php生成随机码的一段代码

3. /*

4. * 说明：生成随机码，并用图形方式显示随机码。
5. */

6. $ViewRandomCode = mt_rand(1000,10000);

7. session_start();

8. $_SESSION['checksum'] = $ViewRandomCode;

9. function set_4pixel($r, $g, $b, $x, $y)

10. {
11. global $sx, $sy, $pixels;

12. $ofs = 3 * ($sx * $y + $x);

13. $pixels[$ofs] = chr($r);
14. $pixels[$ofs + 1] = chr($g);
15. $pixels[$ofs + 2] = chr($b);
16. $pixels[$ofs + 3] = chr($r);
17. $pixels[$ofs + 4] = chr($g);
18. $pixels[$ofs + 5] = chr($b);
19. $ofs += 3 * $sx;
20. $pixels[$ofs] = chr($r);
21. $pixels[$ofs + 1] = chr($g);
22. $pixels[$ofs + 2] = chr($b);
23. $pixels[$ofs + 3] = chr($r);
24. $pixels[$ofs + 4] = chr($g);
25. $pixels[$ofs + 5] = chr($b);
26. }
27. //生成数字图象的函数
28. function draw2digits($x, $y, $number)
29. {
30. draw_digit($x, $y, (int) ($number / 10));
31. draw_digit($x + 11, $y, $number % 10);
32. }

33. function draw_digit($x, $y, $digit)

34. {
35. global $sx, $sy, $pixels, $digits, $lines;

36. $digit = $digits[$digit];

37. $m = 8;
38. for ($b = 1, $i = 0; $i {
39. if (($b & $digit) == $b) {
40. $j = $i * 4;
41. $x0 = $lines[$j] * $m + $x;
42. $y0 = $lines[$j + 1] * $m + $y;
43. $x1 = $lines[$j + 2] * $m + $x;
44. $y1 = $lines[$j + 3] * $m + $y;
45. if ($x0 == $x1) {
46. $ofs = 3 * ($sx * $y0 + $x0);
47. for ($h = $y0; $h $pixels[$ofs] = chr(0);
48. $pixels[$ofs + 1] = chr(0);
49. $pixels[$ofs + 2] = chr(0);
50. }
51. } else {
52. $ofs = 3 * ($sx * $y0 + $x0);
53. for ($w = $x0; $w $pixels[$ofs++] = chr(0);
54. $pixels[$ofs++] = chr(0);
55. $pixels[$ofs++] = chr(0);
56. }
57. }
58. }
59. }
60. }

61. //将文字加入到图象中

62. function add_chunk($type)
63. {
64. global $result, $data, $chunk, $crc_table;

65. // chunk :为层

66. // length: 4 字节: 用来计算 chunk
67. // chunk type: 4 字节
68. // chunk data: length bytes
69. // CRC: 4 字节: 循环冗余码校验

70. // copy data and create CRC checksum

71. $len = strlen($data);
72. $chunk = pack(“c*”, ($len >> 24) & 255,
73. ($len >> 16) & 255,
74. ($len >> 8) & 255,
75. $len & 255);
76. $chunk .= $type;
77. $chunk .= $data;

78. // calculate a CRC checksum with the bytes chunk[4..len-1]

79. $z = 16777215;
80. $z |= 255 $c = $z;
81. for ($n = 4; $n $c8 = ($c >> 8) & 0xffffff;
82. $c = $crc_table[($c ^ ord($chunk[$n])) & 0xff] ^ $c8;
83. }
84. $crc = $c ^ $z;

85. $chunk .= chr(($crc >> 24) & 255);

86. $chunk .= chr(($crc >> 16) & 255);
87. $chunk .= chr(($crc >> 8) & 255);
88. $chunk .= chr($crc & 255);

89. // 将结果加到$result中

90. $result .= $chunk;
91. }

92. //主程序

93. $sx = 55;

94. $sy = 21;
95. $pixels = rand(100,99990)%2?”qwer”:”";

96. // 填充

97. for ($h = 0; $h {
98. for ($w = 0; $w {
99. $r = 100 / $sx * $w + 155;
100. $g = 100 / $sy * $h + 155;
101. $b = 255 – (100 / ($sx + $sy) * ($w + $h));
102. $pixels .= chr($r);
103. $pixels .= chr($g);
104. $pixels .= chr($b);
105. }
106. }

