php生成图像缩略图（支持：JPEG，GIT，PNG，BMP）

1. class Thumb
2. {
4. public function create($srcPath, $dstPath, $dstWidth, $dstHeight)
5. {
6. if (!file_exists($srcPath)) {
7. return false;
8. }
10. @$srcSize = getimagesize($srcPath);
11. if (empty($srcSize)) {
12. return false;
13. }
15. $srcWith = intval($srcSize[0]);
16. $srcHeight = intval($srcSize[1]);
18. //如果原始图片的尺寸大于指定缩略图的尺寸，则生成缩略图，否则拷贝原始文件
19. if ($srcWith return copy($srcPath, $dstPath);
20. }
22. //读取原始图片资源
23. @$srcImage = imagecreatefromjpeg($srcPath);
24. if (empty($srcImage)) {
25. @$srcImage = imagecreatefromgif($srcPath);
26. }
27. if (empty($srcImage)) {
28. @$srcImage = imagecreatefrompng($srcPath);
29. }
30. if (empty($srcImage)) {
31. @$srcImage = $this->_imageCreateFromBMP($srcPath);
32. }
34. if (empty($srcImage)) {
35. return false;
36. }
38. //获取缩略图的尺寸，并据此生成新的图像
39. $dstSize = $this->_getDstSize(
40. $srcWith, $srcHeight, $dstWidth, $dstHeight
41. );
43. @$dstImage = imagecreatetruecolor(
44. $dstSize['width'], $dstSize['height']
45. );
47. @imagecopyresampled(
48. $dstImage, $srcImage , 0, 0, 0, 0,
49. $dstSize['width'], $dstSize['height'],
50. $srcWith, $srcHeight
51. );
53. return @imagepng($srcPath, $dstPath);
54. }
56. private function _imageCreateFromBMP($filePath)
57. {
58. $fileHandle = fopen($filePath, 'rb');
59. if (empty($fileHandle)) {
60. return false;
61. }
63. $file = unpack(
64. 'vfile_type/Vfile_size/Vreserved/Vbitmap_offset',
65. fread($fileHandle, 14)
66. );
68. if ($file['file_type'] != 19778) {
69. return false;
70. }
72. $bmp = unpack(
73. 'Vheader_size/Vwidth/Vheight/vplanes/'.
74. 'vbits_per_pixel/Vcompression/Vsize_bitmap/'.
75. 'Vhoriz_resolution/Vvert_resolution/Vcolors_used/Vcolors_important',
76. fread($fileHandle, 40)
77. );
78. $bmp['colors'] = pow(2, $bmp['bits_per_pixel']);
79. if ($bmp['size_bitmap'] == 0) {
80. $bmp['size_bitmap'] = $file['file_size'] - $file['bitmap_offset'];
81. }
82. $bmp['bytes_per_pixel'] = $bmp['bits_per_pixel'] / 8;
83. $bmp['bytes_per_pixel2'] = ceil($bmp['bytes_per_pixel']);
84. $bmp['decal'] = $bmp['width'] * $bmp['bytes_per_pixel'] / 4;
85. $bmp['decal'] -= floor($bmp['width'] * $bmp['bytes_per_pixel'] / 4);
86. $bmp['decal'] = 4 - (4 * $bmp['decal']);
87. if ($bmp['decal'] == 4) {
88. $bmp['decal'] = 0;
89. }
91. $palette = array();
92. if ($bmp['colors'] $palette = unpack(
93. 'V' . $bmp['colors'],
94. fread($fileHandle, $bmp['colors'] * 4)
95. );
96. }
97. $image = fread($fileHandle, $bmp['size_bitmap']);
98. $vide = chr(0);
99. $res = imagecreatetruecolor($bmp['width'], $bmp['height']);
100. $p = 0;
102. $y = $bmp['height'] - 1;
103. while ($y >= 0) {
104. $x = 0;
105. while ($x if ($bmp['bits_per_pixel'] == 24) {
106. $color = unpack('V', substr($image, $p, 3) . $vide);
107. } else if ($bmp['bits_per_pixel'] == 16) {
108. $color = unpack('n', substr($image, $p, 2));
109. $color[1] = $palette[$color[1]+1];
110. } else if ($bmp['bits_per_pixel'] == 8) {
111. $color = unpack('n', $vide . substr ($image, $p, 1));
112. $color[1] = $palette[$color[1]+1];
113. } else if ($bmp['bits_per_pixel'] ==4) {
114. $color = unpack('n', $vide . substr($image, floor($p), 1));
115. if (($p * 2) % 2 == 0) {
116. $color[1] = ($color[1] >> 4);
117. } else {
118. $color[1] = ($color[1] & 0x0F);
119. }
120. $color[1] = $palette[$color[1] + 1];
121. } else if ($bmp['bits_per_pixel'] == 1) {
122. $color = unpack('n', $vide . substr($image, floor($p), 1));
123. switch (($p * 8) % 8) {
124. case 0:
125. $color[1] = ($color[1] >> 7);
126. break;
127. case 1:
128. $color[1] = ($color[1] & 0x40) >> 6;
129. break;
130. case 2:
131. $color[1] = ($color[1] & 0x20) >> 5;
132. break;
133. case 3:
134. $color[1] = ($color[1] & 0x10) >> 4;
135. break;
136. case 4:
137. $color[1] = ($color[1] & 0x8) >> 3;
138. break;
139. case 5:
140. $color[1] = ($color[1] & 0x4) >> 2;
141. break;
142. case 6:
143. $color[1] = ($color[1] & 0x2) >> 1;
144. break;
145. case 7:
146. $color[1] = ($color[1] & 0x1);
147. break;
148. }
149. $color[1] = $palette[$color[1] + 1];
150. } else {
151. return false;
152. }
153. imagesetpixel($res, $x, $y, $color[1]);
154. $x++;
155. $p += $bmp['bytes_per_pixel'];
156. }
157. $y--;
158. $p += $bmp['decal'];
159. }
160. fclose($fileHandle);
161. return $res;
162. }
164. private function _getDstSize($srcWith, $srcHeight, $dstWidth, $dstHeight)
165. {
166. $size = array('width' => $srcWith, 'height' => $srcHeight);
167. if ($dstWidth > 0 && $dstHeight > 0) {
168. if ($srcWith > 0 && $srcHeight > 0) {
169. if ($srcWith / $srcHeight >= $dstWidth / $dstHeight) {
170. if ($srcWith > $dstWidth) {
171. $size['width'] = $dstWidth;
172. $size['height'] = $srcHeight * $dstWidth / $srcWith;
173. }
174. } else {
175. if ($srcHeight > $dstHeight) {
176. $size['width'] = $srcWith * $dstHeight / $srcHeight;
177. $size['height'] = $dstHeight;
178. }
179. }
180. }
181. }
182. return $size;
183. }
184. }

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JPEG, php, GIT