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<div id="pagetitle"><h1>YUI Library Examples: Overlay: Stack Support</h1></div>
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<div id="bar-note"><p><strong>Note:</strong> This is YUI 3.x. Looking for <a href="http://developer.yahoo.com/yui/">YUI 2.x</a>?</p></div>
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<h2>Overlay: Stack Support</h2>
<div id="example" class="promo">
<p>
<p>This example shows how you can work with the <code>zIndex</code> attribute which the Overlay supports, to implement a simple <code>bringToTop</code> function. The example code also listens for changes in the <code>zIndex</code> attribute, which it uses to update the content of the overlay, when it is brought to the top of the stack.</p> </p>
<div class="module example-container ">
<div class="hd exampleHd">
<p class="newWindowButton yui-skin-sam">
<a href="overlay-stack_clean.html" target="_blank">View example in new window.</a>
</p>
</div> <div id="example-canvas" class="bd">
<!--BEGIN SOURCE CODE FOR EXAMPLE =============================== -->
<p>Click on an Overlay, to switch it's zIndex with the highest zIndex in the stack, bringing it to the top of the stack:</p>
<div class="overlay-example" id="overlay-stack">
<p class="filler">
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nunc pretium quam eu mi varius pulvinar. Duis orci arcu, ullamcorper sit amet, luctus ut, interdum ac, quam. Pellentesque euismod. Nam tincidunt, purus in ultrices congue, urna neque posuere arcu, aliquam tristique purus sapien id nulla. Etiam rhoncus nulla at leo. Cras scelerisque nisl in nibh. Sed eget odio. Morbi elit elit, porta a, convallis sit amet, rhoncus non, felis. Mauris nulla pede, pretium eleifend, porttitor at, rutrum id, orci. Quisque non urna. Nulla aliquam rhoncus est.
<select class="needs-shim">
<option>Prevent IE6 Bleedthrough</option>
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Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nunc pretium quam eu mi varius pulvinar. Duis orci arcu, ullamcorper sit amet, luctus ut, interdum ac, quam. Pellentesque euismod. Nam tincidunt, purus in ultrices congue, urna neque posuere arcu, aliquam tristique purus sapien id nulla. Etiam rhoncus nulla at leo. Cras scelerisque nisl in nibh. Sed eget odio. Morbi elit elit, porta a, convallis sit amet, rhoncus non, felis. Mauris nulla pede, pretium eleifend, porttitor at, rutrum id, orci. Quisque non urna. Nulla aliquam rhoncus est.
</p>
</div>
<script type="text/javascript">
YUI({base:"../../build/", timeout: 10000}).use("overlay", function(Y) {
var overlays = [],
overlay,
n = 6,
xy = Y.Node.get("#overlay-stack").getXY();
function getOverlayXY(xy, i) {
return [xy[0] + i * 60, xy[1] + i * 40];
}
for (var i = 0; i < n; ++i) {
ovrXY = getOverlayXY(xy, i);
ovrZIndex = i+1;
// Setup n Overlays, with increasing zIndex values
overlay = new Y.Overlay({
zIndex:ovrZIndex,
xy:ovrXY,
width:"8em",
height:"8em",
headerContent: 'Overlay <span class="yui-ovr-number">' + i + '</span>',
bodyContent: "zIndex = " + ovrZIndex
});
overlay.render("#overlay-stack");
overlays.push(overlay);
// Update body whenever zIndex changes
overlay.after("zIndexChange", function(e) {
this.set("bodyContent", "zIndex = " + e.newVal);
});
}
function onStackMouseDown(e) {
var widget = Y.Widget.getByNode(e.target);
// If user clicked on an Overlay, bring it to the top of the stack
if (widget && widget instanceof Y.Overlay) {
bringToTop(widget);
}
}
// zIndex comparator
function byZIndexDesc(a, b) {
