View Comments

This is a function to create thumbnail images from a full image file in Joomla!. It uses the powerful JImage library included in the Joomla! Platform.

Edited 17/07/2012 - Added creationMethod parameter to choose the thumbnail creation method. Includes a creation method using crop.

// required libraries
jimport('joomla.image.image');
jimport('joomla.filesystem.folder');
jimport('joomla.filesystem.file');
    /**
     * Function to create thumbs from one image
     * @author Roberto Segura - Digital Disseny, S.L.
     * @version 16/07/2012
     *
     * @param string $imgPath - path to full image
     * @param string/array $thumbSizes - desired thumb sizes. Example: array('50x50','120x250');
     * @param string $thumbsFolder - thumbs destination folder
     * @param integer $creationMethod - thumbnail creation method
     * 
     * @return array of generated thumbnails
     */
function createThumbs($imgPath, $thumbSizes, $thumbsFolder, $creationMethod = 2) {
    if (!empty($thumbSizes) && JFile::exists($imgPath)) {
        // accept a single thumbsize string as parameter
        if (!is_array($thumbSizes)) {
            $thumbSizes = array($thumbSizes);
        }
        // check | try to creaate thumbsfolder
        if (JFolder::exists($thumbsFolder) || JFolder::create($thumbsFolder)) {
            $generated = array();
            // process thumbs
            foreach ($thumbSizes as $thumbSize) {
                // get thumb size
                $size = explode('x',strtolower($thumbSize));
                if (count($size) != 2) {
                    return false;
                }
                $thumbWidth = $desiredWidth = $size[0];
                $thumbHeight = $desiredHeight = $size[1];
                // source object
                $sourceImage = new JImage($imgPath);
                $srcHeight = $sourceImage->getHeight();
                $srcWidth = $sourceImage->getWidth();
                $imgProperties = JImage::getImageFileProperties($imgPath);
                // generate thumb name
                $filename = JFile::getName($imgPath);
                $fileExtension = JFile::getExt($filename);
                $thumbFileName = str_replace('.' . $fileExtension, '_' . $desiredWidth .'x' . $desiredHeight . '.' . $fileExtension, $filename);
                // try to generate the thumb
                if ($creationMethod == 4) {
                    // auto crop centered coordinates
                    $left = round(($srcWidth - $thumbWidth) / 2);
                    $top = round(($srcHeight - $thumbHeight) / 2);
                    // crop image
                    $thumb = $sourceImage->crop($thumbWidth, $thumbHeight, $left, $top, true);
                } else {
                    // resize image
                    $thumb = $sourceImage->resize($thumbWidth, $thumbHeight, true, $creationMethod);
                }
                $thumbFileName = $thumbsFolder . DIRECTORY_SEPARATOR . $thumbFileName;
                $thumb->toFile($thumbFileName, $imgProperties->type);
                if (JFile::exists($thumbFileName)) {
                    $generated[] = $thumb;
                }
            }
            return $generated;
        }
    }
    return false;
}

Example uses:

            $thumbSizes = array( '50x50', '250x100' );
            $thumbsFolder = dirname($destFile) . DIRECTORY_SEPARATOR . 'thumbs';
            // create thumbs resizing with forced proportions
            $createdThumbs = createThumbs($destFile, $thumbSizes, $thumbsFolder, 1);
            // create thumbs resizing proportionally scale inside
            $createdThumbs = createThumbs($destFile, $thumbSizes, $thumbsFolder, 2);
            // create thumbs resizing proportionally scale outside
            $createdThumbs = createThumbs($destFile, $thumbSizes, $thumbsFolder, 3);
            // create thumbs cropping a centered subimage
            $createdThumbs = createThumbs($destFile, $thumbSizes, $thumbsFolder, 4);

This will create a thumbs folder in the same folder as the source image containing 2 thumbnails