Book Image

Canvas Cookbook

Book Image

Canvas Cookbook

Overview of this book

With the growing popularity of HTML5 Canvas, this book offers tailored recipes to help you develop portable applications, presentations, and games. The recipes are simple yet creative and build on each other. At every step, the book inspires the reader to develop his/her own recipe. From basic to advanced, every aspect of Canvas API has been covered to guide readers to develop their own application, presentation, or game.
Table of Contents (16 chapters)
Canvas Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Adding shadows to objects


Here, we will be using our first recipe. Just a few properties are set and we get a different output as shown:

Notice the difference between this and the output of the first recipe. Here you will notice a shadow for each line.

How to do it...

We use a few shadow-related properties to build this recipe:

<html>
<head>
  <title>Line Shadow</title>
    <script type="text/javascript">
      var can;
      var ctx;
      function init() {
        can = document.getElementById("MyCanvasArea");
        ctx = can.getContext("2d");
        drawLine(30,30,300,30,20,"orange","butt");  //default cap style
        drawLine(30,80,300,80,20,"crimson","round");
        drawLine(30,130,300,130,20,"teal","square");
      }
      function drawLine(xstart,ystart,xend,yend,width,color,cap)
      {
        ctx.beginPath();
        ctx.strokeStyle=color;
        ctx.lineWidth=width;

        //adding shadow
        ctx.shadowOffsetX = 4;
        ctx.shadowOffsetY = 4;
        ctx.shadowBlur    = 7;
        ctx.shadowColor   = "gray";
        //shadow properties set above
        
        ctx.lineCap=cap;
        ctx.moveTo(xstart,ystart);  
        ctx.lineTo(xend,yend);
        ctx.stroke();
        ctx.closePath();
      }
    </script>
</head>
<body onload="init()">
  <br/><br/>
  <center>
  <canvas id="MyCanvasArea" width="320" height="200"  style="border:3px solid brown;">
  </canvas>
  </center>
</body>
</html>

How it works...

The properties related to the shadow mentioned in the previous recipe are used here. Here the shadow is applied to the line rather than the text. Thus, shadows can be applied to objects.

There's more...

Try the following:

  • Change the shadow color

  • Change the blur value for the shadow

  • Change the shadowOffsetX and shadowOffsetY value