CODEWITHSUNDEEP
javaswt
hypercube
hypercube

Reputation: 1138

Row layout does not work on nested composites

This is what I am trying to achieve, using SWT:

The goal

For this, I am trying to use RowLayout for a nested Composite, to wrap the composite's controls depending on the available space. The following code works perfectly:

public class RowLayoutExample {

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("SWT RowLayout test");

        shell.setLayout(new RowLayout(SWT.HORIZONTAL));

        for (int i = 0; i < 10; i++) {
            new Label(shell, SWT.NONE).setText("Label " + i);
        }

        shell.setSize(400, 250);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }
}

This is displayed (please notice the nice wrap of the last labels on the next line - also, on shell resize, the components wraps into available horizontal space):

Row layout on shell works!

When I do this, instead:

public class RowLayoutExample {

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("SWT RowLayout test");

        shell.setLayout(new RowLayout(SWT.HORIZONTAL));
        Composite comp = new Composite(shell, SWT.NONE);
        comp.setLayout(new RowLayout(SWT.HORIZONTAL));

        for (int i = 0; i < 10; i++) {
            new Label(comp, SWT.NONE).setText("Label " + i);
        }

        shell.setSize(400, 250);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }
}

I got the following behaviour. If I resize the shell, the labels are not wrapping into multiple lines.

Row layout no longer works on shell control

In the below picture, we can see that the composite expands out of the shell client's area, instead of wrapping into second row. Resizing the shell doesn't affect this wrong behaviour.

enter image description here

I am using the following SWT version:

<dependency>
    <groupId>org.eclipse.swt</groupId>
    <artifactId>org.eclipse.swt.cocoa.macosx.x86_64</artifactId>
    <version>4.3</version>
</dependency>

So, why the second scenario is not working? Furthermore, is it possible to use GridLayout for shell, but RowLayout for a child of this shell?

Upvotes: 2

Views: 530

Answers (1)

Baz
Baz

Reputation: 36904

Here's an example using a GridLayout as the Shell's layout:

public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setText("SWT RowLayout test");

    shell.setLayout(new GridLayout());
    Composite comp = new Composite(shell, SWT.NONE);
    comp.setLayout(new RowLayout(SWT.HORIZONTAL));
    comp.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));

    for (int i = 0; i < 10; i++) {
        new Label(comp, SWT.NONE).setText("Label " + i);
    }

    shell.setSize(400, 250);
    shell.open();

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

Produces the same result as your first example.

The "trick" is to set the GridData to the child of the element with the GridLayout.

Upvotes: 4

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