How to draw a circle in php, how to draw a circle in php_PHP tutorial

How to draw a circle in php, how to draw a circle in php

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

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

1. Create canvas;

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

3. Output to the web page, or save as another file;

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 loss. Advantage: 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:

Copy code The code is as follows:

//1. Create canvas
$im = imagecreatetruecolor(300,200);//Create a new true color image, the default background is black, and return the image identifier. There is also a function imagecreate that has been deprecated.
//2. Draw the required image
$red = imagecolorallocate($im,255,0,0);//Create a color for use
imageellipse($im,30,30,40,40,$red);//Draw a circle. Parameter description: 30, 30 are the center coordinates of the circle; 40, 40 are the width and height, if they are different, it is an ellipse; $red is the color of the circle (frame color)
//3. Output image
header("content-type: image/png");
imagepng($im);//Output to the page. If there is a second parameter [,$filename], it means saving the image
//4. Destroy the image and release memory
imagedestroy($im);
?>

I hope this article will be helpful to everyone’s PHP programming design.

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