java - 在 Swing 中绘画

Question

我有一个扩展 JPanel 的类(Timeline)。时间轴面板包含许多手动定位的 JLabel(绿色和橙色元素)(“空布局”)。时间轴顶部有一些用于在月份之间切换的按钮。有时，当我在几个月之间切换时，swing 不会绘制 JLabels，但总是绘制网格背景。

我已经尝试过许多“神奇”方法(重绘、重新验证、无效、验证、updateUI)。

成功绘制时间轴:

绘画失败:

一个简短的例子:

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);
   }
}

Answer 1

作为替代方案，请考虑 org.jfree.chart.renderer.category.GanttRenderer ，这是时域图的理想选择，并且允许各种定制。如下所示的示例可以在 here 中找到。 .