作者:旧梦半分_399 | 来源:互联网 | 2020-08-05 16:31
php设计验证码的过程是:首先使用imagecolorallocate()创建画布分配颜色;然后通过imagefill()等函数完成绘画过程;接着使用imagepng()函数输出图像;最后通过imagedestroy()函数销毁图片即可。
简述php设计验证码的过程
php使用GD库生成验证码
一、绘图步骤:
1.创建画布,分配颜色,使用以下两个函数(可以在php手册GD库函数中找到):
imagecreatetruecolor()
imagecolorallocate()
2.绘画过程:
imagefill()
imagettftext()
imagesetpixel()
imageline()
3.输出图像:
header(“Content-Type:image/png”);
imagepng();
imagejpeg();
4.销毁图片(释放内存)
imagedestroy();
二、绘图具体步骤
生成验证码字符串
private function getCode(){
$str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
$t='';
for($i=0;$i<$this->m;$i++){
$t.=$str[rand(0,$this->type[&#39;letter&#39;])];
}
return $t;
}
画出验证码
function drawCode(){
$code=$this->getCode();//获取验证码字符串
imagefill($this->im, 0, 0, $this->bg);
for ($i=0; $i <200 ; $i++) {
imagesetpixel($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,255));
}
imageline($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,$this->width), rand(0,$this->height), rand(0,255));
$c=imagecolorallocate($this->im, rand(0,200), rand(0,200), rand(0,200));
for($i=0;$i<$this->m;$i++){
imagettftext($this->im, 18, rand(-40,40), 8+(18*$i), 24, $c, "georgia.ttf",$code[$i] );
}
}
输出图像
function printImage(){
$this->drawCode();
header("Content-Type:image/jpeg");
imagepng($this->im);
$this->destroy();
}
function destroy(){
imagedestroy($this->im);
}
三、代码演示
9,&#39;letter&#39; => 61 );
function __construct($width,$height,$m)
{
$this->width=$width;
$this->height=$height;
$this->m=$m;
$this->im=imagecreatetruecolor($this->width, $this->height);
$this->bg=imagecolorallocate($this->im, 220, 220, 220);
}
private function getCode(){
$str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
$t=&#39;&#39;;
for($i=0;$i<$this->m;$i++){
$t.=$str[rand(0,$this->type[&#39;letter&#39;])];
}
return $t;
}
function drawCode(){
$code=$this->getCode();//获取验证码字符串
imagefill($this->im, 0, 0, $this->bg);
//加干扰点
for ($i=0; $i <200 ; $i++) {
imagesetpixel($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,255));
}
//加干扰线
imageline($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,$this->width), rand(0,$this->height), rand(0,255));
$c=imagecolorallocate($this->im, rand(0,200), rand(0,200), rand(0,200));
for($i=0;$i<$this->m;$i++){
imagettftext($this->im, 18, rand(-40,40), 8+(18*$i), 24, $c, "georgia.ttf",$code[$i] );
}
}
function printImage(){
$this->drawCode();
header("Content-Type:image/jpeg");
imagepng($this->im);
$this->destroy();
}
function destroy(){
imagedestroy($this->im);
}
}
function unit_test(){
$obj=new Image(20*4,30,4);
$obj->printImage();
}
unit_test();
?>
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