php imagecreate实例教程

php imagecreate实例教程

描述
资源imagecreate（$width，$height）
imagecreate（）返回一个图像标识符代表了指定大小的空白图像。

我们建议使用imagecreatetruecolor（）。

看个
<?php
header("Content-type: image/png");
$im = @imagecreate(110, 20)
    or die("Cannot Initialize new GD image stream");
$background_color = imagecolorallocate($im, 0, 0, 0);
$text_color = imagecolorallocate($im, 233, 14, 91);
imagestring($im, 1, 5, 5,  "A Simple Text String", $text_color);
imagepng($im);
imagedestroy($im);
?>

如果您可以访问gd.h（很少在一个共享的主机），您可以修改GD_RESOLUTION并给它所需的价值。

该解决方案，我发现直接操纵的JPEG头字节。
我希望此示例代码将帮助别人，因为我花了5挖掘推测离开系统I小时，没有其他选择。

<?php
header('Content-Disposition: attachment; filename="myimg.jpg"');
header('Cache-Control: private');
$dst    = imagecreatetruecolor(300, 300); /*this creates a 300x300 pixels image*/
ob_start(); /*don't send the output to the browser since we'll need to manipulate it*/
ImageJpeg($dst);
$img = ob_get_contents();
ob_end_clean();

//byte #14 in jpeg sets the resolution type: 0=none, 1=pixels per inch, 2=pixels per cm
//bytes 15-16 sets X resolution
//bytes 17-18 sets Y resolution
$img = substr_replace($img, pack('cnn',1,300,300),13,5);

echo $img;

?>

文件在其文件类型，并返回假的负载如果失败
<?php
function imagecreatefromfile($path, $user_functions = false)
{
    $info = @getimagesize($path);
   
    if(!$info)
    {
        return false;
    }
   
    $functions = array(
        IMAGETYPE_GIF => 'imagecreatefromgif',
        IMAGETYPE_JPEG => 'imagecreatefromjpeg',
        IMAGETYPE_PNG => 'imagecreatefrompng',
        IMAGETYPE_WBMP => 'imagecreatefromwbmp',
        IMAGETYPE_XBM => 'imagecreatefromwxbm',
        );
   
    if($user_functions)
    {
        $functions[IMAGETYPE_BMP] = 'imagecreatefrombmp';
    }
   
    if(!$functions[$info[2]])
    {
        return false;
    }
   
    if(!function_exists($functions[$info[2]]))
    {
        return false;
    }
   
    return $functions[$info[2]]($path);
}
?>

php imagecreatefromgif创建 gif图片

imagecreatefromgif（$filename）
imagecreatefromgif（）返回一个图像标识符代表从给定的文件名获得的图像

$filename是gif图片名称哦。

来看个实例

<?php
function LoadGif($imgname)
{
    /* Attempt to open */
    $im = @imagecreatefromgif($imgname);

    /* See if it failed */
    if(!$im)
    {
        /* Create a blank image */
        $im = imagecreatetruecolor (150, 30);
        $bgc = imagecolorallocate ($im, 255, 255, 255);
        $tc = imagecolorallocate ($im, 0, 0, 0);

        imagefilledrectangle ($im, 0, 0, 150, 30, $bgc);

        /* Output an error message */
        imagestring ($im, 1, 5, 5, 'Error loading ' . $imgname, $tc);
    }

    return $im;
}

header('Content-Type: image/gif');

$img = LoadGif('bogus.image');

imagegif($img);
imagedestroy($img);
?>

php 验证码生成程序[可自动判断php gd库]
function ShowKey()
{
$key=strtolower(domake_password(4));
$set=esetcookie("checkkey",$key);
 //是否支持gd库
if (function_exists("imagejpeg")) {
   header ("Content-type: image/jpeg");
   $img=imagecreate(69,20);
   $black=imagecolorallocate($img,255,255,255);
   $gray=imagecolorallocate($img,102,102,102);
   imagefill($img,0,0,$gray);
   imagestring($img,3,14,3,$key,$black);
   imagejpeg($img);
   imagedestroy($img);
}
elseif (function_exists("imagegif")) {
   header ("Content-type: image/gif");
   $img=imagecreate(69,20);
   $black=imagecolorallocate($img,255,255,255);
   $gray=imagecolorallocate($img,102,102,102);
   imagefill($img,0,0,$gray);
   imagestring($img,3,14,3,$key,$black);
   imagegif($img);
   imagedestroy($img);
}
elseif (function_exists("imagepng")) {
 header ("Content-type: image/png");
   $img=imagecreate(69,20);
   $black=imagecolorallocate($img,255,255,255);
   $gray=imagecolorallocate($img,102,102,102);
   imagefill($img,0,0,$gray);
   imagestring($img,3,14,3,$key,$black);
   imagepng($img);
   imagedestroy($img);
}
elseif (function_exists("imagewbmp")) {
 header ("Content-type: image/vnd.wap.wbmp");
   $img=imagecreate(69,20);
   $black=imagecolorallocate($img,255,255,255);
   $gray=imagecolorallocate($img,102,102,102);
   imagefill($img,0,0,$gray);
   imagestring($img,3,14,3,$key,$black);
   imagewbmp($img);
   imagedestroy($img);
}
else {
 $set=esetcookie("checkkey","ebak");
 @include("class/functions.php");
 echo ReadFiletext("images/ebak.jpg");
}
}
ShowKey();

function displayimg($image)
 {
  $image = './upload/'.imgdecode($image);
  //echo $image;exit;
  if (file_exists($image))
  {
   $info = getimagesize($image);
   header("Content-type:$info[mime]");
   switch ($info[2])
   {
    case 1:  $cimage = imagecreatefromgif($image);
       imagegif($cimage);
       imagedestroy($cimage);
       break;
    case 2:  $cimage = imagecreatefromjpeg($image);
       imagejpeg($cimage);
       imagedestroy($cimage);
       break;
    case 3:  $cimage = imagecreatefrompng($image);
       imagepng($cimage);
       imagedestroy($cimage);
       break;
    case 6:  $cimage = imagecreatefromwbmp($image);
       imagewbmp($cimage);
       imagedestroy($cimage);
       break;
   }
   echo $simage;
  }
  else
  {
   header("HTTP/1.0 404 Not Found");
  }
 }

<?php

$height = 300;

$width = 300;

$im = ImageCreateTrueColor($width, $height);

$white = ImageColorAllocate ($im, 255, 255, 255);

$blue = ImageColorAllocate ($im, 0, 0, 64);

ImageFill($im, 0, 0, $blue);

//ImageLine($im, 0, 0, $width, $height, $white);

ImageString($im, 10, 100, 120, 'Hello,PHP', $white);

Header ('Content-type: image/png');

ImagePng($im);

ImageDestroy($im);

?>