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Canvas Cookbook

You're reading from   Canvas Cookbook Over 80 simple but creative and structured recipes to explore the capabilities of HTML5 Canvas

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Product type Paperback
Published in May 2019
Publisher
ISBN-13 9781785284892
Length 254 pages
Edition 1st Edition
Languages
Tools
Concepts
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Toc

Table of Contents (11) Chapters Close

Preface 1. Paths and Text 2. Shapes and Composites FREE CHAPTER 3. Animation 4. Images and Videos 5. Interactivity through Events 6. Creating Graphs and Charts 7. 3D Modeling 8. Game Development 9. Interoperability and Deployment 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:

Adding shadows to objects

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
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