The latest and most full PHP generation verification Code details (recommended), detailed verification Code _php tutorial

The latest and most full PHP generation verification Code details (recommended), detailed verification code

1 First look at the code first

OK, now combine the above code, to analyze and analyze the above used several functions:

①imagecreatetruecolor ();

imagecreatetruecolor-Create a new true color image (feel wow, so long, actually carefully look at a very good remember image/create/true/color, what is true color image? Look down)

Resource Imagecreatetruecolor (int $width, int $height)

Imagecreatetruecolor () and imagecreate () two functions can create a canvas

Imagecreatetruecolor () creates a black image of size x and Y (the default is black [even if it's a true color image]), and if you want to change the background color, you need to

To use the Fill color function Imagefill ($img, 0,0, $color);

Imagecreate Create a new blank image resource, add a background color with imagecolorallocate ()

The above two functions are nothing more than a function of two ways

②imagecolorallocate ();

imagecolorallocate-assigning colors to an image

int Imagecolorallocate (resource $image, int $red, int $green, int $blue)

The colors are made up of red, green, and blue three-color combinations, which are integers from 0 to 255 or hex 0x00 to 0xFF.

③mt_rand ();

mt_rand-generate a better random number

int Mt_rand (int $min, int $max)

$min optional, returned minimum value (default: 0) $max optional, maximum value returned (default: Mt_getrandmax ())
This is used to let him randomly generate background color, 0-255 random value. So the page does not refresh once the canvas background color is different. ：

2.0 begin to make a disturbance line, which disturbs the point. Prevent verification images from being recognized by seconds

Function Analysis:

①imageline ();

imageline-Drawing a line segment

Imageline () Draws a line segment from coordinates x1,y1 to X2,y2 (0, 0 in the upper left corner of the image) with a color color.

Imageline ($img, Mt_rand (0,150), Mt_rand (0,50), Mt_rand (0,150), Mt_rand (0,50), $linecolor); This means that the canvas $img from coordinates x1,y1 to x2, Y2 random

②imagesetpixel ();

imagesetpixel-draw a single pixel

BOOL Imagesetpixel (resource $image, int $x, int $y, int $color)

Imagesetpixel () Draws a point on the image with a color in x, y coordinates (0,0 in the upper-left corner of the image).

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3.0 Adding a verification letter number

<?phpheader ("content-type:text/html; charset=utf-");//Set the encoding style header (" Content-type:image/jpeg ") of the page,//notify the browser output is JPEG format image $img = Imagecreatetruecolor (,); /create canvas and set size x-axis y-Axis $bgcolor = imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,));//Assign background color//Add interference line, and cycle times, Background color random for ($i =; $i <; $i + +) {$linecolor = Imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,)); Imageline ($img , Mt_rand (,), Mt_rand (,), Mt_rand (,), Mt_rand (,), $linecolor);} Add interference points, and loop the times, background color random for ($i =; $i <; $i + +) {$dotcolor = Imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,)); Imagesetpixel ($img, Mt_rand (,), Mt_rand (,), $dotcolor);} Add letters or numbers that need to be verified $rand_str = "QWERTYUIOPASDFGHJKLZXCVBNM";//need to use some letters and numbers to verify $str_arr = Array (); Name an array for ($i =; $i <; $i + +) {//round robin, there are four random letters or numbers $pos = Mt_rand (, strlen ($rand _str)-); $str _arr[] = $rand _str[$pos] ;//Temporary Swap} $x _start=/;//single character x-axis position foreach ($str _arr as $key) {$fontcolor = Imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,)); Imagettftext ($img,, Mt_rand (-), $x _start,/, $FONTCOlor, "C:/windows/fonts/verdana.ttf", $key); $x _start +=;//traverse a single character along the x-axis +}imagefill ($img,,, $bgcolor); Fill the background with the image imagejpeg ($img); Output Image Imagedestroy ($img);  Destroy Image?>

Function:

Imagettftext ();

imagettftext-writing text to an image with TrueType fonts

Analyze the following code:

$img-----------Canvas

-----------the size of the font.

Mt_rand ( -15,15) angle is----------angle, and 0 degrees is the text that reads from left to right. A higher value indicates a counterclockwise rotation. For example, 90 degrees is the text that reads from the bottom up. (That's the problem with the font angle)

$x _start----------Easy to understand is the x-axis position of the character

50/2 height of----------characters

$fontcolor----------Character Color

Font style path for "C:/windows/fonts/verdana.ttf"----------characters

$key-----------The characters after the traversal

Effect:

The above content is this article to introduce you to the latest and most full PHP production verification Code details (recommended) of the full narrative, I hope to help you!

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