate to clock model (WS messages drop to 19kb)
• Navigate back to plot 1

Result 2:

• (ws messages around 19kb)

It seems that when switching from Plot2 to Plot1, the timespan of plot 2 is retained.

[cesarcarc]

See comment above.

[eidekrist]

It seems that when switching from Plot2 to Plot1, the timespan of plot 2 is retained.

I can't reproduce this.

[cesarcarc]

As discussed over teams, I have checked your last commit.

It seems the issue I have reported is now fixed. Nice!