PHP development verification code creation canvas

Everyone should pay attention, when learning to make verification codes, we need to open the manual

The function of making verification codes is relatively long

imagecreatetruecolor(); Create a canvas, let’s see below His syntax

Syntax:

resource imagecreatetruecolor (int $width, int $height)

Description: Return a Image identifier, width is $width and height is $height

Returns the image resource after success, returns FALSE after failure.

After we create a canvas, we need to assign a color to the canvas

imagecolorallocate

Syntax:

int imagecolorallocate ( resource $image , int $red , int $green , int $blue );

The first parameter,returns a resource type, and the subsequent parameters are in RGB format Color

How to output the image

header("content-type:image/png");
imagepng($image);

Destroy resources

<?php
    //第一步 创建一个画布
    $image = imagecreatetruecolor(100, 30); //创建一个宽为100高为30的黑色图像
    $bgcolor = imagecolorallocate($image, 255, 0, 0); //为图像分配颜色
    imagefill($image,0,0,$bgcolor); //给黑色的背景图像分配白色

    //输出图像
    header("content-type:image/png");
    imagepng($image);

    //销毁资源
    imagedestroy($img);

?>