我应如何防止Tab键激活我的单选按钮，但仍应能够专注于单选按钮的文本

Question

When I'm tabbing through a wizard dialog in swt which contains text boxes, radio buttons, push buttons. Problem is whenever I tab through a disabled radio button which looks like ()radioText, this is getting activated like this (.):radioText:, along with this radio buttons, there are 2 text boxes which are to acting the same way when tab key is clicked. So what is the way so that tab should focus on the radio button but it should not activate it, I mean from ()radioText state to (.)radioText state. Could some one share their experience in implementing this.

Answer 1

I have an ugly solution, but it works.

Instead of allowing focus to get directly to the radio button, you can put another hidden control before it. In my cases, I used a canvas. When that control gets focus, get the selection for the radio buttons following it, set the focus to the first radio button, and then revert the selection back to what it used to be. This works for forward traversal. For backward (CTRL+TAB), you have to do the same with a hidden control after the radio buttons.

Be aware that with this solution selection listeners can be fired during tab traversal. But after it the selection will be as before.

Here is a small snippet that does this. It only works in forward mode, and the canvas is not really hidden. You have to fix the layout for you case.

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

    new Button(shell, SWT.TOGGLE);
    new Scale(shell, SWT.HORIZONTAL);

    final Canvas invisible = new Canvas(shell, SWT.NONE);
    invisible.addListener(SWT.KeyDown, new Listener() {
        @Override
        public void handleEvent(Event event) {
        }
    });

    final Button radioButton1 = new Button(shell, SWT.RADIO);
    radioButton1.setText("text1");

    final Button radioButton2 = new Button(shell, SWT.RADIO);
    radioButton2.setText("text2");

    invisible.addFocusListener(new FocusListener() {
        @Override
        public void focusGained(FocusEvent e) {
            final boolean selection1 = radioButton1.getSelection();
            final boolean selection2 = radioButton2.getSelection();
            radioButton1.setFocus();
            radioButton1.setSelection(selection1);
            radioButton2.setSelection(selection2);
        }

        @Override
        public void focusLost(FocusEvent e) {
        }
    });

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

Answer 2

This answer is for the case where there is a text field after the radio button. In other cases my other answer can be used. It is not perfect, and it is quite ugly, but maybe it solves your problem.

Besides the internal state, I keep the selection value as data ( setData() ) and update the official selection after each selection event.

Here is the complete snippet:

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

    final Composite composite = new Composite(shell, SWT.NO_RADIO_GROUP);
    composite.setLayout(new GridLayout(2, false));

    new Button(composite, SWT.TOGGLE);
    new Scale(composite, SWT.HORIZONTAL);

    final Button radioButton1 = new Button(composite, SWT.RADIO);
    radioButton1.setText("text1");
    radioButton1.setData("selection", false);
    new Text(composite, SWT.SINGLE);

    final Button radioButton2 = new Button(composite, SWT.RADIO);
    radioButton2.setText("text2");
    radioButton2.setData("selection", false);
    new Text(composite, SWT.SINGLE);

    final Button[] radioGroup = {radioButton1, radioButton2};

    final Listener listener = new Listener() {
        @Override
        public void handleEvent(Event event) {
            final Button button = (Button) event.widget;
            switch (event.type) {
                case SWT.MouseDown:
                    event.widget.setData("selection", true);
                    break;
                case SWT.KeyDown:
                    if (event.keyCode == SWT.SPACE) {
                        event.widget.setData("selection", true);
                    }
                    break;
                case SWT.Selection:
                    final boolean selection = (boolean) button.getData("selection");
                    if (selection != button.getSelection()) {
                        button.setSelection(selection);
                    }
                    if (selection) {
                        for (Button radioButton : radioGroup) {
                            if (radioButton != button) {
                                radioButton.setData("selection", false);
                                radioButton.setSelection(false);
                            }
                        }
                    }
                    break;
            }
        }
    };
    radioButton1.addListener(SWT.MouseDown, listener);
    radioButton1.addListener(SWT.KeyDown, listener);
    radioButton1.addListener(SWT.Selection, listener);
    radioButton2.addListener(SWT.MouseDown, listener);
    radioButton2.addListener(SWT.KeyDown, listener);
    radioButton2.addListener(SWT.Selection, listener);

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

Answer 3

package myexamples;

import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.layout.FormLayout;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.graphics.Point;
import org.eclipse.wb.swt.layout.grouplayout.GroupLayout;
import org.eclipse.wb.swt.layout.grouplayout.LayoutStyle;
import org.eclipse.swt.widgets.Combo;

public class MySample {
    private static Text text;
    private static Text text_1;
    private static Text text_2;

