Php-based verification code Applet and php Verification Code Applet

Php-based verification code Applet and php Verification Code Applet

Verification Code function (personal understanding ):

• Reduce the pressure on the server (for example, the verification code 12306 function );
• Prevents violent Registration

Personal thinking: In a-z, A-Z, 1-9 generate n random numbers to form a new verification code.

Several small functions for generating verification Codes

Range () // specify the range to output an array
A) For example: range)
Array_merge () // merge Arrays
A) array_merge (array 1, array 2 ....)
Array_rand (array, quantity)
A) randomly retrieve several subscripts from the array and return an array.

• Shuffle (array) // will disrupt the elements in the array again
• Mt_rand (specify a range) // generate a better Random Number
• For example, mt_rand () // generates an arbitrary number between 1 and 5.

Generate Verification Code

<? Php $ arr1 = range ('A', 'z'); // specify the range to output an array $ arr2 = range ('A', 'z '); $ arr3 = range (1, 9); $ arr = array_merge ($ arr1, $ arr2, $ arr3); // merge arrays $ index = array_rand ($ arr, 5 ); // In $ arr, the number of 5 is random. The returned value is $ arr subscript Shuffle ($ index); $ code = ''; // define an empty string to store the generated verification code. Use 'point' to splice foreach ($ index as $ key => $ value) {// traverse the array $ code. = $ arr [$ value]; // obtain the value in the array according to the subscript} var_dump ($ code);?>

Running result

Perfect: You need to add the verification code to the image to make it realistic.

Before making improvements, let's take a look at the general steps for creating images.

Create an image

Method 1: create a true color image (empty canvas)

Imagecreatetruecolor (width, height) // create a true color image

Note:

• Width: the width (in pixels) of the canvas)
• Height: the height of the canvas in pixels)
• The returned value is image resource.

Note:

True Color Image: fill color

Imagefill (image, x, y, color) // fill the color of image resources

Note:

• Image // image resources
• X, y, fill coordinate point (Note: Fill the closest color to this point)
• Color; // The color used for filling.

True Color Image: Color allocation

imagecolorallocate(image, red, green, blue)

Note:

• Image // image resources
• Red: // the red color (0-255) or 0x (00-ff) // indicates the hexadecimal notation (0xff is 255)
• Green // green color (0-255)
• Blue // blue color (0-255)

Code demonstration of imagefill and imagecolorallocate

Effect when the canvas is not colored

Effects and code when adding colors to the canvas

<? Php // create image resources (blank canvas) Black by default $ image = imagecreatetruecolor (300,400); // 1. image // image resource // 2.red: // red color (0-255) or 0x (00-ff) // that is, hexadecimal representation (0xff is 255) // 3. green // green color (0-255) // 4. blue // blue color (0-255) $ color = imagecolorallocate ($ image, 255, 0, 0); // 1. image // image resource // 2.x, y, fill coordinate point (Note: Fill the closest color to this point) // 3. color; // The color used to fill the imagefill ($ image, 0, 0, $ color); // output image header ('content-type: image/jpeg '); imagejpeg ($ image); // destroy the image resource imagedestr Oy ($ image);?>

Result;

Output image (using jpeg as an example)

Output the image to the browser

A) header ('content-type: image/jpeg '); // you can view the image through browsing.

B) imagejpeg (image resources)

Output images by file

A) imagejpeg (image resource, 'image path', image quality) // the image quality value ranges from 0 to 100.

B) Note:

Note: Only the jpeg format can have the quality parameter.

Destroy Images

Imagedestroy ($ image); // destroy the image to release memory resources.

Note: several image resources are generated and destroyed.

The entire code of the Verification Code:

<? Php // example: Place text in the middle of an image // create an image resource (blank canvas) $ image = imagecreatetruecolor (100, 50); $ color = imagecolorallocate ($ image, mt_rand (20,200), mt_rand (20,200), mt_rand (20,200); // fill the image resource color imagefill ($ image, 0, 0, $ color ); // draw the image $ font = 5; // start of the Verification Code $ arr1 = range ('A', 'z'); $ arr3 = range ('A ', 'Z'); $ arr2 = range (); // array_merge-merges one or more arrays $ arr = array_merge ($ arr1, $ arr2, $ arr3 ); $ index = array_rand ($ arr, 5); // randomly locate 5 subscripts from the original array $ string = ''; foreach ($ index as $ value) {// $ value is the value in $ index and the subscript $ string in $ arr. = $ arr [$ value]; // connect the obtained characters} // end of the Verification Code // mt_rand-generate a better random number // echo mt_rand (); die; // Add point interference $ pointcolor = imagecolorallocate ($ image, mt_rand (20,200), mt_rand (20,200), mt_rand (20,200 )); // create 1000 interference points in a loop for ($ I = 0; $ I <1000; $ I ++) {imagesetpixel ($ image, mt_rand (0, imagesx ($ image), mt_rand (0, imagesy ($ image), $ pointcolor);} // line interference $ lintecolor = imagecolorallocate ($ image, mt_rand (20,200), mt_rand (20,200), mt_rand (20,200); // create 50 line interference for ($ I = 0; $ I <50; $ I ++) {imageline ($ image, mt_rand (0, imagesx ($ image), mt_rand (0, imagesy ($ image), mt_rand (0, imagesx ($ image), mt_rand (0, imagesy ($ image), $ lintecolor) ;}// the width of one character imagefontwidth ($ font) // The number of strings: strlen (string) // width of one character * Number of strings // width of all strings and = width of one character * Number of strings // $ x = (width of the canvas-width of all strings and) /2 $ x = (imagesx ($ image)-imagefontwidth ($ font) * strlen ($ string)/2; // $ y = (canvas height-character height)/2; // character height: imagefontheight ($ font) $ y = (imagesy ($ image) -imagefontheight ($ font)/2; $ stringcolor = imagecolorallocate ($ image, mt_rand (20,200), mt_rand (20,200), mt_rand (20,200); imagestring ($ image, $ font, $ x, $ y, $ string, $ stringcolor); // output image header ('content-type: image/jpeg '); // set to view images through browsing imagejpeg ($ image, '', 100); // output image resources // destroy image resources imagedestroy ($ image ); // destroy the image

Understand some functions in the code

Interference point added

imagesetpixel(image, x, y, color)

Note: coordinates of a vertex x and y

Add interference line

imageline(image, x1, y1, x2, y2, color)

Note: x1, y1 is an endpoint coordinate of the line; x2, y2 is the coordinate of another port of the line; draw a line from two points

Place the verification code in the middle of the image

Imagefontheight (font) to get the font Height: imagefontwidth (font) to get the font width: strlen (string) // to get the length of the string imagesx (image) // obtain the canvas width imagesy (image) // obtain the canvas height

Final running result

Further improvement (combined with html code)

Html code

<! DOCTYPE html> 
Understanding;

Final Result

The above is all the content of this article. I hope this article will help you in your study or work. I also hope to provide more support to the customer's home!