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). -- "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
