PHP drawing technology examples explained

Learn vector pictures (verification codes), draw and generate reports. Hope this article can help everyone.

Steps

创建画布
会只需要的各种图形(圆，直线，矩形，弧线，扇形)
输出图像到网页，也可以另存
销毁图片(释放内存)

Picture format

gif 图片压缩率高，
但是只能显示256色可能造成颜色丢失，但可以显示动画

jpg/jpeg 图片的压缩率高，可以用较小的文件来显示
网页上用的比较多

png，高仿真
综合了gif和jpg的优势，但是不能显示动画

Quick Start

创建画布$img = imagecreatetruecolor(100,100);

取色$red = imagecolorallocate($img, 255, 0, 0);

画图
•imagefilledarc — 画一椭圆弧且填充
•imagefilledellipse — 画一椭圆并填充
•imagefilledpolygon — 画一多边形并填充
•imagefilledrectangle — 画一矩形并填充

输出到浏览器header("content-type: image/png");
imagepng($img);

销毁
imagedestroy($img);

Picture to canvas

$srcImage = imagecreatefromgif(filename);$srcImage_info = getimagesize(filename);
imagecopy(dst_im, src_im, dst_x, dst_y, 
    src_x, src_y, src_w, src_h);
具体参数含义 不懂看文档

Writing

imagettftext(image, size, angle, x, y, 
    color, fontfile, text)

Generate verification code

<?php     /**
    * Created by PhpStorm.
    * User: draymonder
    * Date: 2018/3/1
    * Time: 15:15
    */
    $checkcode ="";    for($i=0;$i<4;$i++){        $checkcode.= dechex(rand(0,15));
    }    $img = imagecreatetruecolor(200,30);    //背景颜色
    $bgcolor = imagecolorallocate($img,0,0,0);
    imagefill($img,0,0,$bgcolor);    //添加干扰线
    for($i=0;$i<10;$i++){        $color = imagecolorallocate($img,rand(0,255),rand(0,255),rand(0,255));
        imageline($img,rand(0,200),rand(0,30),rand(0,200),rand(0,30),$color);
    }    //白色，字体颜色
    $white = imagecolorallocate($img,255,255,255);    //添加字符串
    imagestring($img,rand(4,6),rand(0,180),rand(0,20),$checkcode,$white);
    header("content-type: image/png");
    imagepng($img);
    imagedestroy($img);
?>

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