Craft\ImageResizerPlugin::init PHP Method

    public function init()
    {
        craft()->on('assets.onBeforeUploadAsset', function (Event $event) {
            $path = $event->params['path'];
            $folder = $event->params['folder'];
            $filename = $event->params['filename'];
            // User for overrides on element action
            $width = null;
            $height = null;
            // If we've triggered this from our cropping action, don't resize too
            if (craft()->httpSession->get('ImageResizer_CropElementAction')) {
                craft()->httpSession->remove('ImageResizer_CropElementAction');
                return true;
            }
            // If this has been trigged from the element actions, bypass everything below
            if (!craft()->httpSession->get('ImageResizer_ResizeElementAction')) {
                // We can have settings globally, or per asset source. Check!
                $sourceEnabled = craft()->imageResizer->getSettingForAssetSource($folder->source->id, 'enabled');
                // Should we be modifying images in this source?
                if (!$sourceEnabled) {
                    return true;
                }
            } else {
                // If we are from a element action - delete this so it doesn't persist
                craft()->httpSession->remove('ImageResizer_ResizeElementAction');
                // We also might ne overriding width/height
                $width = craft()->httpSession->get('ImageResizer_ResizeElementActionWidth');
                $height = craft()->httpSession->get('ImageResizer_ResizeElementActionHeight');
                craft()->httpSession->remove('ImageResizer_ResizeElementActionWidth');
                craft()->httpSession->remove('ImageResizer_ResizeElementActionHeight');
            }
            // Is this a manipulatable image?
            if (ImageHelper::isImageManipulatable(IOHelper::getExtension($filename))) {
                craft()->imageResizer_resize->resize($folder->source->id, $path, $width, $height);
            }
        });
    }