• 技术文章 >后端开发 >php教程

    php生成图像缩略图（支持：JPEG，GIT，PNG，BMP）

    2016-07-25 08:45:09原创660
    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. }
    复制代码

    JPEG, php, GIT


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