Detailed explanation of the latest and most complete PHP verification code generation code (recommended), detailed explanation of verification code

Detailed explanation of the latest and most complete PHP verification code generation code (recommended), detailed explanation of verification code

1.0 First, look at the code

<&#63;php
header("Content-Type:text/html;Charset=UTF-");// 设置页面的编码风格
header("Content-Type:image/jpeg");// 通知浏览器输出的是jpeg格式的图像
$img = imagecreatetruecolor(,);//创建画布并设置大小 x轴 y轴
$bgcolor = imagecolorallocate($img, mt_rand(,), mt_rand(,), mt_rand(,));//分配背景颜色
imagefill($img, , , $bgcolor); ////把背景填充到图像
imagejpeg($img); // 输出图像
imagedestroy($img); // 销毁图像
&#63;> 

Okay, now combine the above code to analyze the functions used above:

① Imagecreatetruecolor();

imagecreatetruecolor — Create a new true color image (it feels so long, but it’s actually easy to remember if you look carefully image/create/true/color, what is a true color image? Read on)

resource imagecreatetruecolor ( int $width , int $height )

Both functions imagecreatetruecolor() and imagecreate() can create canvases

resource imagecreate ( int $x_size , int $y_size ) 

imagecreatetruecolor() creates a black image with sizes x and y (the default is black [even if it is called a true color image]), if you want to change the background color, you need to

Use the fill color function imagefill($img,0,0,$color);

imagecreate creates a new blank image resource and uses imagecolorAllocate() to add a background color

The above two functions are just two methods of the same function

②　imagecolorallocate();

imagecolorallocate — Assign a color to an image

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

The colors are a combination of red, green and blue. These parameters are integers from 0 to 255 or hexadecimal 0x00 to 0xFF.

③　mt_rand();

mt_rand — generate better random numbers

int mt_rand ( int $min , int $max )

$min Optional, the minimum value returned (default: 0) $max Optional, the maximum value returned (default: mt_getrandmax())
This is used to randomly generate the background color, with any value from 0-255. Therefore, the canvas background color is different even if the page is refreshed. Rendering:

2.0 Start making interference lines and interference points inside. Prevent verification images from being recognized in seconds

<&#63;php
header("Content-Type:text/html;Charset=UTF-");// 设置页面的编码风格
header("Content-Type:image/jpeg");// 通知浏览器输出的是jpeg格式的图像
$img = imagecreatetruecolor(,);//创建画布并设置大小 x轴 y轴
$bgcolor = imagecolorallocate($img, mt_rand(,), mt_rand(,), mt_rand(,));//分配背景颜色
//添加干扰线，并循环次，背景颜色随机
for($i=;$i<;$i++){
$linecolor = imagecolorallocate($img,mt_rand(,),mt_rand(,),mt_rand(,));
imageline($img, mt_rand(,), mt_rand(,), mt_rand(,), mt_rand(,), $linecolor);
}
//添加干扰点，并循环次，背景颜色随机
for($i=;$i<;$i++){
$dotcolor = imagecolorallocate($img, mt_rand(,), mt_rand(,), mt_rand(,));
imagesetpixel($img, mt_rand(,), mt_rand(,), $dotcolor);
}
imagefill($img, , , $bgcolor); ////把背景填充到图像
imagejpeg($img); // 输出图像
imagedestroy($img); // 销毁图像
&#63;> 

Function analysis:

① imageline();

imageline — draw a line segment

bool imageline ( resource $image , int $x1 , int $y1 , int $x2 , int $y2 , int $color ) 

imageline() draws a line segment in the image image from coordinates x1, y1 to x2, y2 (the upper left corner of the image is 0, 0) using color color.

imageline($img, mt_rand(0,150), mt_rand(0,50), mt_rand(0,150), mt_rand(0,50), $linecolor); This means from coordinates x1, y1 to x2 in canvas $img ,y2random

②　imagesetpixel();

imagesetpixel—draw a single pixel

bool imagesetpixel ( resource $image , int $x , int $y , int $color )

imagesetpixel() draws a point in the image image at the x, y coordinates (the upper left corner of the image is 0, 0) using the color color.

imagesetpixel($img, mt_rand(0,150), mt_rand(0,60), $dotcolor);具体含义同上 

Rendering:

3.0 Add verification alphanumeric

<&#63;php
header("Content-Type:text/html;Charset=UTF-");// 设置页面的编码风格
header("Content-Type:image/jpeg");// 通知浏览器输出的是jpeg格式的图像
$img = imagecreatetruecolor(,);//创建画布并设置大小 x轴 y轴
$bgcolor = imagecolorallocate($img, mt_rand(,), mt_rand(,), mt_rand(,));//分配背景颜色
//添加干扰线，并循环次，背景颜色随机
for($i=;$i<;$i++){
$linecolor = imagecolorallocate($img,mt_rand(,),mt_rand(,),mt_rand(,));
imageline($img, mt_rand(,), mt_rand(,), mt_rand(,), mt_rand(,), $linecolor);
}
//添加干扰点，并循环次，背景颜色随机
for($i=;$i<;$i++){
$dotcolor = imagecolorallocate($img, mt_rand(,), mt_rand(,), mt_rand(,));
imagesetpixel($img, mt_rand(,), mt_rand(,), $dotcolor);
}
//添加需要验证的字母或者数字
$rand_str = "qwertyuiopasdfghjklzxcvbnm";//需要使用到验证的一些字母和数字
$str_arr = array(); //命名一个数组
for($i = ;$i<;$i++){ //循环次，就是有四个随机的字母或者数字 
$pos = mt_rand(,strlen($rand_str)-);
$str_arr[] = $rand_str[$pos];//临时交换
}
$x_start=/;//单个字符X轴位置
foreach ($str_arr as $key) {
$fontcolor = imagecolorallocate($img, mt_rand(,), mt_rand(,), mt_rand(,));
imagettftext($img, , mt_rand(-,), $x_start, /, $fontcolor, "C:/Windows/Fonts/Verdana.TTF", $key);
$x_start +=;//遍历后单个字符沿X轴 +
}
imagefill($img, , , $bgcolor); ////把背景填充到图像
imagejpeg($img); // 输出图像
imagedestroy($img); // 销毁图像
&#63;> 

Function:

imagettftext();

imagettftext — Write text to an image using TrueType fonts

array imagettftext ( resource $image , float $size , float $angle , int $x , int $y , int $color , string $fontfile , string $text ) 

Analyze the code below:

imagettftext($img, 25, mt_rand(-15,15), $x_start, 50/2, $fontcolor, "C:/Windows/Fonts/Verdana.TTF", $key); 

$img----------canvas

25----------The size of the font.

mt_rand(-15,15)----------The angle expressed in the angle system, 0 degrees means text read from left to right. Higher values ​​indicate counterclockwise rotation. For example, 90 degrees represents text that reads from bottom to top. (It’s just a matter of font angle,)

$x_start----------In simple terms, it is the X-axis position of the character

50/2----------Character height

$fontcolor----------Character color

"C:/Windows/Fonts/Verdana.TTF"----------Character font style path

$key----------traverse the following characters

Effect:

The above content is the entire description of the latest and most complete PHP code generation and production verification code detailed (recommended) introduced in this article. I hope it will be helpful to everyone!