Interactive zoom & strange pixel sizes in tile scheme

[ismyrnow]

Interactive zoom (with mouse scroll wheel) fails to pick the correct zoom level when using a tiling scheme with inconsistent zoom factors between levels.

See http://jsfiddle.net/ismyrnow/R8BSj/ :

• When zooming in from 0 to 1, interactive zoom jumps to 2, but explicit zoom works fine.
• When zooming in from 11 to 12, interactive zoom also won't zoom, but explicit zoom works fine.

[ryanttb]

I need to retest this with the latest code that has the new zoomFactor option in geomap. Although, currently zoomFactor is a init-only read-only option.

[ryanttb]

With the new zoomFactor option, I can get a smooth interactive zoom between 0, 1, 2, & 3 by setting a lower than default zoomFactor, but then the map won't zoom further than 3 (similar to 11 to 12 previously) because the factor changes too much between zoom levels.

One way to handle a situation like this is to allow zoomFactor to be set to null or NaN or something to tell double click zoom to use the factor between current & next levels but also tell and wheel zoom to use the smoother/partial version (like touch zoom) instead of full zoomFactor + zoomLevel based zooming.