topic Snappingmanager does not work. is map._getFrameWidth() the problem? in ArcGIS JavaScript Maps SDK Questions

Snappingmanager does not work. is map._getFrameWidth() the problem?

JoëlHempenius1 — Wed, 03 Sep 2014 15:37:17 GMT

I'm working on a webapplication which requires snapping on some layers. I've enabled snapping using these lines of code:

var map = this.app.map;

this.snappingManager = map.enableSnapping({

alwaysSnap: true,

snapPointSymbol: esri.symbol.SimpleMarkerSymbol(),

tolerance: t,//t is a parameter in the complete function

snapKey: dojo.keys.copyKey

});

But when I try to snap to my layers, it does not work. I tried to debug my code and saw some behaviour which seems strange in the SnappingManager.js code from the javascript api

When the Snappingmanager is in the _getSnappingPoint function, the following code is executed:

n = this.map._getFrameWidth(); variable n is used in this function in various places

In my case n has the value undefined and I think therefore the other parts of the function fail.

I had a closer look at the _getFrameWidth function which gives an undefined

_getFrameWidth: function() {

var a = -1, b = this.spatialReference._getInfo();

this.__LOD ? (b = this.__LOD._frameInfo) && (a = b[3]) : b && (a = Math.round(2 * b.valid[1] / (this.extent.getWidth() / this.width)));

return a

In the first line of code I get a null for this.spatialReference._getInfo(); because my map is in WKID 28992

However the map has a .__LOD, so the function will try to use this in the tenary operaion and assign the _frameInfo from the LOD to b and then tries to get a value from this array. However my array is empty, because my __LOD looks like this: "{"scale":1216.7116413886708,"_frameInfo":[]}"

I compared my map to one of the examples from Esri and in this map the __LOD looks like this:

{"level":17,"resolution":1.1943285668550503,"scale":4513.988705,"startTileRow":214,"startTileCol":0,"endTileRow":130857,"endTileCol":131071,"_frameInfo":[131072,0,131071,33554432]}

And snapping works fine when I added a snapping manager from the Chrome Console into the example

Re: Snappingmanager does not work. is map._getFrameWidth() the problem?

KellyHutchins — Wed, 03 Sep 2014 20:04:44 GMT

I put together a quick test case and was not able to reproduce the problem. Here's the test case:

Edit fiddle - JSFiddle

Can you modify this test case to show the problem you are experiencing?

Re: Snappingmanager does not work. is map._getFrameWidth() the problem?

JoëlHempenius1 — Thu, 04 Sep 2014 10:37:25 GMT

Thanks for the test case. I could not reproduce the problem there, but I noticed the __LOD property of my modified test case did not change from undefined to something else (which is the case in my project).

I did some more debugging today to find out why my __LOD property changes and I could trace the source of this bug in Geocortex HTML5 essentials viewer 2.2.1 . Compared to the previous version they added these lines of code:

var b = function() {

x = a.app.map.__LOD;

a.app.map.__LOD = x ? dojo.fromJson(dojo.toJson(x)) : {scale: a.app.map.getScale()};

a.app.map.__LOD._frameInfo = a.app.map.__LOD._frameInfo || []

};

So, to me it's clear they are doing things to the __LOD of the map which breaks the functionality in _getFrameWidth(); of the esri map object.

So my next step is going to be a bug report for Geocortex and to try to create a workaround for this.

Re: Snappingmanager does not work. is map._getFrameWidth() the problem?

MehmetÜNLÜ — Mon, 08 Jun 2015 13:55:55 GMT

Hi. Snapping manager finding featurelayer in map. U have to add to map featurelayer. Or alwaysSnap:true or snapKey: dojo.keys.copyKey u choose one.

Have a good luck.