php 图片缩略图生成代码(支持png透明)

3. /*

4. * desc: Resize Image(png, jpg, gif)
5. */
6. class ResizeImage {
7. //图片类型
8. private $type;
9. //实际宽度
10. private $width;
11. //实际高度
12. private $height;
13. //改变后的宽度
14. private $resize_width;
15. //改变后的高度
16. private $resize_height;
17. //是否裁图
18. private $cut;
19. //源图象
20. private $srcimg;
21. //目标图象地址
22. private $dstimg;
23. //临时创建的图象
24. private $im;

25. function __construct($imgPath, $width, $height, $isCut, $savePath) {

26. $this->srcimg = $imgPath;
27. $this->resize_width = $width;
28. $this->resize_height = $height;
29. $this->cut = $isCut;
30. //图片的类型

31. $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));

32. //初始化图象

33. $this->initi_img();
34. //目标图象地址
35. $this -> dst_img($savePath);
36. //--
37. $this->width = imagesx($this->im);
38. $this->height = imagesy($this->im);
39. //生成图象
40. $this->newimg();
41. ImageDestroy ($this->im);
42. }

43. private function newimg() {

44. //改变后的图象的比例
45. $resize_ratio = ($this->resize_width)/($this->resize_height);
46. //实际图象的比例
47. $ratio = ($this->width)/($this->height);
48. if($this->cut) {
49. //裁图
50. $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
51. if($this->type=="png") {
52. imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));
53. }
54. if($ratio>=$resize_ratio) {
55. //高度优先
56. imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);
57. } else {
58. //宽度优先
59. imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio));
60. }
61. } else {
62. //不裁图
63. if($ratio>=$resize_ratio) {
64. $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);
65. if($this->type=="png") {
66. imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));
67. }
68. imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);
69. } else {
70. $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);
71. if($this->type=="png") {
72. imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));
73. }
74. imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);
75. }
76. }
77. if($this->type=="png") {
78. imagesavealpha($newimg, true);
79. imagepng ($newimg,$this->dstimg);
80. } else {
81. imagejpeg ($newimg,$this->dstimg);
82. }
83. }

84. //初始化图象

85. private function initi_img() {
86. if($this->type=="jpg") {
87. $this->im = imagecreatefromjpeg($this->srcimg);
88. }
89. if($this->type=="gif") {
90. $this->im = imagecreatefromgif($this->srcimg);
91. }
92. if($this->type=="png") {
93. $this->im = imagecreatefrompng($this->srcimg);
94. }
95. }

96. //图象目标地址

97. private function dst_img($dstpath) {
98. $full_length = strlen($this->srcimg);

99. $type_length = strlen($this->type);

100. $name_length = $full_length-$type_length;
102. $name = substr($this->srcimg,0,$name_length-1);
103. $this->dstimg = $dstpath;
104. }
105. }
106. ?>

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使用时直接调用类的构造函数即可，构造函数： $resizeimage = new resizeimage($imgPath, $width, $height, $isCut, $savePath);

参数 $imgPath：原图片地址 $width：缩略图宽 $height：缩略图高 $isCut：是否裁剪，bool值 $savePath：缩略图地址（可以跟原图片地址相同）

例子：

3. include "ResizeImage.php";

4. //jpg

5. $jpgResize = new ResizeImage("img/test_1920_1200.jpg", 320, 240, false, "img/test_320_240.jpg");

6. //png

7. $pngResize = new ResizeImage("img/test_1024_746.png", 320, 240, false, "img/test_320_240.png");
8. ?>

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效果：