本文实例讲述了PHP生成图片缩略图类。分享给大家供大家参考，具体如下：

1. classApp_image_helper {
2. protected$imgFileName;
3. protected$imgWidth;
4. protected$imgHeight;
5. protected$imgMime;
6. protected$imgResource;
7. static $imgMineList
8. =array(
9. 'jpeg'=>'image/jpeg',
10. 'gif'=>'image/gif',
11. 'png'=>'image/png',
12. 'wbmp'=>'image/wbmp',
13. );
14. /**
15. * 根据文件名，初始化图片，
16. * 计算出给定图片的宽、高、图片类型，并获取图片的资源保存到内存，便于下次使用
17. * App_image_helper constructor.
18. *
19. * @param $fileName
20. */
21. publicfunction__construct($fileName) {
22. $this->imgFileName =$fileName;
23. list($this->imgWidth,$this->imgHeight,$this->imgMime) =$this->getImageInfo($this->imgFileName);
24. $this->imgResource =$this->getImageResource($this->imgFileName);
25. }
26. /**
27. * 根据图片路径获取相关宽、高、MIME类型信息
28. *
29. * @param $fileName
30. *
31. * @return array|null
32. */
33. protectedfunctiongetImageInfo($fileName) {
34. $result= null;
35. if(is_file($fileName) ) {
36. $tmpImageInfo=getimagesize($fileName);
37. if($tmpImageInfo) {
38. $result=array($tmpImageInfo[0],$tmpImageInfo[1],$tmpImageInfo['mime']);
39. }
40. }
41. return$result;
42. }
43. /**
44. * 将图片文件转为资源类类型
45. *
46. * @param $fileName
47. *
48. * @return null|resource
49. */
50. protectedfunctiongetImageResource($fileName) {
51. $image= null;
52. if(is_file($fileName) ) {
53. switch($this->imgMime) {
54. caseself::$imgMineList['jpeg']:
55. $image= imagecreatefromjpeg($fileName);
56. break;
57. caseself::$imgMineList['gif']:
58. $image= imagecreatefromgif($fileName);
59. break;
60. caseself::$imgMineList['png']:
61. $image= imagecreatefrompng($fileName);
62. break;
63. caseself::$imgMineList['wbmp']:
64. $image= imagecreatefromwbmp($fileName);
65. break;
66. default:
67. break;
68. }
69. }
70. return$image;
71. }
72. /**
73. * 可根据固定宽，等比缩放图片；或根据百分比，等比缩放图片
74. *
75. * @param int $width
76. * @param int $percent
77. *
78. * @return array|null
79. */
80. protectedfunctiongetSizeByScale($width= 360,$percent= 1) {
81. $result= null;
82. if($this->imgWidth &&$this->imgHeight ) {
83. if($width) {
84. $result=array($width,intval($width*$this->imgHeight /$this->imgWidth));
85. }elseif($percent) {
86. $result=array(intval($this->imgWidth *$percent),intval($this->imgHeight *$percent));
87. }
88. }
89. return$result;
90. }
91. /**
92. * 外调
93. *
94. * @param int $percentOrWidth int整数表示图片缩放为固定宽度，0.0~0.99999表示缩放百分比
95. * @param null $fileName
96. * @param int $quality
97. * @param bool $reSample 重新采样图片，默认是
98. *
99. * @return bool
100. */
101. publicfunctioncreateImage($percentOrWidth= 1,$fileName= null,$quality= 75,$reSample= true) {
102. $result= false;
103. $fileName? header('Content-Type: '.$this->imgMime) : false;
104. $size=$this->getSizeByScale(($percentOrWidth<= 1) ? null :$percentOrWidth,$percentOrWidth);
105. if($size) {
106. $thumb= imagecreatetruecolor($size[0],$size[1]);
107. if($reSample) {
108. imagecopyresampled($thumb,$this->imgResource, 0, 0, 0, 0,$size[0],$size[1],$this->imgWidth,$this->imgHeight);
109. }else{
110. imagecopyresized($thumb,$this->imgResource, 0, 0, 0, 0,$size[0],$size[1],$this->imgWidth,$this->imgHeight);
111. }
112. $result= imagejpeg($thumb,$fileName,$quality);
113. }
114. return$result;
115. }
116. }