如何在复合SWT Java中居中标记

Question

I have created a Java SWT application and I have a composite containing a label with dimensions that change from time to time. The label displays an Image and have listener. How can I center the label inside the composite?

I have created a shell with:

Composite conteinerBox = new Composite(shell, SWT.NONE);
conteinerBox.setBackground(SWTResourceManager.getColor(SWT.COLOR_RED));
conteinerBox.setBounds(342, 10, 410, 384);

Label imageContainer = new Label(conteinerBox,SWT.NONE);
imageContainer.setBackground(SWTResourceManager.getColor(SWT.COLOR_WIDGET_DARK_SHADOW));

I used this function:

private void openImage() {

    if(isAnImage(file.getPath())){
        System.out.println("FILE OPEN : " + file.getPath());
        Image image = getImage(file.getPath());


        //attach image

          imageContainer.setSize(image.getBounds().width,image.getBounds().height);
        imageContainer.setImage(image);

                   //set image mouse listener
        imageContainer.addMouseMoveListener(new MouseMoveListener() {

            @Override
            public void mouseMove(MouseEvent event) {

                x_mouse_cordinate.setText("" + event.x);
                y_mouse_cordinate.setText("" + event.y);

            }
        });
}

The label containing the image is attached on point(0,0) but I want to center it inside the composite.....suggestions?

Answer 1

Please DO NOT use setBounds or setSize unless necessary, use Layout s instead.

Please read this:

Understanding Layouts in SWT

Here is some example code that centers the Label horizontally:

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

    final Label centered = new Label(shell, SWT.NONE);
    centered.setText("Small text");
    centered.setLayoutData(new GridData(SWT.CENTER, SWT.FILL, true, true));

    Button changeText = new Button(shell, SWT.PUSH);
    changeText.setText("Change text");
    changeText.addListener(SWT.Selection, new Listener()
    {
        @Override
        public void handleEvent(Event arg0)
        {
            centered.setText("Loooooooooooooooooooong text");
            centered.getParent().layout();
        }
    });


    shell.pack();
    shell.setSize(600, 200);
    shell.open();
    while (!shell.isDisposed())
    {
        while (!display.readAndDispatch())
        {
            display.sleep();
        }
    }
}

Looks like this: