ol-layerswitcher
Version:
Layer switcher control for OpenLayers v3/v4
298 lines (248 loc) • 8.85 kB
JavaScript
import Control from 'ol/control/control';
import Observable from 'ol/observable';
/**
* OpenLayers Layer Switcher Control.
* See [the examples](./examples) for usage.
* @constructor
* @extends {ol.control.Control}
* @param {Object} opt_options Control options, extends olx.control.ControlOptions adding:
* **`tipLabel`** `String` - the button tooltip.
*/
export default class LayerSwitcher extends Control {
constructor(opt_options) {
var options = opt_options || {};
var tipLabel = options.tipLabel ?
options.tipLabel : 'Legend';
var element = document.createElement('div');
super({element: element, target: options.target});
this.mapListeners = [];
this.hiddenClassName = 'ol-unselectable ol-control layer-switcher';
if (LayerSwitcher.isTouchDevice_()) {
this.hiddenClassName += ' touch';
}
this.shownClassName = 'shown';
element.className = this.hiddenClassName;
var button = document.createElement('button');
button.setAttribute('title', tipLabel);
element.appendChild(button);
this.panel = document.createElement('div');
this.panel.className = 'panel';
element.appendChild(this.panel);
LayerSwitcher.enableTouchScroll_(this.panel);
var this_ = this;
button.onmouseover = function(e) {
this_.showPanel();
};
button.onclick = function(e) {
e = e || window.event;
this_.showPanel();
e.preventDefault();
};
this_.panel.onmouseout = function(e) {
e = e || window.event;
if (!this_.panel.contains(e.toElement || e.relatedTarget)) {
this_.hidePanel();
}
};
}
/**
* Set the map instance the control is associated with.
* @param {ol.Map} map The map instance.
*/
setMap(map) {
// Clean up listeners associated with the previous map
for (var i = 0, key; i < this.mapListeners.length; i++) {
Observable.unByKey(this.mapListeners[i]);
}
this.mapListeners.length = 0;
// Wire up listeners etc. and store reference to new map
super.setMap(map);
if (map) {
var this_ = this;
this.mapListeners.push(map.on('pointerdown', function() {
this_.hidePanel();
}));
this.renderPanel();
}
}
/**
* Show the layer panel.
*/
showPanel() {
if (!this.element.classList.contains(this.shownClassName)) {
this.element.classList.add(this.shownClassName);
this.renderPanel();
}
}
/**
* Hide the layer panel.
*/
hidePanel() {
if (this.element.classList.contains(this.shownClassName)) {
this.element.classList.remove(this.shownClassName);
}
}
/**
* Re-draw the layer panel to represent the current state of the layers.
*/
renderPanel() {
this.ensureTopVisibleBaseLayerShown_();
while(this.panel.firstChild) {
this.panel.removeChild(this.panel.firstChild);
}
var ul = document.createElement('ul');
this.panel.appendChild(ul);
this.renderLayers_(this.getMap(), ul);
}
/**
* Ensure only the top-most base layer is visible if more than one is visible.
* @private
*/
ensureTopVisibleBaseLayerShown_() {
var lastVisibleBaseLyr;
LayerSwitcher.forEachRecursive(this.getMap(), function(l, idx, a) {
if (l.get('type') === 'base' && l.getVisible()) {
lastVisibleBaseLyr = l;
}
});
if (lastVisibleBaseLyr) this.setVisible_(lastVisibleBaseLyr, true);
}
/**
* Toggle the visible state of a layer.
* Takes care of hiding other layers in the same exclusive group if the layer
* is toggle to visible.
* @private
* @param {ol.layer.Base} The layer whos visibility will be toggled.
*/
setVisible_(lyr, visible) {
var map = this.getMap();
lyr.setVisible(visible);
if (visible && lyr.get('type') === 'base') {
// Hide all other base layers regardless of grouping
LayerSwitcher.forEachRecursive(map, function(l, idx, a) {
if (l != lyr && l.get('type') === 'base') {
l.setVisible(false);
}
});
}
}
/**
* Render all layers that are children of a group.
* @private
* @param {ol.layer.Base} lyr Layer to be rendered (should have a title property).
* @param {Number} idx Position in parent group list.
*/
renderLayer_(lyr, idx) {
var this_ = this;
var li = document.createElement('li');
var lyrTitle = lyr.get('title');
var lyrId = LayerSwitcher.uuid();
var label = document.createElement('label');
if (lyr.getLayers && !lyr.get('combine')) {
li.className = 'group';
label.innerHTML = lyrTitle;
li.appendChild(label);
var ul = document.createElement('ul');
li.appendChild(ul);
this.renderLayers_(lyr, ul);
} else {
li.className = 'layer';
var input = document.createElement('input');
if (lyr.get('type') === 'base') {
input.type = 'radio';
input.name = 'base';
} else {
input.type = 'checkbox';
}
input.id = lyrId;
input.checked = lyr.get('visible');
input.onchange = function(e) {
this_.setVisible_(lyr, e.target.checked);
};
li.appendChild(input);
label.htmlFor = lyrId;
label.innerHTML = lyrTitle;
var rsl = this.getMap().getView().getResolution();
if (rsl > lyr.getMaxResolution() || rsl < lyr.getMinResolution()){
label.className += ' disabled';
}
li.appendChild(label);
}
return li;
}
/**
* Render all layers that are children of a group.
* @private
* @param {ol.layer.Group} lyr Group layer whos children will be rendered.
* @param {Element} elm DOM element that children will be appended to.
*/
renderLayers_(lyr, elm) {
var lyrs = lyr.getLayers().getArray().slice().reverse();
for (var i = 0, l; i < lyrs.length; i++) {
l = lyrs[i];
if (l.get('title')) {
elm.appendChild(this.renderLayer_(l, i));
}
}
}
/**
* **Static** Call the supplied function for each layer in the passed layer group
* recursing nested groups.
* @param {ol.layer.Group} lyr The layer group to start iterating from.
* @param {Function} fn Callback which will be called for each `ol.layer.Base`
* found under `lyr`. The signature for `fn` is the same as `ol.Collection#forEach`
*/
static forEachRecursive(lyr, fn) {
lyr.getLayers().forEach(function(lyr, idx, a) {
fn(lyr, idx, a);
if (lyr.getLayers) {
LayerSwitcher.forEachRecursive(lyr, fn);
}
});
}
/**
* **Static** Generate a UUID
* Adapted from http://stackoverflow.com/a/2117523/526860
* @returns {String} UUID
*/
static uuid() {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
return v.toString(16);
});
}
/**
* @private
* @desc Apply workaround to enable scrolling of overflowing content within an
* element. Adapted from https://gist.github.com/chrismbarr/4107472
*/
static enableTouchScroll_(elm) {
if(LayerSwitcher.isTouchDevice_()){
var scrollStartPos = 0;
elm.addEventListener("touchstart", function(event) {
scrollStartPos = this.scrollTop + event.touches[0].pageY;
}, false);
elm.addEventListener("touchmove", function(event) {
this.scrollTop = scrollStartPos - event.touches[0].pageY;
}, false);
}
}
/**
* @private
* @desc Determine if the current browser supports touch events. Adapted from
* https://gist.github.com/chrismbarr/4107472
*/
static isTouchDevice_() {
try {
document.createEvent("TouchEvent");
return true;
} catch(e) {
return false;
}
}
}
// Expose LayerSwitcher as ol.control.LayerSwitcher if using a full build of
// OpenLayers
if (window.ol && window.ol.control) {
window.ol.control.LayerSwitcher = LayerSwitcher;
}