How to draw a circle in php?

This article mainly introduces the method of drawing a circle in PHP, and analyzes in detail the basic steps of drawing graphics in PHP and the implementation method of drawing a circle. Friends in need can refer to it

The examples in this article describe PHP How to draw a circle. Share it with everyone for your reference. The specific implementation method is as follows:

phpBasic steps for drawing, there are four steps (the extension = php_gb2.dll component in php.ini needs to be enabled first)

1. Create a canvas;

2. Draw the required image (circle, straight line, rectangle, sector, arc...);

3 , output to the web page, or save as another;

4. Destroy the image (the purpose is to release the memory occupied by the image).

The three most commonly used image formats for website development: gif, jpg/jpeg, png

(1) Gif format: has the highest compression rate, but can only display 256 colors, which may cause color distortion lost. Advantages: Possibility to display animated images.

(2) jpg/jpeg format: The compression rate is also relatively high (lossy compression will also lose some colors), and it is often used on web pages.

(3) png format: It combines the advantages of gif and jpg, but it cannot display animated images. High fidelity, supports lossless compression, has the best color preservation, and is relatively larger than jpg/jpeg.

php draws a circle, the code is as follows:

The code is as follows:

<?php
//1、创建画布
$im = imagecreatetruecolor(300,200);//新建一个真彩色图像，默认背景是黑色，返回图像标识符。另外还有一个函数 imagecreate 已经不推荐使用。
//2、绘制所需要的图像
$red = imagecolorallocate($im,255,0,0);//创建一个颜色，以供使用
imageellipse($im,30,30,40,40,$red);//画一个圆。参数说明：30，30为圆形的中心坐标；40，40为宽和高，不一样时为椭圆；$red为圆形的颜色（框颜色）
//3、输出图像
header("content-type: image/png");
imagepng($im);//输出到页面。如果有第二个参数[,$filename],则表示保存图像
//4、销毁图像，释放内存
imagedestroy($im);
?>

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