PHP study notes: Scale images proportionally

Go directly to the code. The function imgzip($src,$newwid,$newhei) brings in the original image, the width required for scaling, and the length of scaling. The codes are all noted, if you don’t understand, you can leave a message haha

<?php 

//压缩图片  缩略图

$src= "xiezheng.jpg";
$newwid=640;
$newhei= 480;
function imgzip($src,$newwid,$newhei){
    $imgInfo = getimagesize($src);

    $imgType = image_type_to_extension($imgInfo[2], false);

    $fun = "imagecreatefrom{$imgType}";

//声明图片   打开图片 在内存中
    $image = $fun($src);
//方便配置长度宽度、高度，设置框为变量wid,高度为hei
    $wid=$imgInfo[0];
    $hei=$imgInfo[1];
//判断长度和宽度，以方便等比缩放,规格按照500, 320
    if($wid>$hei){
        $wid=$newwid;
        $hei=$newwid/($wid/$hei);
    }else {
        $wid = $newhei * ($wid / $hei);
        $hei = $newhei;
    }

//在内存中建立一张图片
    $images2 = imagecreatetruecolor($newwid, $newhei); //建立一个500*320的图片

//将原图复制到新建图片中
//imagecopyresampled($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h)

    imagecopyresampled($images2, $image, 0, 0, 0, 0, $wid,$hei, $imgInfo[0],$imgInfo[1]);

//销毁原始图片
    imagedestroy($image);


//直接输出图片文件

    header("Content-type: ".$imgInfo[&#39;mime&#39;]);
    imagejpeg($images2);

//保存图片 到新文件
    imagejpeg($images2, &#39;new.jpg&#39;, 100); //10代码输出图片的质量 0-100 100质量最高

//销毁
    imagedestroy($images2);
}
imgzip($src,$newwid,$newhei);


?>

Effect

Before compression

After compression