package glg_demos; import java.io.*; import java.net.*; import javax.servlet.*; import javax.servlet.http.*; import javax.imageio.*; import java.awt.image.*; import com.genlogic.*; public final class GlgAvionicsServlet extends HttpServlet implements GlgErrorHandler { static final long serialVersionUID = 0; static GlgObject drawing = null; // Drawing path relative to the servlet app's dir. static final String drawing_name = "/drawings/avionics.g"; // Array of demo datasources to animate drawing's 15 dynamic resources. GlgDemoDataSource datasource_array[] = new GlgDemoDataSource[ 15 ]; ///////////////////////////////////////////////////////////////// // A wrapper around the main method, doGet2(), to properly handle // the access synchronization and unlocking on an error. ///////////////////////////////////////////////////////////////// public void doGet( HttpServletRequest request, HttpServletResponse response ) throws ServletException { try { doGet2( request, response ); } catch( Exception e ) { // Unlock if was interrupted by the exception while locked. GlgObject.UnlockThread(); throw new ServletException( e ); // Re-throw to log an error } // Unlock just in case the code did not do it due to a programming error. GlgObject.UnlockThread(); } ///////////////////////////////////////////////////////////////// // Main servlet's method: everything is handled here. ///////////////////////////////////////////////////////////////// public void doGet2( HttpServletRequest request, HttpServletResponse response ) { InitGLG(); // Init the Toolkit // Get requested width/height of the image. int width = GetIntegerParameter( request, "width", 750 ); int height = GetIntegerParameter( request, "height", 600 ); // Limit max. size to avoid running out of heap space creating an image. if( width > 1000 ) width = 1000; if( height > 1000 ) height = 1000; // This servlet reuses the same drawings for all servlets. // Therefore lock to synchronize and prevent other servlets from // changing the drawing size, etc., before we are done. GlgObject.Lock(); // Load the drawing just once and share it between all servlets and // threads. Alternatively, each servlet may load its own drawing. // if( drawing == null ) // First time: load the drawing. { drawing = LoadDrawing( drawing_name ); drawing.SetImageSize( width, height ); drawing.SetupHierarchy(); // Setup to prepare to receive data CreateDemoData(); } else // Already loaded, reuse the drawing. drawing.SetImageSize( width, height ); UpdateDrawingWithData(); // Setup after data update to prepare to generate image. drawing.SetupHierarchy(); // Create an image of the drawing's graphics. BufferedImage image = (BufferedImage) drawing.CreateImage( null ); GlgObject.Unlock(); // Write the image try { response.setContentType("image/png"); OutputStream out_stream = response.getOutputStream(); ImageIO.write( image, "png", out_stream ); out_stream.close(); } catch( IOException e ) { // Log( "Aborted writing of image file." ); } } ///////////////////////////////////////////////////////////////// // Helper methods ///////////////////////////////////////////////////////////////// int GetIntegerParameter( HttpServletRequest request, String name, int default_value ) { String parameter_string = request.getParameter( name ); if( parameter_string == null || parameter_string.equals( "" ) ) return default_value; try { return Integer.parseInt( parameter_string ); } catch( NumberFormatException e ) { Log( "Invalid parameter value for: " + name + " = " + parameter_string ); return default_value; } } ///////////////////////////////////////////////////////////////// void Log( String msg ) { getServletContext().log( "GlgAvionicsServlet: " + msg ); } // GlgErrorHandler interface method for error handling. public void Error( String message, int error_type, Exception