php生成图片与验证码图片生成原理

作者：袖梨 2022-06-24

 代码如下 复制代码
$w?$RESIZEWIDTH=$w:$RESIZEWIDTH=400;// 生成图片的宽度
$h?$RESIZEHEIGHT=$h:$RESIZEHEIGHT=400;// 生成图片的高度
function ResizeImage($im,$maxwidth,$maxheight,$name){
    $width = imagesx($im);
    $height = imagesy($im);
    if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
        if($maxwidth && $width > $maxwidth){
            $widthratio = $maxwidth/$width;
            $RESIZEWIDTH=true;//www.111com.net
        }
        if($maxheight && $height > $maxheight){
            $heightratio = $maxheight/$height;
            $RESIZEHEIGHT=true;
        }
        if($RESIZEWIDTH && $RESIZEHEIGHT){
            if($widthratio < $heightratio){
                $ratio = $widthratio;
            }else{
                $ratio = $heightratio;
            }
        }elseif($RESIZEWIDTH){
            $ratio = $widthratio;
        }elseif($RESIZEHEIGHT){
            $ratio = $heightratio;
        }
        $newwidth = $width * $ratio;
        $newheight = $height * $ratio;
        if(function_exists("imagecopyresampled")){
              $newim = imagecreatetruecolor($newwidth, $newheight);
              imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
        }else{
            $newim = imagecreate($newwidth, $newheight);
              imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
        }
        ImageJpeg ($newim,$name);
        ImageDestroy ($newim);
    }else{
        ImageJpeg ($im,$name);
    }
}
 代码如下 复制代码
if($_FILES['uploadfile']['size']){
    if($_FILES['uploadfile']['type'] == "image/pjpeg"){
        $im = imagecreatefromjpeg($_FILES['uploadfile']['tmp_name']);
    }elseif($_FILES['uploadfile']['type'] == "image/x-png"){
        $im = imagecreatefrompng($_FILES['uploadfile']['tmp_name']);
    }elseif($_FILES['uploadfile']['type'] == "image/gif"){
        $im = imagecreatefromgif($_FILES['uploadfile']['tmp_name']);
    }
    if($im){
        if(file_exists('bbs.jpg')){
            unlink('www.111com.net.jpg');
        }
        ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,'bbs.jpg');
        ImageDestroy ($im);
  
    }
}
//$uploadfile="bbs.jpg";

?>

创建图片后记得用ImageDestroy 清空内存哦。

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