[OpenLayers-Users] Zoomify and fractional zoom

[Andreas Hocevar]

To achieve this, it should be enough to configure your layer's
serverResolutions with the same array that you have set for
resolutions.

Andreas.

On Wed, Jun 27, 2012 at 2:46 PM, David Régade <dregade at viewsurf.com> wrote:
> 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
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>>
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-- 
Andreas Hocevar
OpenGeo - http://opengeo.org/
Expert service straight from the developers.