Painting in Swing

Question

I have a class (Timeline) which extends JPanel. The Timeline Panel contains many JLabels (green and orange elements) which are positioned manually ("null-Layout"). On top of the Timeline are some buttons for switching between months. Sometimes when i switch between months swing won't paint the JLabels but always paints the grid background.

I've already tried many of the "magic" methods(repaint, revalidate, invalidate, validate, updateUI).

Successfully painted Timeline:

Timeline succesful

Failed painting:

Timeline failed

A short example:

public interface IDateSelectorRegistrar {

  void addListener(DateSelectorListener listener);

  void removeListener(DateSelectorListener listener);
}

public interface DateSelectorListener {
  void dateChanged(Timestamp from, Timestamp to);
}

public interface ITimelineModel {
  Timespan[] getTimespans(Timestamp from, Timestamp to);
}

public class Timespan {
  private String title;
  private Timestamp to;
  private Timestamp from;

  public Timespan(String title, Timestamp from, Timestamp to) {
    this.title = title;
    this.from = from; 
    this.to = to;
  }

  // setters and getters
}

public class TimelineLabel extends JLabel {
  public TimelineLabel(Timespan timespan) {
    super(timespan.getTitle());
  }

  @Override
  protected void paintComponent(Graphics g) {
    // paint colored background
    super.paintComponent(g);
  }
}

public class Timeline extends JPanel {

   public Timeline(final ITimelineModel model, IDateSelectorRegistrar registrar) {
     registrar.addListener(new DateSelectorListener() {
       public void dateChanged(Timestamp from, Timestamp to) {
         Timeline.this.removeAll();
         Timespan[] timespans = model.getTimespans(from, to);
         for(Timespan timespan : timespans) {
           TimelineLabel label = new TimelineLabel(timespan);
           Timeline.this.add(label);
           // label positioning because of Timestamp object data
         }
         // repaint of timeline
         Timeline.this.invalidate();
         Timeline.this.repaint();
       }
     });
   }

   @Override
   protected void paintComponent(Graphics g) {
      // paint background grid
      super.paintComponent(g);
   }
}

When the painting fails, have you checked whether your relevant paint/paintComponent method is called ? — ARRG, Jan 24 '12 at 14:39
@endian I never saw that, did you place those JLabels to the JPanel by implements Insets ???, — mKorbel, Jan 24 '12 at 14:44
@mKorbel no, i use no layout manager and position the labels manually — endian, Jan 24 '12 at 14:45
@endian > Then you'll have to show us how you build your components and how you dispatch your paint/repaint calls. — ARRG, Jan 24 '12 at 14:46
1) no layout manager is AbsoluteLayout or NullLayout, 2) Container returns Insets 3) for switching betweens view is there CardLayout or you place JLabels manually for every view (on Runtime) — mKorbel, Jan 24 '12 at 14:51
For better help sooner, post an [SSCCE](http://sscce.org/). For the sake of sanity, wrap the positioning logic in a (custom) `TimeLineLayout`. — Andrew Thompson, Jan 24 '12 at 14:52
@ARRG The only moment when i repaint manually is if a button click (when selecting another month) triggers — endian, Jan 24 '12 at 14:57
astonished that you _do_ see the labels occasionally ;-) In the snippet, you don't size nor locate them when adding. Which is your responsibility if you insist on not using a LayoutManager. Which is **WRONG** in Swing. — kleopatra, Jan 25 '12 at 10:58

score 2 · Answer 1 · edited May 23 '17 at 12:30

2

As an alternative, consider org.jfree.chart.renderer.category.GanttRenderer, which is ideal for time domain charts and admits a variety of customization. An example, illustrated below, may be found here.

Gantt Subtasks

edited May 23 '17 at 12:30

Community

1
1

answered Jan 24 '12 at 20:10

trashgod

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score 0 · Accepted Answer · answered Mar 01 '12 at 09:25

0

Calling following methods in the following order fixed the problem:

invalidate();
repaint();
validate();

answered Mar 01 '12 at 09:25

endian

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Painting in Swing

2 Answers2