Introduction

In this article, we are going to understand joining lines using an HTML 5 canvas. In this section, to set the line join style of an HTML5 Canvas path, we can use the lineJoin context property. Paths can have one of the three-line joins: miter, round, or bevel. Unless otherwise specified, the HTML5 Canvas line join property is defaulted with the miter style.
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 CanvasLineJoining 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
0000.jpg
This is where we will create an HTML5 application.
canvasliine1.gif
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
  1. <style>
  2. body
  3. {
  4. margin: 0px;
  5. padding: 0px;
  6. }
  7. Canvas
  8. {
  9. border: 2px solid #9C9898;
  10. margin-top: 50px;
  11. margin-left: 50px;
  12. background-color: #F4D19F;
  13. box-shadow: 5px 5px 8px #222;
  14. }
  15. .title
  16. {
  17. text-align: center;
  18. font-family: Segoe UI Light, Arial, Helvetica;
  19. font-size: 2.2em;
  20. margin: 1em;
  21. }
  22. .info
  23. {
  24. text-align: center;
  25. font-family: Segoe UI Light, Arial, Helvetica;
  26. font-size: 1.2em;
  27. margin: 0.25em;
  28. }
  29. </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 CanvasLineJoining application.
The whole JavaScript looks as in the following:
  1. <script>
  2. window.onload = function ()
  3. {
  4. var canvas = document.getElementById("myCanvas");
  5. var context = canvas.getContext("2d");
  6. // miter line joine (left)
  7. context.beginPath();
  8. context.moveTo(canvas.width / 2 - 50 - 140, canvas.height - 50); // line 1
  9. context.lineTo(canvas.width / 2 - 140, 50); // line 1
  10. context.lineTo(canvas.width / 2 + 50 - 140, canvas.height - 50); // line 1
  11. context.lineWidth = 25;
  12. context.lineJoin = "miter";
  13. context.stroke();
  14. // round line join (middle)
  15. context.beginPath();
  16. context.moveTo(canvas.width / 2 - 50, canvas.height - 50); // line 1
  17. context.lineTo(canvas.width / 2, 50); // line 1
  18. context.lineTo(canvas.width / 2 + 50, canvas.height - 50); // line 1
  19. context.lineWidth = 25;
  20. context.lineJoin = "round";
  21. context.stroke();
  22. // bevel line join (right)
  23. context.beginPath();
  24. context.moveTo(canvas.width / 2 - 50 + 140, canvas.height - 50); // line 1
  25. context.lineTo(canvas.width / 2 + 140, 50); // line 1
  26. context.lineTo(canvas.width / 2 + 50 + 140, canvas.height - 50); // line 1
  27. context.lineWidth = 25;
  28. context.lineJoin = "bevel";
  29. context.stroke();
  30. };
  31. </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 Default.aspx page. Here we pass a Canvas in the canvas tag.
  1. <body style="background-color: #C9E0E6">
  2. <center>
  3. <h1>
  4. Canvas Line Joining In HTML 5
  5. </h1>
  6. </center>
  7. <hr />
  8. <canvas id="myCanvas" width="578" height="200">
  9. </canvas>
  10. </body>
Step 5: The complete code for the CanvasLineJoining application.
  1. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  3. <html xmlns="http://www.w3.org/1999/xhtml">
  4. <head runat="server">
  5. <style>
  6. </style>
  7. <script>
  8. </script>
  9. </head>
  10. <body style="background-color: #C9E0E6">
  11. <center>
  12. <h1>
  13. Canvas Line Joining In HTML 5
  14. </h1>
  15. </center>
  16. <hr />
  17. <canvas id="myCanvas" width="578" height="200">
  18. </canvas>
  19. </body>
  20. </html>
Step 6: Output Press F5 Note: For the accurate output of HTML5 applications, you must have the Google Chrome browser on your PC. Here the Canvas line joining displays when the application runs on the browser.
canvasline.gif
Here are some useful resources