Code for displaying thumbnail images - php

Question

I have a simple PHP script that enables users to upload images on a server. I am after some help in displaying these images as thumbnails in an HTMl page and then letting the user click on these thumbnails and then the original picture is displayed in a new page.
Can I use straight HTML for this? Or do I need some combination of javascript or PHP variant?
I know that there are many questions about this on stackoverflow, and I have tried them, but nothing is what I am after.
I would prefferably like the thumbnails be created on the 'fly' rather than me personally having to create each thumbnal when a user uploads an image.
So basically what language should I use to do this? And also can I have some source code if possible?
thanks

Answer 1

Creating thumbnails every time they are requested is a very bad idea - it takes a lot of processing power, which would be easily saved by keeping them around the first time you create them. I would suggest putting the thumbnail creation in the php script that processes the file upload, so that you save the image and its thumbnail to disk at the same time. You can also keep the thumbnail in memory, or wait until the first time it's requested to create it, but either way you cannot re-generate it every time it is requested.
It is possible to use html to change an image's size, by simply setting the width and/or height properties:
<img src='foo.jpg' alt='foo' width='500' height='300'/>
However, this is a bad idea if you aren't certain that the user will later want to view the full-sized image. The reason is that a thumbnail has a smaller filesize than the full image: if the client only wants to view the thumbnail, then you don't want to waste bandwidth (= your money and the client's time) sending them the full image.
As for your interface, you don't need javascript to accomplish that, just html. However, you will need a server-side script to create the thumbnails that your html page links to.

Answer 2

There are plenty of php thumbnail scripts out there.
Either you use a rewriter to still show the original path, but server a php thumbnail version. Or you have to have the url change to something like:
<img src="thumb.php?file=path/to/picture.jpg&size=128" />
Mighty Stuff
phpThumb
Are just such two. Best configured to utilize the cached folder. I use a modified version of the first script at work.

Answer 3

Here's a PHP script you can build appon only works with jpg images.
It will scan through a directory, normalize the image to a decent dimension and also make a thumb on the fly, then on next refresh it wont need to reprocess the image as its already present in the thumbs dir. Hope it helps...
Script placement
Root>
thisscript.php
/images/
someimage.jpg
someimage2.jpg
thisscript.php
<?php
// config section
$path = "./images/";
$thpath = $path."thumbs/";
// end configration
// Open the directory
$do = dir($path);
// now check if the thumb dir is available if not, create it!!
if (!is_dir($thpath)){
mkdir($thpath);
}
$output = '<div>';
while (($file = $do->read()) !== false){
if (is_dir($path.$file)){
continue;
}else{
$info = pathinfo($path.$file);
$fileext = $info['extension'];
if (strtolower($fileext) == 'jpg'){
if (!is_file($thpath.$file)){
//Normalize Super lrg Image to 750x550
thumb_it($path, $file, $path,750,550,99);
//Make Thumb 200x125
thumb_it($path, $file, $thpath,200,125,99);
$output .='<p><img src="'.$thpath.$file.'" title="" alt="" /></p>';
}else{
$output .='<p><img src="'.$thpath.$file.'" title="" alt="" /></p>';
}
}
}
}
$output .='</div>';
echo $output;
//Functions
function thumb_it($dirn, $file, $thumbdir,$rwidth,$rheight,$quality){
set_time_limit(0);
$filename = $dirn.$file;
$thfilename = $thumbdir.preg_replace('/[^a-zA-Z0-9.-]/s', '_', $file);
// get the filename and the thumbernail directory
if (is_file($filename)){
// create the thumbernail from the original picture
$im = #ImageCreateFromJPEG($filename);
if($im==false){return false;}
$width = ImageSx($im); // Original picture width is stored
$height = ImageSy($im); // Original picture height is stored
if (($width < $rwidth) && ($height < $rheight)){
$n_height = $height;
$n_width = $width;
}else{
// saveing the aspect ratio
$aspect_x = $width / $rwidth;
$aspect_y = $height / $rheight;
if ($aspect_x > $aspect_y){
$n_width = $rwidth;
$n_height = $height / $aspect_x;
}else{
$n_height = $rheight;
$n_width = $width / $aspect_y;
}
}
$newimage = imagecreatetruecolor($n_width, $n_height);
// resizing the picture
imageCopyResized($newimage, $im, 0, 0, 0, 0, $n_width, $n_height, $width, $height);
// writing to file the thumbnail
if(file_exists($thfilename)){chmod($thfilename, 0777);}
Imagejpeg($newimage, $thfilename, $quality);
imagedestroy($newimage);
imagedestroy($im);
}
}
?>