旋转Swing JLabel [英] Rotate a Swing JLabel

问题描述

我目前正在尝试实现一个Swing组件，继承自 JLabel ，它应该只代表一个可以垂直定向的标签。

I am currently trying to implement a Swing component, inheriting from JLabel which should simply represent a label that can be oriented vertically.

从这开始：

public class RotatedLabel extends JLabel {

  public enum Direction {
    HORIZONTAL,
    VERTICAL_UP,
    VERTICAL_DOWN
  }

  private Direction direction;

我认为改变 getPreferredSize的结果是个不错的主意（ ）：

  @Override
  public Dimension getPreferredSize() {
    // swap size for vertical alignments
    switch (getDirection()) {
    case VERTICAL_UP:
    case VERTICAL_DOWN:
      return new Dimension(super.getPreferredSize().height, super
          .getPreferredSize().width);
    default:
      return super.getPreferredSize();
    }
  }

然后只需转换在我将绘画卸载到原始 JLabel 之前的图形对象：

and then simply transform the Graphics object before I offload painting to the original JLabel:

  @Override
  protected void paintComponent(Graphics g) {
    Graphics2D gr = (Graphics2D) g.create();

    switch (getDirection()) {
    case VERTICAL_UP:
      gr.translate(0, getPreferredSize().getHeight());
      gr.transform(AffineTransform.getQuadrantRotateInstance(-1));
      break;
    case VERTICAL_DOWN:
      // TODO
      break;
    default:
    }

    super.paintComponent(gr);
  }
}

似乎工作 - 不知何故 - 在文本中现在垂直显示。但是，展示位置和尺寸已关闭：

It seems to work—somehow—in that the text is now displayed vertically. However, placement and size are off:

实际上，背景的宽度（在这种情况下为橙色）与周围的高度相同JFrame 这不是我的想法。

Actually, the width of the background (orange in this case) is identical with the height of the surrounding JFrame which is ... not quite what I had in mind.

任何想法如何以正确的方式解决这个问题？是否鼓励将渲染委托给超类？

Any ideas how to solve that in a proper way? Is delegating rendering to superclasses even encouraged?

推荐答案

我现在在同事的帮助下完成了它的工作。基本上我现在有一个字段，指示是否交换高度/宽度，该高度/宽度仅在原始 JLabel 进行绘制时才有效。

I got it to work now with a little help of a coworker. Basically I now have a field that indicates whether to swap height/width which is only active for the time when the original JLabel does its painting.

private boolean needsRotate;

@Override
public Dimension getSize() {
  if (!needsRotate) {
    return super.getSize();
  }

  Dimension size = super.getSize();

  switch (getDirection()) {
  case VERTICAL_DOWN:
  case VERTICAL_UP:
      return new Dimension(size.height, size.width);
  default:
    return super.getSize();
  }
}

@Override
public int getHeight() {
  return getSize().height;
}

@Override
public int getWidth() {
  return getSize().width;
}

@Override
protected void paintComponent(Graphics g) {
  Graphics2D gr = (Graphics2D) g.create();

  switch (getDirection()) {
  case VERTICAL_UP:
    gr.translate(0, getSize().getHeight());
    gr.transform(AffineTransform.getQuadrantRotateInstance(-1));
    break;
  case VERTICAL_DOWN:
    gr.transform(AffineTransform.getQuadrantRotateInstance(1));
    gr.translate(0, -getSize().getWidth());
    break;
  default:
  }

  needsRotate = true;
  super.paintComponent(gr);
  needsRotate = false;
}

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