PHP generates random code for a segment

/* * Description: Generate random codes and display random codes graphically. */ $ViewRandomCode = Mt_rand (1000,10000); Session_Start (); $_session[' checksum '] = $ViewRandomCode; function Set_4pixel ($r, $g, $b, $x, $y) { Global $SX, $sy, $pixels; $ofs = 3 * ($SX * $y + $x); $pixels [$ofs] = Chr ($r); $pixels [$ofs + 1] = Chr ($g); $pixels [$ofs + 2] = Chr ($b); $pixels [$ofs + 3] = Chr ($r); $pixels [$ofs + 4] = Chr ($g); $pixels [$ofs + 5] = Chr ($b); $ofs + = 3 * $SX; $pixels [$ofs] = Chr ($r); $pixels [$ofs + 1] = Chr ($g); $pixels [$ofs + 2] = Chr ($b); $pixels [$ofs + 3] = Chr ($r); $pixels [$ofs + 4] = Chr ($g); $pixels [$ofs + 5] = Chr ($b); } Functions for generating digital images function Draw2digits ($x, $y, $number) { Draw_digit ($x, $y, (int) ($number/10)); Draw_digit ($x + one, $y, $number% 10); } function Draw_digit ($x, $y, $digit) { Global $SX, $sy, $pixels, $digits, $lines; $digit = $digits [$digit]; $m = 8; for ($b = 1, $i = 0; $i < 7; $i + +, $b *= 2) { if ($b & $digit) = = $b) { $j = $i * 4; $x 0 = $lines [$j] * $m + $x; $y 0 = $lines [$j + 1] * $m + $y; $x 1 = $lines [$j + 2] * $m + $x; $y 1 = $lines [$j + 3] * $m + $y; if ($x 0 = = $x 1) { $ofs = 3 * ($SX * $y 0 + $x 0); for ($h = $y 0; $h <= $y 1, $h + +, $ofs + = 3 * $sx) { $pixels [$ofs] = chr (0); $pixels [$ofs + 1] = chr (0); $pixels [$ofs + 2] = chr (0); } } else { $ofs = 3 * ($SX * $y 0 + $x 0); for ($w = $x 0; $w <= $x 1; $w + +) { $pixels [$ofs + +] = chr (0); $pixels [$ofs + +] = chr (0); $pixels [$ofs + +] = chr (0); } } } } } Add text to an image function Add_chunk ($type) { Global $result, $data, $chunk, $CRC _table; Chunk: For layers Length:4 bytes: Used to calculate chunk Chunk Type:4 bytes Chunk Data:length bytes Crc:4 bytes: Cyclic Redundancy code Check Copy data and create CRC checksum $len = strlen ($data); $chunk = Pack ("c*", ($len >>) & 255, ($len >>) & 255, ($len >> 8) & 255, $len & 255); $chunk. = $type; $chunk. = $data; Calculate a CRC checksum with the bytes chunk[4..len-1] $z = 16777215; $z |= 255 << 24; $c = $z; for ($n = 4; $n < strlen ($chunk); $n + +) { $c 8 = ($c >> 8) & 0xFFFFFF; $c = $CRC _table[($c ^ ord ($chunk [$n])) & 0xFF] ^ $c 8; } $CRC = $c ^ $z; $chunk. = Chr (($CRC >>) & 255); $chunk. = Chr (($CRC >>) & 255); $chunk. = Chr (($CRC >> 8) & 255); $chunk. = Chr ($CRC & 255); Add results to $result $result. = $chunk; } Main program $SX = 55; $sy = 21; $pixels = rand (100,99990)%2? " Qwer ":" "; Fill for ($h = 0; $h < $sy; $h + +) { for ($w = 0; $w < $sx; $w + +) { $r = 100/$SX * $w + 155; $g = 100/$sy * $h + 155; $b = 255– ($sx + $sy) * ($w + $h)); $pixels. = Chr ($r); $pixels. = Chr ($g); $pixels. = Chr ($b); } } $checknum = Isset ($ViewRandomCode)? $ViewRandomCode: 1234; $h = (int) ($checknum/100); $m = (int) ($checknum%100); $digits = Array (95, 5, 118, 117, 45, 121, 123, 69, 127, 125); $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); Draw2digits (4, 2, $h); Draw2digits (2, $m); Set_4pixel (0, 0, 0, 26, 7); Set_4pixel (0, 0, 0, 26, 13); Create a cyclic redundancy check table $z =-306674912; = 0xedb88320 for ($n = 0; $n < $n + +) { $c = $n; for ($k = 0; $k < 8; $k + +) { $c 2 = ($c >> 1) & 0x7fffffff; if ($c & 1) $c = $z ^ ($c 2); else $c = $c 2; } $CRC _table[$n] = $c; } PNG File Signature $result = Pack ("c*", 137,80,78,71,13,10,26,10); IHDR Chunk Data: Width:4 bytes Height:4 bytes Bit depth:1 byte (8 bits per RGB value) Color Type:1 byte (2 = RGB) Compression Method:1 byte (0 = deflate/inflate) Filter Method:1 byte (0 = Adaptive filtering) Interlace method:1 byte (0 = no interlace) $data = Pack ("c*", ($sx >>) & 255, ($sx >>) & 255, ($SX >> 8) & 255, $SX & 255, ($sy >>) & 255, ($sy >>) & 255, ($sy >> 8) & 255, $sy & 255, 8, 2, 0, 0, 0); Add_chunk ("IHDR"); The following do not dare to translate, please refer yourself Scanline: Filter byte:0 = None RGB bytes for the line The scanline is compressed with "zlib", Method 8 (RFC-1950): Compression method/flags code:1 byte ($78 = Method 8, 32k window) Additional Flags/check bits:1 byte ($01:fcheck = 1, fdict = 0, flevel = 0) Compressed data blocks:n bytes One block (RFC-1951): Bit 0:bfinal:1 for the last block Bit 1 and 2:btype:0 for no compression Next 2 Bytes:len (LSB first) Next 2 Bytes:one ' s complement of LEN LEN bytes Uncompressed Data Check value:4 bytes (Adler-32 checksum of the uncompressed data) // $len = ($SX * 3 + 1) * $SY; $data = Pack ("c*", 0x78, 0x01, 1, $len & 255, ($len >> 8) & 255, 255– ($len & 255), 255– (($len >> 8) & 255)); $start = strlen ($data); $i 2 = 0; for ($h = 0; $h < $sy; $h + +) { $data. = chr (0); for ($w = 0; $w < $SX * 3; $w + +) { $data. = $pixels [$i 2++]; } } Calculate a Adler32 checksum with the bytes Data[start. LEN-1] $s 1 = 1; $s 2 = 0; for ($n = $start; $n < strlen ($data); $n + +) { $s 1 = ($s 1 + ord ($data [$n]))% 65521; $s 2 = ($s 2 + $s 1)% 65521; } $adler = ($s 2 << 16) | $s 1; $data. = Chr (($adler >>) & 255); $data. = Chr (($adler >>) & 255); $data. = Chr (($adler >> 8) & 255); $data. = Chr ($adler & 255); Add_chunk ("IDAT"); Iend:marks the end of the Png-file $data = ""; Add_chunk ("Iend"); Print image Echo ($result); ?> Copy Code

