protected function initColumns()
    {
        if($this->columns===array())
        {
            if($this->dataProvider instanceof CActiveDataProvider)
                $this->columns=$this->dataProvider->model->attributeNames();
            elseif($this->dataProvider instanceof IDataProvider)
            {
                // use the keys of the first row of data as the default columns
                $data=$this->dataProvider->getData();
                if(isset($data[0]) && is_array($data[0]))
                    $this->columns=array_keys($data[0]);
            }
        }
        $id=$this->getId();
        foreach($this->columns as $i=>$column)
        {
            if(is_string($column))
                $column=$this->createDataColumn($column);
            else
            {
                if(!isset($column['class'])) {
                    $column['class'] = 'CDataColumn';
                }
                $column=Yii::createComponent($column, $this);
            }
            if(!$column->visible)
            {
                unset($this->columns[$i]);
                continue;
            }
            if($column->id===null)
                $column->id=$id.'_c'.$i;
            $this->columns[$i]=$column;
        }

        $tree_initiated = false;
        foreach($this->columns as $column) {
            $column->init();

            if ($column instanceof CDataColumn && $this->tree && !$tree_initiated) {
                $this->tree_column_name = $column->name;
                $tree_initiated = true;
            }
        }
    }

    public function renderItems()
    {
        if($this->dataProvider->getItemCount()>0 || $this->showTableOnEmpty)
        {
            echo CHtml::openTag($this->itemsTag, array('class'=>$this->itemsCssClass, 'style'=>$this->itemsStyle));
            //render container only
            //content render in javascript
            echo CHtml::closeTag($this->itemsTag);
        }
        else
            $this->renderEmptyText();
    }

    public function registerClientScript()
    {
        $id = $this->getId();

        if($this->ajaxUpdate===false)
            $ajaxUpdate=false;
        else
            $ajaxUpdate=array_unique(preg_split('/\s*,\s*/',$this->ajaxUpdate.','.$id,-1,PREG_SPLIT_NO_EMPTY));

        $itemsSelector = $this->itemsTag;
        $itemsCssClass = explode(' ',$this->itemsCssClass,2);
        if (is_array($itemsCssClass)) {
            $itemsSelector .= '.'.$itemsCssClass[0];
        }

        $options=array(
            'ajaxUpdate'=>$ajaxUpdate,
            'ajaxVar'=>$this->ajaxVar,
            'pagerClass'=>$this->pagerCssClass,
            'loadingClass'=>$this->loadingCssClass,
            'filterClass'=>$this->filterCssClass,
//            'tableClass'=>$this->itemsCssClass,
//            'selectableRows'=>$this->selectableRows,
            'enableHistory'=>$this->enableHistory,
            'updateSelector'=>$this->updateSelector,
            'filterSelector'=>$this->filterSelector,
            'itemsSelector'=>$itemsSelector,
        );
        if($this->ajaxUrl!==null)
            $options['url']=CHtml::normalizeUrl($this->ajaxUrl);
        if($this->ajaxType!==null)
            $options['ajaxType']=strtoupper($this->ajaxType);
        if($this->enablePagination)
            $options['pageVar']=$this->dataProvider->getPagination()->pageVar;
        foreach(array('beforeAjaxUpdate', 
                    'afterAjaxUpdate', 
                    'ajaxUpdateError', 
                    'onTaskSelected', 
                    'onTaskOpened',
                    'onTaskClosed', 
                    'onTaskDragStart', 
                    'onTaskDrag',
                    'onBeforeTaskDrag',
                    'onBeforeTaskChanged',
                    'onAfterTaskDrag',
                    /*, 'selectionChanged'*/) as $event)
        {
            if($this->$event!==null)
            {
                if($this->$event instanceof CJavaScriptExpression)
                    $options[$event]=$this->$event;
                else
                    $options[$event]=new CJavaScriptExpression($this->$event);
            }
        }

