PHP generate a graphic verification code program with a background _ PHP Tutorial

PHP generates a graphic verification code program with a background. In the past, we used php to generate verification codes with no background or the same color background. However, this verification is easy for machines to recognize, next, I will introduce some verification codes that we used php to generate a graphic verification code with a background. in the past, all the verification codes were generated with no background or the same color background. However, this verification is easy for the machine to recognize, below I will introduce some examples of generating graphic verification codes with backgrounds.

Example

1. generate a png image
2. set the background color for the image
3. set the font color and style
4. generate a 4-digit random verification code
5. adjust the rotation angle and position of each generated character to the png image.
6. add noise and interference lines to prevent registration machines from malicious registration by analyzing original images
7. output image
8. release memory occupied by images
Authcode. php file

Code

The code is as follows:

Session_start (); Header ('content-type: image/png '); // Create an image $ Im = imagecreate ($ x = 130, $ y = 45 ); $ Bg = imagecolorallocate ($ im, rand (50,200), rand (0,155), rand (0,155); // The first time on imagecolorallocate () will fill the background color for the image based on the color palette. $ FontColor = imageColorAllocate ($ im, 255,255,255); // font color $ Fontstyle = 'rock. ttf'; // font style, which can be found in the c: windowsFonts folder. I put it in the same way as authcode. the PHP file is in the same directory. other font styles can be replaced here. // Generate random characters For ($ I = 0; $ I <4; $ I ++ ){ $ RandAsciiNumArray = array (rand (48, 57), rand (65, 90 )); $ RandAsciiNum = $ randAsciiNumArray [rand (0, 1)]; $ RandStr = chr ($ randAsciiNum ); Imagettftext ($ im, 30, rand ()-rand (), 5 + $ I * 30, rand (), $ fontColor, $ fontstyle, $ randStr ); $ Authcode. = $ randStr; } $ _ SESSION ['authcode'] = $ randFourStr; // compare the verification code entered by the user with that entered by the user // Interference line For ($ I = 0; $ I <8; $ I ++ ){ $ LineColor = imagecolorallocate ($ im, rand (0,255), rand (0,255), rand (0,255 )); Imageline ($ im, rand (0, $ x), 0, rand (0, $ x), $ y, $ lineColor ); } // Interference point For ($ I = 0; I I <250; $ I ++ ){ Imagesetpixel ($ im, rand (0, $ x), rand (0, $ y), $ fontColor ); } Imagepng ($ im ); Imagedestroy ($ im ); ?>

Example 2

• Create a php file captcha_code_file.php

The code is as follows:

// Enable the session first Session_start (); // Define the front-end verification code length and width $ Image_width = 120; $ Image_height = 40; $ Characters_on_image = 6; $ Font = './monofont. ttf '; // The characters that can be used in the CAPTCHA code. // Avoid confusing characters (l 1 and I for example) $ Possible_letters = '23456789bcdfghjkmnpqrstvwxyz '; $ Random_dots = 10; $ Random_lines = 30; $ Captcha_tex_color = "0x142864 "; $ Captcha_noice_color = "0x142864 "; // Define the string to generate the verification code $ Code = ''; $ I = 0; While ($ I <$ characters_on_image ){ $ Code. = substr ($ possible_letters, mt_rand (0, strlen ($ possible_letters)-1), 1 ); $ I ++; } $ Font_size = $ image_height * 0.75; $ Image = @ imagecreate ($ image_width, $ image_height ); /* Setting the background, text and noise colours here */ $ Background_color = imagecolorallocate ($ image, 255,255,255 ); $ Arr_text_color = hexrgb ($ captcha_text_color ); $ Text_color = imagecolorallocate ($ image, $ arr_text_color ['red'], $ Arr_text_color ['green'], $ arr_text_color ['blue']); $ Arr_noice_color = hexrgb ($ captcha_noice_color ); $ Image_noise_color = imagecolorallocate ($ image, $ arr_noice_color ['red'], $ Arr_noice_color ['green'], $ arr_noice_color ['blue']); /* Generating the dots randomly in background */ For ($ I = 0; $ I <$ random_dots; $ I ++ ){ Imagefilledellipse ($ image, mt_rand (0, $ image_width ), Mt_rand (0, $ image_height), 2, 3, $ image_noise_color ); } /* Generating lines randomly in background of image */ For ($ I = 0; $ I <$ random_lines; $ I ++ ){ Imageline ($ image, mt_rand (0, $ image_width), mt_rand (0, $ image_height ), Mt_rand (0, $ image_width), mt_rand (0, $ image_height), $ image_noise_color ); } /* Create a text box and add 6 letters code in it */ $ Textbox = imagettfbbox ($ font_size, 0, $ font, $ code ); $ X = ($ image_width-$ textbox [4])/2; $ Y = ($ image_height-$ textbox [5])/2; Imagettftext ($ image, $ font_size, 0, $ x, $ y, $ text_color, $ font, $ code ); /* Show captcha image in the page html page */ Header ('content-Type: image/jpeg '); // defining the image type to be shown in browser widow Imagejpeg ($ image); // showing the image Imagedestroy ($ image); // destroying the image instance // Set the session for verification $ _ SESSION ['6 _ letters_code '] = $ code; Function hexrgb ($ hexstr) { $ Int = hexdec ($ hexstr ); Return array ("red" => 0xFF & ($ int> 0x10 ), "Green" => 0xFF & ($ int> 0x8 ), "Blue" => 0xFF & $ int ); } Index. php Session_start (); If (isset ($ _ REQUEST ['submit ']) { // Code for check server side validation If (empty ($ _ SESSION ['6 _ letters_code ']) | Strcasecmp ($ _ SESSION ['6 _ letters_code '], $ _ POST ['6 _ letters_code'])! = 0) { $ Msg = "The verification code you entered is incorrect. please enter it again! "; } Else { Echo "You entered the correct one! "; // Captcha verification is Correct. Final Code Execute here! } } ?>