PHP GD库生成验证码

1.引入GD库，在php.ini中吧extension=php_gd2.dll中把前面；去掉。print_r(gd_info());打印出来相关信息。

 

学GD库重在理解，1.画图的过程    2,计算机的坐标体系

 

 

GD库画图典型流程

1.创建画布    imagecreatetruecolor();

也可以打开一张图片作画布 imagecreatefromjpeg($path);

2.创建颜料 imagecolorcate();

3.画图泼墨渲染 imagefill();

画直线 imageline()

4.保持 imagepng()    imagejpeg()     imagegif();

5.销毁画布，释放资源 imagedestroy($img);

 

 一些基本操作

代码如下：

<?php 
    // //创建画布
    // $width = 500;
    // $height = 300;
    // $img = imagecreate($width, $height);

    // //画笔颜色设置
    // $red = imagecolorallocate($img, 255, 0,0);
    // $orange = imagecolorallocate($img,255,125,0);
    // $yellow = imagecolorallocate($img,255,255,0);
    // $green = imagecolorallocate($img,0,255,0);
    // $blue = imagecolorallocate($img,0,0,255);
    // $indigo = imagecolorallocate($img,0,255,255);
    // $purple = imagecolorallocate($img,255,0,255);

    // $x1 = 0;
    // $y1 = 0;
    // $x2 = 5;
    // $y2 = 5;

    // imagefill($img,$x1,$y1,$green);

    // imageline($img, $x1, $y1, $x2, $y2, $orange);

    /*
    * 绘制椭圆
    */

    $width = 500;
    $height = 300;
    //产生画布
    $img = imagecreate($width, $height);

    //设置颜色
    $orange = imagecolorallocate($img, 255, 125, 0);
    $red = imagecolorallocate($img, 255, 0, 0);
    $green = imagecolorallocate($img, 0, 255, 0);
    //画布背景
    $x2 = 500;
    $y2 = 300;
    imagefill($img, $x2, $y2, $orange);

    //绘制圆1
    $cx = 100;
    $cy = 60;
    $w = 80;
    $h = 80;
    imageellipse($img, $cx, $cy, $w, $h, $green);

    //绘制圆2
    $cx2 = 400;
    $cy2 = 60;
    $w2 = 80;
    $h2 = 80;
    imageellipse($img, $cx2, $cy2, $w2, $h2, $green);

    //绘制多边形
    $points = array(
        250,100,
        300,150,
        200,150
        );
    $num_points = count($points)/2;
    imagepolygon($img, $points, $num_points, $green);

    //绘制圆弧
    $cx3 = 250;
    $cy3 = 200;
    $w3 = 200;
    $h3 = 150;
    $s3 = 5;
    $e3 = 175;
    imagearc($img, $cx3, $cy3, $w3, $h3, $s3, $e3, $green);

    header("Content_type: image/png");
    imagepng($img);        //输出图像
    imagedestroy($img);        //释放与图像相关联的内存
 ?>

 

 

 

生产随机验证码

代码如下

<?php 
    $rand_num = rand();        //生成随机数
    $str = md5($rand_num);  //取得该数md5值

    $num_code = 5;        //验证码字符数
    $str_code = substr($str, 0, $num_code);     //从md5截取字符串作为验证码

    $width = 120;        //验证码图片宽度
    $height = 55;        //高度
    $img = imagecreate($width, $height);    //创建图像句柄

    $bg_color = imagecolorallocate($img, 255, 255, 255);      //背景色
    $border_color = imagecolorallocate($img, 0, 0, 0);        //前景色
    imagerectangle($img, 0, 0, $width-1, $height-1, $border_color);    //绘制边框


    //随机字体颜色
    for ($i=0; $i < $num_code; $i++) { 
        # code...
        $str_color = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255));
        $font_size = 10;
        $str_x = floor( ($width / $num_code) * $i ) + rand(0,5);
        $str_y = rand( 2,$height - 15 );
        imagestring($img, $font_size, $str_x, $str_y, $str_code[$i], $str_color);
    }

    //绘制随机干扰点颜色
    $num_disturb_points = 200;
    for ($i=0; $i < $num_disturb_points; $i++) { 
        # code...
        $point_color = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255));
        $point_x = rand(2,$width - 2);
        $point_y = rand(2,$height - 2);
        imagesetpixel($img, $point_x, $point_y, $point_color);
        
    }

    //绘制随机颜色直线
    $line = 5;
    for ($i=0; $i < $line; $i++) { 
        # code...
        $line_color = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255));
        $line_x1 = rand(2,$width - 2);
        $line_y1 = rand(2,$height - 2);
        $line_x2 = rand(2,$width - 2);
        $line_y2 = rand(2,$height - 2);
        imageline($img, $line_x1, $line_y1, $line_x2, $line_y2, $line_color);
    }
    

    header("Content-type: image/png");        //发送header信息
    imagepng($img);            //输出图像
    imagedestroy($img);        //释放与图像关联内存
 ?>