function calcTooltipPosition(position, rect, contentSize) {
	        var domWidth = contentSize[0];
	        var domHeight = contentSize[1];
	        var gap = 5;
	        var x = 0;
	        var y = 0;
	        var rectWidth = rect.width;
	        var rectHeight = rect.height;
	        switch (position) {
	            case 'inside':
	                x = rect.x + rectWidth / 2 - domWidth / 2;
	                y = rect.y + rectHeight / 2 - domHeight / 2;
	                break;
	            case 'top':
	                x = rect.x + rectWidth / 2 - domWidth / 2;
	                y = rect.y - domHeight - gap;
	                break;
	            case 'bottom':
	                x = rect.x + rectWidth / 2 - domWidth / 2;
	                y = rect.y + rectHeight + gap;
	                break;
	            case 'left':
	                x = rect.x - domWidth - gap;
	                y = rect.y + rectHeight / 2 - domHeight / 2;
	                break;
	            case 'right':
	                x = rect.x + rectWidth + gap;
	                y = rect.y + rectHeight / 2 - domHeight / 2;
	        }
	        return [x, y];
	    }
Resize method bound to the polar
@param {module:echarts/coord/polar/PolarModel} polarModel
@param {module:echarts/ExtensionAPI} api