topic zoom slider bar in ArcGIS JavaScript Maps SDK Questions

zoom slider bar

JulieRecker — Thu, 12 May 2011 18:05:17 GMT

hi,
newbie question here: i have a map viewer with a zoom slider bar (the default one) in the top left. problem is, the initial extent - which i define in my map constructor:

map = new esri.Map("map", { extent:initialExtent, logo:false});

the problem is the default view is halfway up the zoom bar (which only leaves around 3 tics until it is maxed out. what i would like is the default view to be at the bottom of the zoom slider so the user has several tics to zoom in further. in other words, so the user can only zoom in, not zoom out past my initial extent.

how would i do this?

thanks!

Re: zoom slider bar

HemingZhu — Thu, 12 May 2011 18:13:27 GMT

hi,
newbie question here: i have a map viewer with a zoom slider bar (the default one) in the top left. problem is, the initial extent - which i define in my map constructor:

map = new esri.Map("map", { extent:initialExtent, logo:false});

the problem is the default view is halfway up the zoom bar (which only leaves around 3 tics until it is maxed out. what i would like is the default view to be at the bottom of the zoom slider so the user has several tics to zoom in further. in other words, so the user can only zoom in, not zoom out past my initial extent.

how would i do this?

thanks!

Use the map option lods to specify the zoom level. like the following:
var lods = [
            {
              "level": 13,
              "resolution": 19.1092570712683,
              "scale": 72223.819286
            },
            {
              "level": 14,
              "resolution": 9.55462853563415,
              "scale": 36111.909643
            },
            {
              "level": 15,
              "resolution": 4.77731426794937,
              "scale": 18055.954822
            },
            {
              "level": 16,
              "resolution": 2.38865713397468,
              "scale": 9027.977411
            },
            {
              "level": 17,
              "resolution": 1.19432856685505,
              "scale": 4513.988705
            },
            {
              "level": 18,
              "resolution": 0.597164283559817,
              "scale": 2256.994353
            },
            {
              "level": 19,
              "resolution": 0.298582141647617,
              "scale": 1128.497176
            }
            ];
         ....
        map = new esri.Map("map", { extent: initialExtent, logo: false, slider: true, lods: lods });

Re: zoom slider bar

JulieRecker — Thu, 12 May 2011 19:15:36 GMT

thanks for your reply. i added the lods as suggested, and i'm seeing no change. for the map, i am loading first a dynamic layer, then 3 tiled layers. i used levels 0-6 of the tiled layers (all three had the same resolution and scale for each level id)

could it be since i'm defining my initial extent, and then using the dynamic layer as my first layer, it is ignoring lods?

thanks for the help

Re: zoom slider bar

HemingZhu — Thu, 12 May 2011 20:24:21 GMT

thanks for your reply. i added the lods as suggested, and i'm seeing no change. for the map, i am loading first a dynamic layer, then 3 tiled layers. i used levels 0-6 of the tiled layers (all three had the same resolution and scale for each level id)

could it be since i'm defining my initial extent, and then using the dynamic layer as my first layer, it is ignoring lods?

thanks for the help

First lods only apply for tiled map. The sample code i am using is for ESRI base map/google/bing tile scale level, you have to look into your serivce directory to set your lods. initial extent has not impact on scacle level once your specify map lods option. My sample worked on my project, i had esri base map as my first layer, so i guess lods is honored. Since i do not have a dynamic layer as my first layer, i am not sure if that is the cause but it is worth testing.

Re: zoom slider bar

JulieRecker — Fri, 13 May 2011 13:36:07 GMT

yep, after some more testing, i needed to add more levels than i did, and some of my json input had syntax errors, but now it works great. thanks for your help, you saved me hours of coding frustration!