Upload Assets with jQuery File Upload - see https://blueimp.github.io/jQuery-File-Upload/

UploadsController.php

<?php
namespace Craft;

class UploadsController extends BaseController {
	
	/**
	 * Process uploaded files
	 *
	 * @author Bob Olde Hampsink
	 */
	public function actionProcess() {
	
	    // Disable devmode script log
	    craft()->config->set('devMode', false);
	
	    // Get given folder id
	    $folderId = craft()->request->getParam('folder');
	
	    // Process files for source
	    $response = craft()->uploads->process($folderId);
	    
	    // Process files as assets
	    foreach($response['files'] as $key => $file) {
	    
	        // Index file
	        $asset = craft()->uploads->index($file, $folderId);
	    
	        // Add asset to array
	        $response['files'][$key]->asset = $asset->id;
	    
	    }	    
	    
	    // Return response as JSON
	    $this->returnJson($response);
		
	}
		
}

UploadsService.php

<?php
namespace Craft;

class UploadsService extends BaseApplicationComponent
{
   
    // UploadHandler niet direct initialiseren
    protected $initialize = false;
    
    // Source settings
    protected $settings = array();
    
    // Extra opties voor UploadHandler
    protected $options = array();
    
    // UploadHandler error messages
    protected $errorMessages = array(
        1 => 'The uploaded file exceeds the upload_max_filesize directive in php.ini',
        2 => 'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form',
        3 => 'The uploaded file was only partially uploaded',
        4 => 'No file was uploaded',
        6 => 'Missing a temporary folder',
        7 => 'Failed to write file to disk',
        8 => 'A PHP extension stopped the file upload',
        'post_max_size' => 'The uploaded file exceeds the post_max_size directive in php.ini',
        'max_file_size' => 'File is too big',
        'min_file_size' => 'File is too small',
        'accept_file_types' => 'Filetype not allowed',
        'max_number_of_files' => 'Maximum number of files exceeded',
        'max_width' => 'Image exceeds maximum width',
        'min_width' => 'Image requires a minimum width',
        'max_height' => 'Image exceeds maximum height',
        'min_height' => 'Image requires a minimum height'
    );
    
    // Verwerk geuploade files
    public function process($folderId) {
    
        // Include UploadHandler class that comes with jQuery File Upload
        require(CRAFT_PLUGINS_PATH.'uploads/libraries/UploadHandler.php');
        
        // Get source settings by ID
        $sourceId = craft()->assets->getFolderById($folderId)->sourceId;
        $this->settings = craft()->assetSources->getSourceById($sourceId)->settings;
        
        // Stel opties in
        $this->options = array(
            'upload_dir' => $this->settings['path'],
            'upload_url' => $this->settings['url'],
            'image_versions' => array(

                // The empty image version key defines options for the original image:
                '' => array(
                    // Automatically rotate images based on EXIF meta data:
                    'auto_orient' => true
                )
            )
        );
        
        // Initialiseer UploadHandler
        $handler = new \UploadHandler($this->options, $this->initialize, $this->errorMessages);
        
        // Vang post requests op en return de response
        return $handler->post(false);
    
    }
    
    // Indexeer geuploade files
    public function index($file, $folderId) {
    
        // Create new AssetFile Model
        $asset = new AssetFileModel();
        $asset->sourceId = craft()->assets->getFolderById($folderId)->sourceId;
        $asset->folderId = $folderId;
        $asset->filename = IOHelper::getFileName($file->name);
        $asset->kind = IOHelper::getFileKind(IOHelper::getExtension($file->name));
        $asset->size = $file->size;
        $asset->dateModified = IOHelper::getLastTimeModified($this->settings['path'].$file->name);
        
        if ($asset->kind == 'image')
        {
            list($width, $height) = getimagesize($this->settings['path'].$file->name);
            $asset->width = $width;
            $asset->height = $height;
        }
        
        // Index file
        craft()->assets->storeFile($asset);
        
        return $asset;
    
    }
        
}