impress.js requires a Root Element. All the content of the presentation will be created inside that element. It is not recommended to manipulate any of the styles, attributes or classes that are created by impress.js inside the Root Element after initialization.
Example:
<div id="impress"></div>A Step Element is an element that contains metadata that defines how it is going to be presented in the screen.
A Step Element should contain a .step class and an optional id attribute.
The content represents an html fragment that will be positioned at the center of the camera.
In the Step Element, you can define a specific set of default attributes and positioning, that are documented below.
Example:
<div id="bored" class="step" data-x="-1000">
<q>Aren’t you just <b>bored</b> with all those slides-based presentations?</q>
</div>Define the pixel based position in which the center of the Step Element will be positioned inside the infinite canvas.
Example:
<div id="bored" class="step" data-x="-1000" data-y="-1500">
<q>Aren’t you just <b>bored</b> with all those slides-based presentations?</q>
</div>Defines the scaling multiplier of the Step Element relative to other Step Elements. For example, data-scale="4" means that the element will appear to be 4 times larger than the others. From the presentation and transitions point of view, it means that it will have to be scaled down (4 times) to make it back to its correct size.
Example:
<div id="title" class="step" data-x="0" data-y="0" data-scale="4">
<span class="try">then you should try</span>
<h1>impress.js<sup>*</sup></h1>
<span class="footnote"><sup>*</sup> no rhyme intended</span>
</div>Represents the amount of clockwise rotation of the element relative to 360 degrees.
Example:
<div id="its" class="step" data-x="850" data-y="3000" data-rotate="90" data-scale="5">
<p>
It’s a <strong>presentation tool</strong> <br>
inspired by the idea behind <a href="http://prezi.com">prezi.com</a> <br>
and based on the <strong>power of CSS3 transforms and transitions</strong> in modern browsers.
</p>
</div>Define the pixel based position in which the center of the Step Element will be positioned inside the infinite canvas on the third dimension (Z) axis. For example, if we use data-z="-3000", it means that the Step Element will be positioned far away from the camera (by 3000px).
Example:
<div id="tiny" class="step" data-x="2825" data-y="2325" data-z="-3000" data-rotate="300" data-scale="1">
<p>and <b>tiny</b> ideas</p>
</div>Note: The introduction of the rel plugin includes a slight backward incompatible change.
Previously the default value for data-x, data-y and data-z was zero. The rel plugin changes the default to inherit
the value of the previous slide. This means, you need to explicitly set these values to zero, if they ever were non-zero.
You can not only position a Step Element in 3D, but also rotate it around any axis.
Example:
The example below will get rotated by -40 degrees (40 degrees anticlockwise) around X axis and 10 degrees (clockwise) around Y axis.
You can of course rotate it around Z axis with data-rotate-z - it has exactly the same effect as data-rotate (these two are basically aliases).
<div id="its-in-3d" class="step" data-x="6200" data-y="4300" data-z="-100" data-rotate-x="-40" data-rotate-y="10" data-scale="2">
<p>
<span class="have">have</span>
<span class="you">you</span>
<span class="noticed">noticed</span>
<span class="its">it’s</span>
<span class="in">in</span>
<b>3D<sup>*</sup></b>?
</p>
<span class="footnote">* beat that, prezi ;)</span>
</div>The order in which the CSS rotateX(), rotateY(), rotateZ() transforms are applied matters. This is because each rotation is relative to the then current position of the element.
By default the rotation order is data-rotate-order="xyz". For some advanced uses you may need to change it. The demo presentation 3D rotations sets this attribute to rotate some steps into positions that are impossible to reach with the default order.
The .future class is added to all Step Elements that haven't been visited yet.
Example:
.future {
display: none;
}The .present class is added to the Step Element that is currently at the center of the camera. This is useful to create animations inside the step once the camera navigates to it.
Example:
.present .rotating {
transform: rotate(-10deg);
transition-delay: 0.25s;
}The .past class is added to all Step Elements that have been visited at least once.
Example:
.past {
display: none;
}The .active class is added to the Step Element that is currently visible at the center of the camera.
Example:
.step {
opacity: 0.3;
transition: opacity 1s;
}
.step.active {
opacity: 1
}At the same time, the impress-on-* class is added to the body element, the class name represents the active Step Element id. This allows for custom global styling, since you can't match a CSS class backwards from the active Step Element to the body.
Example:
.impress-on-overview .step {
opacity: 1;
cursor: pointer;
}
.impress-on-step-1,
.impress-on-step-2,
.impress-on-step-3 {
background: LightBlue;
}The .impress-not-supported class is added to the body element if the browser doesn't support the features required by impress.js to work, it is useful to apply some fallback styles in the CSS.
It's not necessary to add it manually on the body element. If the script detects that the browser lacks important features it will add this class.
It is recommended to add the class manually to the body element though, because that means that users without JavaScript will also get fallback styles. When impress.js script detects that the browser supports all required features, the .impress-not-support class will be removed from the body element.
Example:
.impress-not-supported .step {
display: inline-block;
}Many new features are implemented as plugins. The Plugins documentation is the starting place to learn about those, as well as the README.md of each plugin.
A factory function that creates the ImpressAPI.
Accepts a String that represents the id of the root element in the page. If omitted, impress.js will lookup for the element with the id "impress" by default.
Example:
var impressAPI = impress( "root" );The main impress.js API that handles common operations of impress.js, listed below.
Initializes impress.js globally in the page. Only one instance of impress.js is supported per document.
Example:
impress().init();Triggers the impress:init event in the Root Element after the presentation is initialized.
Example:
var rootElement = document.getElementById( "impress" );
rootElement.addEventListener( "impress:init", function() {
console.log( "Impress init" );
});
impress().init();Resets the DOM to its original state, as it was before init() was called.
This can be used to "unload" impress.js. A particular use case for this is, if you want to do
dynamic changes to the presentation, you can do a teardown, apply changes, then call init()
again. (In most cases, this will not cause flickering or other visible effects to the user,
beyond the intended dynamic changes.)
Example:
impress().tear();Navigates to the next step of the presentation using the goto() function.
Example:
var api = impress();
api.init();
api.next();Navigates to the previous step of the presentation using the goto() function.
Example:
var api = impress();
api.init();
api.prev();Accepts a Number that represents the step index.
Navigates to the step given the provided step index.
Example:
var api = impress();
api.init();
api.goto(7);Accepts a String that represents the Step Element id.
Navigates to the step given the provided Step Element id.
Example:
var api = impress();
api.init();
api.goto( "overview" );Accepts an HTMLElement that represents the Step Element.
Navigates to the step given the provided Step Element.
Example:
var overview = document.getElementById( "overview" );
var api = impress();
api.init();
api.goto( overview );Accepts an optional Number in the last argument that represents the duration of the transition in milliseconds. If not provided, the default transition duration for the presentation will be used.
Triggers the impress:stepenter event in the Root Element when the presentation navigates to the target Step Element.
Example:
var rootElement = document.getElementById( "impress" );
rootElement.addEventListener( "impress:stepenter", function(event) {
var currentStep = event.target;
console.log( "Entered the Step Element '" + currentStep.id + "'" );
});Triggers the impress:stepleave event in the Root Element when the presentation navigates away from the current Step Element.
Example:
var rootElement = document.getElementById( "impress" );
rootElement.addEventListener( "impress:stepleave", function(event) {
var currentStep = event.target;
var nextStep = event.detail.next;
console.log( "Left the Step Element '" + currentStep.id + "' and about to enter '" + nextStep.id );
});Did you find something that can be improved? Then create an issue so that we can discuss it!