JScrollPane viewport size

Question

I'm trying to have hist (HistoryPanel extends JPanel) be the viewport of the JScrollPane, histScroll. The problem is that the horizontal scroll bar doesn't show up unless I force it to show up with the scrollbar policy (in the code below), and even if I force it to, there's nowhere for it to scroll. The problem is that the size of the HistoryPanel refuses to increase horizontally. I tried different ways of setting the size of hist, but it continues to stay horizontally fixed in size. Vertically, however, it works perfectly fine. I don't understand what the problem is.

public SuperPanel(GoPanel panel)
{
    super(new BorderLayout());
    setFocusable(false);
    score = new ScorePanel();
    go = panel;
    go.scorePanel = score;
    score.setPreferredSize(new Dimension(panel.getWidth(), 20));
    hist = new HistoryPanel(go);
    hist.setPreferredSize(new Dimension(panel.getWidth()*20, 100*5));
    //hist.setMinimumSize(new Dimension(panel.getWidth()*20, 100*5));
    //hist.setSize(new Dimension(panel.getWidth()*20, 100*5));
    go.histPanel = hist;
    histScroll = new JScrollPane(hist, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    histScroll.setPreferredSize(new Dimension(panel.getWidth(), 100));
    add(score, "North");
    add(panel, "Center");
    add(histScroll, "South");
}

I can scroll down all I want, but I can't scroll to the right. Which is a big problem because it cuts off some of the image, and in this program, horizontal scrolling is actually a lot more important than vertical scrolling.

enter image description here

Thank you @wxyz Lol. I printed that value to the console, and I discovered that it was in fact 0. The problem is that I was calling `panel.getWidth()` before the width was even set of `panel`. The preferred width had already been set, but I think `getWidth()` will continue to be 0 until the layout manager takes care of it. You can post that as your answer if you want since your question brought me to the solution. :-) — iamstickfigure, Jan 09 '14 at 12:57

score 1 · Answer 1 · edited May 23 '17 at 12:13

1

You needn't to set prefered size to component which you add to JScrollPane, because it will be not scrollable, just remove next line :

hist.setPreferredSize(new Dimension(panel.getWidth()*20, 100*5));

Also read next post about setting size to component.

edited May 23 '17 at 12:13

Community

1
1

answered Jan 09 '14 at 12:03

alex2410

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I don't think that really helps. That panel must be a large canvas which displays an image that I can pan around on. If I remove that line, I'm not able to scroll at all. – iamstickfigure Jan 09 '14 at 12:39
And there are no components inside that panel, so it's not as simple as just letting the layout manager take care of it. It's just a canvas that I paint to with paintComponent. I posted a screenshot in a comment above – iamstickfigure Jan 09 '14 at 12:46

JScrollPane viewport size

1 Answers1