class.ilPreviewRenderer.php

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<?php
/* Copyright (c) 1998-2012 ILIAS open source, Extended GPL, see docs/LICENSE */

require_once("./Services/Preview/classes/class.ilPreviewSettings.php");

abstract class ilPreviewRenderer
{
    public function getName()
    {
        $name = get_class($this);
        
        if (strpos($name, "il") === 0) {
            $name = substr($name, 2);
        }
        
        if (strpos($name, "Renderer") === (strlen($name) - 8)) {
            $name = substr($name, 0, strlen($name) - 8) . " Renderer";
        }
        
        return $name;
    }
    
    final public function isPlugin()
    {
        $filepath = "./Services/Preview/classes/class." . get_class($this) . ".php";
        return !is_file($filepath);
    }
    
    abstract public function getSupportedRepositoryTypes();
    
    public function supports($preview)
    {
        // contains type?
        return in_array($preview->getObjType(), $this->getSupportedRepositoryTypes());
    }
    
    final public function render($preview, $obj, $async)
    {
        $preview->setRenderDate(ilUtil::now());
        $preview->setRenderStatus(ilPreview::RENDER_STATUS_PENDING);
        $preview->save();
        
        // TODO: this should be done in background if $async is true
        
        // the deriving renderer should deliver images
        require_once("./Services/Preview/classes/class.ilRenderedImage.php");
        $images = $this->renderImages($obj);
        
        // process each image
        if (is_array($images) && count($images) > 0) {
            $success = false;
            foreach ($images as $idx => $image) {
                // create the ending preview image
                $success |= $this->createPreviewImage(
                    $image->getImagePath(),
                    sprintf($preview->getFilePathFormat(), $idx + 1)
                );

                // if the image is temporary we can delete it
                if ($image->isTemporary()) {
                    $image->delete();
                }
            }

            $preview->setRenderDate(ilUtil::now());
            $preview->setRenderStatus($success ? ilPreview::RENDER_STATUS_CREATED : ilPreview::RENDER_STATUS_FAILED);
            return $success;
        } else {
            $preview->setRenderDate(ilUtil::now());
            $preview->setRenderStatus(ilPreview::RENDER_STATUS_FAILED);
            return false;
        }
    }
    
    private function createPreviewImage($src_img_path, $dest_img_path)
    {
        // create resize argument
        $imgSize = $this->getImageSize();
        $resizeArg = $imgSize . "x" . $imgSize . (ilUtil::isWindows() ? "^" : "\\") . ">";
        
        // cmd: convert $src_img_path -background white -flatten -resize 280x280 -quality 85 -sharpen 0x0.5 $dest_img_path
        $args = sprintf(
            "%s -background white -flatten -resize %s -quality %d -sharpen 0x0.5 %s",
            ilUtil::escapeShellArg($src_img_path),
            $resizeArg,
            $this->getImageQuality(),
            ilUtil::escapeShellArg($dest_img_path)
        );
    
        ilUtil::execQuoted(PATH_TO_CONVERT, $args);
        
        return is_file($dest_img_path);
    }
    
    abstract protected function renderImages($obj);
    
    final protected function getImageSize()
    {
        return ilPreviewSettings::getImageSize();
    }
    
    final protected function getImageQuality()
    {
        return ilPreviewSettings::getImageQuality();
    }
    
    final protected function getMaximumNumberOfPreviews()
    {
        return ilPreviewSettings::getMaximumPreviews();
    }
}