Php generates a random code segment

Php generates a random code segment

/* * Note: generate a random code and display the random code 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 ); } // Function for generating digital images Function draw2digits ($ x, $ y, $ number) { Draw_digit ($ x, $ y, (int) ($ number/10 )); Draw_digit ($ x + 11, $ 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; $ X0 = $ lines [$ j] * $ m + $ x; $ Y0 = $ lines [$ j + 1] * $ m + $ y; $ X1 = $ lines [$ j + 2] * $ m + $ x; $ Y1 = $ lines [$ j + 3] * $ m + $ y; If ($ x0 = $ x1 ){ $ Ofs = 3 * ($ sx * $ y0 + $ x0 ); For ($ h = $ y0; $ h <= $ y1; $ h ++, $ ofs + = 3 * $ sx ){ $ Pixels [$ ofs] = chr (0 ); $ Pixels [$ ofs + 1] = chr (0 ); $ Pixels [$ ofs + 2] = chr (0 ); } } Else { $ Ofs = 3 * ($ sx * $ y0 + $ x0 ); For ($ w = $ x0; $ w <= $ x1; $ w ++ ){ $ Pixels [$ ofs ++] = chr (0 ); $ Pixels [$ ofs ++] = chr (0 ); $ Pixels [$ ofs ++] = chr (0 ); } } } } } // Add text to the image Function add_chunk ($ type) { Global $ result, $ data, $ chunk, $ crc_table; // Chunk: Layer // Length: 4 bytes: used to calculate chunk // Chunk type: 4 bytes // Chunk data: length bytes // CRC: 4 bytes: cyclic verification // Copy data and create CRC checksum $ Len = strlen ($ data ); $ Chunk = pack ("c *", ($ len> 24) & 255, ($ Len> 16) & 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 ++ ){ $ C8 = ($ c> 8) & 0 xffffff; $ C = $ crc_table [($ c ^ ord ($ chunk [$ n]) & 0xff] ^ $ c8; } $ Crc = $ c ^ $ z; $ Chunk. = chr ($ crc> 24) & 255 ); $ Chunk. = chr ($ crc> 16) & 255 ); $ Chunk. = chr ($ crc> 8) & 255 ); $ Chunk. = chr ($ crc & 255 ); // Add the result to $ result $ Result. = $ chunk; } // Main program $ Sx = 55; $ Sy = 21; $ Pixels = rand (, 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-(100/($ 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 (30, 2, $ m ); // Set_4pixel (0, 0, 0, 26, 7 ); // Set_4pixel (0, 0, 0, 26, 13 ); // Create a cyclic verification table $ Z =-306674912; // = 0xedb88320 For ($ n = 0; $ n <256; $ n ++ ){ $ C = $ n; For ($ k = 0; $ k <8; $ k ++ ){ $ C2 = ($ c> 1) & 0 × 7fffffff; If ($ c & 1) $ c = $ z ^ ($ c2); else $ c = $ c2; } $ Crc_table [$ n] = $ c; } // PNG file signature $ Result = pack ("c ); // 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> 24) & 255, ($ Sx> 16) & 255, ($ Sx> 8) & 255, $ Sx & 255, ($ Sy> 24) & 255, ($ Sy> 16) & 255, ($ Sy> 8) & 255, $ Sy & 255, 8, 2, 0, 0, 0 ); Add_chunk ("IHDR "); // Do not translate the text below. please refer to it 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, 32 k 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 ); $ I2 = 0; For ($ h = 0; $ h <$ sy; $ h ++ ){ $ Data. = chr (0 ); For ($ w = 0; $ w <$ sx * 3; $ w ++ ){ $ Data. = $ pixels [$ i2 ++]; } } // Calculate a Adler32 checksum with the bytes data [start .. len-1] $ S1 = 1; $ S2 = 0; For ($ n = $ start; $ n <strlen ($ data); $ n ++ ){ $ S1 = ($ s1 + ord ($ data [$ n]) % 65521; $ S2 = ($ s2 + $ S1.) % 65521; } $ Adler = ($ s2 <16) | $ s1; $ Data. = chr ($ adler> 24) & 255 ); $ Data. = chr ($ adler> 16) & 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 the image Echo ($ result ); ?>