[Resolved] Create tumbnails

axjo

How do I create thumbnails with pure php?

Someone told me to use something called gd, but I suppose that it's some kind of extra program, right?

wchris

gd means the GD-Library. it´s a library to create, change, manipulate images ...

if you are using php in a windows environment, this library is normally already added. but it could be, that it is not activated by default. look in your php.ini -> section extensions -> extension=php_gd2.dll (it should be decommented)

now for your question about using this library. this is not so easy to explain, so you shall read the manual!
somewhere here: php.net manual

here some rough steps:

 /*
  *  i´ve deleted the uncorrect code
  *  look at my next example
  */

i hope it´s working, because at the moment it is not possible for me to test this code

cu
chris

axjo

Thanks!

I'll try it. I better read the manual to.

wchris

i have changed some code lines in my example from top, because there were some better ways to do it.

to use it you should save this code in one php file (e.g. thmb.php) an call it from another page:
<img src="thmb.php" border=0>

to make it more dynamical you can change the fix variables to the $GET[]-way. so for example you can change $thmb_width to $GET["thmb_width"] to use a html-code like this:
<img src="thmb.php?thmb_width=50" border=0>

...... etc.

cu
chris

axjo

I can't make it work.

At first I did't do any changes. Then I could see the picture but it
was as large as before. Then I tried to change the factor, but it didn't work.

At last I figured out that the script moves to this line:

// original image is smaller than thumnbnail

Am I supposed to do any changes in the code?
For exemple format[1], 2, 3 and 4?

By the way. GD wasn't installed at first, but it is now.

axjo

I also tried this code from http://se2.php.net/manual/en/function.imagecopyresampled.php

<?php
// The file
$filename = 'test.jpg';
$percent = 0.5;

// Content type
header('Content-type: image/jpeg');

// Get new dimensions
list($width, $height) = getimagesize($filename);
$new_width = $width * $percent;
$new_height = $height * $percent;

// Resample
$image_p = imagecreatetruecolor($new_width, $new_height);
$image = imagecreatefromjpeg($filename);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

// Output
imagejpeg($image_p, null, 100);
?>

It resulted in a page filled with symbols. How should I handle the Output? I guess i didn't got it right this time =)

axjo

I have figured out the last script now. But I still doesn't understand wchris:s script.

And how do i write to save the thumbnail?

wchris

first, i´m sorry that i not managed to write a better explanation.
i think i have gone much to far for someone who has never done something with gd2-lib.
and the most important thing is, that i have made a mistake - i have forgotten to initialize some variables with content :bemused:

you are right, the other example is easier, but it is only resizing jpg-images and is not resizing a image to a wanted dimension.

here a functional code (i´ve tested it):

/
file: thumbnail.php
*/

// create full path to image
$original_image = $_SERVER['DOCUMENT_ROOT'] . $_GET["original_image"];


/*
* Reading imageinformation
* ARRAY [0] width
* ARRAY [1] height
* ARRAY [2] formt
* ARRAY [3] HTML-width und -height (height=+++ width=+++)
*/
$format = getimagesize($original_image);

// different functions for different imageformats (create new image with old content)
switch($format[2]) 
{
    // GIF
    case 1:
        $src = imagecreatefromgif($original_image);
        break;

// JPEG
case 2:
    $src = imagecreatefromjpeg($original_image);
    break;

// PNG
case 3:
    $src = imagecreatefrompng($original_image);
    break;    
}


// original image is more height than width
if ($format[1] > $format[0] && $format[1] > $_GET["thmb_height"]) 
{
    $factor = $format[1] / $_GET["thmb_height"];   

}
// original image is more width than height
elseif ($format[0] > $format[1] && $format[0] > $_GET["thmb_width"]) 
{
    $factor = $format[0] / $_GET["thmb_width"];         

}
// original image is quadratical and greater than thumbnail
elseif ($format[0] == $format[1] && $format[0] > $_GET["thmb_width"])
{
    $factor = $format[0] / $_GET["thmb_width"]; 
}
// original image is smaller than thumnbnail
else
{
    // direkt output
    header ("Location: " . $_GET["original_image"]);
    exit();

} // end if


// proportional resizing
$x = $format[0] / $factor;
$y = $format[1] / $factor;

$new_src = imagecreatetruecolor($x, $y);
ImageCopyResampled($new_src, $src, 0, 0, 0, 0, $x, $y, $format[0], $format[1]);


// header and imageoutput
switch($format[2]) 
{
    // GIF
    case 1:
        header('Content-Type: ' . image_type_to_mime_type(IMAGETYPE_GIF));
        (function_exists("imagegif"))? imagegif($new_src): imagepng($new_src);
        break;

// JPEG
case 2:
    header('Content-Type: ' . image_type_to_mime_type(IMAGETYPE_JPEG));
    imagejpeg($new_src, "", 85);
    break;        

// PNG
case 3:
    header('Content-Type: ' . image_type_to_mime_type(IMAGETYPE_PNG));    
    imagepng($new_src);
    break;

// Default
default:
    header('Content-Type: ' . image_type_to_mime_type(IMAGETYPE_JPEG));    
    imagejpeg($new_src, "", 85);
}

// free image from memory
imagedestroy($new_src);

/
file: test.htm
*/

<html>

<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<title>Testpage</title>
</head>

<body>
<img border="0" vspace="4" hspace="4" src="thumbnail.php?thmb_width=50&thmb_height=50&original_image=/test.jpg">
</body>

</html>

perhaps there is a way to make it more easier...

cu
chris

wchris

to save a image you need only to fill in a filename in the functions:

imagepng ( resource image [, string filename] )
imagegif ( resource image [, string filename] )
imagejpeg ( resource image [, string filename [, int quality]] )

cu
chris

axjo

Great stuff. Thank you very much!