處理方法是:
1.當(dāng)原圖的寬或高任一比規(guī)定的尺寸小,只進行等比縮略處理,
2.當(dāng)原圖的寬與高都比規(guī)定尺寸大,先進行等比縮略處理,然后算出居中位置進行裁剪

以下是源代碼： <?php /* *        $o_photo 原圖路徑 *        $d_photo 處理后圖片路徑 *        $width   定義寬 *        $height  定義高 *        調(diào)用方法  cutphoto("test.jpg","temp.jpg",256,146); */ function cutphoto($o_photo,$d_photo,$width,$height){ $temp_img = imagecreatefromjpeg($o_photo); $o_width  = imagesx($temp_img);                                //取得原圖寬 $o_height = imagesy($temp_img);                                //取得原圖高 //判斷處理方法 if($width>$o_width || $height>$o_height){        //原圖寬或高比規(guī)定的尺寸小,進行壓縮         $newwidth=$o_width;         $newheight=$o_height;         if($o_width>$width){                 $newwidth=$width;                 $newheight=$o_height*$width/$o_width;         }         if($newheight>$height){                 $newwidth=$newwidth*$height/$newheight;                 $newheight=$height;         }         //縮略圖片         $new_img = imagecreatetruecolor($newwidth, $newheight);          imagecopyresampled($new_img, $temp_img, 0, 0, 0, 0, $newwidth, $newheight, $o_width, $o_height);          imagejpeg($new_img , $d_photo);                         imagedestroy($new_img); }else{                                                                                //原圖寬與高都比規(guī)定尺寸大,進行壓縮后裁剪         if($o_height*$width/$o_width>$height){        //先確定width與規(guī)定相同,如果height比規(guī)定大,則ok                 $newwidth=$width;                 $newheight=$o_height*$width/$o_width;                 $x=0;                 $y=($newheight-$height)/2;         }else{                                                                        //否則確定height與規(guī)定相同,width自適應(yīng)                 $newwidth=$o_width*$height/$o_height;                 $newheight=$height;                 $x=($newwidth-$width)/2;                 $y=0;         }         //縮略圖片         $new_img = imagecreatetruecolor($newwidth, $newheight);          imagecopyresampled($new_img, $temp_img, 0, 0, 0, 0, $newwidth, $newheight, $o_width, $o_height);          imagejpeg($new_img , $d_photo);                         imagedestroy($new_img);                  $temp_img = imagecreatefromjpeg($d_photo);         $o_width  = imagesx($temp_img);                                //取得縮略圖寬         $o_height = imagesy($temp_img);                                //取得縮略圖高         //裁剪圖片         $new_imgx = imagecreatetruecolor($width,$height);         imagecopyresampled($new_imgx,$temp_img,0,0,$x,$y,$width,$height,$width,$height);         imagejpeg($new_imgx , $d_photo);         imagedestroy($new_imgx); } } ?>