HTML5 discovery tutorial

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Version de 10:58, 6 Mai 2024

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Introduction

In this part of the tutorial, you will discover interactive examples (you will be able to change the code and see the results interactively) of HTML features. Some APIs or features are not yet available on every web browser, so you may need to try switch from one browser to another in order to run all the examples.

Forms

Excellent, detailed presentations with lots of examples of HTML5 forms by:

New attributes for input fields : placeholder, pattern, autofocus CSS pseudo classes...

Selecting files and directory

  • Use of the new "multiple" attribute for selecting several files at a time. In addition, uses the HTML5 File API for reading pictures and preview them : http://jsbin.com/ozacel/2/edit
     
  • Use of the new "directory" attribute for selecting a directory. Works only in webkit-based browsers (Chrome, Safari) : http://jsbin.com/iyixaf/3/edit
    Note that in the example the attribute is named "webkitdirectory" instead of "directory" as this is still an experimental implementation.

Date, time, etc.

Color

Number

Range

Progress

Email

Tel

Url, search, voice recognition

The new <output> field

The new <datalist> element

  • Try this example that shows a <datalist> element in action for autocompleting an input field without the need of JavaScript code : http://jsbin.com/uwozih/2/edit

Declare <input> fields out of the <form></form>

Drag'n'drop and File API

Access file details (name, size, type) :

Instant preview of dropped images

  • Simple "drag images and instant preview"example  : http://jsbin.com/ewarak/2/edit
     
  • Same example but this time we added two input fields : one for selecting multiple files (<input type="file" multiple/>) and one for selecting a directory. Notice that both dropped files or selected files can be processed by the same piece of code for instant preview : http://jsbin.com/orurip/11/edit

Canvas

Good references :

Simple examples

Shadows

Gradients

Clipping/using mask to draw only a part of the canvas

Track mouse events

Stack canvases in layers

  • This example shows how we create two canvases one on top of another. Mouse draws in the canvas at the back, while the mouse position is displayed in the front canvas. Each the mouse moves, the front canvas is cleared before redrawing the mouse position, while the back canvas remains intact. Try it : http://jsbin.com/ogehin/2/edit

Images

2D Transformations

  • Try this example that shows how to translate/rotate/scale objects + how to save/restore the current context in a stack : http://jsbin.com/azacaf/3/edit

Save canvas content

Access pixels inside a canvas

Video

Basic usage

Change properties on the fly (size, position, angle etc.)

Video special effects : incrustation / blue screening

Most of these special effects consist in drawing the current image from the <video> element into a <canvas>, then grab the canvas content, modify it in real time, then draw in another canvas or set the canvas content as the source of an <img>.

Video capture

For these example to run, you need a browser that supports the getUserMedia API. See : Get a web browser that supports the getUserMedia API.

Resources :

Display webcam stream in a video element

Apply CSS effects on a video element with live webcam

Take a snapshot from the live webcam stream

Other demos

WebSockets

In order to test how WebSockets work, you need a WebSocket server and some code on the server. Some examples run on a very simple online WebSocket server and do not need any installation.

Check if your browser supports WebSockets

Simple example

Use the "view plain menu", copy the source in a testWebSocket.html file, open it in your browser. It will send a message to the html5rocks.websocket.org/echo URL (WebSocket server that echos messages it receives) and display some alerts to check if WebSockets are supported, if the message has been correctly sent or received as an echo.

<!DOCTYPE HTML>
<html>
<head>
    <script type="text/javascript">
        function WebSocketTest()
        {
            if ("WebSocket" in window)
            {
                alert("WebSocket is supported by your Browser!");
                // Let us open a web socket
                var ws = new WebSocket("ws://html5rocks.websocket.org/echo");
                ws.onopen = function()
                {
                    // Web Socket is connected, send data using send()
                    ws.send("Message to send");
                    alert("Message is sent...");
                };
                ws.onmessage = function (evt)
                {
                    var received_msg = evt.data;
                    alert("Message is received..." + received_msg);
                };
                ws.onclose = function()
                {
                    // websocket is closed.
                    alert("Connection is closed...");
                };
            }
            else
            {
                // The browser doesn't support WebSocket
                alert("WebSocket NOT supported by your Browser!");
            }
        }
    </script>
</head>
<body>
<div id="sse">
    <a href="javascript:WebSocketTest()">Run WebSocket</a>
</div>
</body>
</html>

High level library over WebSockets

A more complete example involving real use cases is proposed in the "advanced tutorial for geeks" :  A multi-participant Paint in HTML5 that proposes to install the NodeJS server + some additional modules that ease the development of multi-participants over WebSockets. This tutorial uses the NowJS library that provides ditributed JavaScript objecs + session and group management over WebSockets.

Popular libraries for NodeJS, like socket.io, propose fallback mecanisms in case the web browser used by a participant does not support web browsers (while your code remains unchanged, the lib will switch from WebSockets to Flash WebSockets or Ajax Long Calling...), handle deconnexions, etc.

NowJS is built upon socket.io and proposes Remote function/method calls and shared objects between client and server code. Such libraries dramatically reduce the amount of code necessary to write classic use cases for multi-participant sofware.

Geolocation

Most example are variations of : http://www.w3schools.com/html5/html5_geolocation.asp

Simple example

With Google Maps

Track position in real time

Device Orientation and Acceleration