Bug 194371 Use page emitter framework to implement ppt emitter.
In order to keep consistent with pdf and postscript, ppt need to use page emitter framework.
engine/org.eclipse.birt.report.engine.emitter.ppt/src/org/eclipse/birt/report/engine/emitter/ppt/PPTRender.java
* Draws background image for the container.
	 * 
	 * @param containerStyle
	 *            the style of the container we draw background image for
	 * @param startX
	 *            the absolute horizontal position of the container
	 * @param startY
	 *            the absolute vertical position of the container
	 * @param width
	 *            container width
	 * @param height
	 *            container height
	 */
	private void drawBackgroundImage( IStyle containerStyle, double startX,
			double startY, double width, double height )
	{
		String bi = PropertyUtil.getBackgroundImage( containerStyle.getProperty( StyleConstants.STYLE_BACKGROUND_IMAGE ) );
		if ( bi == null )
		{
			return;
		}
		FloatValue positionValX = (FloatValue) containerStyle.getProperty( StyleConstants.STYLE_BACKGROUND_POSITION_X );
		FloatValue positionValY = (FloatValue) containerStyle.getProperty( StyleConstants.STYLE_BACKGROUND_POSITION_Y );
		if ( positionValX == null || positionValY == null )
		{
			return;
		}
		boolean xMode, yMode;
		double positionX, positionY;
		if ( positionValX.getPrimitiveType( ) == CSSPrimitiveValue.CSS_PERCENTAGE )