PHP CLASS TO CREATE IMAGE THUMBANILS
Some years ago, I wrote a PHP class to create image thumbnails because I needed it for a project. There were needed certain things that I could not able to find in other PHP classes, and I decided to create one with my specific needs. Today, after some improvements and fixes to perfect it, I have decided to share it with anyone that wants to use it.
Features of this class:
- It is possible to work with the main image formats (jpg, png, and gif).
- It is possible to resize images setting a width or a height and maintaining the original proportion.
- It is possible to crop the images to a custom size maintaining its original proportion (it is also possible to chose the cropping position).
- It is possible to store the resulting image in the server.
- Is is possible to show the image in the browser on the fly.
- It is possible to keep the alpha channel of PNG and GIFs images.
This class needs the GD library installed in the server (included in PHP from version 4.3)
1 class Thumb { 2 3 private $image; 4 private $type; 5 private $mime; 6 private $width; 7 private $height; 8 9 //---读取图像的方法 10 public function loadImage($name) { 11 12 //---存储图像尺寸 13 $info = getimagesize($name); 14 15 $this->width = $info[0]; 16 $this->height = $info[1]; 17 $this->type = $info[2]; 18 $this->mime = $info['mime']; 19 20 //---根据原始格式创建新图像 21 switch($this->type){ 22 23 case IMAGETYPE_JPEG: 24 $this->image = imagecreatefromjpeg($name); 25 break; 26 27 case IMAGETYPE_GIF: 28 $this->image = imagecreatefromgif($name); 29 break; 30 31 case IMAGETYPE_PNG: 32 $this->image = imagecreatefrompng($name); 33 break; 34 35 default: 36 trigger_error('It is not possible to create a thumbnail using the specified format', E_USER_ERROR); 37 38 } 39 40 } 41 42 //---存储图像的方法 43 public function save($name, $quality = 100, $type = false) { 44 45 //---如果格式不存在，请选择原始图像的格式
46 $type = ($type) ? $type : $this->type;
47 //---使用正确的格式存储图像 48 switch($type){ 49 50 case IMAGETYPE_JPEG: 51 imagejpeg($this->image, $name . image_type_to_extension($type), $quality); 52 break; 53 54 case IMAGETYPE_GIF: 55 imagegif($this->image, $name . image_type_to_extension($type)); 56 break; 57 58 case IMAGETYPE_PNG: 59 $pngquality = floor($quality / 100 * 9); 60 imagepng($this->image, $name . image_type_to_extension($type), $pngquality); 61 break; 62 default: 63 trigger_error('The specified image format is not correct', E_USER_ERROR); 64 } 65 } 66 //---即时显示图像的方法 67 public function show($type = false, $base64 = false) { 68 69 //---如果格式不存在，请选择原始图像的格式 70 $type = ($type) ? $type : $this->type; 71 if($base64) ob_start(); 72 73 //---使用正确的格式显示图像 74 switch($type){ 75 case IMAGETYPE_JPEG: 76 imagejpeg($this->image); 77 break; 78 79 case IMAGETYPE_GIF: 80 imagegif($this->image); 81 break; 82 83 case IMAGETYPE_PNG: 84 $this->prepareImage($this->image); 85 imagepng($this->image); 86 break; 87 88 default: 89 trigger_error('The specified image format is not correct', E_USER_ERROR); 90 exit; 91 } 92 93 if($base64) { 94 $data = ob_get_contents(); 95 ob_end_clean (); 96 return 'data:' . $this->mime . ';base64,' . base64_encode($data); 97 } 98 99 } 100 101 //---按比例调整图像大小的方法 102 public function resize($value, $prop){ 103 104 //---确定resize属性 105 $prop_value = ($prop == 'width') ? $this->width : $this->height; 106 $prop_versus = ($prop == 'width') ? $this->height : $this->width; 107 108 //---Determine the opposite resize property 109 $pcent = $value / $prop_value; 110 $value_versus = $prop_versus * $pcent; 111 112 //---使用resize属性创建图像 113 $image = ($prop == 'width') ? imagecreatetruecolor($value, $value_versus) : imagecreatetruecolor($value_versus, $value); 114 115 //---Treat the image 116 if($this->type == IMAGETYPE_GIF || $this->type == IMAGETYPE_PNG) $this->prepareImage($image); 117 118 //---制作一张考虑了resize属性的图像副本 119 switch($prop){ 120 case 'width': 121 imagecopyresampled($image, $this->image, 