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:
