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php生成图像缩略图（支持：JPEG，GIT，PNG，BMP）

时间：2021-07-01 10:21:17 帮助过：18人阅读

  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 <= $dstWidth && $srcHeight <= $dstHeight) {
  20. return copy($srcPath, $dstPath);
  21. }
  23. //读取原始图片资源
  24. @$srcImage = imagecreatefromjpeg($srcPath);
  25. if (empty($srcImage)) {
  26. @$srcImage = imagecreatefromgif($srcPath);
  27. }
  28. if (empty($srcImage)) {
  29. @$srcImage = imagecreatefrompng($srcPath);
  30. }
  31. if (empty($srcImage)) {
  32. @$srcImage = $this->_imageCreateFromBMP($srcPath);
  33. }
  35. if (empty($srcImage)) {
  36. return false;
  37. }
  39. //获取缩略图的尺寸，并据此生成新的图像
  40. $dstSize = $this->_getDstSize(
  41. $srcWith, $srcHeight, $dstWidth, $dstHeight
  42. );
  44. @$dstImage = imagecreatetruecolor(
  45. $dstSize['width'], $dstSize['height']
  46. );
  48. @imagecopyresampled(
  49. $dstImage, $srcImage , 0, 0, 0, 0,
  50. $dstSize['width'], $dstSize['height'],
  51. $srcWith, $srcHeight
  52. );
  54. return @imagepng($srcPath, $dstPath);
  55. }
  57. private function _imageCreateFromBMP($filePath)
  58. {
  59. $fileHandle = fopen($filePath, 'rb');
  60. if (empty($fileHandle)) {
  61. return false;
  62. }
  64. $file = unpack(
  65. 'vfile_type/Vfile_size/Vreserved/Vbitmap_offset',
  66. fread($fileHandle, 14)
  67. );
  69. if ($file['file_type'] != 19778) {
  70. return false;
  71. }
  73. $bmp = unpack(
  74. 'Vheader_size/Vwidth/Vheight/vplanes/'.
  75. 'vbits_per_pixel/Vcompression/Vsize_bitmap/'.
  76. 'Vhoriz_resolution/Vvert_resolution/Vcolors_used/Vcolors_important',
  77. fread($fileHandle, 40)
  78. );
  79. $bmp['colors'] = pow(2, $bmp['bits_per_pixel']);
  80. if ($bmp['size_bitmap'] == 0) {
  81. $bmp['size_bitmap'] = $file['file_size'] - $file['bitmap_offset'];
  82. }
  83. $bmp['bytes_per_pixel'] = $bmp['bits_per_pixel'] / 8;
  84. $bmp['bytes_per_pixel2'] = ceil($bmp['bytes_per_pixel']);
  85. $bmp['decal'] = $bmp['width'] * $bmp['bytes_per_pixel'] / 4;
  86. $bmp['decal'] -= floor($bmp['width'] * $bmp['bytes_per_pixel'] / 4);
  87. $bmp['decal'] = 4 - (4 * $bmp['decal']);
  88. if ($bmp['decal'] == 4) {
  89. $bmp['decal'] = 0;
  90. }
  92. $palette = array();
  93. if ($bmp['colors'] < 16777216) {
  94. $palette = unpack(
  95. 'V' . $bmp['colors'],
  96. fread($fileHandle, $bmp['colors'] * 4)
  97. );
  98. }
  99. $image = fread($fileHandle, $bmp['size_bitmap']);
  100. $vide = chr(0);
  101. $res = imagecreatetruecolor($bmp['width'], $bmp['height']);
  102. $p = 0;
  104. $y = $bmp['height'] - 1;
  105. while ($y >= 0) {
  106. $x = 0;
  107. while ($x < $bmp['width']) {
  108. if ($bmp['bits_per_pixel'] == 24) {
  109. $color = unpack('V', substr($image, $p, 3) . $vide);
  110. } else if ($bmp['bits_per_pixel'] == 16) {
  111. $color = unpack('n', substr($image, $p, 2));
  112. $color[1] = $palette[$color[1]+1];
  113. } else if ($bmp['bits_per_pixel'] == 8) {
  114. $color = unpack('n', $vide . substr ($image, $p, 1));
  115. $color[1] = $palette[$color[1]+1];
  116. } else if ($bmp['bits_per_pixel'] ==4) {
  117. $color = unpack('n', $vide . substr($image, floor($p), 1));
  118. if (($p * 2) % 2 == 0) {
  119. $color[1] = ($color[1] >> 4);
  120. } else {
  121. $color[1] = ($color[1] & 0x0F);
  122. }
  123. $color[1] = $palette[$color[1] + 1];
  124. } else if ($bmp['bits_per_pixel'] == 1) {
  125. $color = unpack('n', $vide . substr($image, floor($p), 1));
  126. switch (($p * 8) % 8) {
  127. case 0:
  128. $color[1] = ($color[1] >> 7);
  129. break;
  130. case 1:
  131. $color[1] = ($color[1] & 0x40) >> 6;
  132. break;
  133. case 2:
  134. $color[1] = ($color[1] & 0x20) >> 5;
  135. break;
  136. case 3:
  137. $color[1] = ($color[1] & 0x10) >> 4;
  138. break;
  139. case 4:
  140. $color[1] = ($color[1] & 0x8) >> 3;
  141. break;
  142. case 5:
  143. $color[1] = ($color[1] & 0x4) >> 2;
  144. break;
  145. case 6:
  146. $color[1] = ($color[1] & 0x2) >> 1;
  147. break;
  148. case 7:
  149. $color[1] = ($color[1] & 0x1);
  150. break;
  151. }
  152. $color[1] = $palette[$color[1] + 1];
  153. } else {
  154. return false;
  155. }
  156. imagesetpixel($res, $x, $y, $color[1]);
  157. $x++;
  158. $p += $bmp['bytes_per_pixel'];
  159. }
  160. $y--;
  161. $p += $bmp['decal'];
  162. }
  163. fclose($fileHandle);
  164. return $res;
  165. }
  167. private function _getDstSize($srcWith, $srcHeight, $dstWidth, $dstHeight)
  168. {
  169. $size = array('width' => $srcWith, 'height' => $srcHeight);
  170. if ($dstWidth > 0 && $dstHeight > 0) {
  171. if ($srcWith > 0 && $srcHeight > 0) {
  172. if ($srcWith / $srcHeight >= $dstWidth / $dstHeight) {
  173. if ($srcWith > $dstWidth) {
  174. $size['width'] = $dstWidth;
  175. $size['height'] = $srcHeight * $dstWidth / $srcWith;
  176. }
  177. } else {
  178. if ($srcHeight > $dstHeight) {
  179. $size['width'] = $srcWith * $dstHeight / $srcHeight;
  180. $size['height'] = $dstHeight;
  181. }
  182. }
  183. }
  184. }
  185. return $size;
  186. }
  187. }

JPEG, php, GIT

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