On Fri, May 21, 2010 at 2:09 AM, Joshua Judson Rosen <[email protected]> wrote: > John Stowers <[email protected]> writes: >> >> > The only issues that I see right now that don't even have work-arounds >> > are that there's no way for to communicate `overzoom bounds' down to >> > osm_gps_map_render_missing_tile() or any of the logic underneath it, >> > and that there actually is no tile-scaling functionality except in the >> > handler for *missing* tiles; if we're to replace FoxtrotGPS' map-drawing >> > code with osm-gps-map, I'd need some sort of `tile zoom' knob to replace >> > the one that we have integrated into our current tile-loader/-renderer. >> >> Im not sure I understand you here. Could you please explain furthur. >> >> Are you referring to how osm-gps-map first upscales the low res tile >> while it waits for the high res one to arrive? > > Yes--there's no way for me to specify limits on the upscaling. > I'm not sure how much I should be concerned with the upper limit > (tangoGPS used a hard-coded limit of 3; Stefan Fröbe has raised it > to 5 in his geocaching patchset), but there are times when we want > to set a *lower* limit on upscaling--because we don't actually always > want to use higher-res tiles. In particular, the pixel-densities of > some of the phone/tablet screens are so much higher (3x!) than typical > desktop resolutions (which the map-renderers target) that we basically > need to upscale just to make a lot of the details (lines, text, icons) > scrutable by the naked eye at a reasonable distance. > > The FreeRunner's screen is ~300 px/inch, so text and icons that are > perfectly legible at 96 px/inch can be extremely difficult to read > from more than about a foot (~30 cm) away, which is absolutely > necessary when driving--as is being to see things at a glance > rather than with intentful scrutiny. :) > > Nokia's N-series tablets are somewhat lower-density (~200 px/inch?), > but presumably still high enough to cause issues. > > The same issue actually still manifests with lower-density displays > like most laptops (though mine's still ~145 px/inch...), just at > greater distances. > > Some other aspects were described on the openmoko community list > <http://article.gmane.org/gmane.comp.handhelds.openmoko.community/55877>: > > So, when you select `fewer, bigger details', the code just decreases > *pixel-density* and a `zoom-level offset' adjusted accordingly. > The map remains at the same zoom-level; but the text and icons get > bigger, the streets and other lines get wider; the amount of > visual `clutter' decreases, and information-clarity goes up. > > If you select `more, smaller details', the pixel-density is increased > and the zoom-offset adjusted in the other direction. Again, the map > remains at the same zoom-level; but the text and icons get smaller, > the streets and other lines become thinner; the amount of information > visible at a given zoom-level (the information-density) increases. > > > If you want to see what I mean, I merged the back-end code into FoxtrotGPS's > trunk at revid [email protected], and the > UI was merged at [email protected] > (about 2 weeks ago).
Ahh OK, I see now, this (and in particular your previous mail on openmoko list) has cleared things up. Very interesting, and I will be sure to take a look next week. John > > -- > "Don't be afraid to ask (λf.((λx.xx) (λr.f(rr))))." > _______________________________________________ > This message is sent to you from [email protected] mailing list. > Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your > subscription > For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS > _______________________________________________ This message is sent to you from [email protected] mailing list. Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your subscription For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
