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强大的PHP生成缩略图函数

各位小盆友使用前记得打开 GD 库的支持

<?php

 

/**

 * 生成缩略图

 * @author yangzhiguo0903@163.com

 * @param string     源图绝对完整地址{带文件名及后缀名}

 * @param string     目标图绝对完整地址{带文件名及后缀名}

 * @param int        缩略图宽{0:此时目标高度不能为0,目标宽度为源图宽*(目标高度/源图高)}

 * @param int        缩略图高{0:此时目标宽度不能为0,目标高度为源图高*(目标宽度/源图宽)}

 * @param int        是否裁切{宽,高必须非0}

 * @param int/float  缩放{0:不缩放, 0<this<1:缩放到相应比例(此时宽高限制和裁切均失效)}

 * @return boolean

 */

function img2thumb($src_img, $dst_img, $width = 75, $height = 75, $cut = 0, $proportion = 0)

{

    if(!is_file($src_img))

    {

        return false;

    }

    $ot = fileext($dst_img);

    $otfunc = 'image' . ($ot == 'jpg' ? 'jpeg' : $ot);

    $srcinfo = getimagesize($src_img);

    $src_w = $srcinfo[0];

    $src_h = $srcinfo[1];

    $type  = strtolower(substr(image_type_to_extension($srcinfo[2]), 1));

    $createfun = 'imagecreatefrom' . ($type == 'jpg' ? 'jpeg' : $type);

 

    $dst_h = $height;

    $dst_w = $width;

    $x = $y = 0;

 

    /**

     * 缩略图不超过源图尺寸(前提是宽或高只有一个)

     */

    if(($width> $src_w && $height> $src_h) || ($height> $src_h && $width == 0) || ($width> $src_w && $height == 0))

    {

        $proportion = 1;

    }

    if($width> $src_w)

    {

        $dst_w = $width = $src_w;

    }

    if($height> $src_h)

    {

        $dst_h = $height = $src_h;

    }

 

    if(!$width && !$height && !$proportion)

    {

        return false;

    }

    if(!$proportion)

    {

        if($cut == 0)

        {

            if($dst_w && $dst_h)

            {

                if($dst_w/$src_w> $dst_h/$src_h)

                {

                    $dst_w = $src_w * ($dst_h / $src_h);

                    $x = 0 - ($dst_w - $width) / 2;

                }

                else

                {

                    $dst_h = $src_h * ($dst_w / $src_w);

                    $y = 0 - ($dst_h - $height) / 2;

                }

            }

            else if($dst_w xor $dst_h)

            {

                if($dst_w && !$dst_h//有宽无高

                {

                    $propor = $dst_w / $src_w;

                    $height = $dst_h  = $src_h * $propor;

                }

                else if(!$dst_w && $dst_h//有高无宽

                {

                    $propor = $dst_h / $src_h;

                    $width  = $dst_w = $src_w * $propor;

                }

            }

        }

        else

        {

            if(!$dst_h//裁剪时无高

            {

                $height = $dst_h = $dst_w;

            }

            if(!$dst_w//裁剪时无宽

            {

                $width = $dst_w = $dst_h;

            }

            $propor = min(max($dst_w / $src_w, $dst_h / $src_h), 1);

            $dst_w = (int)round($src_w * $propor);

            $dst_h = (int)round($src_h * $propor);

            $x = ($width - $dst_w) / 2;

            $y = ($height - $dst_h) / 2;

        }

    }

    else

    {

        $proportion = min($proportion, 1);

        $height = $dst_h = $src_h * $proportion;

        $width  = $dst_w = $src_w * $proportion;

    }

 

    $src = $createfun($src_img);

    $dst = imagecreatetruecolor($width ? $width : $dst_w, $height ? $height : $dst_h);

    $white = imagecolorallocate($dst, 255, 255, 255);

    imagefill($dst, 0, 0, $white);

 

    if(function_exists('imagecopyresampled'))

    {

        imagecopyresampled($dst, $src, $x, $y, 0, 0, $dst_w, $dst_h, $src_w, $src_h);

    }

    else

    {

        imagecopyresized($dst, $src, $x, $y, 0, 0, $dst_w, $dst_h, $src_w, $src_h);

    }

    $otfunc($dst, $dst_img);

    imagedestroy($dst);

    imagedestroy($src);

    return true;

}
补充:
 function fileext($file)
 {
 return pathinfo($file, PATHINFO_EXTENSION);
 }
$src_img = "./ROSI_050_002.JPG";

$dst_img = "./ROSI_050_002_thumb.jpg";

$stat = img2thumb($src_img, $dst_img, $width = 200, $height = 300, $cut = 0, $proportion = 0);

if($stat){

    echo 'Resize Image Success!<br />';

    echo '<img src="'.$dst_img.'" />';    

}else{

    echo 'Resize Image Fail!'

}
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