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Canvas Cookbook

By : Purushottam Joshi

Canvas Cookbook

By: Purushottam Joshi

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.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Sections

Conventions

Reader feedback

Customer support

Free Chapter

1. Paths and Text

1. Paths and Text

Introduction

Drawing lines

Drawing horizontal, vertical, and assorted lines

Drawing joins

Drawing arc1

Drawing arc2

Drawing a quadratic curve

Drawing a rainbow

Drawing a Bezier curve

Drawing a flag

Drawing text

Drawing 3D text with shadows

Adding shadows to objects

Drawing a house

2. Shapes and Composites

2. Shapes and Composites

Introduction

Drawing rectangles

Drawing triangles

Drawing circles

Drawing gradients

Working with custom shapes and styles

Demonstrating translation, rotation, and scaling

Drawing an ellipse

Saving and restoring canvas state

Demonstrating composites

Drawing a mouse

3. Animation

3. Animation

Introduction

Creating an animation class

Demonstrating acceleration

Demonstrating gravity

Animating a line

Animating text

Animating a clock

Animating a solar system

Animating particles

Animating a particle fountain

Animating a rain effect

Animating a snow effect

4. Images and Videos

4. Images and Videos

Introduction

Drawing and cropping an image

Rendering effects to images

Drawing a mirror image

Clipping a path

Animated clipping

Converting canvas to image and back to canvas

Working with videos

Rendering effects to videos

Creating a pixelated image focus

5. Interactivity through Events

5. Interactivity through Events

Introduction

Working with mouse coordinates

Making a face smile

Detecting a point in a path

Simulating car movements

Dragging and dropping

Combining events and animation

Demonstrating a touch event

6. Creating Graphs and Charts

6. Creating Graphs and Charts

Introduction

Drawing the axes

Drawing a simple equation

Drawing a sinusoidal wave

Drawing a line graph

Drawing a bar graph

Drawing a pie chart

7. 3D Modeling

7. 3D Modeling

Introduction

Rendering 3D objects

Drawing 3D cubes

Drawing a 3D cylinder and a cone

Drawing a 3D sphere and a torus

Drawing 3D text decorated by particles

Drawing a panorama

Drawing a snowman

8. Game Development

8. Game Development

Introduction

Understanding the gaming states

Drawing on canvas

Playing some music

Using sprites from the sprite sheet

Demonstrating animation

Demonstrating collision

Demonstrating physics

Game 1 – Fruit Basket

Game 2 – Catapult

9. Interoperability and Deployment

9. Interoperability and Deployment

Introduction

Understanding interoperability

Styling text and background using CSS

Deploying a game on Android mobile

Index

Index

Customer Reviews

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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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