        $options['config'] = array(
            //The default date format for JSON and XML data is "%d-%m-%Y" http://docs.dhtmlx.com/gantt/desktop__loading.html#loadingfromadatabase
            'xml_date'=>'%Y-%m-%d',
            'columns'=>array_map(function($column){
                if ($column instanceof CCheckBoxColumn) {
                    $ret = array('name'=>$column->name);
                } elseif ($column instanceof AlxdStatusrefColumn) {
                    $ret = array('name'=>$column->name.($column->format ? '.'.$column->format : ''));
                } elseif ($column instanceof AlxdAttributerefColumn) {
                    $ret = array('name'=>$column->name.($column->attribute ? '.'.$column->attribute : ''));
                } else {
                    $ret = array('name'=>$column->name);
                }

                $r = new ReflectionMethod($column, 'renderHeaderCellContent');
                $r->setAccessible(true);
                ob_start();
                $r->invoke($column);
                $ret['label'] = ob_get_contents();
                ob_end_clean();

                if ($column instanceof CCheckBoxColumn) {
                    $ret['width'] = 36;
                } else {
                    $headerHtmlOptions = $column->headerHtmlOptions;
                    if (isset($headerHtmlOptions['style'])) {
                        $styles = explode(';', rtrim($headerHtmlOptions['style'], ';'));
                        foreach ($styles as $style) {
                            $pair = explode(':', $style, 2);
                            if (count($pair) == 2 && strtolower(trim($pair[0])) == 'width') {
                                $l = strlen($pair[1]);
                                if (strtolower(substr($pair[1], $l-2, 2)) == 'px') {
                                    $ret['width'] = substr($pair[1], 0, $l - 2);
                                }
                            }
                        }
                    }

                    if ($this->tree && $column->name == $this->tree_column_name) {
                        $ret['tree'] = $this->tree;
                    }
                }
                return $ret;
            }, $this->columns),
            'filters'=>array_map(function($column){
                $r = new ReflectionMethod($column, 'renderFilterCellContent');
                $r->setAccessible(true);
                ob_start();
                $r->invoke($column);
                $filter = ob_get_contents();
                ob_end_clean();

                return array(
                    'name'=>$column->name,
                    'control'=>$filter
                );
            }, $this->columns),
            'data'=>$this->getData(),
        );

        $options['config']['scale_unit'] = $this->scales[0]['unit'];
        $options['config']['date_scale'] = $this->scales[0]['date'];
        if (count($this->scales) > 1) {
            $options['config']['subscales'] = array_slice($this->scales, 1);
        }

        if ($this->filter !== null) {
            $options['config']['scale_height_auto'] = true;
            $options['config']['filter'] = true;
        }

        if (isset($this->dataProcessorUrl)) {
            $options['dataProcessorUrl'] = $this->dataProcessorUrl;
        }

        $options=CJavaScript::encode($options);
        $cs=Yii::app()->getClientScript();
        if ($this->_assets == null) {
            $path = dirname(__FILE__) . DIRECTORY_SEPARATOR . 'assets';
            $this->_assets = Yii::app()->assetManager->publish($path);
        }

        $cs->registerCoreScript('jquery');
        $cs->registerCoreScript('bbq');

        if($this->enableHistory)
            $cs->registerCoreScript('history');

        $cs->registerCssFile($this->_assets . DIRECTORY_SEPARATOR . 'dhtmlxgantt.css');
        $cs->registerScriptFile($this->_assets . DIRECTORY_SEPARATOR . 'dhtmlxgantt.js', CClientScript::POS_BEGIN);
        $cs->registerScriptFile($this->_assets . DIRECTORY_SEPARATOR . 'locale/locale_'.Yii::app()->language.'.js', CClientScript::POS_BEGIN);
        $cs->registerScriptFile($this->_assets . DIRECTORY_SEPARATOR . 'alxd.dhtmlxgantt.js', CClientScript::POS_BEGIN);
        $cs->registerScript(__CLASS__.'#'.$id,"jQuery('#$id').alxdDhtmlxGantt($options);", CClientScript::POS_READY);
    }

gantt._render_grid_header = function () {
    var columns = this.getGridColumns();
    var filters = this.config.filters;
    var title_cells = [];
    var filter_cells = [];
    var width = 0,
        labels = this.locale.labels;

    var lineHeigth = this.config.scale_height - 2;

