Permalink: Added support for overlays

[buche]

I've added support for overlays in my project (sorry, no github pull request availabe).

It works using flags (T/F) for each overlay (e.g. ...&overlays=TFTT). Dynamically changing overlays in layer control will break it, because it relies on the sequence of the overlays in layer control.

It needs leaflet from github with merged pull request #1286 (layer control events for overlays): Leaflet/Leaflet#1286

Permalink.Overlay.js: http://pastebin.com/wChyR7bD

Feel free to reuse the code as you like!

[Firefishy]

+1 :)

[tormi]

Thanks, works like a charm!
+1

[brunob]

Copying proposed code here in order to keep it :

/**
 * This file is licensed under Creative Commons Zero (CC0)
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

L.Control.Permalink.include({

    initialize_overlay: function() {
        this.on('update', this._set_overlays, this);
        this.on('add', this._onadd_overlay, this);
    },

    _onadd_overlay: function(e) {
        this._map.on('overlayadd', this._update_overlay, this);
        this._map.on('overlayremove', this._update_overlay, this);
        this._update_overlay();
    },

    _update_overlay: function() {
        if (!this.options.layers) return;
        var overlayflags = this.options.layers.overlayFlags();
        if (overlayflags && overlayflags != '') {
            this._update({overlays: overlayflags});
        }
    },

    _set_overlays: function(e) {
        var p = e.params;
        if (!this.options.layers || !p.overlays) return;
        this.options.layers.setOverlays(p.overlays);
    }
});

L.Control.Layers.include({
    setOverlays: function(overlayflags) {
        var layer, obj, idx=0;
        for (var i in this._layers) {
            if (!this._layers.hasOwnProperty(i)) continue;
            obj = this._layers[i];
            if (obj.overlay) {
                // visible if not specified or flag==T
                var visible = (idx >= overlayflags.length || overlayflags[idx] == 'T');
                idx++;
                if (!visible && this._map.hasLayer(obj.layer)) {
                    this._map.removeLayer(obj.layer)
                } else if (visible && !this._map.hasLayer(obj.layer)) {
                    this._map.addLayer(obj.layer)
                }
            }
        }
    },

    overlayFlags: function() {
        var flags = '';
        for (var i in this._layers) {
            if (!this._layers.hasOwnProperty(i))
                continue;
            var obj = this._layers[i];
            if (!obj.overlay) continue;
            if (obj.overlay) {
                if (this._map.hasLayer(obj.layer)) {
                    flags += 'T';
                } else {
                    flags += 'F';
                }
            }
        }
        return flags;
    }
});

[brunob]

@buche would you like to make a pull request for it or you prefer that i do it + credit yourself in the commit ?

[buche]

@brunob feel free to make a pull request yourself. No credit is needed.