【PHP縮圖類】手機照片不能產生縮圖問題以及解決方案

標籤：php   縮圖   png   

【本文原創，謝絕轉載】

一、出現的問題這幾天做了手機上傳照片並裁出縮圖的介面的測試，發現不管怎麼，產生的縮圖都是一片漆黑。:-(然後就把這個縮圖類單拿出來進行測試，發現只要是手機拍出來的照片都不能進行縮圖的處理。。。。
二、問題分析以及解決方案
經過群裡的請教，發現問題可能是出現在檔案的類型的判斷上，因為png圖片內建一個透明的圖層，導致不能直接轉換成jpg的檔案，而手機排出的照片副檔名是jpg.所以，得出的結論是 手機拍出的是jpg副檔名的png圖片。
由於副檔名是可以隨意修改的，不是很能保證檔案的資訊的準確性，所以我們採用了 getimagesize 函數進行檔案類型的擷取。

//擷取真實的圖片類型 list($width, $height, $type, $attr) = getimagesize($this->sur_file);    switch($type) {          case 1 :              $img_type = 'gif';              break;          case 2 :              $img_type = 'jpeg';              break;          case 3 :              $img_type = 'png';              break;          case 15 :              $img_type = 'wbmp';              break;          default :              return false;      }  

三、產生縮圖類
下面把修改後的產生縮圖的類貼出來，供大家指正~

/** * php產生縮圖類 * 修改者 點點細雨  * 文章出處 ： http://blog.csdn.net/diandianxiyu_geek * 2014-07-23 解決了圖片類型不能正常識別的問題 */class thumb {    public $sur_file; //讀取的原圖片    public $des_file; //產生靶心圖表片    public $tem_file; //臨時圖片    public $tag;  //縮減標籤  0,預設,按固定的高寬產生  1,按比列或固定最大長度產生  -1,按某個寬度或某個高度縮小    public $resize_width;  //$tag為0時,目標檔案寬    public $resize_height;  //$tag為0時,目標檔案高    public $sca_max; //$tag為1時,<0$sca_max<1時為縮小比例;$sca_max>1時為最大長度(高或寬之中的最大值)    public $type;  //圖片類型    public $width;  //原圖片寬    public $height;  //原圖片高    public $size;     //原圖大小    //建構函式    public function __construct($surpic, $reswid, $reshei, $despic, $mark, $scamax) {        $this->sur_file = $surpic;        $this->resize_width = $reswid;        $this->resize_height = $reshei;        $this->tag = $mark;        $this->sca_max = $scamax;        list($width, $height, $type, $attr) = getimagesize($this->sur_file);        switch ($type) {            case 1 :                $img_type = 'gif';                break;            case 2 :                $img_type = 'jpeg';                break;            case 3 :                $img_type = 'png';                break;            case 15 :                $img_type = 'wbmp';                break;            default :                return false;        }        $this->type = $img_type; //擷取圖片類型        $this->init_img(); //初始化圖片        $this->des_file = $despic; //靶心圖表片地址        $this->width = $width;        $this->height = $height;        $this->size = filesize($surpic);        $this->new_img();        imagedestroy($this->tem_file);    }    //圖片初始化函數    private function init_img() {        if ($this->type == 'jpeg') {            $this->tem_file = imagecreatefromjpeg($this->sur_file);        } elseif ($this->type == 'jpg') {            $this->tem_file = imagecreatefromjpeg($this->sur_file);        } elseif ($this->type == 'gif') {            $this->tem_file = imagecreatefromgif($this->sur_file);        } elseif ($this->type == 'png') {            $this->tem_file = imagecreatefrompng($this->sur_file);        } elseif ($this->type == 'bmp') {            $this->tem_file = imagecreatefrombmp($this->sur_file); //bmp.php中包含        }    }    //圖片產生函數    private function new_img() {        $ratio = ($this->width) / ($this->height); //原圖比例        $resize_ratio = ($this->resize_width) / ($this->resize_height); //縮減後比例        $newimg = imagecreatetruecolor($this->resize_width, $this->resize_height); //產生新圖片        imagealphablending($newimg, false); //這裡很重要,意思是不合并顏色,直接用$img映像顏色替換,包括透明色;        imagesavealpha($newimg, true);        if ($this->tag == 0) { //按固定高寬截取縮圖            $newimg = imagecreatetruecolor($this->resize_width, $this->resize_height); //產生新圖片            if ($ratio >= $resize_ratio) {//即等比例下,縮圖的高比原圖長,因此高不變                imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, $this->resize_width, $this->resize_height, (($this->height) * $resize_ratio), $this->height);            } elseif ($ratio < $resize_ratio) {//即等比例下,縮圖的寬比原圖長,因此寬不變                imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width) / $resize_ratio));            }        } elseif ($this->tag == 1) { //按固定比例或最大長度縮小            if ($this->sca_max < 1) { //按比例縮小                $newimg = imagecreatetruecolor((($this->width) * ($this->sca_max)), (($this->height) * ($this->sca_max))); //產生新圖片                imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, (($this->width) * ($this->sca_max)), (($this->height) * ($this->sca_max)), $this->width, $this->height);            } elseif ($this->sca_max > 1) { //按某個最大長度縮小                if ($ratio >= 1) { //寬比高長                    $newimg = imagecreatetruecolor($this->sca_max, ($this->sca_max / $ratio)); //產生新圖片                    imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, $this->sca_max, ($this->sca_max / $ratio), $this->width, $this->height);                } else {                    $newimg = imagecreatetruecolor(($this->sca_max * $ratio), $this->sca_max); //產生新圖片                    imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, ($this->sca_max * $ratio), $this->sca_max, $this->width, $this->height);                }            }        } elseif ($this->tag == -1) { //按某個寬度或某個高度縮小            if ($resize_ratio >= 1) {//新高小於新寬,則圖片按新寬度縮小                $newimg = imagecreatetruecolor($this->resize_width, ($this->resize_width / $ratio)); //產生新圖片                imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, $this->resize_width, ($this->resize_width / $ratio), $this->width, $this->height);            } elseif ($resize_ratio < 1) {//新寬小於新高,則圖片按新高度縮小                $newimg = imagecreatetruecolor(($this->resize_height * $ratio), $this->resize_height); //產生新圖片                imagecopyresampled($newimg, $this->tem_file, 0, 0, 0, 0, ($this->resize_height * $ratio), $this->resize_height, $this->width, $this->height);            }        }        //輸出新圖片        if ($this->type == 'jpeg' || $this->type == 'jpg') {            imagejpeg($newimg, $this->des_file);        } elseif ($this->type == 'gif') {            imagegif($newimg, $this->des_file);        } elseif ($this->type == 'png') {            imagepng($newimg, $this->des_file);        } elseif ($this->type == 'bmp') {            imagebmp($newimg, $this->des_file); //bmp.php中包含        }    }#function new_img() end}

【PHP縮圖類】手機照片不能產生縮圖問題以及解決方案