    /**
     * Launch the application.
     * @param args
     */
    public static void main(String[] args) {
        Display display = Display.getDefault();
        Shell shell = new Shell();

        Composite composite = new Composite(shell, SWT.NONE);
        composite.setBounds(197, 177, 393, 110);
        composite.setLayout(new GridLayout(2, false));
        new Label(composite, SWT.NONE);
        new Label(composite, SWT.NONE);

        Button btnButton = new Button(composite, SWT.RADIO);
        btnButton.setText(" Button1");

        Composite composite_1 = new Composite(composite, SWT.NONE);
        composite_1.setLayout(new GridLayout(4, false));
        GridData gd_composite_1 = new GridData(SWT.LEFT, SWT.CENTER, false, false, 1, 1);
        gd_composite_1.heightHint = 37;
        gd_composite_1.widthHint = 306;
        composite_1.setLayoutData(gd_composite_1);

        text = new Text(composite_1, SWT.BORDER);
        text.setSize(new Point(10, 8));
        GridData gd_text = new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1);
        gd_text.widthHint = 72;
        text.setLayoutData(gd_text);

        Label lblLabel = new Label(composite_1, SWT.NONE);
        lblLabel.setLayoutData(new GridData(SWT.RIGHT, SWT.CENTER, false, false, 1, 1));
        lblLabel.setText("Label2");

        text_1 = new Text(composite_1, SWT.BORDER);
        text_1.setSize(new Point(12, 8));
        GridData gd_text_1 = new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1);
        gd_text_1.widthHint = 60;
        text_1.setLayoutData(gd_text_1);

        Label lblLabel_1 = new Label(composite_1, SWT.NONE);
        lblLabel_1.setText(" Label3");
        new Label(composite_1, SWT.NONE);
        new Label(composite_1, SWT.NONE);
        new Label(composite_1, SWT.NONE);
        new Label(composite_1, SWT.NONE);

        Button btnButton_1 = new Button(composite, SWT.RADIO);
        btnButton_1.setText(" Button2");

        Composite composite_2 = new Composite(composite, SWT.NONE);
        composite_2.setLayout(new GridLayout(5, false));
        GridData gd_composite_2 = new GridData(SWT.LEFT, SWT.CENTER, false, false, 1, 1);
        gd_composite_2.widthHint = 305;
        gd_composite_2.heightHint = 30;
        composite_2.setLayoutData(gd_composite_2);

        Combo combo = new Combo(composite_2, SWT.NONE);
        combo.setSize(new Point(10, 8));
        combo.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1));
        combo.setEnabled(false);
        Combo combo_1 = new Combo(composite_2, SWT.NONE);
        combo_1.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1));
        combo_1.setEnabled(false);
        Label lblLabelxyz = new Label(composite_2, SWT.NONE);
        lblLabelxyz.setLayoutData(new GridData(SWT.RIGHT, SWT.CENTER, false, false, 1, 1));
        lblLabelxyz.setText("LabelXYZ1");

        text_2 = new Text(composite_2, SWT.BORDER);
        text_2.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 1, 1));

        Label lblLabelxyz_1 = new Label(composite_2, SWT.NONE);
        lblLabelxyz_1.setText("LabelXYZ2");
        text_2.setEnabled(false);
        Label label = new Label(shell, SWT.NONE);
        label.setBounds(62, 112, 55, 15);
        label.setText("");
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
    }
}

Answer 4

In a form, if you want to ask a question to a user and that question requires a Yes/No answer, it is nice to display empty options.

Besides it is clearer if the user is not able to provide an answer, as he can clearly see what was left out in the form.

This indeed requires a tweak (as the answers above suggest). I achieved it by adding a 3rd button that I artificially hide and that gets the initial selection (ie the "true" value).

Composite c = toolkit.createComposite(parent);
c.setLayout(new RowLayout());

yesButton = toolkit.createButton(c, "Yes", SWT.RADIO);
noButton = toolkit.createButton(c, "No", SWT.RADIO);

yesButton.setSelection(false);
noButton.setSelection(false);

hiddenButton = toolkit.createButton(c, "", SWT.RADIO);
hiddenButton.setSelection(true);
hiddenButton.addPaintListener(new PaintListener() {
    @Override
    public void paintControl(PaintEvent paintevent) {
        // before you paint, shrink the button size to zero
        ((Button)paintevent.widget).setSize(0, 0);
    }
});

The trick is that you cannot hide the button using setVisible(false), otherwise, the next button in the row will get the selection.

To work around that, you can force the size of the component to zero by intercepting the PaintEvents on the button