if (!a || !b || !a.hasImpl(Y.WidgetStack) || !b.hasImpl(Y.WidgetStack)) {
return 0;
} else {
var aZ = a.get("zIndex");
var bZ = b.get("zIndex");
if (aZ > bZ) {
return -1;
} else if (aZ < bZ) {
return 1;
} else {
return 0;
}
}
}
function bringToTop(overlay) {
// Sort overlays by their numerical zIndex values
overlays.sort(byZIndexDesc);
// Get the highest one
var highest = overlays[0];
// If the overlay is not the highest one, switch zIndices
if (highest !== overlay) {
var highestZ = highest.get("zIndex");
var overlayZ = overlay.get("zIndex");
overlay.set("zIndex", highestZ);
highest.set("zIndex", overlayZ);
}
}
Y.on("mousedown", onStackMouseDown, "#overlay-stack");
});
</script>
<!--END SOURCE CODE FOR EXAMPLE =============================== -->
</div>
</div>
</div>
<h3>Basic Overlay Stackability (zIndex and shim support)</h3>
<h4>Setting Up The YUI Instance</h4>
<p>As with the <a href="overlay-xy.html">"Basic XY Positioning"</a> example, to create an instance of an Overlay on your page, the only module you need to request is the <code>overlay</code> module. The <code>overlay</code> module will pull in the <code>widget</code>, <code>widget-stack</code>, <code>widget-position</code>, <code>widget-position-ext</code> and <code>widget-stdmod</code> dependencies it has.</p>
<textarea name="code" class="JScript" rows="1" cols="60">
YUI({...}).use("overlay", function(Y) {
// We'll write example code here, where we have a Y.Overlay class available.
});
</textarea>
<p>Using the <code>overlay</code> module will also pull down the default CSS required for overlay, on top of which we only need to add our required look/feel CSS for the example.</p>
<h4>Instantiating The Overlay</h4>
<p>For this example we'll instantiate Overlays from script, as we did for the <a href="overlay-align.html">"Extended XY Positioning"</a> example. We'll create 6 Overlay instances and give them increasing zIndex and xy attribute values:</p>
<textarea name="code" class="JScript" rows="1" cols="60">
function getOverlayXY(xy, i) {
return [xy[0] + i * 60, xy[1] + i * 40];
}
for (var i = 0; i < n; ++i) {
ovrXY = getOverlayXY(xy, i);
ovrZIndex = i+1;
// Setup n Overlays, with increasing zIndex values and xy positions
overlay = new Y.Overlay({
zIndex:ovrZIndex,
xy:ovrXY,
width:"8em",
height:"8em",
headerContent: 'Overlay <span class="yui-ovr-number">' + i + '</span>',
bodyContent: "zIndex = " + ovrZIndex
});
overlay.render("#overlay-stack");
...
}
</textarea>
<p>We store the Overlay instances in an <code>overlays</code> array, which we'll later use to sort the Overlays by their zIndex values. We also setup a listener for the <code>zIndex</code> attribute change event, which will update the body section of the Overlay to display its new zIndex value.</p>
<textarea name="code" class="JScript" rows="1" cols="60">
overlays.push(overlay);
// Update body whenever zIndex changes
overlay.after("zIndexChange", function(e) {
this.set("bodyContent", "zIndex = " + e.newVal);
});
</textarea>
<h4>Handling MouseDown Using Widget.getByNode</h4>
<p>The <code>Widget</code> class has a static <code>getByNode</code> method which can be used to retrieve Widget instances based on a node reference. The method will return the closest Widget which contains the given node.</p>
<p>
We'll use this method in a click listener bound to the container of the example ("#overlay-stack"). Target nodes of click events bubbled up to this example container, will be passed to the <code>Widget.getByNode</code> method, to see if an Overlay was clicked on.
