[GIS] Building a custom, dynamic legend using ArcGis-server js and dynamicMapServiceLayer

arcgis-serverjavascript

I have a dynamicMapServiceLayer that I am using to build a map application. There are about 10 layers in the mapservice that I am toggling using the setVisibleLayers action.

I would like to build my own custom, dynamic map legend. When a layers' visiblity is toggled, the corresponding legend item would also hide() / show()

My mapServer has a url that links to a page with all the corresponding legend items like below except my legend's url has 10 legend items

http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Petroleum/KGS_OilGasFields_Kansas/MapServer/legend

Is there a way I can access the individual legend items (Name and symbol) from a existing mapServer? I am comfortable building the legend, I just need to know how to access the layers' symbols which I will then append to a legend dialog.

I should also mention that I am avoiding using DOJO and using pure javascript and jQuery.

Best Answer

If you access that service via the REST API:

http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Petroleum/KGS_OilGasFields_Kansas/MapServer/legend?f=json&pretty=true

You can get the JSON using jQuery http://api.jquery.com/jQuery.getJSON/ So build the legend yourself from that data you have retrieved.

To add the legend symbols, you can use jQuery to create an img, and insert each legend item's contentType and imageData into the src to render the symbol.

https://stackoverflow.com/questions/5000710/receive-image-data-as-json-and-injecting-it-into-the-dom/5000778#5000778

Make sense?

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[GIS] Selecting/highlighting point feature in ArcGIS Server using JavaScript

Below I have put the code that I have used to display a black crosshair over a point feature in a map. It was quite simple in the end, but the overall implementation is a bit more involved and beyond the scope of this answer - but in essence -

The user clicks on the map and I capture the coordinates.
Coordinates are sent to webservice by XmlHttpRequest and a spatial filter is conducted.
XML recieved from webservice after a successful spatial filter with results is found.
The REAL x and y coordinates are passed back too from the spatial filter.
These real x and y coordinates are used to place the graphic on the map - so it will only show if a successful query has been made - if not the graphic will never show - which is pretty much an emulation of the a select funcitonality.
```
//you must use a unique ID each time you create a graphic
//this is incremented at the end of the drawGraphic function.
var graphicCount = 0; 
var newPoint = new ESRI.ADF.Geometries.Point(456465, 354141);
drawGraphic(newPoint);
```

    function drawGraphic(point) {
        //I am using a png graphic file here to mark a point in a kind of crosshair
        //24x24 pixels big and it looks pretty cool - make sure you have the background
        //transparent or else you won't be able to see underneath the graphic.

        var symbol = new ESRI.ADF.Graphics.MarkerSymbol("blacktarget.png", 12, 12, "");
        var coords = point.toString("<br>", ",");
        var attributes = { "ID": graphicCount, "featureCoordinates": coords };

        graphicFeature = $create(ESRI.ADF.Graphics.GraphicFeature, { "id": graphicCount.toString(), "geometry": point, "symbol": symbol, "attributes": attributes});
        map.addGraphic(graphicFeature);
        graphicCount++;
        }

[GIS] Difference between DynamicMapServiceLayer and TiledMapServiceLayer

What is the difference between DynamicMapServiceLayers and TiledMapServiceLayers?

A dynamic layer generates an image each time the map view changes - panning and zooming, turning sublayers on/off, etc. This image is then served in your map viewer.

A tiled layer is pre-cached on the server, as a series of small images optimised for each zoom level - as you change the zoom level, a different set of image tiles displays. This allows the server to display the information very quickly (as with the background tiles on Google Maps).

Do separate services need to be published to use each type for a single map?

Typically a dataset would be more suited for one format over another (eg a geology layer is probably quite complex and doesn't change very often, therefore it would be suitable for caching) but there's no reason why you couldn't also serve this as a dynamic layer.

You should create a separate non-cached service in this case.

Are both valid types one can use in Esri's FLEX API?

Yep, you can use either type. Note that there is also the option to stream vectors directly to the client as feature layers.

Best Answer

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[GIS] Selecting/highlighting point feature in ArcGIS Server using JavaScript

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