Swing/SnapToTicksDrag のバックアップの現在との差分(No.5)

JSliderのSnapToTicksをマウスのドラッグでも適用する

#screenshot

サンプルコード

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* サンプルコード [#sourcecode]
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#code(link){{
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slider.setUI(new MetalSliderUI() {
  protected TrackListener createTrackListener(final JSlider slider) {
  @Override protected TrackListener createTrackListener(final JSlider slider) {
    return new TrackListener() {
      public void mouseDragged(MouseEvent e) {
        //case JSlider.HORIZONTAL:
        int halfThumbWidth    = thumbRect.width / 2;
        int trackLength = trackRect.width;
        int trackLeft  = trackRect.x-halfThumbWidth;
        int trackRight = trackRect.x+(trackRect.width-1)+halfThumbWidth;
      @Override public void mouseDragged(MouseEvent e) {
        if (!slider.getSnapToTicks() || slider.getMajorTickSpacing() == 0) {
          super.mouseDragged(e);
          return;
        }
        // case SwingConstants.HORIZONTAL:
        int halfThumbWidth = thumbRect.width / 2;
        final int trackLength = trackRect.width;
        final int trackLeft = trackRect.x - halfThumbWidth;
        final int trackRight = trackRect.x + trackRect.width - 1 + halfThumbWidth;
        int xPos = e.getX();
        int snappedPos = xPos;
        if (xPos < = trackLeft) {
        if (xPos <= trackLeft) {
          snappedPos = trackLeft;
        } else if (xPos > = trackRight) {
        } else if (xPos >= trackRight) {
          snappedPos = trackRight;
        } else {
          //int tickSpacing = slider.getMajorTickSpacing();
          //float actualPixelsForOneTick = trackLength * tickSpacing
          //                                 / (float)slider.getMaximum();
          // a problem if you choose to set a negative MINIMUM for
          // the JSlider; the calculated drag-positions are wrong.
          // int tickSpacing = slider.getMajorTickSpacing();
          // float actualPixelsForOneTick =
          //     trackLength * tickSpacing / (float) slider.getMaximum();
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          // a problem if you choose to set a negative MINIMUM for the JSlider;
          // the calculated drag-positions are wrong.
          // Fixed by bobndrew:
          int possibleTickPositions=slider.getMaximum()-slider.getMinimum();
          int tickSpacing = (slider.getMinorTickSpacing()==0)
                            ? slider.getMajorTickSpacing()
                            : slider.getMinorTickSpacing();
          float actualPixelsForOneTick = trackLength * tickSpacing
                                         / (float)possibleTickPositions;
          int possibleTickPositions = slider.getMaximum() - slider.getMinimum();
          int tickSpacing = (slider.getMinorTickSpacing() == 0)
              ? slider.getMajorTickSpacing()
              : slider.getMinorTickSpacing();
          float actualPixelsForOneTick =
              trackLength * tickSpacing / (float) possibleTickPositions;
          xPos -= trackLeft;
          snappedPos=(int)((Math.round(xPos/temp)*temp)+0.5)+trackLeft;
          snappedPos = (int) (Math.round(
              xPos / actualPixelsForOneTick) * actualPixelsForOneTick + .5) + trackLeft;
          offset = 0;
          // System.out.println(snappedPos);
        }
        MouseEvent me = new MouseEvent(
          e.getComponent(), e.getID(), e.getWhen(), e.getModifiers(),
          snappedPos, e.getY(),
          e.getXOnScreen(), e.getYOnScreen(),
          e.getClickCount(), e.isPopupTrigger(), e.getButton());
        super.mouseDragged(me);
        e.translatePoint(snappedPos - e.getX(), 0);
        super.mouseDragged(e);
      }
    };
  }
});

• 上:デフォルト
  • slider.setSnapToTicks(true);としているので、マウスをリリースした時点で、ノブを置いた位置にもっとも近い目盛にスナップされる
• 下:
  • TrackListener#mouseDraggedをオーバーライドして、マウスでドラッグ中でもカーソルからもっとも近い目盛にスナップされる

解説

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