iron-overlay-manager.html
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<!--
@license
Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->
<link rel="import" href="../polymer/polymer.html">
<script>
Polymer.IronOverlayManager = {
_overlays: [],
// iframes have a default z-index of 100, so this default should be at least
// that.
_minimumZ: 101,
_backdrops: [],
_applyOverlayZ: function(overlay, aboveZ) {
this._setZ(overlay, aboveZ + 2);
},
_setZ: function(element, z) {
element.style.zIndex = z;
},
// track overlays for z-index and focus managemant
addOverlay: function(overlay) {
var minimumZ = Math.max(this.currentOverlayZ(), this._minimumZ);
this._overlays.push(overlay);
var newZ = this.currentOverlayZ();
if (newZ <= minimumZ) {
this._applyOverlayZ(overlay, minimumZ);
}
},
removeOverlay: function(overlay) {
var i = this._overlays.indexOf(overlay);
if (i >= 0) {
this._overlays.splice(i, 1);
this._setZ(overlay, '');
}
},
currentOverlay: function() {
var i = this._overlays.length - 1;
while (this._overlays[i] && !this._overlays[i].opened) {
--i;
}
return this._overlays[i];
},
currentOverlayZ: function() {
var z = this._minimumZ;
var current = this.currentOverlay();
if (current) {
var z1 = window.getComputedStyle(current).zIndex;
if (!isNaN(z1)) {
z = Number(z1);
}
}
return z;
},
/**
* Ensures that the minimum z-index of new overlays is at least `minimumZ`.
* This does not effect the z-index of any existing overlays.
*
* @param {number} minimumZ
*/
ensureMinimumZ: function(minimumZ) {
this._minimumZ = Math.max(this._minimumZ, minimumZ);
},
focusOverlay: function() {
var current = this.currentOverlay();
// We have to be careful to focus the next overlay _after_ any current
// transitions are complete (due to the state being toggled prior to the
// transition). Otherwise, we risk infinite recursion when a transitioning
// (closed) overlay becomes the current overlay.
//
// NOTE: We make the assumption that any overlay that completes a transition
// will call into focusOverlay to kick the process back off. Currently:
// transitionend -> _applyFocus -> focusOverlay.
if (current && !current.transitioning) {
current._applyFocus();
}
},
trackBackdrop: function(element) {
// backdrops contains the overlays with a backdrop that are currently
// visible
if (element.opened) {
this._backdrops.push(element);
} else {
var index = this._backdrops.indexOf(element);
if (index >= 0) {
this._backdrops.splice(index, 1);
}
}
},
getBackdrops: function() {
return this._backdrops;
}
};
</script>