PHP 实现等比压缩图片尺寸和大小实例代码

废话不多说了，直接给大家贴php等比压缩图片大小的相关代码了，具体代码如下所示：

    <?php
    $im = imagecreatefromjpeg('D:phpplace.jpeg');
    resizeImage($im,,,'xinde','.jpg');
    function resizeImage($im,$maxwidth,$maxheight,$name,$filetype)
    {
    $pic_width = imagesx($im);
    $pic_height = imagesy($im);
    echo "start-----------------" ;
    if(($maxwidth && $pic_width > $maxwidth) && ($maxheight && $pic_height > $maxheight))
    {
    if($maxwidth && $pic_width>$maxwidth)
    {
    $widthratio = $maxwidth/$pic_width;
    $resizewidth_tag = true;
    }
    if($maxheight && $pic_height>$maxheight)
    {
    $heightratio = $maxheight/$pic_height;
    $resizeheight_tag = true;
    }
    if($resizewidth_tag && $resizeheight_tag)
    {
    if($widthratio<$heightratio)
    $ratio = $widthratio;
    else
    $ratio = $heightratio;
    }
    if($resizewidth_tag && !$resizeheight_tag)
    $ratio = $widthratio;
    if($resizeheight_tag && !$resizewidth_tag)
    $ratio = $heightratio;
    $newwidth = $pic_width * $ratio;
    $newheight = $pic_height * $ratio;
    if(function_exists("imagecopyresampled"))
    {
    $newim = imagecreatetruecolor($newwidth,$newheight);
    imagecopyresampled($newim,$im,,,,,$newwidth,$newheight,$pic_width,$pic_height);
    }
    else
    {
    $newim = imagecreate($newwidth,$newheight);
    imagecopyresized($newim,$im,,,,,$newwidth,$newheight,$pic_width,$pic_height);
    }
    $name = $name.$filetype;
    imagejpeg($newim,$name);
    imagedestroy($newim);
    }
    else
    {
    $name = $name.$filetype;
    imagejpeg($im,$name);
    }
    }

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