0, 0, 0, 0, $value, $value_versus, $this->width, $this->height); 122 break; 123 124 default: 125 imagecopyresampled($image, $this->image, 0, 0, 0, 0, $value_versus, $value, $this->width, $this->height); 126 } 127 128 //---Update the image and its dimensions 129 $this->width = imagesx($image); 130 $this->height = imagesy($image); 131 $this->image = $image; 132 } 133 134 //---Method to extract a portion of the image maintaining its proportion 135 public function crop($cwidth, $cheight, $pos = 'center') { 136 137 $pcent = min($this->width / $cwidth, $this->height / $cheight); 138 $bigw = (int) ($pcent * $cwidth); 139 $bigh = (int) ($pcent * $cheight); 140 141 //---Create the image 142 $image = imagecreatetruecolor($cwidth, $cheight); 143 144 //---Treat the image 145 if($this->type == IMAGETYPE_GIF || $this->type == IMAGETYPE_PNG) $this->prepareImage($image); 146 147 //---Depending of the crop position 148 switch($pos){ 149 150 case 'left': 151 imagecopyresampled($image, $this->image, 0, 0, 0, abs(($this->height - $bigh) / 2), $cwidth, $cheight, $bigw, $bigh); 152 break; 153 154 case 'right': 155 imagecopyresampled($image, $this->image, 0, 0, $this->width - $bigw, abs(($this->height - $bigh) / 2), $cwidth, $cheight, $bigw, $bigh); 156 break; 157 158 case 'top': 159 imagecopyresampled($image, $this->image, 0, 0, abs(($this->width - $bigw) / 2), 0, $cwidth, $cheight, $bigw, $bigh); 160 break; 161 162 case 'bottom': 163 imagecopyresampled($image, $this->image, 0, 0, abs(($this->width - $bigw) / 2), $this->height - $bigh, $cwidth, $cheight, $bigw, $bigh); 164 break; 165 166 default: 167 imagecopyresampled($image, $this->image, 0, 0, abs(($bigw - $this->width) / 2), abs(($bigh - $this->height) / 2), $cwidth, $cheight, $bigw, $bigh); 168 } 169 $this->width = $cwidth; 170 $this->height = $cheight; 171 $this->image = $image; 172 } 173 //---Private method to treat the images before show them 174 private function prepareImage($image){ 175 //---Depending on the image type 176 switch($this->type){ 177 case IMAGETYPE_GIF: 178 $background = imagecolorallocate($image, 0, 0, 0); 179 imagecolortransparent($image, $background); 180 break; 181 182 case IMAGETYPE_PNG: 183 imagealphablending($image, FALSE); 184 imagesavealpha($image, TRUE); 185 break; 186 } 187 } 188 }
Public methods |
|
|---|---|
//Reads the image from the specified path
loadImage(string $name) |
|
| $name | Image path |
//Stores the image in the specified path
save(string $name [, int $quality = 100] [, int $type = false]) |
|
| $name | Image path |
| $quality | Image quality with a value between 0 and 100 |
| $type | Image type defined by a constant IMAGETYPE_XXX (IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF). It is optional, if it is not sent, the original format will be used |
// Shows the image directly on the page or returns a base64 representation of it
show([int $type = false] [,boolean $base64 = false]) |
|
| $type | Image type defined by a constant IMAGETYPE_XXX (IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF). It is optional, if it is not sent, the original format will be used |
| $base64 | Specifies if the image flow should be printed on the page or should be returned as a base64. |
//Resizes the image maintaining its proprtion
resize(int $value, string $reference) |
|
| $value | The value of width or height that should be used to resize the image |
| $reference | String that defines if the image should be resized taking into account the with or the height (possible values: ‘width’ or ‘height’) |
//Crops the image creating a thumbnail of it
crop(int $width, int $height [, string $position = 'center']) |
|
| $width | Width of the thumbnail |
| $height | Height of the thumbnail |
| $position | The position from which the thumbnail should be extracted (possible values: ‘top’, ‘right’, ‘bottom’, ‘left’ or ‘center’) |
效果图:
