PHP实现图片裁剪与缩放的几种方法

图片指定大小然后由php相关函数来实现图片裁剪功能，前段的js效果在这里就不介绍了，大家可以到网上找有很多这类代码，我只整理了php操作部份。

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方法一

代码如下

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图片裁剪缩放函数，支持方位裁剪和自定义坐标裁剪     /**      * 图片裁剪函数，支持指定定点裁剪和方位裁剪两种裁剪模式      * @param   $src_file       原图片路径      * @param      $new_width      裁剪后图片宽度（当宽度超过原图片宽度时，去原图片宽度）      * @param      $new_height     裁剪后图片高度（当宽度超过原图片宽度时，去原图片高度）      * @param      $type           裁剪方式，1-方位模式裁剪；0-定点模式裁剪。      * @param      $pos            方位模式裁剪时的起始方位（当选定点模式裁剪时，此参数不起作用）      *                                      1为顶端居左，2为顶端居中，3为顶端居右；      *                                      4为中部居左，5为中部居中，6为中部居右；      *                                      7为底端居左，8为底端居中，9为底端居右；      * @param      $start_x        起始位置X （当选定方位模式裁剪时，此参数不起作用）      * @param      $start_y        起始位置Y（当选定方位模式裁剪时，此参数不起作用）      * @return                  裁剪图片存储路径      */     function thumb($src_file, $new_width, $new_height, $type = 1, $pos = 5, $start_x = 0, $start_y = 0) {         $pathinfo = pathinfo($src_file);         $dst_file = $pathinfo['dirname'] . '/' . $pathinfo['filename'] .'_'. $new_width . 'x' . $new_height . '.' . $pathinfo['extension'];         if (!file_exists($dst_file)) {             if ($new_width                 echo "params width or height error !";                 exit();             }             if (!file_exists($src_file)) {                 echo $src_file . " is not exists !";                 exit();             }             // 图像类型             $img_type = exif_imagetype($src_file);             $support_type = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);             if (!in_array($img_type, $support_type, true)) {                 echo "只支持jpg、png、gif格式图片裁剪";                 exit();             }             /* 载入图像 */             switch ($img_type) {                 case IMAGETYPE_JPEG :                     $src_img = imagecreatefromjpeg($src_file);                     break;                 case IMAGETYPE_PNG :                     $src_img = imagecreatefrompng($src_file);                     break;                 case IMAGETYPE_GIF :                     $src_img = imagecreatefromgif($src_file);                     break;                 default:                 echo "载入图像错误!";                 exit();             }             /* 获取源图片的宽度和高度 */             $src_width = imagesx($src_img);             $src_height = imagesy($src_img);             /* 计算剪切图片的宽度和高度 */             $mid_width = ($src_width             $mid_height = ($src_height             /* 初始化源图片剪切裁剪的起始位置坐标 */             switch ($pos * $type) {                 case 1://1为顶端居左                     $start_x = 0;                     $start_y = 0;                     break;                 case 2://2为顶端居中                     $start_x = ($src_width - $mid_width) / 2;                     $start_y = 0;                     break;                 case 3://3为顶端居右                     $start_x = $src_width - $mid_width;                     $start_y = 0;                     break;                 case 4://4为中部居左                     $start_x = 0;                     $start_y = ($src_height - $mid_height) / 2;                     break;                 case 5://5为中部居中                     $start_x = ($src_width - $mid_width) / 2;                     $start_y = ($src_height - $mid_height) / 2;                     break;                 case 6://6为中部居右                     $start_x = $src_width - $mid_width;                     $start_y = ($src_height - $mid_height) / 2;                     break;                 case 7://7为底端居左                     $start_x = 0;                     $start_y = $src_height - $mid_height;                     break;                 case 8://8为底端居中                     $start_x = ($src_width - $mid_width) / 2;                     $start_y = $src_height - $mid_height;                     break;                 case 9://9为底端居右                     $start_x = $src_width - $mid_width;                     $start_y = $src_height - $mid_height;                     break;                 default://随机                     break;             }             // 为剪切图像创建背景画板             $mid_img = imagecreatetruecolor($mid_width, $mid_height);             //拷贝剪切的图像数据到画板，生成剪切图像             imagecopy($mid_img, $src_img, 0, 0, $start_x, $start_y, $mid_width, $mid_height);             // 为裁剪图像创建背景画板             $new_img = imagecreatetruecolor($new_width, $new_height);             //拷贝剪切图像到背景画板，并按比例裁剪             imagecopyresampled($new_img, $mid_img, 0, 0, 0, 0, $new_width, $new_height, $mid_width, $mid_height);             /* 按格式保存为图片 */             switch ($img_type) {                 case IMAGETYPE_JPEG :                     imagejpeg($new_img, $dst_file, 100);                     break;                 case IMAGETYPE_PNG :                     imagepng($new_img, $dst_file, 9);                     break;                 case IMAGETYPE_GIF :                     imagegif($new_img, $dst_file, 100);                     break;                 default:                     break;             }         }         return ltrim($dst_file, '.');     }

附件是一个有样例图片的测试demo。
不过，这个函数不支持动态gif图片的裁剪缩放。

方法二，

代码如下

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list($src_w,$src_h)=getimagesize($src_img);  // 获取原图尺寸 $dst_scale = $dst_h/$dst_w; //目标图像长宽比 $src_scale = $src_h/$src_w; // 原图长宽比 if($src_scale>=$dst_scale) {   // 过高  $w = intval($src_w);  $h = intval($dst_scale*$w);  $x = 0;  $y = ($src_h - $h)/3; } else { // 过宽  $h = intval($src_h);  $w = intval($h/$dst_scale);  $x = ($src_w - $w)/2;  $y = 0; } // 剪裁 $source=imagecreatefromjpeg($src_img); $croped=imagecreatetruecolor($w, $h); imagecopy($croped,$source,0,0,$x,$y,$src_w,$src_h); // 缩放 $scale = $dst_w/$w; $target = imagecreatetruecolor($dst_w, $dst_h); $final_w = intval($w*$scale); $final_h = intval($h*$scale); imagecopysampled($target,$croped,0,0,0,0,$final_w,$final_h,$w,$h); // 保存 $timestamp = time(); imagejpeg($target, "$timestamp.jpg"); imagedestroy($target); ?>

方法三

根据自定义的目标图, 按目标图高宽比裁剪、缩放源图.

传入参数:

代码如下

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$source_path string 源图路径 $target_width integer 目标图宽度 $target_height integer 目标图高度 支持图片类型: image/gif, image/jpeg, image/png. function imagecropper($source_path, $target_width, $target_height) {  $source_info   = getimagesize($source_path);  $source_width  = $source_info[0];  $source_height = $source_info[1];  $source_mime   = $source_info['mime'];  $source_ratio  = $source_height / $source_width;  $target_ratio  = $target_height / $target_width;  // 源图过高  if ($source_ratio > $target_ratio)  {   $cropped_width  = $source_width;   $cropped_height = $source_width * $target_ratio;   $source_x = 0;   $source_y = ($source_height - $cropped_height) / 2;  }  // 源图过宽  elseif ($source_ratio  {   $cropped_width  = $source_height / $target_ratio;   $cropped_height = $source_height;   $source_x = ($source_width - $cropped_width) / 2;   $source_y = 0;  }  // 源图适中  else  {   $cropped_width  = $source_width;   $cropped_height = $source_height;   $source_x = 0;   $source_y = 0;  }  switch ($source_mime)  {   case 'image/gif':    $source_image = imagecreatefromgif($source_path);    break;   case 'image/jpeg':    $source_image = imagecreatefromjpeg($source_path);    break;   case 'image/png':    $source_image = imagecreatefrompng($source_path);    break;   default:    return false;    break;  }  $target_image  = imagecreatetruecolor($target_width, $target_height);  $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);  // 裁剪  imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);  // 缩放  imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);  header('Content-Type: image/jpeg');  imagejpeg($target_image);  imagedestroy($source_image);  imagedestroy($target_image);  imagedestroy($cropped_image); }