topic Re: Click to download a map tile in ArcGIS JavaScript Maps SDK Questions

Click to download a map tile

MarkLewin — Tue, 19 Aug 2014 13:44:55 GMT

Hi,

I'm building an application where users can click on the map to download a map tile. I can see that the ArcGISTiledMapServiceLayer has a getTileUrl() method, but has anyone got any idea about how I can identify a particular tile beneath a user's map click?

The Silverlight API has a TileLoading event, but I can't find anything similar in the ArcGIS Server API for JavaScript. My idea was to attach a click event handler to each tile as it loads, and then use getTileUrl(coords) to locate the required tile.

What would also be great to do is add a feature layer graticule to identify the individual tiles, but I can't figure out a good way to do this.

I would really appreciate any suggestions.

Thanks,

Mark

Re: Click to download a map tile

TimWitt2 — Tue, 19 Aug 2014 13:53:04 GMT

Mark,

you could use the identify task identifytask-amd | API Reference | ArcGIS API for JavaScript‌

Here is an example: Display identify results in popup | ArcGIS API for JavaScript‌

Hope this helps!

Tim

Re: Click to download a map tile

MarkLewin — Tue, 19 Aug 2014 14:05:05 GMT

Thanks Tim ... but would that help me identify individual map

tiles?

Re: Click to download a map tile

TimWitt2 — Tue, 19 Aug 2014 15:31:54 GMT

I made this fiddle quickly. Here you can click on the map and it returns the tiles for you that you clicked on.

Edit fiddle - JSFiddle‌

In my example a popup appears.

Re: Click to download a map tile

MarkLewin — Tue, 19 Aug 2014 16:51:18 GMT

Thanks Tim, I really appreciate your efforts, but does this

tell me how to access the map tile? I apologize if I'm missing

something.

Basically, I want to be able to click on a tile and see the

individual tile URL.

Mark

Re: Click to download a map tile

TimWitt2 — Tue, 19 Aug 2014 17:07:11 GMT

Mark,

my bad, I missunderstood. Let me see if I can figure this out

Tim

Re: Click to download a map tile

MarkLewin — Tue, 19 Aug 2014 17:11:42 GMT

Thanks Tim - I really appreciate your help!

Re: Click to download a map tile

TimWitt2 — Tue, 19 Aug 2014 17:18:04 GMT

Mark,

just to understand, this would be an example link that you would like to retrieve?

http://server.arcgisonline.com/arcgis/rest/services/World_Imagery/MapServer/tile/0/0/0‌

Tim

Re: Click to download a map tile

MarkLewin — Tue, 19 Aug 2014 17:29:42 GMT

Hi Tim,

Yes! That's just it!

Ideally I'd like to be able to retrieve any features within the

tile space too, but let's start with that.

If there was an event that got fired when a tile loads, I could

use that to hook up a click event handler, but I can't seem to

find any such event, so I'm at a loss.

Thank you.

Mark

Re: Click to download a map tile

JohnGrayson — Tue, 19 Aug 2014 18:46:53 GMT

Mark, I could be wrong, but I believe the issue you'll find with this use case is that the dom nodes used for the tiled service are below all graphics layers, so normal events will not be raised for them. One possible solution is to compare the 'map click location' with the coordinates of all the dom nodes of the tiled layer. Probably not the most elegant of solutions, but it seems to work:

Edit fiddle - JSFiddle‌

Re: Click to download a map tile

MarkLewin — Tue, 19 Aug 2014 18:52:17 GMT

That's fantastic John! Just what I needed. Thank you very much. And thanks to Tim for his offers of assistance too.

Mark