php使用GD创建保持宽高比的缩略图

1. /**
2. * Create a thumbnail image from $inputFileName no taller or wider than
3. * $maxSize. Returns the new image resource or false on error.
4. * Author: mthorn.net
5. */
6. function thumbnail($inputFileName, $maxSize = 100)
7. {
8. $info = getimagesize($inputFileName);
10. $type = isset($info['type']) ? $info['type'] : $info[2];
12. // Check support of file type
13. if ( !(imagetypes() & $type) )
14. {
15. // Server does not support file type
16. return false;
17. }
19. $width = isset($info['width']) ? $info['width'] : $info[0];
20. $height = isset($info['height']) ? $info['height'] : $info[1];
22. // Calculate aspect ratio
23. $wRatio = $maxSize / $width;
24. $hRatio = $maxSize / $height;
26. // Using imagecreatefromstring will automatically detect the file type
27. $sourceImage = imagecreatefromstring(file_get_contents($inputFileName));
29. // Calculate a proportional width and height no larger than the max size.
30. if ( ($width {
31. // Input is smaller than thumbnail, do nothing
32. return $sourceImage;
33. }
34. elseif ( ($wRatio * $height) {
35. // Image is horizontal
36. $tHeight = ceil($wRatio * $height);
37. $tWidth = $maxSize;
38. }
39. else
40. {
41. // Image is vertical
42. $tWidth = ceil($hRatio * $width);
43. $tHeight = $maxSize;
44. }
46. $thumb = imagecreatetruecolor($tWidth, $tHeight);
48. if ( $sourceImage === false )
49. {
50. // Could not load image
51. return false;
52. }
54. // Copy resampled makes a smooth thumbnail
55. imagecopyresampled($thumb, $sourceImage, 0, 0, 0, 0, $tWidth, $tHeight, $width, $height);
56. imagedestroy($sourceImage);
58. return $thumb;
59. }
61. /**
62. * Save the image to a file. Type is determined from the extension.
63. * $quality is only used for jpegs.
64. * Author: mthorn.net
65. */
66. function imageToFile($im, $fileName, $quality = 80)
67. {
68. if ( !$im || file_exists($fileName) )
69. {
70. return false;
71. }
73. $ext = strtolower(substr($fileName, strrpos($fileName, '.')));
75. switch ( $ext )
76. {
77. case '.gif':
78. imagegif($im, $fileName);
79. break;
80. case '.jpg':
81. case '.jpeg':
82. imagejpeg($im, $fileName, $quality);
83. break;
84. case '.png':
85. imagepng($im, $fileName);
86. break;
87. case '.bmp':
88. imagewbmp($im, $fileName);
89. break;
90. default:
91. return false;
92. }
94. return true;
95. }
97. $im = thumbnail('temp.jpg', 100);
98. imageToFile($im, 'temp-thumbnail.jpg');

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