PanZoomBar doesn't handle forceFixedZoomLevel correct

[patzi]

When setting up a map with fractionalZoom: true and a PanZoomBar control with forceFixedZoomLevel: true there seems to be a bug in the implementation. If you start at a fixed zoom level and use the zoombar slider you will get a fixed zoom level back (i.e. start from 2 move up 3 get 5). But if you start with a non fixed zoom level you will get a non fixed back (i.e. start from 2.345 move up 3 get 5.345). Maybe this is the way somebody wanted it to be, but for me it feels a bit broken. Also there is an error when you move the slider to the bottom of the bar. Then it returns a negative zoom level and can not zoom to it. In the attached patch I fixed both issues so that you will get back a fixed level and 0 as the minimum zoom level.

[bartvde]

I think these changes make sense, also adding Marc Jansen to the cc since he originally came up with forceFixedZoomLevel IIRC.

@patzi: do we have a CLA from you already?

[marcjansen]

I could reproduce the reported behaviour and do think that this is a bug in the original implementation of the forceFixedZoomLevel.

As the original patch by patzi did not include tests, I added a new one (attachment:OpenLayers-2725-001.patch ) with tests.

In any case, thanks for your contribution, patzi.

Thanks for any review of the patch.

[bartvde]

in w r11229

Thanks to both of you for your work!