php使用GD库生成bmp格式的图片(imagebmp)

3. /**

4. * 创建bmp格式图片
5. *
6. * @author: legend
7. * @description: create Bitmap-File with GD library
8. * @version: 0.1
9. *
10. * @param resource $im 图像资源
11. * @param string $filename 如果要另存为文件，请指定文件名，为空则直接在浏览器输出
12. * @param integer $bit 图像质量(1、4、8、16、24、32位)
13. * @param integer $compression 压缩方式，0为不压缩，1使用RLE8压缩算法进行压缩
14. *
15. * @return integer
16. */
17. function imagebmp(&$im, $filename = ”, $bit = 8, $compression = 0)
18. {
19. if (!in_array($bit, array(1, 4, 8, 16, 24, 32)))
20. {
21. $bit = 8;
22. }
23. else if ($bit == 32) // todo:32 bit
24. {
25. $bit = 24;
26. }

27. $bits = pow(2, $bit);

28. // 调整调色板

29. imagetruecolortopalette($im, true, $bits);
30. $width = imagesx($im);
31. $height = imagesy($im);
32. $colors_num = imagecolorstotal($im);

33. if ($bit {

34. // 颜色索引
35. $rgb_quad = ”;
36. for ($i = 0; $i {
37. $colors = imagecolorsforindex($im, $i);
38. $rgb_quad .= chr($colors['blue']) . chr($colors['green']) . chr($colors['red']) . “\0″;
39. }

40. // 位图数据

41. $bmp_data = ”;

42. // 非压缩

43. if ($compression == 0 || $bit {
44. if (!in_array($bit, array(1, 4, 8)))
45. {
46. $bit = 8;
47. }

48. $compression = 0;

49. // 每行字节数必须为4的倍数，补齐。

50. $extra = ”;
51. $padding = 4 – ceil($width / (8 / $bit)) % 4;
52. if ($padding % 4 != 0)
53. {
54. $extra = str_repeat(“\0″, $padding);
55. }

56. for ($j = $height – 1; $j >= 0; $j –)

57. {
58. $i = 0;
59. while ($i {
60. $bin = 0;
61. $limit = $width – $i

62. for ($k = 8 – $bit; $k >= $limit; $k -= $bit)

63. {
64. $index = imagecolorat($im, $i, $j);
65. $bin |= $index $i ++;
66. }

67. $bmp_data .= chr($bin);

68. }

69. $bmp_data .= $extra;

70. }
71. }
72. // RLE8 压缩
73. else if ($compression == 1 && $bit == 8)
74. {
75. for ($j = $height – 1; $j >= 0; $j –)
76. {
77. $last_index = “\0″;
78. $same_num = 0;
79. for ($i = 0; $i {
80. $index = imagecolorat($im, $i, $j);
81. if ($index !== $last_index || $same_num > 255)
82. {
83. if ($same_num != 0)
84. {
85. $bmp_data .= chr($same_num) . chr($last_index);
86. }

87. $last_index = $index;

88. $same_num = 1;
89. }
90. else
91. {
92. $same_num ++;
93. }
94. }

95. $bmp_data .= “\0\0″;

96. }

97. $bmp_data .= “\0\1″;

98. }

99. $size_quad = strlen($rgb_quad);

100. $size_data = strlen($bmp_data);
101. }
102. else
103. {
104. // 每行字节数必须为4的倍数，补齐。
105. $extra = ”;
106. $padding = 4 – ($width * ($bit / 8)) % 4;
107. if ($padding % 4 != 0)
108. {
109. $extra = str_repeat(“\0″, $padding);
110. }

111. // 位图数据

112. $bmp_data = ”;

113. for ($j = $height – 1; $j >= 0; $j –)

114. {
115. for ($i = 0; $i {
116. $index = imagecolorat($im, $i, $j);
117. $colors = imagecolorsforindex($im, $index);

118. if ($bit == 16)

119. {
120. $bin = 0

121. $bin |= ($colors['red'] >> 3) $bin |= ($colors['green'] >> 3) $bin |= $colors['blue'] >> 3;

122. $bmp_data .= pack(“v”, $bin);

123. }
124. else
125. {
126. $bmp_data .= pack(“c*”, $colors['blue'], $colors['green'], $colors['red']);
127. }

128. // todo: 32bit;

129. }

130. $bmp_data .= $extra;

131. }

132. $size_quad = 0;

133. $size_data = strlen($bmp_data);
134. $colors_num = 0;
135. }

136. // 位图文件头

137. $file_header = “BM” . pack(“V3″, 54 + $size_quad + $size_data, 0, 54 + $size_quad);

138. // 位图信息头

139. $info_header = pack(“V3v2V*”, 0×28, $width, $height, 1, $bit, $compression, $size_data, 0, 0, $colors_num, 0);

140. // 写入文件

141. if ($filename != ”)
142. {
143. $fp = fopen(“test.bmp”, “wb”);

144. fwrite($fp, $file_header);

145. fwrite($fp, $info_header);
146. fwrite($fp, $rgb_quad);
147. fwrite($fp, $bmp_data);
148. fclose($fp);

149. return 1;

150. }

151. // 浏览器输出

152. header(“Content-Type: image/bmp”);
153. echo $file_header . $info_header;
154. echo $rgb_quad;
155. echo $bmp_data;

156. return 1;

157. }
158. ?>

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