HTML Canvas 变得简单：初学者指南。-js教程-PHP中文网

HTML Canvas 变得简单：初学者指南。

Mary-Kate Olsen

发布： 2024-12-20 13:38:10

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？简介

HTML 是一个带有标签

HTML Canvas Made Simple: A Guide for Beginners.

HTML

绘制形状和线条：它可以绘制形状、图案和线条，包括为对象添加颜色和渐变。
动画和交互：
图像操作：这可用于调整图像大小或裁剪图像。
游戏图形：游戏开发者也用它来创建漂亮的游戏用户界面
数据可视化：用于创建图形和图表。

?开始

HTML

<!doctype html>
   <html lang="en">
     <head>
       <meta charset="UTF-8" />
       <meta name="viewport" content="width=device-width, initial-scale=1.0" />
       <title>HTML Canvas Example</title>
     </head>
     <body>
       <canvas>



<p>Then we add a script tag so we can define the behavior of the object.<br>
</p>

<pre class="brush:php;toolbar:false"><!doctype html>
   <html lang="en">
     <head>
       <meta charset="UTF-8" />
       <meta name="viewport" content="width=device-width, initial-scale=1.0" />
       <title>HTML Canvas Example</title>
     </head>
     <body>
       <canvas>



<p>Wowu !!! We get the output.</p>

<p><img src="https://img.php.cn/upload/article/000/000/000/173467309470040.jpg" alt="HTML Canvas Made Simple: A Guide for Beginners."></p>

<p>Looking at the structure of the code. We define canvas wrapper having an id attribute, this is can only be done by id and not class because of uniqueness which is used to reference the canvas with the id name.<br>
To access this we need to retrieve the node created in the Document Object Model(DOM) by using the getElementById("myCanvas") and have access to it using the getContext("2d") method.</p>

<p>This method make us to have access to different drawing methods like</p>

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fillRect(x, y, width, height): This method is to draw a filled rectangle at a position(x, y) with a specified width and height.
fillStyle = colorName: It is a property to set the color for the object. It could be a colorname, RGB or hex code for the object.

Other methods are:

strokeRect(x, y, width, height): This method to to make a outline stroke on the rectangle, this may be used independently or combined with fillStyle and fillRect(x, y, width, height).
clearRect(x, y, width, height): to clear the rectangle by making it transparent.

HTML Canvas Made Simple: A Guide for Beginners.

? Drawing basics

Different shapes and lines can be drawn using some specific methods depending on the object.

1. Path:

Examples are line, wavy line, zigzag e.t.c

HTML Canvas Made Simple: A Guide for Beginners.

For creating a line, the following method needs to be set up:

beginPath(): This method is to start a new path for a drawing.
moveTo(x, y): This is to move the drawing to the specified points.
lineTo(x, y): This is to draw from the current position to the specified points.
stroke(): This is to draw the line.

HTML Canvas Made Simple: A Guide for Beginners.

2. Rectangle and Square

Rectangle

HTML Canvas Made Simple: A Guide for Beginners.

Square

HTML Canvas Made Simple: A Guide for Beginners.

These following methods are used in creating a rectangle or square:

fillRect: this method is for create rectangle and square only.
clearRect(x, y, width, height): this method is to clear rectangle hence making it transparent.
strokeRect(x, y, width, height): is used to create an outline rectangle or square.
fillStyle: this is used to fill the container of the rectangle or square.
strokeStyle: this method is for add stroke color to an outline rectangle.
roundRect(x, y, width, height, radii): this method is for creating round border rectangle.

3. Circle

HTML Canvas Made Simple: A Guide for Beginners.
These following methods are used in creating a circle:

beginPath(): this method to begin a path.
arc(x, y, radius, startAngle, endAngle, anticlockwise): this is for to create circle where x and y is for center coordinate of the center, radius is the radius of the circle, startAngle and endAngle which is an angle for the circle.

4. Polygon

To create a polygon, you need to determine the sides of the shape, it could be a triangle(3 sides), pentagon (5 sides), hexagon(6 sides) or decagon (10 sides).

HTML Canvas Made Simple: A Guide for Beginners.