Sunday, February 10, 2013

HTML5 Video

Video on the Web

Until now, there has not been a standard for showing a video/movie on a web page.
Today, most videos are shown through a plug-in (like flash). However, different browsers may have different plug-ins.
HTML5 defines a new element which specifies a standard way to embed a video/movie on a web page: the <video> element.

Browser Support

Internet ExplorerFirefoxOperaGoogle ChromeSafari
Internet Explorer 9, Firefox, Opera, Chrome, and Safari support the <video> element.
Note: Internet Explorer 8 and earlier versions, do not support the <video> element.

HTML5 Video - How It Works

To show a video in HTML5, this is all you need:

Example

<video width="320" height="240" controls>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
Your browser does not support the video tag.
</video>

Try it yourself »
The control attribute adds video controls, like play, pause, and volume.
It is also a good idea to always include width and height attributes. If height and width are set, the space required for the video is reserved when the page is loaded. However, without these attributes, the browser does not know the size of the video, and cannot reserve the appropriate space to it. The effect will be that the page layout will change during loading (while the video loads).
You should also insert text content between the <video> and </video> tags for browsers that do not support the <video> element.
The <video> element allows multiple <source> elements. <source> elements can link to different video files. The browser will use the first recognized format.

Video Formats and Browser Support

Currently, there are 3 supported video formats for the <video> element: MP4, WebM, and Ogg:
BrowserMP4WebMOgg
Internet Explorer 9+YESNONO
Chrome 6+YESYESYES
Firefox 3.6+NOYESYES
Safari 5+YESNONO
Opera 10.6+NOYESYES
  • MP4 = MPEG 4 files with H264 video codec and AAC audio codec
  • WebM = WebM files with VP8 video codec and Vorbis audio codec
  • Ogg = Ogg files with Theora video codec and Vorbis audio codec

MIME Types for Video Formats

FormatMIME-type
MP4video/mp4
WebMvideo/webm
Oggvideo/ogg

HTML5 <video> - DOM Methods and Properties

HTML5 has DOM methods, properties, and events for the <video> and <audio> elements.
These methods, properties, and events allow you to manipulate <video> and <audio> elements using JavaScript.
There are methods for playing, pausing, and loading, for example and there are properties (like duration and  volume). There are also DOM events that can notify you when the <video> element begins to play, is paused, is ended, etc.
The example below illustrate, in a simple way, how to address a <video> element, read and set properties, and call methods.

Example 1

Create simple play/pause + resize controls for a video:

    

Video courtesy of Big Buck Bunny.
The example above calls two methods: play() and pause(). It also uses two properties: paused and width.
Try it yourself »
For a full reference go to our HTML5 Audio/Video DOM Reference.

HTML5 Video Tags

TagDescription
<video>Defines a video or movie
<source>Defines multiple media resources for media elements, such as <video> and <audio>
<track>Defines text tracks in mediaplayers
courtesy : http://www.w3schools.com/html/html5_video.asp
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Saturday, February 9, 2013

Drag and Drop In HTML 5


Drag and Drop

Drag and drop is a very common feature. It is when you "grab" an object and drag it to a different location.
In HTML5, drag and drop is part of the standard, and any element can be draggable.

Browser Support

Internet ExplorerFirefoxOperaGoogle ChromeSafari
Internet Explorer 9, Firefox, Opera 12, Chrome, and Safari 5 support drag and drop.
Note: Drag and drop does not work in Safari 5.1.2.

HTML5 Drag and Drop Example

The example below is a simple drag and drop example:

Example

<!DOCTYPE HTML>
<html>
<head>
<script>
function allowDrop(ev)
{
ev.preventDefault();
}

function drag(ev)
{
ev.dataTransfer.setData("Text",ev.target.id);
}

function drop(ev)
{
ev.preventDefault();
var data=ev.dataTransfer.getData("Text");
ev.target.appendChild(document.getElementById(data));
}
</script>
</head>
<body>

<div id="div1" ondrop="drop(event)"
ondragover="allowDrop(event)"></div>

<img id="drag1" src="img_logo.gif" draggable="true"
ondragstart="drag(event)" width="336" height="69">

</body>
</html>

It might seem complicated, but lets go through all the different parts of a drag and drop event.

Make an Element Draggable

First of all: To make an element draggable, set the draggable attribute to true:
<img draggable="true">

What to Drag - ondragstart and setData()

Then, specify what should happen when the element is dragged.
In the example above, the ondragstart attribute calls a function, drag(event), that specifies what data to be dragged.
The dataTransfer.setData() method sets the data type and the value of the dragged data:
function drag(ev)
{
ev.dataTransfer.setData("Text",ev.target.id);
}
In this case, the data type is "Text" and the value is the id of the draggable element ("drag1").

Where to Drop - ondragover

The ondragover event specifies where the dragged data can be dropped.
By default, data/elements cannot be dropped in other elements. To allow a drop, we must prevent the default handling of the element.
This is done by calling the event.preventDefault() method for the ondragover event:
event.preventDefault()

Do the Drop - ondrop

When the dragged data is dropped, a drop event occurs.
In the example above, the ondrop attribute calls a function, drop(event):
function drop(ev)
{
ev.preventDefault();
var data=ev.dataTransfer.getData("Text");
ev.target.appendChild(document.getElementById(data));
}
Code explained:
  • Call preventDefault() to prevent the browser default handling of the data (default is open as link on drop)
  • Get the dragged data with the dataTransfer.getData("Text") method. This method will return any data that was set to the same type in the setData() method
  • The dragged data is the id of the dragged element ("drag1")
  • Append the dragged element into the drop element
Content Courtesy: http://www.w3schools.com
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