Dynamic thumbnailing with PHP and the GD library
Posted on June 27, 2004 by snipe in PHP/mySQL
This post was published 7 years 6 months 29 days ago. There is a chance that some APIs or software versions discussed have changed since this article was written. Although there are loads of ways you can do this, for this example, we’re assuming that the fullsize image is located in a directory called “images”, and the thumbnails will have the same name as the fullsize, but will be copied into a directory called “thumbs”.
<?php
// find out the current size info
$photo_filename = "myimage.jpg"
$path = "/home/snipe/www/images/";
$image_stats = GetImageSize($path.$photo_filename);
$imagewidth = $image_stats[0];
$imageheight = $image_stats[1];
$img_type = $image_stats[2];
$new_w = 100; $ratio = ($imagewidth / $new_w);
$new_h = round($imageheight / $ratio);
// Find out if we need to resize it by checking to
// see if the original image is larger than the
// defined new width, and making sure the
// resized version does not exist yet
if (($imagewidth > $new_w)&& (!file_exists($path.$photo_filename))) {
// if this is a jpeg, resize as a jpeg
if ($img_type==2) {
$src_img = imagecreatefromjpeg($path.$photo_filename);
$dst_img = imagecreate($new_w,$new_h);
imagecopyresized($dst_img,$src_img,0,0,0,0,$new_w,$new_h,imagesx($src_img),imagesy($src_img));
imagejpeg($dst_img, $path.$photo_filename);
} elseif ($img_type==3) {
// if image is a png, copy it
$dst_img=ImageCreate($new_w,$new_h);
$src_img=ImageCreateFrompng($path.$photo_filename);
ImageCopyResized($dst_img,$src_img,0,0,0,0,$new_w,$new_h,ImageSX($src_img),ImageSY($src_img));
Imagepng($dst_img, $path.$photo_filename);
// Normally if image is neither png nor jpeg
// (ie, invalid image or a gif file), I use
// the fullsize as the thumbnail and just
// resize it through the html size tags. For this
// example tho, we’ll pretend we have a version of
// Gdlib that can handle gif resizing
} elseif ($img_type==1) {
$dst_img=ImageCreate($new_w,$new_h);
$src_img=ImageCreateFromGif($path.$photo_filename);
ImageCopyResized($dst_img,$src_img,0,0,0,0,$new_w,$new_h,ImageSX($src_img),ImageSY($src_img));
ImageGif($dst_img, $path.$photo_filename);
} else {
// if it doesn’t show up as any of the valid formats, give an error
echo ‘error’;
} // endif img_type sequence
}
?>
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