Daily organization of simple graphics processing in PHP (classic), php graphics processing_PHP tutorial

Daily arrangement of simple graphics processing in PHP (classic), PHP graphics processing

1. Load the GD library

The GD library is an open function library for dynamic image creation and open source code. It can be downloaded from the official website http://www.boutell.com/gd. Currently, the GD library supports multiple image formats such as GIF, PNG, JPEG, WBMP and XBM for image processing.

The GD library is installed by default in PHP 5, but to activate the GD library, you must modify the php.ini file. Delete the semicolon ";" before the ";extension=php_gd2.dll" option in the file, save the modified file and restart the Apache server to take effect.

2. Create a simple image

Use the GD2 function library to process various graphics and images. Creating a canvas is the first step to create an image using the GD2 function library. No matter what kind of image you create, you first need to create a canvas, and all other operations will be completed on this canvas. Creating a canvas in the GD2 function library can be achieved through the imagecreate() function.

Use the imagecreate() function to create a canvas with a width of 200 pixels and a height of 60 pixels, and set the canvas color RGB (225, 66, 159), and finally output an image in GIF format. The code is as follows:

<&#63;php
$im = imagecreate(200,60);           //创建一个画布
$white = imagecolorallocate($im, 225,66,159);   //设置画布的背景颜色为浅绿色
imagegif($im);                //输出图像
&#63;>

3. Use GD2 function to add text on photos

The GD library in PHP supports Chinese, but it must be passed in UTF-8 format parameters. If you use the imageString() function to directly draw a Chinese string, garbled characters will be displayed. This is because GD2 can only accept Chinese. UTF-8 encoding format, and English fonts are used by default, so to output Chinese strings, the Chinese strings must be transcoded and the fonts used for Chinese characters must be set. Otherwise, the output will only be garbled characters.

Use the imageTTFText() function to output the text "This is a test" into the image. The code is as follows:

<&#63;php
header("content-type:image/jpeg");    //定义输出为图像类型
$im=imagecreatefromjpeg("images/photo.jpg");    //载入照片
$textcolor=imagecolorallocate($im,56,73,136);//设置字体颜色为蓝色，值为RGB颜色值
$fnt="c:/windows/fonts/simhei.ttf";   //定义字体
$motto=iconv("gb2312","utf-8","这是一个测试");   //定义输出字体串
imageTTFText($im,220,0,480,340,$textcolor,$fnt,$motto);   //写TTF文字到图中
imagejpeg($im);    //建立JPEG图形
imagedestroy($im);  //结束图形，释放内存空间
&#63;>

4. PHP generates verification code

Create a checks.php file, use the GD2 function in the file to create a 4-digit verification code, and save the generated verification code to the session:

<&#63;php
session_start();
header("content-type:image/png");    //设置创建图像的格式
$image_width=70;           //设置图像宽度
$image_height=18;           //设置图像高度
srand(microtime()*100000);        //设置随机数的种子
for($i=0;$i<4;$i++){         //循环输出一个4位的随机数
  $new_number.=dechex(rand(0,15));
}
$_SESSION[check_checks]=$new_number;  //将获取的随机数验证码写入到SESSION变量中   

$num_image=imagecreate($image_width,$image_height); //创建一个画布
imagecolorallocate($num_image,255,255,255);     //设置画布的颜色
for($i=0;$i<strlen($_SESSION[check_checks]);$i++){ //循环读取SESSION变量中的验证码
  $font=mt_rand(3,5);                //设置随机的字体
  $x=mt_rand(1,8)+$image_width*$i/4;        //设置随机字符所在位置的X坐标
  $y=mt_rand(1,$image_height/4);          //设置随机字符所在位置的Y坐标
  $color=imagecolorallocate($num_image,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200));    //设置字符的颜色
  imagestring($num_image,$font,$x,$y,$_SESSION[check_checks][$i],$color);           //水平输出字符
}
imagepng($num_image);         //生成PNG格式的图像
imagedestroy($num_image);       //释放图像资源
&#63;>

Create a user login form and call checks.php to output the content of the image in the form:

<&#63;php
session_start();
if($_POST["Submit"]!=""){
$checks=$_POST["checks"];
if($checks==""){
echo "<script> alert('验证码不能为空');window.location.href='index.php';</script>";
}
if($checks==$_SESSION[check_checks]){
  echo "<script> alert('用户登录成功!');window.location.href='index.php';</script>";
}else{
  echo "<script> alert('您输入的验证码不正确!');window.location.href='index.php';</script>";
}
}
&#63;>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>rand函数的应用</title>
<style type="text/css">
<!--
.STYLE1 {
  font-size: 12px;
  color: #FFFFFF;
  font-weight: bold;
}
.style2 {font-weight: bold; font-size: 12px;}
-->
</style>
</head>
<body>
<form name="form" method="post" action="">
 <table width="1003" border="0" cellspacing="0" cellpadding="0">
  <tr>
   <td width="168" height="169" background="images/index_01.gif"> </td>
   <td width="685" background="images/index_02.gif"> </td>
   <td width="150" background="images/index_03.gif"> </td>
  </tr>
  <tr>
   <td width="168" height="311" background="images/index_04.gif"> </td>
   <td background="images/index_05.gif"><table width="675" height="169" border="0" cellpadding="0" cellspacing="0">
    <tr>
     <td height="43" align="center" valign="baseline"> </td>
     <td align="center" valign="middle"> </td>
     <td align="center" valign="baseline"> </td>
    </tr>
    <tr>
     <td width="382" height="24" align="center" valign="baseline"> </td>
     <td width="207" height="24" valign="middle"><span class="style2">用户名</span><span class="STYLE1">
      <input name="txt_user" id="txt_user" style="height:20px " size="10">
       </span></td>
     <td width="86" height="24" align="center" valign="baseline"> </td>
    </tr>
    <tr>
     <td height="24" align="center" valign="baseline"> </td>
     <td height="24" valign="middle"><span class="style2">密码</span><span class="STYLE1">
     <input name="txt_pwd" type="password" id="txt_pwd" style="FONT-SIZE: 9pt; height:20px" size="10">
     </span></td>
     <td height="24" align="center" valign="baseline"> </td>
    </tr>
    <tr>
     <td height="24" align="center" valign="baseline"> </td>
     <td height="24" valign="middle"><span class="style2">验证码</span><span class="STYLE1">
     <input name="checks" size="6" style="height:20px ">
     <img src="checks.php" width="70" height="18" border="0" align="bottom"></span>  </td>
     <td height="24" align="center" valign="baseline"> </td>
    </tr>
    <tr>
     <td height="40" align="center" valign="baseline"> </td>
     <td align="center" valign="baseline">    <input type="submit" name="Submit" value="登录"></td>
     <td align="center" valign="baseline"> </td>
    </tr>
   </table></td>
   <td background="images/index_06.gif"> </td>
  </tr>
  <tr>
   <td height="100"> </td>
   <td> </td>
   <td> </td>
  </tr>
 </table>
</form>
</body>
</html>

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