Bug 193886 NPE is thrown when preview external CSS style in ppt[1205]
engine/org.eclipse.birt.report.engine.emitter.ppt/src/org/eclipse/birt/report/engine/emitter/ppt/PPTRender.java
boolean isSvg = false;
		TranscoderInput transInput = null;
		Base64 base = new Base64( );
		byte[] imageData = null;
		try
		{
			if ( imageContent.getURI( ) == null )
			{
				imageData = imageContent.getData( );
				if ( imageContent.getExtension( ) != null
						&& imageContent.getExtension( )
								.equalsIgnoreCase( "svg" ) )
				{
					isSvg = true;
				}
			}
			else
			{
				
				switch ( imageContent.getImageSource( ) )
				{
					case IImageContent.IMAGE_FILE :
						if ( imageContent.getURI( ) == null )
							return;
						URL url = reportDesign.findResource( imageContent.getURI( ),
								IResourceLocator.IMAGE );
						InputStream imageInput = url.openStream( );
						if ( imageContent.getURI( ).endsWith( ".svg" ) ) 
						{
							isSvg = true;