src/org/tiefaces/components/websheet/utility/ColorUtility.java
public static XColor getBgColor(final CTPlotArea ctPlot,
			final ThemesTable themeTable) {

		CTSolidColorFillProperties colorFill = null;
		try {
			colorFill = ctPlot.getSpPr().getSolidFill();
		} catch (Exception ex) {
			LOG.log(Level.FINE, "No entry in bgcolor for solidFill", ex);
		}
		XColor xcolor = findAutomaticFillColor(themeTable, colorFill);
		if (xcolor != null) {
			return xcolor;
		} else {
			return new XColor(new XSSFColor(Color.WHITE));
		}
	}
public static XColor getBgColor(final CTPlotArea ctPlot,
			final ThemesTable themeTable) {

		CTSolidColorFillProperties colorFill = null;
		try {
			colorFill = ctPlot.getSpPr().getSolidFill();
		} catch (Exception ex) {
			LOG.log(Level.FINE, "No entry in bgcolor for solidFill", ex);
		}
		XColor xcolor = findAutomaticFillColor(themeTable, colorFill);
		if (xcolor != null) {
			return xcolor;
		} else {
			return new XColor(new XSSFColor(Color.WHITE));
		}
	}
retrieve background color for plot area.

@param ctPlot
plot area instance.
@param themeTable
theme table contain theme color.
@return xssfcolor with alpha setting.