


Detailed explanation of the latest and most complete PHP code to generate verification code (recommended), detailed explanation of verification code_PHP tutorial
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
<?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 ?>
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
<?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 ?>
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
<?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 ?>
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!

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