e ) { Log( message ); // Log errors Log( GlgObject.GetStackTraceAsString() ); // Print stack } ///////////////////////////////////////////////////////////////// void InitGLG() { // Set an error handler to log errors. GlgObject.SetErrorHandler( this ); GlgObject.Init(); // Init GlgToolkit } ///////////////////////////////////////////////////////////////// GlgObject LoadDrawing( String drawing_name ) { GlgObject drawing; // Get drawing URL relative to the servlet's directory. URL drawing_url = null; try { drawing_url = getServletConfig().getServletContext().getResource( drawing_name ); } catch( MalformedURLException e ) { Log( "Malformed URL: " + drawing_name ); return null; } if( drawing_url == null ) { Log( "Can't find drawing: " + drawing_name ); return null; } // Load drawing from the URL drawing = GlgObject.LoadWidget( drawing_url.toString(), GlgObject.URL ); if( drawing == null ) { Log( "Can't load drawing: " + drawing_name ); return null; } // Disable viewport border in the image: let html define it if needed. drawing.SetDResource( "LineWidth", 0. ); return drawing; } ///////////////////////////////////////////////////////////////// // Create demo datasources for animation. In the application, any // custom source of data may be used. ///////////////////////////////////////////////////////////////// void CreateDemoData() { datasource_array[ 0 ] = new GlgDemoDataSource( 20., 80., 1, 1000 ); datasource_array[ 1 ] = new GlgDemoDataSource( 30., 85., 1, 1000 ); datasource_array[ 2 ] = new GlgDemoDataSource( 3.5, 7.5, 1, 1000 ); datasource_array[ 3 ] = new GlgDemoDataSource( 4.5, 7.8, 1, 1000 ); datasource_array[ 4 ] = new GlgDemoDataSource( 2000., 8000., 1, 1000 ); datasource_array[ 5 ] = new GlgDemoDataSource( 0.6, 1., 1, 1000 ); datasource_array[ 6 ] = new GlgDemoDataSource( 0.7, 1.2, 1, 1000 ); datasource_array[ 7 ] = new GlgDemoDataSource( 0., 20., 1, 1000 ); datasource_array[ 8 ] = new GlgDemoDataSource( 0., 1., 1, 1000 ); datasource_array[ 9 ] = new GlgDemoDataSource( 0., 1., 1, 1000 ); datasource_array[ 10 ] = new GlgDemoDataSource( -10., 10., 1, 1000 ); datasource_array[ 11 ] = new GlgDemoDataSource( -10., 10., 1, 1000 ); datasource_array[ 12 ] = new GlgDemoDataSource( -20., 20., 1, 1000 ); datasource_array[ 13 ] = new GlgDemoDataSource( -10., 10., 1, 1000 ); datasource_array[ 14 ] = new GlgDemoDataSource( 30., 160., 1, 1000 ); } ///////////////////////////////////////////////////////////////// // Create demo datasources for animation. In the application, any // custom source of data may be used. ///////////////////////////////////////////////////////////////// void UpdateDrawingWithData() { for( int i=0; i<15; ++i ) datasource_array[i].UpdateData(); // Get new data for all variables. drawing.SetDResource( "RPM/Value", datasource_array[0].GetValue() ); drawing.SetDResource( "RPM/Value2", datasource_array[1].GetValue() ); drawing.SetDResource( "EGT/Value", datasource_array[2].GetValue() ); drawing.SetDResource( "EGT/Value2", datasource_array[3].GetValue() ); drawing.SetDResource( "FUEL/Value", datasource_array[4].GetValue() ); drawing.SetDResource( "MACH/Value", datasource_array[5].GetValue() ); drawing.SetDResource( "MACH/Value2", datasource_array[6].GetValue() ); drawing.SetDResource( "ADA/Value", datasource_array[7].GetValue() ); drawing.SetDResource( "NOZ/Value", datasource_array[8].GetValue() ); drawing.SetDResource( "NOZ/Value2", datasource_array[9].GetValue() ); drawing.SetDResource( "HORIZON/Pitch", datasource_array[10].GetValue() ); drawing.SetDResource( "HORIZON/Roll", datasource_array[11].GetValue() ); drawing.SetDResource( "HORIZON/LeftRudder", datasource_array[12].GetValue() ); drawing.SetDResource( "HORIZON/RightRudder", datasource_array[13].GetValue() ); drawing.SetDResource( "COMPASS/Value", datasource_array[14].GetValue() ); } }