Question

I wanted to have a Text widget that could display a message in it when the user has not entered a value into the field yet. I extended composite and essentially wrapped a text field in it. Added a focus listener to remove the message on focus, and to replace the message when the focus is lost if the field is empty. That all works as expected.

The issue I am having is I wanted the prompt to be styled differently when it is placed in the text field. The font does not seem to be being used initially. Once the field has had focus and loses focus it looks correct.

For example this is how it looks when it initially loads:

And this is how it should look on initial load and how it looks after having and lost focus:

It gets a little stranger, as when I run this inside a simple shell, it works how it should. When I run it as an Eclipse application is when it does not get styled correctly.

Here is the code for my composite:

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.FocusAdapter;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.ModifyListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Text;

/**
 * The <code>PromptingTextInput</code> component is a small enhancement to
 * standard <code>Text</code>. It adds the ability to specify a prompt value
 * that displays when the text is empty and the field does not have focus.
 */
public class PromptingTextInput extends Composite {

    private String prompt;
    private Text input;
    private boolean textEmpty;

    Font emptyFont;
    Font inputFont;

    public PromptingTextInput(String prompt, Composite parent, int style, boolean passwordField) {
        super(parent, style);

        this.prompt = prompt;
        setLayout(new FillLayout());

        this.textEmpty = true;
        this.input = new Text(this, (passwordField ? SWT.PASSWORD : SWT.NONE));
        setEmptyInputStyle();

        this.input.setText(this.prompt);
        this.input.addFocusListener(new FocusAdapter() {
            public void focusGained(FocusEvent e) {
                PromptingTextInput.this.focusGained();
            }

            public void focusLost(FocusEvent e) {
                PromptingTextInput.this.focusLost();
            }
        });
        addDisposeListener(new DisposeListener() {
             public void widgetDisposed(DisposeEvent e) {
                 disposeFonts();
             }
         });
    }   

    protected void focusGained() {
        if (this.textEmpty) {
            this.input.setText("");
            setInputStyle();
        }
    }

    protected void focusLost() {
        if (input.getText() == null || input.getText().trim().length() == 0) {
            this.input.setText(this.prompt);
            setEmptyInputStyle();
            this.textEmpty = true;
        } else {
            this.textEmpty = false;
        }
    }

    protected void setInputStyle() {    
        if (this.inputFont == null){
            this.inputFont = new Font(Display.getCurrent(), "Verdana", 8, SWT.DEFAULT);
        }
        this.input.setFont(this.inputFont);
        this.input.setForeground(Display.getCurrent().getSystemColor(SWT.COLOR_BLACK));
    }

    protected void setEmptyInputStyle() {   
        if (this.emptyFont == null){
            this.emptyFont = new Font(Display.getCurrent(), "Verdana", 6, SWT.ITALIC);
        }
        this.input.setFont(this.emptyFont);
        this.input.setForeground(Display.getCurrent().getSystemColor(SWT.COLOR_GRAY));
    }

    public String getPrompt() {
        return prompt;
    }

    public void setPrompt(String prompt) {
        this.prompt = prompt;
        if(!this.input.isFocusControl()){
            this.input.setText(this.prompt);
            setEmptyInputStyle();
        }
    }

    public Text getInput() {
        return input;
    }

    public boolean isTextEmpty() {
        return textEmpty;
    }

    public String getText() {
        return this.input.getText();
    }

    public void addModifyListener (ModifyListener listener) {
        this.input.addModifyListener(listener);
    }

    public void disposeFonts(){
        if (this.inputFont != null){
            this.inputFont.dispose();
        }
        if (this.emptyFont != null){
            this.emptyFont.dispose();
        }
    }   
}

UPDATE: As Baz has shown this is not an issue in Indigo and only seems to be an issue with an E4 app in Juno.

Answer 1

Building upon sambi’s answer, I got the following working. Maybe this works in Juno:

private static Font italic;

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

    italic = new Font(Display.getCurrent(), "Verdana", 6, SWT.ITALIC);

    final Text text = new Text(shell, SWT.BORDER);

    text.addListener(SWT.Paint, new Listener() {

        @Override
        public void handleEvent(Event event) {

            if(text.getText().length() < 1 && !text.isFocusControl())
            {
                GC gc = event.gc;
                gc.setFont(italic);
                gc.setForeground(display.getSystemColor(SWT.COLOR_GRAY));

                Point size = text.computeSize(SWT.DEFAULT, SWT.DEFAULT);

                /* Strangely the y positioning doesn't work correctly */
                //gc.drawText("Please enter text", 1, (size.y / 2) - (italic.getFontData()[0].getHeight() / 2));
                gc.drawText("Please enter text", 1, 4);
            }
        }
    });

    text.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, true));

    Button button = new Button(shell, SWT.PUSH);
    button.setText("Dummy");

    button.forceFocus();

    shell.setSize(200, 100);
    shell.open();

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

Without focus and empty text:

With focus or text: