All, 

I think the general idea that Beau is describing is "No white screen"!!  Always 
hate a blank screen when transistioning a map, especially when zooming.  Even 
something wildly pixelated is valuable to the end user to key on reference 
points, it also allows for rapid transitioning without waiting for the final 
rendering of things. 

Using a wheel zoom on this interface would be my example of how zooming should 
work visually: http://gis.ci.stpaul.mn.us/gis/gismo_public/html/, this could 
use possibly more transistion steps as well as better end loop control, as in I 
should be able to pan, while waiting for the new tiles to download and replace 
the previously rescaled tiles.  Right now the user needs to wait for the new 
tiles to display before rezooming or panning.   This interface has been in use 
for a number of years (before OpenLayers even . . .) and is a preferred 
transistion effect.  We've done some smaller implementations of OpenLayers from 
time to time, and the "always on" Map Feature is usually brought up at some 
point as a desirable feature, this is especially important in a emergency 
response/preparedness situation. 

bobb 





>>> Beau Anderson <elb...@gmail.com> wrote:


No, the "resize" behavior is not the same as what I am describing. Using Google 
maps as an example, as you pinch to zoom in/out the raster image tiles resize 
to sized in-between the zoom levels. The "resize" transitionEffect does do a 
raster resize, but only to an actual zoom level. In other words, there is no 
graceful zooming to fractional zoom levels. In order to get an effect similar 
to Google's, you need to not only make the background tiles zoom to fractional 
zoom levels, but the actual foreground tiles themselves need to do the same, 
because if you've pinched to zoom in to a fractional zoom level, you need any 
newly loaded tiles to also be resized appropriately. 



To put it another way, if you're loading tiles whose actual dimensions are 
256X256 pixels, it doesn't mean that you will actually be displaying the image 
at 256X256. The fractional zooming is second-nature for users on iOS and the 
newer versions of Android mobile devices these days. The other benefit you get 
for desktop computer users is that once you have fractional zooming, then even 
if the're doing a zoom to a new zoom level, it's not hard to do an animated 
zoom-in/zoom-out (again, the same way Google does). In the end, OpenLayers is 
AWESOME in it's support for various formats, but there are a couple UI 
paradigms that I really want to tweak before I turn it loose on my user base. 
The thing I HAVEN'T delved into yet is how easy/hard this will be to implement 
on other types of layers so that the whole UI acts appropriately :s 



On Sun, Dec 26, 2010 at 6:13 AM, Tom Hughes <t...@compton.nu> wrote:



On 23 December 2010 17:21, Beau Anderson <elb...@gmail.com> wrote:



I've got an existing successful iPhone application that I'm porting to other 
platforms. There's a lot that I want to add to my app's mapping functionality 
and OpenLayers looks like it would fit the bill great, but the user experience 
is just not as smooth as Google and Bing provide. The headache that I've been 
working on is getting layers that extend from OpenLayers.Grid to act more like 
Google where when you zoom in or out it simply scales the tiles you already 
have loaded then loads new tiles on top of them. To accomplish this we need to 
rethink the way that Grid layers layout their tiles so that there are multiple 
layers of tiles within one Grid (not just foreground and background img's in 
Image.js).
 



Doesn't setting transitionEffect to "resize" on the layer already do that?

Tom

--
Tom Hughes (t...@compton.nu)
http://compton.nu/
  


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