Open layer 3 click on layer best practice - openlayers-3

Question

I am new to OL.
I need to implement a logic that should happen if I pressed on a specific item in a specific layer.
I have to state that I'm not writing a project from scratch, and I actually inherited a very basic but complex system.
The system gets the layers from MapGuide 2.5.
This is how the map is initiated:
var map = new ol.Map({
loadTilesWhileInteracting:true,
layers: this.layers,
target: this._element[0],
controls: controls,
interactions: interactions,
view: view
});
view.fit(that.extent, map.getSize());
I tried adding a select interaction - it didn't work (my promise was never called).
var select_interaction = new ol.interaction.Select();
select_interaction.getFeatures().on("add", function (e) {
var feature = e.element; //the feature selected
});
map.addInteraction(select_interaction);
I tried:
map.on('click', function (evt) {
var feature = map.forEachFeatureAtPixel(evt.pixel,
function (feature, layer) {
debugger;
this.log("fff")
});
});
In this case, the promise works but I get no features.
EDIT:
I also tried:
var feature = map.forEachLayerAtPixel(evt.pixel,
function (feature, layer) {..}
but I get the exception:
uncaught security error: Failed to execute 'getImageData' on 'CanvasRenderingContext2D': The canvas has been tainted by cross-origin data. ol.js:341
How can I do this?
Thanks,
Ido

Answer 1

I was getting the same error while I was trying to loop through layers at pixel via forEachLayerAtPixel method.
Thanks to #kagelos comment, I managed to solve the problem simply by filtering the layers and looping through only Vector layers.
Layer types are roughly separated in two categories in OL. Image layers (tiles etc.) and vector layers. You have to inspect the contents of this.layers that you pass as an argument in the constructor of the map and see what type of layers it contains. You can only interact directly with vector type layers.
Here is the final code:
Map.forEachLayerAtPixel( cursorPosition, function ( _layer ) {
// you will get the vector layer here
}, this, function ( _layer ) {
if ( _layer instanceof ol.layer.Vector ) {
return true;
}
});