Bug 179431 [Automation]Chart background color issue[0602]
Details: [Automation]Chart background color issue[0602] Step: 1. Add a chart and set output format as jpg/bmp. 2. Add a chart and set output format as png/svg. Actual result: Step 1: Background color of chart is baby blue. Step 2: Background color of chart is black.
chart/org.eclipse.birt.chart.device.extension/src/org/eclipse/birt/chart/device/image/JavaxImageIOWriter.java
* 
	 * @see org.eclipse.birt.chart.device.IImageMapEmitter#getMimeType()
	 */
	public abstract String getMimeType( );
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.chart.device.IImageMapEmitter#getImageMap()
	 */
	public String getImageMap( )
	{
		List saList = getShapeActions( );
		if ( saList == null || saList.size( ) == 0 )
		{
			return null;
		}
		
		StringBuffer sb = new StringBuffer( );
		for ( Iterator iter = saList.iterator( ); iter.hasNext( ); )
		{
			ShapedAction sa = (ShapedAction) iter.next( );
			userCallback( sa, sb );
			String coords = shape2polyCoords( sa.getShape( ) );
			if ( coords != null )
			{
				HTMLTag tag = new HTMLTag( "AREA" ); 
				tag.addAttribute( HTMLAttribute.SHAPE, POLY_SHAPE );
				tag.addAttribute( HTMLAttribute.COORDS, coords );
				boolean changed = false;
				changed |= processOnFocus( sa, tag );