Improve default map view (projection and tile weirdness at small zooms)

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Start Vespucci after not using it for a while

What is the expected output? What do you see instead?

I would expect a map of near to where I currently or where I last edited. 
Instead I'm given a very low zoom map centred on 0,0. If I drag the map down 
with my finger, it hits the point that it vertically tries to stretch the map. 
I would expect a zoom of close by my area so that I don't have to hit the zoom 
in button about 15 times before I can decide to download some data to be able 
to start editing.

What version of the product are you using? On what operating system?
0.8.0r380.

Please provide any additional information below.

Original issue reported on code.google.com by shaunmcd...@gmail.com on 1 Oct 2012 at 3:57

[GoogleCodeExporter]

Original comment by Marcus.W...@gmail.com on 2 Oct 2012 at 8:27

• Added labels: Type-Enhancement, Component-UI
• Removed labels: Type-Defect

[GoogleCodeExporter]

This is partly a defect and partly an enhancement issue. 

If loading saved data failed (for example due to a version change or a 
corrupted file) this went unnoticed in the code, causing undeterminate 
behaviour instead of showing the bounding box picker, further there was likely 
a race condition between loading the data and determining the bounding box. 
I'll be commiting fixes to these two issues shortly.

The above should greatly reduce the number of times that you get a zoomed out 
map instead of the bounding box picker, in any case you can select "Download 
other location" to get it.

What currently is still painful is being thrown back to a fully zoomed out map 
when you haven't downloaded any data, this should be limited to the normal 
minimum zoom possible and centered somewhere "reasonable".

Original comment by sp8...@gmail.com on 28 Jul 2013 at 10:40

• Changed state: Started
• Added labels: Type-Defect
• Removed labels: Type-Enhancement

[GoogleCodeExporter]

I've done some further work on this, including trying to get a handle on the 
projection weirdness. For the later the reason for the projection problems is 
clear (using an approximation for the projection based on projecting the 
mid-screen coordinates, which naturally doesn't work if zoomed out to any 
larger region). I haven't been able (yet) to get the solution (using non-approx 
projection) to work at all zoom levels. In any case the last commits fix some 
bugs and make the code more robust. 

Original comment by sp8...@gmail.com on 24 Aug 2013 at 3:59

[GoogleCodeExporter]

Original comment by sp8...@gmail.com on 15 Dec 2013 at 12:01

[GoogleCodeExporter]

I've done some more work on this and related issues:

a) fix issue that the WGS84 coordinates in the bounding box did not match with 
the region on the screen display (fixing this breaks the approx. projection 
code, if somebody knows how this is supposed to work (mathematically), please 
comment). This on the one hand allows non-approx projection code to work and 
fixes the issue of not being able to pan up to the maximum latitude.
b) use non-approx projection for tile placement, this fixes the "stretching" 
tiles issue, further improvements to the tile placement code
c) use non-approx projection code for drawing and input, this is likely to 
result in a performance hit (subjectively I've not noticed anything on real 
devices, but it is difficult to do a direct comparison), so it would be nice if 
the approx. projecting code could be revived (see a))   

Original comment by sp8...@gmail.com on 30 Jan 2014 at 11:46

• Changed title: Improve default map view (projection and tile weirdness at small zooms)

[GoogleCodeExporter]

http://code.google.com/p/osmeditor4android/source/detail?r=682

Original comment by sp8...@gmail.com on 23 Feb 2014 at 9:51

• Changed state: Fixed