Re: Custom JScrollPane - Double JScrollBars

From:
pek <kimwlias@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 30 Apr 2008 12:18:41 -0700 (PDT)
Message-ID:
<93b20fb7-45eb-46c6-81af-340af16dd965@24g2000hsh.googlegroups.com>
On Apr 29, 5:07 pm, "David A. Redick" <tinyweldingto...@gmail.com>
wrote:

I played around some more this morning and I think I figured it out.
Just add the SpringyScrollBar class and replace the DoubleScrollPane
class.
The rest is the same.

class SpringyScrollBar extends JScrollBar
{
        public SpringyScrollBar(int iOrientation)
        {
                super(iOrientation);

                setMaximum(99);
                setMinimum(0);
                moveToMid();
        }

        public int getMid()
        {
                int iMid = getMaximum() - getMinimum() + 1;
                iMid /= 2;

                int iSize = getVisibleAmount()/2;

                iMid -= iSize;

                return iMid;
        }

        public void moveToMid()
        {
                setValue(getMid());
        }

        public int getSpeed()
        {
                int i = getValue();
                i -= getMid();

                if(i < 0)
                        i *= -1;

                return i;
        }

        public int getDir()
        {
                int i = getValue();
                i -= getMid();

                if(i < 0)
                        return -1;

                return 1;
        }

}

// 2 horiz. bars and 2 vert. bars.
class DoubleScrollPane extends JScrollPane implements
AdjustmentListener
{
        protected SpringyScrollBar m_pHSB2;
        protected SpringyScrollBar m_pVSB2;

        DoubleScrollPane(Component pView)
        {
                super(pView);

setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);

                m_pHSB2 = new SpringyScrollBar(JScrollBar.HORIZONTAL);
                m_pVSB2 = new SpringyScrollBar(JScrollBar.VERTICAL);

                m_pHSB2.addAdjustmentListener(this);
                m_pVSB2.addAdjustmentListener(this);

                m_pHSB2.setVisible(true);
                m_pVSB2.setVisible(true);

                add(m_pHSB2);
                add(m_pVSB2);

                setLayout(new DoubleScrollPaneLayout(m_pHSB2, m_pVSB2));
        }

        public void adjustmentValueChanged(AdjustmentEvent e)
        {
                SpringyScrollBar p = (SpringyScrollBar) e.getAdjustable();
                boolean bIsHoriz = p.equals(m_pHSB2);
                int iSpeed = p.getSpeed();
                int iDir = p.getDir();

                // Adjust position.
                JScrollBar pBar;
                if(bIsHoriz)
                        pBar = horizontalScrollBar;
                else
                        pBar = verticalScrollBar;

                int iInc = pBar.getUnitIncrement(iDir);
                iInc *= iSpeed;
                int iValue = pBar.getValue();
                iValue += iDir*iInc;
                pBar.setValue(iValue);

                if(!e.getValueIsAdjusting())
                {
                        // move back to center
                        p.moveToMid();
                }
        }

}


Amazing! ;) Exactly how I wanted it! I can't thank you enough. I'll
tweak some things and report back. Oh. In case you have any website/
blog, I'd like to hear about it. I want to post the source code in my
blog and have some kind of reference to you.. ;)

By the way, there is a little problem. I'm running Linux, and when the
knob is being dragged, it moves the view perfectly. But if let's say,
I drag the knob from the middle to 1/3 position and just hold the knob
there, the view doesn't move. As long as the knob is being dragged it
does. I hope you understand what I'm saying.

I tried adding MouseMotionListener and MouseListener but again, when
the knob is still, no event is fired, no matter in which position it
is.

Other than that, excellent! ;)

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