PHP图片裁剪类

 <?php 

 class ImageTool {

     //以宽为标准，如果小于宽，则不剪裁
     public static function thumb_img_by_width($src_path, $dest_path,$width,$height){

         $info_arr = getimagesize($src_path);
         $src_width = $info_arr[0];
         $src_height = $info_arr[1];

         switch( $info_arr['mime'] ) {
             case 'image/gif':
                 $src_img = imagecreatefromgif( $src_path );
                 break;
             case 'image/jpeg':
                 $src_img = imagecreatefromjpeg( $src_path );
                 break;
             case 'image/png':
                 $src_img = imagecreatefrompng( $src_path );
                 break;
         }

         if($src_width > $width){
             //裁剪
             // 改变后的图象的比例
             $resize_ratio = ($width) / ($height);
             // 实际图象的比例
             $ratio = ($src_width) / ($src_height);

             if ($ratio >= $resize_ratio) {
                 // 高度优先
                 //截取图片中间那一段
                 $img_center_x = intval(($src_width-($src_height * $resize_ratio))/2);
                 //如果不需要只截取中间那一段，而是从图片x＝0的地方截取，则$img_center_x=0
                 $newimg = @imagecreatetruecolor($width, $height);
                 $color = imagecolorallocate($newimg,255,255,255);
                 imagecolortransparent($newimg,$color);
                 imagefill($newimg,0,0,$color);
                 @imagecopyresampled($newimg, $src_img, 0, 0, $img_center_x, 0, $width, $height, (($src_height) * $resize_ratio), $src_height);
                 // ImageJpeg($newimg);
             }else{
                 // 宽度优先
                 //截取图片中间那一段
                 $img_center_y = intval(($src_height-($src_width / $resize_ratio))/2);
                 //如果不需要只截取中间那一段，而是从图片y＝0的地方截取，则$img_center_y=0
                 $newimg = @imagecreatetruecolor($width, $height);
                 $color = imagecolorallocate($newimg,255,255,255);
                 imagecolortransparent($newimg,$color);
                 imagefill($newimg,0,0,$color);
                 @imagecopyresampled($newimg, $src_img, 0, 0, 0, $img_center_y, $width, $height, $src_width, (($src_width) / $resize_ratio));
             }
         }else{
             //不裁剪
             $newimg = @imagecreatetruecolor($src_width, $src_height);
             $color = imagecolorallocate($newimg,255,255,255);
             imagecolortransparent($newimg,$color);
             imagefill($newimg,0,0,$color);
             @imagecopyresampled($newimg, $src_img, 0, 0, 0, 0, $src_width, $src_height, $src_width, $src_height);
         }

         //统一保存为png格式
         imagepng($newimg, $dest_path);

         //gc
         imagedestroy($src_img);
         imagedestroy($newimg);
     }

     public static function thumb_img($src_path, $dest_path,$width,$height){

         $info_arr = getimagesize($src_path);
         $src_width = $info_arr[0];
         $src_height = $info_arr[1];

         switch( $info_arr['mime'] ) {
             case 'image/gif':
                 $src_img = imagecreatefromgif( $src_path );
                 break;
             case 'image/jpeg':
                 $src_img = imagecreatefromjpeg( $src_path );
                 break;
             case 'image/png':
                 $src_img = imagecreatefrompng( $src_path );
                 break;
         }

          // 改变后的图象的比例
         $resize_ratio = ($width) / ($height);
         // 实际图象的比例
         $ratio = ($src_width) / ($src_height);

         if ($ratio >= $resize_ratio) {
             // 高度优先
             //截取图片中间那一段
             $img_center_x = intval(($src_width-($src_height * $resize_ratio))/2);
             //如果不需要只截取中间那一段，而是从图片x＝0的地方截取，则$img_center_x=0
             $newimg = @imagecreatetruecolor($width, $height);
             $color = imagecolorallocate($newimg,255,255,255);
             imagecolortransparent($newimg,$color);
             imagefill($newimg,0,0,$color);
             @imagecopyresampled($newimg, $src_img, 0, 0, $img_center_x, 0, $width, $height, (($src_height) * $resize_ratio), $src_height);
             // ImageJpeg($newimg);
         }else{
             // 宽度优先
             //截取图片中间那一段
             $img_center_y = intval(($src_height-($src_width / $resize_ratio))/2);
             //如果不需要只截取中间那一段，而是从图片y＝0的地方截取，则$img_center_y=0
             $newimg = @imagecreatetruecolor($width, $height);
             $color = imagecolorallocate($newimg,255,255,255);
             imagecolortransparent($newimg,$color);
             imagefill($newimg,0,0,$color);
             @imagecopyresampled($newimg, $src_img, 0, 0, 0, $img_center_y, $width, $height, $src_width, (($src_width) / $resize_ratio));
         }

