php method to automatically generate verification codes: [session_start(); $width = 150; $height = 40; $image = imagecreatetruecolor($width, $height);$bgcol...].
The operating environment of this article: windows10 system, php 7, thinkpad t480 computer.
Nowadays, verification codes are used more and more in forms, but it is always inconvenient to implement it with js, so I use php to implement it and record it here.
Of course, we can also encapsulate it into a function, which is very convenient for future use. It is not encapsulated here, and interested friends can encapsulate it by themselves.
Specific implementation code:
Create a new cap_sz.php file:
<?php
session_start(); //设置session,一定要在顶部
$width = 150; //设置图片宽为300像素
$height = 40; //设置图片高为40像素
$image = imagecreatetruecolor($width, $height); //设置验证码大小的函数
$bgcolor = imagecolorallocate($image, 255, 255, 255); //验证码颜色RGB为(255,255,255)#ffffff
imagefill($image, 0, 0, $bgcolor); //区域填充
$cap_code = "";
for($i=0;$i<4;$i++){
$fontsize = 7; //设置字体大小
$fontcolor = imagecolorallocate($image, rand(0,120), rand(0,120), rand(0,120));
//数字越大，颜色越浅，这里是深颜色0-120
$fontcontent = rand(0,9);
$cap_code.=$fontcontent; //.=连续定义变量
$x = ($i*150/4)+rand(5,10);
$y = rand(5,10);
//设置坐标
imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);
}
$_SESSION['code'] = $cap_code; //存到session
//设置干扰元素，设置雪花点
for($i=0;$i<300;$i++){
$inputcolor = imagecolorallocate($image, rand(50,200), rand(20,200), rand(50,200));
//设置颜色，20-200颜色比数字浅，不干扰阅读
imagesetpixel($image, rand(1,149), rand(1,39), $inputcolor);
//画一个单一像素的元素
}
//增加干扰元素，设置横线(先设置线的颜色，在设置横线)
for ($i=0;$i<4;$i++) {
$linecolor = imagecolorallocate($image, rand(20,220), rand(20,220),rand(20,220));
//设置线的颜色
imageline($image, rand(1,149), rand(1,39), rand(1,299), rand(1,149), $linecolor);
}
//因为有些浏览器，访问的content-type会是文本型（乱码），所以我们需要设置成图片的格式类型
header('Content-Type:image/png');
imagepng($image); //建立png函数
imagedestroy($image); //结束图形函数，消除$imageThen create a new index.php for verification
<?php
header("Content-Type: text/html;charset=utf-8");
if (isset($_REQUEST['code'])){
session_start();
if ($_REQUEST['code'] == $_SESSION['code']){
echo "输入正确";
}else{
echo "输入错误，请重新输入";
}
exit();
}
?>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> //这里不能少，不然乱码
<title>验证码测试</title>
</head>
<body>
<form>
<p>验证码:<img src="/static/imghwm/default1.png" data-src="cap_sz.php" class="lazy" onClick="this.src='cap_sz.php?nocache='+Math.random()" style="max-width:90%" alt="点击换一张"/>点击图片可更换验证码</p>
<p>请输入图片中的内容:<input type="text" name="code" value=""/></p>
<p><input type="submit" width="20px" height=19px value="提交"></input></p>
</form>
</body>
</html> Recommended learning: phptraining
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