    for (var i = 0; i < columns.length; i++) {
        var last = i == columns.length - 1;
        var col = columns[i];
        var colWidth = col.width*1;
        if (last && this._get_grid_width() > width + colWidth)
            col.width = colWidth = this._get_grid_width() - width;
        width += colWidth;
        var sort = (this._sort && col.name == this._sort.name) ? ("<div class='gantt_sort gantt_" + this._sort.direction + "'></div>") : "";
        var cssClass = ["gantt_grid_head_cell",
            ("gantt_grid_head_" + col.name),
            (last ? "gantt_last_cell" : ""),
            this.templates.grid_header_class(col.name, col)].join(" ");

        var style = "width:" + (colWidth - (last ? 1 : 0)) + "px;";
        var label = (col.label || labels["column_" + col.name]);
        label = label || "";
        var title_cell = "<div class='" + cssClass + "' style='" + style + "' column_id='" + col.name + "'>" + label + sort + "</div>";
        title_cells.push(title_cell);

        if (filters.length >= i) {
            var filter = filters[i];
            var filter_cell = "<div class='" + cssClass + "' style='" + style + "'>" + filter.control + "</div>";
            filter_cells.push(filter_cell);
        }
    }

    this.$grid_scale.innerHTML = "<div class='gantt_grid_scale_row'>" + title_cells.join("") + "</div>" + (this.config.filter ? "<div class='gantt_grid_scale_row'>" + filter_cells.join("") + "</div>" : "");
    this.$grid_scale.style.width = (width - 1) + "px";

    if (this.config.scale_height_auto == true) {
        var $grid_scale = $(this.$grid_scale);
        $grid_scale.removeAttr("style");
        this.config.scale_height = $grid_scale.height();
        this.$grid_scale.style.height = (this.config.scale_height - 1) + "px";
        this.$grid_scale.style.lineHeight = "1.42857143";
    } else {
        this.$grid_scale.style.height = (this.config.scale_height - 1) + "px";
        this.$grid_scale.style.lineHeight = lineHeigth + "px";
    }
};

gantt._render_grid_item = function (item) {
    var btn_cell_width = 20;
    if (!gantt._is_grid_visible())
        return null;

    var columns = this.getGridColumns();
    var cells = [];
    var width = 0;
    for (var i = 0; i < columns.length; i++) {
        var last = i == columns.length - 1;
        var col = columns[i];
        var cell;

        var value;
        var actions = null;
        if (col.template)
            value = col.template(item);
        else
            value = item[col.name];

        if (value.actions) {
            actions = value.actions;
            value = value.content;
        }

        if (value instanceof Date)
            value = this.templates.date_grid(value, item);

        value = "<div class='gantt_tree_content'>" + value + "</div>";
        var css = "gantt_cell" + (last ? " gantt_last_cell" : "");

        var tree = "";
        if (col.tree) {
            for (var j = 0; j < item.$level; j++)
                tree += this.templates.grid_indent(item);

            var has_child = this._has_children(item.id);
            if (has_child) {
                tree += this.templates.grid_open(item);
                tree += this.templates.grid_folder(item);
            } else {
                tree += this.templates.grid_blank(item);
                tree += this.templates.grid_file(item);
            }
        }
        var style = "width:" + (col.width - (actions ? btn_cell_width : 0) - (last ? 1 : 0)) + "px;";
        if (this.defined(col.align))
            style += "text-align:" + col.align + ";";
        cell = "<div class='" + css + "' style='" + style + "'>" + tree + value + "</div>";
        cells.push(cell);

        if (actions) {
            cells.push(actions);
        }
    }
    var css = item.$index % 2 === 0 ? "" : " odd";
    css += (item.$transparent) ? " gantt_transparent" : "";

    css += (item.$dataprocessor_class ? " " + item.$dataprocessor_class : "");

    if (this.templates.grid_row_class) {
        var css_template = this.templates.grid_row_class.call(this, item.start_date, item.end_date, item);
        if (css_template)
            css += " " + css_template;
    }

    if (this.getState().selected_task == item.id) {
        css += " gantt_selected";
    }
    var el = document.createElement("div");
    el.className = "gantt_row" + css;
    el.style.height = this.config.row_height + "px";
    el.style.lineHeight = (gantt.config.row_height) + "px";
    el.setAttribute(this.config.task_attribute, item.id);
    el.innerHTML = cells.join("");
    return el;
};