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John Smith
John Smith

Reputation: 105

How to set max composite size in SWT

Is there any way to set maximal size of composite? Only what i have found methods

setMinimumSize(Point point)
setSize(Point point)

which allow me to set minimal and prefered size.

Upvotes: 4

Views: 15005

Answers (2)

benez
benez

Reputation: 2001

i am curious about why you want to set a maximum size. can you give a concrete example? i had a situation where i wanted this option, but i came up with a solution, that was even better. just think of a widget in a layout that has a preferred size based on its contents, e.g. a text widget. now you want that widget to be as big as the available space allows it. but since that widget is claiming space based on its contents, it might claim more space than necessary. so what i needed was a maximum size, but if more space is available, that widget will still be able to take the space without claiming more.

but lets have a look at an example:

public static void main(final String[] args) {
    final Display display = new Display();
    final Shell shell = new Shell(display);
    shell.setLayout(new GridLayout(1, false));

    final Text text = new Text(shell, SWT.WRAP | SWT.MULTI | SWT.V_SCROLL);
    text.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true, 1, 1));
    text.setText(getLongText());

    shell.pack();
    shell.open();
    while (!shell.isDisposed()) {
        if (!display.readAndDispatch()) display.sleep();
    }
    display.dispose();
}

the call to shell.pack() will make the shell use the preferred size to display its contents. the layout will then ask the text widget to compute its preferred size. the text widget does not know, that the shell will be expanded as well and does not have a fixed size.

well this problem can be solved if we could give the text widget a maximum size. but it will cause another problem with the grid layout, since we don't want the text widget to be smaller in case that the shell has a minimum size which is bigger than the preferred size of the text widget. i cannot give you a code example of this case, since there is no maximum size, but just imagine the shell be of a fixed size, and the the text widget inside has a maximum size that is smaller.

the solution is to limit the preferred size computed by the widget to be of a maximum preferred size. i didn't find yet a method to set this value, but you can achieve this effect by overriding the computeSize method of the widget:

final Text text = new Text(shell, SWT.WRAP | SWT.MULTI | SWT.V_SCROLL) {

    /** The maximum preferred size. */
    private final Point maxSize = new Point(500, 400);

    @Override
    public Point computeSize(final int wHint, final int hHint, final boolean changed) {
        final Point preferredSize = super.computeSize(wHint, hHint, changed);
        return new Point(Math.min(maxSize.x, preferredSize.x), Math.min(maxSize.y, preferredSize.y));
    }

    @Override
    protected void checkSubclass() {
        // noop, allow subclassing, since we know what we are doing
    }
};

now you are still able to increase the shells size by a user drag operation and the widget will still we able to grab more space above the maximum size.

Upvotes: 5

Baz
Baz

Reputation: 36884

As far as I know, there is no Layout, that has a setting for maximal size, which is a good thing in my opinion.

Consider the following szenario: You set the maximal size of a Widget/Composite to a value that you think "looks good". Depending on the screen resolution and text size of the end-user, the chosen maximal size might just look wrong. This is why the layouts usually adapt to the available space.

Nevertheless, here is some code, that restricts the size:

public static void main(String[] args)
{
    Display display = new Display();
    final Shell shell = new Shell(display);
    shell.setText("StackOverflow");
    shell.setLayout(new GridLayout(1, false));

    final Button left = new Button(shell, SWT.PUSH);
    left.setText("Restricted width");
    left.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));

    left.addListener(SWT.Resize, new Listener()
    {
        @Override
        public void handleEvent(Event arg0)
        {
            Point size = left.getSize();

            if(size.x > 200)
            {
                left.setSize(200, size.y);
            }
        }
    });

    shell.pack();
    shell.open();
    while (!shell.isDisposed())
    {
        if (!display.readAndDispatch())
            display.sleep();
    }
    display.dispose();
}

Before resizing:

enter image description here

After resizing:

enter image description here

Upvotes: 9

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