         //统一保存为png格式
         imagepng($newimg, $dest_path);

         //gc
         imagedestroy($src_img);
         imagedestroy($newimg);
     }

     /*
     * 按比例缩放图片，然后居中裁剪
     * $src_path 源文件路劲
     * $dest_path 裁剪图片存放位置
     * $width 裁剪图片宽带
     * $height 裁剪图片高度
     */
     public static function clip_img($src_path, $dest_path, $width, $height) {
         if( file_exists($src_path) ) {
             $info_arr = getimagesize($src_path);
             $src_width = $info_arr[0];
             $src_height = $info_arr[1];
             $src_ratio = $src_height / $src_width;
             $dest_ratio = $height / $width;

             if( $src_ratio < $dest_ratio ) {
                 $ratio_width = $width;
                 $ratio_height = ( $height * $src_height ) / $src_width;
             }else if( $src_ratio > $dest_ratio ) {
                 $ratio_height = $height;
                 $ratio_width = ( $width * $src_width ) / $src_height;
             }else {
                 $ratio_height = $height;
                 $ratio_width = $width;
             }

             switch( $info_arr['mime'] ) {
                 case 'image/gif':
                     $src_img = imagecreatefromgif( $src_path );
                     break;
                 case 'image/jpeg':
                     $src_img = imagecreatefromjpeg( $src_path );
                     break;
                 case 'image/png':
                     $src_img = imagecreatefrompng( $src_path );
                     break;
                 case 'image/bmp':
                     //待处理
                     break;
             }

             //等比例缩放图片
             $thumb_img = imagecreatetruecolor( intval($ratio_width), intval($ratio_height) ) ;
             $color = imagecolorallocate($thumb_img,255,255,255);
             imagecolortransparent($thumb_img,$color);
             imagefill($thumb_img,0,0,$color);
             imagecopyresampled( $thumb_img, $src_img, 0, 0, 0, 0, $ratio_width, $ratio_height, $src_width, $src_height);

             //剪裁
             $clip_img = imagecreatetruecolor( intval($width), intval($height) );
             imagecopy( $clip_img, $thumb_img, 0, 0, ( $ratio_width - $width ) / 2, ( $ratio_height - $height ) / 2, $width, $height );

             //统一保存为png格式
             imagepng($clip_img, $dest_path);

             //gc
             imagedestroy($src_img);
             imagedestroy($thumb_img);
             imagedestroy($clip_img);
         }
     }

     /*
     * 按比例缩放图片
     * type = 1 按宽为标准缩放 2 按高为标准缩放
     */
     public static function scale_img($src_path,$dest_path,$type,$len){
         if( file_exists($src_path) ){
             $info_arr = getimagesize($src_path);
             $src_width = $info_arr[0];
             $src_height = $info_arr[1];
             if($type == 1){
                 $des_width = $len;
                 $des_height = ( $src_height * $des_width ) / $src_width;
             }else{
                 $des_height = $len;
                 $des_width = ( $src_width * $des_height ) / $src_height;
             }

             switch( $info_arr['mime'] ) {
                 case 'image/gif':
                     $src_img = imagecreatefromgif( $src_path );
                     break;
                 case 'image/jpeg':
                     $src_img = imagecreatefromjpeg( $src_path );
                     break;
                 case 'image/png':
                     $src_img = imagecreatefrompng( $src_path );
                     break;
                 case 'image/bmp':
                     //待处理
                     break;
             }

             $thumb_img = imagecreatetruecolor( intval($des_width), intval($des_height) );
             $color = imagecolorallocate($thumb_img,255,255,255);
             imagecolortransparent($thumb_img,$color);
             imagefill($thumb_img,0,0,$color);
             imagecopyresampled( $thumb_img, $src_img, 0, 0, 0, 0, $des_width, $des_height, $src_width, $src_height);

             //统一保存为png格式
             imagepng($thumb_img, $dest_path);

             //gc
             imagedestroy($src_img);
             imagedestroy($thumb_img);
         }
     }

 }