PHP生成缩略图

在生成缩略图的过程当中我们需要用到GD库当中的几个函数：

getimagesize(string filename [,array var])),取得图像的信息，返回值是一人array,包括几项信息$var[0]----返回图像的width,$var[1]----返回height,[2]返回图像文件的type,[4]返回的是与<img src="">当中的wdith,height有关的width="",height=""信息。

imageX(resource image)

imageY(resource image)   返回图像的宽和高

imagecopyresized(des img,src img,int des_x,int des_y,int src_x,int src_y,int des_w,int des_h,int src_w,int src_y)   复制并截取区域图像

imagecreatetruecolor(int width,int height)   创建一个真彩图

imagejpeg(resource image)

<?php
# Constants
define(IMAGE_BASE, '/var/www/html/mbailey/images');
define(MAX_WIDTH, 150);
define(MAX_HEIGHT, 150);

# Get image location
$image_file = str_replace('..', '', $_SERVER['QUERY_STRING']);
$image_path = IMAGE_BASE . "/$image_file";
$image_path = 'D:/WebRoot/www/photo.trade.cn/upload/2008/01/30/1201661264.4b7qde0b9.7f1377.jpg';
# Load image
$img = null;
$ext = strtolower(end(explode('.', $image_path)));
if ($ext == 'jpg' || $ext == 'jpeg') {
     $img = @imagecreatefromjpeg($image_path);
} else if ($ext == 'png') {
     $img = @imagecreatefrompng($image_path);
# Only if your version of GD includes GIF support
} else if ($ext == 'gif') {
     $img = @imagecreatefrompng($image_path);
}

# If an image was successfully loaded, test the image for size
if ($img) {
     # Get image size and scale ratio
     $width = imagesx($img);
     $height = imagesy($img);
     $scale = min(MAX_WIDTH/$width, MAX_HEIGHT/$height);

     # If the image is larger than the max shrink it
     if ($scale < 1) {
         $new_width = floor($scale*$width);
         $new_height = floor($scale*$height);

         # Create a new temporary image
         $tmp_img = imagecreatetruecolor($new_width, $new_height);

         # Copy and resize old image into new image
         imagecopyresized($tmp_img, $img, 0, 0, 0, 0,
                          $new_width, $new_height, $width, $height);
         imagedestroy($img);
         $img = $tmp_img;
     }
}

# Create error image if necessary
if (!$img) {
     $img = imagecreate(MAX_WIDTH, MAX_HEIGHT);
     imagecolorallocate($img,0,0,0);
     $c = imagecolorallocate($img,70,70,70 );
     imageline($img,0,0,MAX_WIDTH,MAX_HEIGHT,$c2);
     imageline($img,MAX_WIDTH,0,0,MAX_HEIGHT,$c2);
}

# Display the image
header("Content-type: image/jpeg");
imagejpeg($img);
?>