</p>
<textarea name="code" class="JScript" rows="1" cols="60">
function onStackMouseDown(e) {
var widget = Y.Widget.getByNode(e.target);
// If user clicked on an Overlay, bring it to the top of the stack
if (widget && widget instanceof Y.Overlay) {
bringToTop(widget);
}
}
Y.on("mousedown", onStackMouseDown, "#overlay-stack");
</textarea>
<p>If an Overlay was clicked on, we invoke the simple bringToTop method which will set the zIndex of the clicked Overlay to the highest current Overlay zIndex value.</p>
<h4>The <code>bringToTop</code> Implementation</h4>
<p>We use a basic comparator function to sort the array of Overlays we have. The comparator makes sure the array element we're dealing with <a href="../widget/widget-build.html">has a <code>WidgetStack</code> implementation</a> (which Overlays do) and if so, sorts them in descending <code>zIndex</code> attribute value order:</p>
<textarea name="code" class="JScript" rows="1" cols="60">
// zIndex comparator
function byZIndexDesc(a, b) {
if (!a || !b || !a.hasImpl(Y.WidgetStack) || !b.hasImpl(Y.WidgetStack)) {
return 0;
} else {
var aZ = a.get("zIndex");
var bZ = b.get("zIndex");
if (aZ > bZ) {
return -1;
} else if (aZ < bZ) {
return 1;
} else {
return 0;
}
}
}
</textarea>
<p>Once sorted, for the purposes of the example, we simply switch the <code>zIndex</code> of the "highest" Overlay, with the Overlay which was clicked on, giving the selected Overlay the highest zIndex value:</p>
<textarea name="code" class="JScript" rows="1" cols="60">
function bringToTop(overlay) {
// Sort overlays by their numerical zIndex values
overlays.sort(byZIndexDesc);
// Get the highest one
var highest = overlays[0];
// If the overlay is not the highest one, switch zIndices
if (highest !== overlay) {
var highestZ = highest.get("zIndex");
var overlayZ = overlay.get("zIndex");
overlay.set("zIndex", highestZ);
highest.set("zIndex", overlayZ);
}
}
</textarea>
<h4>CSS: Overlay Look/Feel</h4>
<p>As mentioned in the <a href="overlay-xy.html">"Basic XY Positioning"</a> example, the overlay.css Sam Skin file (build/overlay/assets/skins/sam/overlay.css) provides the default functional CSS for the overlay. Namely the CSS rules to hide the overlay, and position it absolutely. However there's no default out-of-the-box look/feel applied to the Overlay widget.</p>
<p>The example provides it's own look and feel for the Overlay, by defining rules for the content box, header and body sections:</p>
<textarea name="code" class="CSS" rows="1" cols="60">
/* Overlay Look/Feel */
.yui-overlay-content {
padding:2px;
border:1px solid #000;
background-color:#aaa;
font-size:93%;
}
.yui-overlay-content .yui-widget-hd {
font-weight:bold;
text-align:center;
padding:2px;
border:2px solid #aa0000;
background-color:#fff;
}
.yui-overlay-content .yui-widget-bd {
text-align:left;
padding:2px;
border:2px solid #0000aa;
background-color:#fff;
}
.yui-overlay-content .yui-widget-hd .yui-ovr-number {
color:#aa0000;
}
</textarea> </div>
<div class="yui-u sidebar">
<div id="examples" class="mod box4">
<div class="hd">
<h4>
Overlay Examples:</h4>
</div>
<div class="bd">
<ul>
<li><a href='../overlay/overlay-xy.html'>Basic XY Positioning</a></li><li><a href='../overlay/overlay-align.html'>Extended XY Positioning</a></li><li class='selected'><a href='../overlay/overlay-stack.html'>Stack Support</a></li><li><a href='../overlay/overlay-stdmod.html'>Standard Module Support</a></li><li><a href='../overlay/overlay-io-plugin.html'>IO Plugin</a></li><li><a href='../overlay/overlay-anim-plugin.html'>Animation Plugin</a></li><li><a href='../node-focusmanager/node-focusmanager-3.html'>Accessible Menu Button (included with examples for Focus Manager Node Plugin)</a></li> </ul>
</div>
</div>
<div class="mod box4">
<div class="hd">
<h4>More Overlay Resources:</h4>
</div>
<div class="bd">
<ul>
<!-- <li><a href="http://developer.yahoo.com/yui/overlay/">User's Guide</a> (external)</li> -->
<li><a href="../../api/module_overlay.html">API Documentation</a></li>
</ul>
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