How to create canvas in HTML5?


In web pages, canvas does not exist by default. Users need to create a canvas first, and then draw patterns in the canvas through some objects and methods. The following steps will explain how to use the canvas.

1. Create canvas

Using the canvas tag in HTML5, you can create a canvas in a web page. The basic syntax for creating a canvas is as follows.


In the above syntax format, the canvas tag is used to define the canvas, and the ID attribute is used to reference the canvas in JavaScript code. Canvas tag is a double tag, users can enter text in the middle, when the browser does not support canvas tag, the text information will be displayed. Canvas has two attributes, width and height, which are used to define the width and height of the canvas. The values can be numbers or pixels.

The created canvas is transparent without any style. You can use CSS to set its border, background, etc. It should be noted that when setting the width and height of the canvas, try not to use CSS style to control its width and height, otherwise the pattern in the canvas may be deformed.

2. Get the canvas

To control the canvas in JavaScript, you first need to get the canvas. The getelementbyid () method is used to get thegameA canvas object in a web page. For example, the following example Code is to get the canvas with ID “Cavs” and save the obtained canvas object in the variable “canvas”.

3. Prepare the brush

After having the canvas, to start drawing, you need to prepare a brush, which is the context object. The context object is also known as the drawing environment, through which you can draw graphics in the canvas. The context object can be obtained by JavaScript script, and the specific syntax is as follows:

In the above syntax, the parameter “2D” represents the type of brush and represents the brush of two-dimensional drawing. If you draw three-dimensional graphics, you can replace the parameter with “webgl”. Because three-dimensional operation is not widely used, you can understand it here.

In JavaScript, we usually define a variable to hold the obtained context object, such as the following code.