I'd like to introduce the tiling engine based on Dojo Toolkit.

It is designed to present arbitrary tiled content and could be a separate
project under dojox.

At the moment I envisage 3 use cases for the tiling engine:
1) geographical web-maps (right now bitmap based and in the future vector
based)
2) tiled 360 degrees panoramas
3) high resolution tiled photos

At the moment the tiling engine is based on dojox.mobile.Scrollable and
resides in the github repo https://github.com/vvoovv/tiles

You might take look at the small demo
http://vvoovv.github.com/dojox/tiles/tests/tiles.html. Bitmap tiles are
taken from OpenStreetMap.org, red large numbers display a tile number. Double
click to zoom in, "-"button at the top of the page to zoom out.

Here I'd like to request an advice.

I'd like to achieve smooth transition between zoom levels (like in
http://maps.google.com).
I am going to employ 2 means for that:
1) preload images in the background during transition between zoom levels;
when they are downloaded, instantly display them
2) CSS3 scaling

Here how it would work. There are 2 divs. The first one (div1) is used to
display the current zoom level (zoom1). The other one (div2) is used to
display a different zoom level (zoom2) a user might request. display:none
is set for div2.

Suppose the user requests a different zoom level via GUI.
* div2 is brought in front of div1 and made visible
* Preloading of images for zoom2 is started in the background.
* Animation between CSS transforms scale1 and scale2 is played for the div1
* When any image for zoom2 is downloaded, it is displayed in the div2
* When all images for zoom2 are downloaded and displayed, div1 is cleaned
and made invisible

Could you provide a code snippet for images preloading? Are there
pitfalls? Is there anything in Dojo for that task?

I'd highly appreciate other suggestions and comments.

Thanks,
Vladimir
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postedDec 19, '11 at 9:37a
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Vladimir Elistratov: 1 post

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