problem with the trip altitude

Hello. There seems to be a problem with the trip altitude display of the activity across the day. There is no problem with the display of trip speed.

Hi @ikuhiromorita!

Yeah that is rather broken looking. I suspect it’ll be due to the phone providing some incredibly wrong altitude data while going through a tunnel. Though I don’t know why it’s broken the graph. The graph does filter the data before using it, so it shouldn’t be messed up by bad data. But… there it is!

One of the next major Arc updates is going to be focused on a complete rebuild of all the graphs in the app. Apple’s new Swift Charts allows for building attractive and readable charts really easily, unlike the current charts framework I’m using, which is powerful but old and clunky and easy to upset.

The catch will be the new charts will require iOS 16, due to Swift Charts being introduced with iOS 16. So I’m holding off on doing that big update until iOS 16 has enough market share. Thankfully people tend to update iOS quite quickly, so that shouldn’t be too far away.

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The altitude data is probably correct. We did not go through the tunnel, and we actually crossed the pass at about 22:13.
The problem is that the horizontal axis of the Trip Altitude graph starts at 0:00, and the data line was redrawn from the left edge at the time of the date change.

This is one of those weird date time issues caused by travel overlapping into the next day, the line is correct, but there’s no good way to show the data

Though it does look like trip speed is done correctly so idk is Matt has a way to fix this?

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It’ll be possible to fix it. It’ll just be some quirk on the old charts framework I’m using, where data of a certain shape upsets it and makes it act strangely.

But rather than fix the old system it’ll be better to just replace it wholesale, with the new Swift Charts based system. I’ll probably start working on that in the next week or two, on the assumption that iOS 16 uptake has been high enough already.