Php circle drawing method

This article describes how to draw a circle in php. It analyzes in detail the basic steps and implementation methods of drawing a circle in php. For more information, see

This article describes how to draw a circle in php. It analyzes in detail the basic steps and implementation methods of drawing a circle in php. For more information, see

This example describes how to draw a circle in php. Share it with you for your reference. The specific implementation method is as follows:

The basic steps for php plotting are as follows: (the extension = php_gb2.dll component in php. ini must be enabled first)

1. Create a canvas;

2. Draw the desired image (circle, straight line, rectangle, slice, arc .......);

3. output to a webpage or save it as another one;

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

Three most common image formats for website development: gif, jpg/jpeg, and png

(1) gif format: the maximum compression rate, but only 256 colors can be displayed, which may cause color loss. Advantage: animated images may be displayed.

(2) jpg/jpeg format: the compression ratio is also relatively high (lossy compression, may also lose some colors), and many web pages are used.

(3) png format: combining the advantages of gif and jpg, it cannot display animated images. High Fidelity, support lossless compression, and the best color storage, relatively larger than jpg/jpeg.

Php draws a circle with the following code:

The Code is as follows:

<? Php
// 1. Create a canvas
$ Im = imagecreatetruecolor (300,200); // create a real-color image. The default background is black and the image identifier is returned. Another function, imagecreate, is not recommended.
// 2. Draw the desired image
$ Red = imagecolorallocate ($ im, 255, 0, 0); // create a color for use
Imageellipse ($ im, 30, 40, 40, $ red); // draw a circle. Parameter description: 30, 30 is the center coordinate of the circle; 40, 40 is the width and height, when not the same as the elliptical; $ red is the circle color (Box color)
// 3. output image
Header ("content-type: image/png ");
Imagepng ($ im); // output to the page. If the second parameter [, $ filename] exists, the image is saved.
// 4. Destroy images and release memory
Imagedestroy ($ im );
?>

I hope this article will help you with php programming.