JTabbedPane tab component resize to fit

问题

I want to make my tab labels share the JTabbedPane width. If there's one tab, fit whole width, if two tabs, share width, if three, 1/3 for each and so on...

i don't even know if it's possible to do it without putting a component there and resizing it, maybe JTabbedPane has a way of resizing it's tab label via method and i don't know...

Anyone got any idea how to make it by the easiest way possible?

回答1:

As @trashgod already noted, the tab layout is handled by the LAF-specific SomeLAFTabbedPaneUI, more specifically the TabbedPaneLayout. So the way to go is

implement a custom subclass MySomeLAFTabbedPaneUI which has a custom extended TabbedPaneLayout (you need to do that for every SomeLAF you want to support
replace the normal ui by your custom class

The first boils down to hook into the calculation of the rectangles which are used for painting the tabs/locating custom tabComponents. Something like (note: obviously not production ready :-)

public class XMetalTabbedPaneUI extends MetalTabbedPaneUI {

    public static ComponentUI createUI(JComponent c) {
        return new XMetalTabbedPaneUI();
    }

    @Override
    protected LayoutManager createLayoutManager() {
        return new XTabbedPaneLayout();
    }


    protected class XTabbedPaneLayout extends MetalTabbedPaneUI.TabbedPaneLayout {

        protected Container tabContainer;

        @Override
        protected void calculateTabRects(int tabPlacement, int tabCount) {
            super.calculateTabRects(tabPlacement, tabCount);
            // TODO: check if it makes sense to stretch
            int max = 0;
            int sum = 0;
            Rectangle r = new Rectangle();
            for (int i = 0; i < tabCount; i++) {
                getTabBounds(i, r);
                max = Math.max(max, r.width);
                sum += r.width;
            }
            // TODO: calculate real width, that is -insets
            int paneWidth = tabPane.getWidth() - 10; 
            int free = paneWidth - sum;
            // nothing to distribute
            if (free < tabCount) return;
            int add = free /tabCount;
            int offset = 0;
            for (int i = 0; i < tabCount; i++) {
                r = rects[i]; 
                r.x += offset;
                r.width += add;
                offset += add;
            }

        }

    }
}

The second is highly simplified (biased me, as the maintainer of the project :-) by the plaf enhancement mechanism provided by SwingX (actually all you need is its plaf module and dependencies). Its basic building block is a TabbedPaneAddon which loads the custom ui:

public class TabbedPaneAddon extends AbstractComponentAddon {

    /**
     * @param name
     */
    public TabbedPaneAddon() {
        super("TabbedPane");
    }

    @Override
    protected void addMetalDefaults(LookAndFeelAddons addon,
            DefaultsList defaults) {
        // remove old ui
        UIManager.getLookAndFeelDefaults().put("TabbedPaneUI", null);
        defaults.add("TabbedPaneUI",
                // here goes the full classname of your custom ui
                // this is an example only :-)
                "org.jdesktop.swingx.XMetalTabbedPaneUI");
    }

    // implement other addXXDefault as needed for 
    // supporting more LAFs
}

The make the replacement happen, you have to contribute the addon ("early") in your application:

LookAndFeelAddons.contribute(new TabbedPaneAddon());

回答2:

Is there a Look & Feel that has this "tab fitting" capability?

I don't know of one, but you might post an illustration for others who may have seen something similar. As the appearance is controlled by the L&F's UI delegate, TabbedPaneUI, you need to either look for an existing implementation or subclass one of its descendants: BasicTabbedPaneUI or MetalTabbedPaneUI.

来源：https://stackoverflow.com/questions/17754098/jtabbedpane-tab-component-resize-to-fit

标签

java

swing

tabs

width

jtabbedpane