Php generates an image verification code,

Php generates an image verification code,

First, let's take a look at the general effect.

Then, paste the Code directly.

<? Php $ image = imagecreatetruecolor (100, 30); // create a canvas $ imagecolor = imagecolorallocate ($ image, 255,255,255); // background color imagefill ($ image, 0, 0, $ imagecolor); // fill in the background color for ($ I = 0; $ I <4; $ I ++) {// loop 4 digits $ fontsize = 6; $ fontcolor = imagecolorallocate ($ images, rand (0,200), rand (0,200), rand (0,200); $ fontcontent = rand (0, 9 ); $ x = $ I * 100/4 + rand (5, 15); $ y = rand (5, 10); imagestring ($ image, $ fontsize, $ x, $ y, $ Fontcontent, $ fontcolor);} for ($ I = 0; $ I <200; $ I ++) {// Add interference points cyclically $ pointcolor = imagecolorallocate ($ image, rand (50,200), rand (50,200), rand (50,200); $ x = rand (1, 99); $ y = rand (1, 29 ); imagesetpixel ($ image, $ x, $ y, $ pointcolor) ;}for ($ I = 0; $ I <3; $ I ++) {// Add interference lines cyclically $ linecolor = imagecolorallocate ($ image, rand (100,250), rand (100,250), rand (100,250); $ x1 = rand (1, 25); $ x2 = rand (50, 75); $ y1 = r And (1, 15); $ y2 = rand (15, 25); imageline ($ image, $ x1, $ y1, $ x2, $ y2, $ linecolor );} header ("content-type: image/png"); imagepng ($ image); imagedestroy ($ image);?>

I will share with you a Chinese verification code that can be generated.

<? Php // 1. qi enables the gd library of the GD library to provide a series of APIS for image processing. The GD library can be used to process images or generate images. // The GD library on the website is usually used to generate thumbnails, add watermarks to images, or generate reports on website data. Session_start (); // converts a GBK encoded string to a UTF-8 string. The first parameter is written in GBK, is because the PHP file stored in the host encoding is GBK encoding // UTF-8 encoding browser universal support, versatility, here is converted to UTF-8 $ str = iconv ("GBK ", "UTF-8", "all sentient beings, green mountains, scenic spots, and monuments are open to us."); if (! Is_string ($ str) |! Mb_check_encoding ($ str, "UTF-8") {exit ("not a string or UTF-8");} $ zhongwenku_size; // get the length of the string by UTF-8 encoding $ zhongwenku_size = mb_strlen ($ str, "UTF-8"); // import the above character into the array $ zhongwenku = array (); for ($ I = 0; $ I <$ zhongwenku_size; $ I ++) {$ zhongwenku [$ I] = mb_substr ($ str, $ I, 1, "UTF-8") ;}$ result = ""; // four characters to write to the image for ($ I = 0; $ I <4; $ I ++) {switch (rand (0, 1) {case 0: $ result. = $ zhongwenku [rand (0, $ zhongwenku_size-1)]; break; case 1: $ r Esult. = dechex (rand (100); break ;}$ _ SESSION ["check"] = $ result; // create a true color image with a width, height 30 $ img = imagecreatetruecolor (100, 30); // assign the background color $ bg = imagecolorallocate ($ img, 0, 0, 0 ); // assign the text color $ te = imagecolorallocate ($ img, 255,255,255); // write the string on the image // imagestring ($ img, rand (), rand ), rand (), $ result, $ te); // you can write special fonts imagettftext ($ img, 13, rand (2, 9), 20, 20, $ te, "MSYH. TTF ", $ result); $ _ SESSION ["Check"] = $ result; for ($ I = 0; $ I <3; $ I ++) {// $ t = imagecolorallocate ($ img, rand (0,255), rand (0,255), rand (0,255); // draw line imageline ($ img, 0, rand (0, 20), rand (70,100 ), rand (0, 20), $ te) ;}$ t = imagecolorallocate ($ img, rand (0,255), rand (0,255), rand (0,255 )); // Add noise for ($ I = 0; $ I <200; $ I ++) {imagesetpixel ($ img, rand (1,100), rand (1, 30), $ t) ;}// send http header information to specify that the sender header ("Content-type: image/ Jpeg "); // output the jpeg image to the browser imagejpeg ($ img);?>

Let's try another instance.

<? Php session_start (); function random ($ len) {$ srcstr = "1a2s3d4f5g6hj8k9qwertyupzxcvbnm"; mt_srand (); $ strs = ""; for ($ I = 0; $ I <$ len; $ I ++) {$ strs. = $ srcstr [mt_rand (0, 30)];} return $ strs;} // randomly generated string $ str = random (4 ); // The width of the Verification Code image $ width = 50; // The height of the Verification Code image $ height = 25; // declare the image format of the layer to be created @ header ("Content-Type: image/png "); // create a layer $ im = imagecreate ($ width, $ height); // background color $ back = imagecolorallocate ($ I M, 0xFF, 0xFF, 0xFF); // blurred dot color $ pix = imagecolorallocate ($ im, 187,230,247); // font color $ font = imagecolorallocate ($ im, 41,163,238 ); // plot the Blur point mt_srand (); for ($ I = 0; $ I <1000; $ I ++) {imagesetpixel ($ im, mt_rand (0, $ width), mt_rand (0, $ height), $ pix);} // output character imagestring ($ im, 5, 7, 5, $ str, $ font ); // output rectangular imagerectangle ($ im, 0, 0, $ width-1, $ height-1, $ font); // output image imagepng ($ im ); imagedestroy ($ im); $ st R = md5 ($ str); // select cookie // SetCookie ("verification", $ str, time () + 7200 ,"/"); // select Session $ _ SESSION ["verification"] = $ str;?>

Next, you just need to call it on the page:

If you want to achieve "cannot see clearly? For a different effect, add the following JS to the page.

function changing(){  document.getElementById('checkpic').src="/images/checkcode.php?"+Math.random();} 

The above is all the content of this article. I hope you will like it.