Question

i am developing a java swing application that doesn’t fit the normal application profile. It contains a tabbed pane (and some other panels) and each tab contains a Canvas with active rendering (only one thread paints at a time).

The problem is that when i resize the main application window the canvas content doesn’t show (it shows up when i stop dragging the mouse) and i cant figure why. I’ve also noticed that some tutorials render the content to a buffered image:

http://jamesgames.org/resources/double_buffer/double_buffering_and_active_rendering.html

Could that be the reason the Canvas is flickering (the way i understand the tutorial buffered image was only use to remove the title bar offset)?

The GUI is structured like this:

JFrame 
  - TabbedPane
      - ScrollPane
          - Canvas 1
      - ScrollPane
          - Canvas 2
  - JPanel
    - labels,buttons,..

The code:

class Renderer extends Canvas implements Runnable
{
   Thread hThread = null;
   BufferStrategy strategy = null;  

   Renderer()
   {
       setIgnoreRepaint(true);
   }

   public void run()
   {
         while(active)
         {  
              g = strategy.getDrawGraphics();

              draw(g); // renderer elements

              strategy.show();
              g.dispose(); 
         }
   }

   // Called when switched to in Tabbed pane
   public void start()
   {
       createBufferStrategy(2); 
       strategy = getBufferStrategy();
       hThread = new Thread(this); 
       hThread.start();
   }

   // Called when switched off in Tabbed pane
   public void stop(){
       hThread.stop();
   }

} 

Answer 1

fixed my problem. The solution was to remove the JScrollPane and replace it with a JPanel. I then add the canvas to the JPanel and handle scrolling on my own (with JScrollBar). The canvas isnt flickering anymore and also resizing performs better.