The latest most complete PHP production verification Code code detailed (recommended) _php example

1 first read the code first

<?php
Header ("content-type:text/html; charset=utf-")//sets the encoding style
header (" Content-type:image/jpeg ") of the page;//notifies the browser that the image is in JPEG format
$img = Imagecreatetruecolor (,);//create canvas and set size x axis y axis
$bgcolor = Imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,)) ;//Assign Background color
Imagefill ($img,,, $bgcolor);////fill the background to the image
imagejpeg ($img);//Output Image
Imagedestroy ($img);//Destroy image

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

①imagecreatetruecolor ();

imagecreatetruecolor-new A true color image (feel wow, so long, in fact, a very good look at the 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 X and Y (the default is black [even if the name is True Color image]), and you want to change the background color

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

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

The top two functions are just two ways to function

②imagecolorallocate ();

imagecolorallocate-assign color to an image

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

The colors are combined in red, green and blue, which are 0 to 255 integers or hexadecimal 0x00 to 0xFF.

③mt_rand ();

mt_rand-to generate better random numbers

int Mt_rand (int $min, int $max)

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

2.0 start to the inside to do disturbing lines, disturbances points. Prevent validating images from being recognized by seconds

<?php
Header ("content-type:text/html; charset=utf-")//sets the encoding style
header (" Content-type:image/jpeg ") of the page;//notifies the browser that the image is in JPEG format
$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 loop, background color randomly for
($i =; $i <; $i + +) {
$linecolor = imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,));
Imageline ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,), Mt_rand (,), $linecolor);
}
Add interference points, and cycle times, background color random for
($i =; $i <; $i + +) {
$dotcolor = imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), MT _rand (,));
Imagesetpixel ($img, Mt_rand (,), Mt_rand (,), $dotcolor);
}
Imagefill ($img,,, $bgcolor); Fill the background to the image
imagejpeg ($img);//Output Image
Imagedestroy ($img);//Destroy image

Function Analysis:

①imageline ();

imageline-Draw a line segment

Imageline () Draws a line segment from the coordinate x1,y1 to the x2,y2 (0, 0) in image images in color color.

Imageline ($img, Mt_rand (0,150), Mt_rand (0,50), Mt_rand (0,150), Mt_rand (0,50), $linecolor); This means 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 image in the X,y coordinate (0,0 in the upper-left corner of the image) in color.

Effect Chart:

3.0 Add validated Alphanumeric

<?php header ("content-type:text/html; charset=utf-");//Set the encoding style header (" Content-type:image/jpeg ") of the page;//notification browser output is JPEG image $img = Imagecreatetruecolor (,);
/Create the canvas and set the 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 (,), $linecolor);
//Add interference points, and cycle times, background color randomly for ($i =; $i <; $i + +) {$dotcolor = Imagecolorallocate ($img, Mt_rand (,), Mt_rand (,), Mt_rand (,));
Imagesetpixel ($img, Mt_rand (,), Mt_rand (,), $dotcolor); //Add the letters or numbers that need to be validated $rand _str = "qwertyuiopasdfghjklzxcvbnm";//need to use some letters and numbers to verify $STR _arr = Array (); Name an array for ($i =; $i <; $i + +) {//cycle times, there are four random letters or numbers $pos = Mt_rand (, strlen ($rand _str)-), $str _arr[] = $rand _str[$pos]; Temporary swap} $x _start=/;//a single character x axis position foreach ($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); $x _start +=;//traverse the single character along the x-axis +} imagefill ($img,,, $bgcolor); Fill the background to the image imagejpeg ($img); Output Image Imagedestroy ($img);  Destroying Images?>

Function:

Imagettftext ();

Imagettftext-writes text to an image with a TrueType font

Analyze the following code:

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

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

Mt_rand ( -15,15)----------angle, 0 degrees is read from left to right text. A higher number indicates a counter-clockwise rotation. For example, 90 degrees represents text that is read from the bottom up. (is the font angle of the problem,)

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

50/2 the height of the----------character

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

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

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

Effect:

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