Canvas Rotating Rectangles Animation Using HTML 5

Deepak Dwij
Mar 28, 2012
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Introduction

In this article we are going to understand rotating rectangles animation using the HTML 5 canvas. In this section we'll rotate a light green rectangle about the top left corner, a yellow rectangle about its center, and a red rectangle about an outside point.

Here we will use some JavaScript and some styles along with HTML code. Just go through the steps to see how to create this application.

Let's see how the CanvasRotatingAnimation application can be created. To do so use the following steps.

Step 1 : Open a HTML editor or Visual Studio.

Open File menu ->select new ->Choose Website

This is where we will create the HTML5 application.

Go to Solution Explorer
Right-click on the Application name
Select Add-->add new item
Now in the window that opens, select an HTML page or new Web form
Rename it to canvasrotatingrects.aspx

Step 2 : In this section we will create the style for the media and create the .css on the media screen. Put the given script in the Head section of the HTML or between the <head>--</head> tags. Here the CSS is used for design purposes.

CSS Script

<style>
body
{
  margin: 0px;
  padding: 0px;
}
Canvas
{
   border: 2px solid #9C9898;
   margin-top: 50px;
   margin-left: 50px;
   background-color: #009999;
   box-shadow: 5px 5px 8px #222;
}
.title
{
   text-align: center;
   font-family: Segoe UI Light, Arial, Helvetica;
   font-size: 2.2em;
   margin: 1em;
}
.info
{
   text-align: center;
   font-family: Segoe UI Light, Arial, Helvetica;
   font-size: 1.2em;
   margin: 0.25em;
}
</style>

Step 3 : In this part we need to work on some JavaScript. To fully understand how JavaScript works, download the attached .rar file and run the CanvasRotatingAnimation application.

The whole JavaScript looks as in the following:

<script>
        window.onload = function ()
         {
            var stage = new Kinetic.Stage({
                container: "container",
                width: 578,
                height: 200
            });
            var layer = new Kinetic.Layer();
            var blueRect = new Kinetic.Rect({
                x: 50,
                y: 75,
                width: 100,
                height: 50,
                fill: "#99FFCC",
                stroke: "black",
                strokeWidth: 4
           });
            var yellowRect = new Kinetic.Rect({
                x: 220,
                y: 75,
              width: 100,
              height: 50,
                fill: "yellow",
                stroke: "black",
                strokeWidth: 4,
                centerOffset: {
                    x: 50,
                    y: 25
                }
            });
            var redRect = new Kinetic.Rect({
                x: 400,
                y: 75,
                width: 100,
                height: 50,
                fill: "red",
                stroke: "black",
                strokeWidth: 4,
                centerOffset: {
                    x: -100,
                    y: 0
                }
            });
            layer.add(blueRect);
            layer.add(yellowRect);
            layer.add(redRect);
            stage.add(layer);
            stage.onFrame(function (frame) {
                blueRect.rotate(Math.PI / 100);
                yellowRect.rotate(Math.PI / 100);
                redRect.rotate(Math.PI / 100);
                layer.draw();
            });
             stage.start();
       };
</script>

Step 4 : In this section we are going to become familiar with the body part of HTML scripting. Replace this script from the body section of the canvasrotatingrects.aspx page. Here we pass a Canvas in the canvas tag.

<body style="background-color: #FFCC66">
    <center>
        <h1>
            Canvas Rotating Rectangles Animation
        </h1>
    </center>
    <hr />
    <div id="container">
    </div>
</body>

Step 5 : The complete code for the CanvasRotatingAnimation application is:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="canvasrotatingrects.aspx.cs" Inherits="CanvasRotatingAnimation._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <style>
    </style>
    <script src="jscript.js"></script>
    <script>
  </script>
</head>
<body style="background-color: #FFCC66">
    <center>
        <h1>
            Canvas Rotating Rectangles Animation
        </h1>
    </center>
    <hr />
    <div id="container">
    </div>
</body>
</html>

Step 6 : Output Press F5

Note : For the accurate output of HTML5 applications, you must have the Google Chrome browser in your PC. A rotating light green rectangle about the top left corner, a yellow rectangle about its center, and a red rectangle about an outside point, while the application is running in the browser.

Here are some useful resources