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How to implement hollow square in javascript

PHPz

Release： 2023-04-27 10:33:01

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In web development, we often need to use graphics to enrich the display effect of the page, among which the square is one of the simplest and most basic graphics. If we want to achieve a hollow square, we can do it by writing simple code in JavaScript.

The following will show you how to use JavaScript to implement a hollow square.

Create HTML file

First, you need to create an HTML file to implement the basic framework of the page. The code is as follows:

<!DOCTYPE html>
<html>
<head>
    <title>JavaScript实现空心正方形</title>
    <meta charset="UTF-8">
</head>
<body>
    <canvas id="canvas"></canvas>
</body>
<script src="script.js"></script>
</html>

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Here, we use the HTML5 canvas tag to draw graphics, with the id "canvas". This tag will be referenced in the JavaScript script.

Write JavaScript script

Next, we need to write a JavaScript script to realize the function of drawing hollow squares and introduce it into the HTML file.

In the script file, we need to obtain the canvas object and set its width and height for use in the subsequent drawing process.

The code is as follows:

var canvas = document.getElementById("canvas");
canvas.width = 500;
canvas.height = 500;

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Next, we need to get the context object "ctx" of canvas in order to draw graphics on it.

The code is as follows:

var ctx = canvas.getContext("2d");

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Next, we need to write a function to draw a hollow square.

The code is as follows:

function drawSquare(x, y, sideLength) {
  ctx.beginPath();
  ctx.moveTo(x, y);
  ctx.lineTo(x + sideLength, y);
  ctx.lineTo(x + sideLength, y + sideLength);
  ctx.lineTo(x, y + sideLength);
  ctx.closePath();
  ctx.stroke();
}

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In this function, we first use the beginPath() method to open a new path, then use the moveTo() method to move the brush to the starting point, and then use lineTo( ) method to connect the straight line, draw the four sides of the square, and finally use the closePath() method to connect the last line segment and close the path. Use the stroke() method to draw the border.

Next, we need to call this function to draw the actual hollow square. The code is as follows:

drawSquare(100, 100, 300);

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Here, we set the starting point of the hollow square to (100,100) and the side length to 300. This will draw a 300×300 square on the canvas.

Open the HTML file and you will see the hollow square drawn.

Summary

In this article, we introduced how to implement a hollow square using JavaScript. This method works not only for drawing squares, but also for drawing other types of polygons. In actual projects, we usually need to draw a variety of graphics to display different information, so mastering these basic drawing skills is very important for us to develop excellent page effects.

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