[OpenLayers-Users] Zoomify and fractional zoom

[David Régade]

I tried this solution too and it didn't work. I had a look to this example:

http://openlayers.org/dev/examples/fractional-zoom.html

In this example tile size is allways 256x256 whatever the zoom level. But with 
zoomify it can't be allways 256x256 because tiles have to be streched or 
shrinked according to zoom level. zoomify relies on direct tile image url , not 
a mapserver like the example above. These direct images urls have fixed 
dimensions and represent allways the same "world region".
That's why I can't figure out fractionalZoom can work with Zoomify layer if the 
displayed tile have allways the same size.

A solution could be to setup the integer zoom for the layer and scale the layer 
(like transformDiv() does) to obtain the good result.

Regards
David

On 27/06/2012 12:12, Andreas Hocevar wrote:
> I see. So maybe you need to leave the original z assignement as-is
> (without Math.round or Math.floor), and only change the lines that say
>
> this.tierSizeInTiles[z]
>
> to something like
>
> this.tierSizeInTiles[z|0]
>
> (z|0 being a more efficient way of saying Math.floor(z)).
>
> Andreas.
>
> On Wed, Jun 27, 2012 at 12:04 PM, David Régade<dregade at viewsurf.com>  wrote:
>> I tried Math.floor and the problem is the same. I'm not sure the problem
>> comes from Math.round/floor because with my example, for an integer zoom
>> value (3 for example), top left displayed tile is 256px width (thanks
>> firebug). For a 3.4 zoom value should the top left tile image width be
>> greater than 256px ?
>>
>> So if the displayed tile images are 256px for 3.4 zoom level, you need more
>> tile to cover the layer extent in resolution associated to this zoom level.
>> That's why on my axample, when you click on the button the displayed tile
>> images are not centered as is it should be and another image tile (that
>> doesn't exist) is required and tried to be drawn. Am I wrong ?
>>
>> Here is a screenshot of what I observed:
>> http://david.regade.free.fr/openlayers/z3.4.jpg
>>
>> Regards
>> David
>>
>>
>> On 27/06/2012 11:41, Andreas Hocevar wrote:
>>>
>>> Try Math.floor instead of Math.round - currently the client zoom
>>> implementation only supports oversampling, so you need the next
>>> smallest zoom level.
>>>
>>> Andreas.
>>>
>>> On Wed, Jun 27, 2012 at 10:51 AM, David Régade<dregade at viewsurf.com>
>>>   wrote:
>>>>
>>>> Hi,
>>>>
>>>> It can't be so easy. I fixed line 225 with:
>>>>              var z = Math.round(this.map.getZoom());
>>>>
>>>> And another bug appeared line 201, same fix:
>>>>              var z = Math.round(this.map.getZoom());
>>>>
>>>> However on this example, http://david.regade.free.fr/openlayers/, setting
>>>> zoom to 3.4 doesn't generate javascript errors anymore but the result
>>>> isn't
>>>> correct. A tile is tried to be drawn and it shouldn't.
>>>>
>>>> I tried to trace where and why this tile is drawn but I'm to new to
>>>> openlayers to find where the problem comes from.
>>>>
>>>> Regards
>>>> David
>>>>
>>>> On 27/06/2012 08:05, Andreas Hocevar wrote:
>>>>>
>>>>>
>>>>> I just see that there is a bug in Zoomify.js, line 225:
>>>>>
>>>>>              var z = this.map.getZoom();
>>>>>
>>>>> We need the integer of getZoom() here instead.
>>>>>
>>>>> Maybe you want to send a pull request with a fix?
>>>>>
>>>>> Andreas.
>>>>>
>>>>> On Tue, Jun 26, 2012 at 11:33 PM, David Régade<dregade at viewsurf.com>
>>>>>   wrote:
>>>>>>
>>>>>>
>>>>>> I get the last OpenLayers master and this feature doesn't work with the
>>>>>> following example:
>>>>>>
>>>>>> http://david.regade.free.fr/openlayers/
>>>>>>
>>>>>> Is there something I'm doing wrong ?
>>>>>>
>>>>>> When setting up a fractional zoom (by clicking on the button for
>>>>>> example)
>>>>>> Firebug catches an error.
>>>>>> Layer is resized but the tiles are not set correctly.
>>>>>>
>>>>>> David
>>>>>>
>>>>>>
>>>>>> On 26/06/2012 16:32, Andreas Hocevar wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> This is supported in OpenLayers master and the upcoming 2.12 release.
>>>>>>>
>>>>>>> Andreas.
>>>>>>>
>>>>>>> On Tue, Jun 26, 2012 at 3:12 PM, David Régade<dregade at viewsurf.com>
>>>>>>>   wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>> We use openlayers to display large panoramas. We use ZoomifyImage to
>>>>>>>> split
>>>>>>>> original image in tiles and Zoomify layer to display these tiles.
>>>>>>>> I would like to use fractionalZoom with Zoomify layer but this layer
>>>>>>>> doesn't
>>>>>>>> support this feature. The main goal is to able to resize displayed
>>>>>>>> tiles
>>>>>>>> for
>>>>>>>> zoom level 3 from 2.5 to 3.4.
>>>>>>>>
>>>>>>>> Does anyone knows how to do that ?
>>>>>>>>
>>>>>>>> Thanks in advance
>>>>>>>> --
>>>>>>>> David REGADE
>>>>>>>> _______________________________________________
>>>>>>>> Users mailing list
>>>>>>>> Users at lists.osgeo.org
>>>>>>>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> _______________________________________________
>>>>>> Users mailing list
>>>>>> Users at lists.osgeo.org
>>>>>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>>
>>
>
>
>