Opened 12 years ago

Closed 12 years ago

#720 closed enhancement (fixed)

about draw.rawgps.max-line-length cost of computation

Reported by: anonymous Owned by: framm
Priority: minor Milestone:
Component: Core Version: latest
Keywords: Cc:


At the moment you (re-)compute the distance fairly oftern, if I understand it correctly. However, if the assumption "if a has a previous, that will never change" is true, you could cache the result of the computation in e.g.
19 public int cachedDistance = -1;

323 if (maxLineLength > -1) {
324 if (trkPnt.cachedDistance <= -1)
325 trkPnt.cachedDistance = trkPnt.latlon.distance(oldWp.latlon);
326 if (trkPnt.cachedDistance > maxLineLength) continue;
327 }

Attachments (2)

patch.diff (9.0 KB) - added by Henry Loenwind 12 years ago.
patch.2.diff (9.0 KB) - added by Henry Loenwind 12 years ago.
Patch v2

Download all attachments as: .zip

Change History (8)

comment:1 Changed 12 years ago by framm

I think that the assumption may be broken by loading new GPX data (which might just be sorted in between the existing data, I'm not sure) but in that case one could clear the cache on loading.

comment:2 Changed 12 years ago by ramack

I don't think that data will be sorted in between atm. But updating the distance cache should be easy on inserting new data.

comment:3 Changed 12 years ago by Henry Loenwind

Owner: changed from framm to Henry Loenwind

I thought on storing a flag about the validity of the data in the layer instead in the points. So it can easily be cleared when loading data or merging layers. I think, I'll separate the compute-loop from the draw-loop, too. That may save some ifs in the draw loop.

Changed 12 years ago by Henry Loenwind

Attachment: patch.diff added

comment:4 Changed 12 years ago by Henry Loenwind

Owner: changed from Henry Loenwind to framm

ok, here's the patch.

I added 2 new configuration values (einstein mode only for now):

Set to "true" to have arrows drawn with less math. They will be off by up to 22.5°, but MAY be rendered faster. On my machine the effect was not really noticeable.

Set to "true" to have lines rendered as 2 lines, like the arrow lines, but over the whole length of the line. Does not look really nice, but on my machine this renders more than 10 times faster than straight lines!

Changed 12 years ago by Henry Loenwind

Attachment: patch.2.diff added

Patch v2

comment:5 Changed 12 years ago by Henry Loenwind

a minor update for the patch, no need to paint the arrows if the line was ommited because it would have had 0-length

comment:6 Changed 12 years ago by ramack

Resolution: fixed
Status: newclosed

patch from #966 applied in [721]

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