107. $checknum = isset($ViewRandomCode)?$ViewRandomCode:1234;

108. $h = (int)($checknum/100);
109. $m = (int)($checknum%100);
110. $digits = array(95, 5, 118, 117, 45, 121, 123, 69, 127, 125);
111. $lines = array(1, 1, 1, 2, 0, 1, 0, 2, 1, 0, 1, 1, 0, 0, 0, 1, 0, 2, 1, 2, 0, 1, 1, 1, 0, 0, 1, 0);

112. draw2digits(4, 2, $h);

113. draw2digits(30, 2, $m);

114. // set_4pixel(0, 0, 0, 26, 7);

115. // set_4pixel(0, 0, 0, 26, 13);

116. // 创建循环冗余码校验表

117. $z = -306674912; // = 0xedb88320
118. for ($n = 0; $n $c = $n;
119. for ($k = 0; $k $c2 = ($c >> 1) & 0×7fffffff;
120. if ($c & 1) $c = $z ^ ($c2); else $c = $c2;
121. }
122. $crc_table[$n] = $c;
123. }

124. // PNG file signature

125. $result = pack(“c*”, 137,80,78,71,13,10,26,10);

126. // IHDR chunk data:

127. // width: 4 bytes
128. // height: 4 bytes
129. // bit depth: 1 byte (8 bits per RGB value)
130. // color type: 1 byte (2 = RGB)
131. // compression method: 1 byte (0 = deflate/inflate)
132. // filter method: 1 byte (0 = adaptive filtering)
133. // interlace method: 1 byte (0 = no interlace)
134. $data = pack(“c*”, ($sx >> 24) & 255,
135. ($sx >> 16) & 255,
136. ($sx >> 8) & 255,
137. $sx & 255,
138. ($sy >> 24) & 255,
139. ($sy >> 16) & 255,
140. ($sy >> 8) & 255,
141. $sy & 255,
142. 8,
143. 2,
144. 0,
145. 0,
146. 0);
147. add_chunk(“IHDR”);

148. // 以下不敢乱翻译，请自行参考

149. // scanline:
150. // filter byte: 0 = none
151. // RGB bytes for the line
152. // the scanline is compressed with “zlib”, method 8 (RFC-1950):
153. // compression method/flags code: 1 byte ($78 = method 8, 32k window)
154. // additional flags/check bits: 1 byte ($01: FCHECK = 1, FDICT = 0, FLEVEL = 0)
155. // compressed data blocks: n bytes
156. // one block (RFC-1951):
157. // bit 0: BFINAL: 1 for the last block
158. // bit 1 and 2: BTYPE: 0 for no compression
159. // next 2 bytes: LEN (LSB first)
160. // next 2 bytes: one’s complement of LEN
161. // LEN bytes uncompressed data
162. // check value: 4 bytes (Adler-32 checksum of the uncompressed data)
163. //
164. $len = ($sx * 3 + 1) * $sy;
165. $data = pack(“c*”, 0×78, 0×01,
166. 1,
167. $len & 255,
168. ($len >> 8) & 255,
169. 255 – ($len & 255),
170. 255 – (($len >> 8) & 255));
171. $start = strlen($data);
172. $i2 = 0;
173. for ($h = 0; $h $data .= chr(0);
174. for ($w = 0; $w $data .= $pixels[$i2++];
175. }
176. }

177. // calculate a Adler32 checksum with the bytes data[start..len-1]

178. $s1 = 1;
179. $s2 = 0;
180. for ($n = $start; $n $s1 = ($s1 + ord($data[$n])) % 65521;
181. $s2 = ($s2 + $s1) % 65521;
182. }
183. $adler = ($s2

184. $data .= chr(($adler >> 24) & 255);

185. $data .= chr(($adler >> 16) & 255);
186. $data .= chr(($adler >> 8) & 255);
187. $data .= chr($adler & 255);
188. add_chunk(“IDAT”);

189. // IEND: marks the end of the PNG-file

190. $data = “”;
191. add_chunk(“IEND”);

192. // 列印图象

193. echo($result);

194. ?>

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