Title.java

/*******************************************************************************
 * Copyright (c) 2008-2009 SWTChart project. All rights reserved. 
 * 
 * This code is distributed under the terms of the Eclipse Public License v1.0
 * which is available at http://www.eclipse.org/legal/epl-v10.html
 *******************************************************************************/
package org.swtchart.internal;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Transform;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Display;
import org.swtchart.Chart;
import org.swtchart.Constants;
import org.swtchart.ITitle;

/**
 * A base class for title.
 */
public class Title extends Canvas implements ITitle, PaintListener
{

    /** the chart */
    protected Chart chart;

    /** the title text */
    protected String text;

    /** the visibility state of axis */
    protected boolean isVisible;

    /** the default font */
    private Font defaultFont;

    /** the default font size */
    private static final int DEFAULT_FONT_SIZE = Constants.LARGE_FONT_SIZE;

    /** the default color */
    private static final int DEFAULT_FOREGROUND = SWT.COLOR_BLUE;

    /** the default text */
    private static final String DEFAULT_TEXT = "";

    /**
     * Constructor.
     * 
     * @param parent
     *            the parent composite
     * @param style
     *            the style
     */
    public Title ( Chart parent, int style )
    {
        super ( parent, style );

        this.chart = parent;
        text = getDefaultText ();
        isVisible = true;

        defaultFont = new Font ( Display.getDefault (), "Tahoma", DEFAULT_FONT_SIZE, SWT.BOLD );
        setFont ( defaultFont );
        setForeground ( Display.getDefault ().getSystemColor ( DEFAULT_FOREGROUND ) );

        addPaintListener ( this );
    }

    /*
     * @see ITitle#setText(String)
     */
    public void setText ( String text )
    {
        if ( text == null )
        {
            this.text = getDefaultText ();
        }
        else
        {
            this.text = text;
        }
        chart.updateLayout (); // text could be changed to blank
    }

    /**
     * Gets the default title text.
     * 
     * @return the default title text
     */
    protected String getDefaultText ()
    {
        return DEFAULT_TEXT;
    }

    /*
     * @see ITitle#getText()
     */
    public String getText ()
    {
        return text;
    }

    /*
     * @see Canvas#setFont(Font)
     */
    @Override
    public void setFont ( Font font )
    {
        if ( font == null )
        {
            super.setFont ( defaultFont );
        }
        else
        {
            super.setFont ( font );
        }
        chart.updateLayout ();
    }

    /*
     * @see Control#setForeground(Color)
     */
    @Override
    public void setForeground ( Color color )
    {
        if ( color == null )
        {
            super.setForeground ( Display.getDefault ().getSystemColor ( DEFAULT_FOREGROUND ) );
        }
        else
        {
            super.setForeground ( color );
        }
    }

    /*
     * @see Control#setVisible(boolean)
     */
    @Override
    public void setVisible ( boolean isVisible )
    {
        if ( this.isVisible == isVisible )
        {
            return;
        }

        this.isVisible = isVisible;
        chart.updateLayout ();
    }

    /*
     * @see Control#isVisible()
     */
    @Override
    public boolean isVisible ()
    {
        return isVisible;
    }

    /**
     * Gets the state indicating if showing title horizontally.
     * 
     * @return the state indicating if showing title horizontally
     */
    protected boolean isHorizontal ()
    {
        return true;
    }

    /**
     * Updates the title layout data.
     */
    public void updateLayoutData ()
    {
        int height;
        int width;
        if ( isVisible () && !text.trim ().equals ( "" ) )
        {
            Point p = Util.getExtentInGC ( getFont (), text );
            width = p.x;
            height = p.y;
        }
        else
        {
            width = 0;
            height = 0;
        }
        if ( isHorizontal () )
        {
            setLayoutData ( new ChartLayoutData ( width, height ) );
        }
        else
        {
            setLayoutData ( new ChartLayoutData ( height, width ) );
        }
    }

    /*
     * @see Widget#dispose()
     */
    @Override
    public void dispose ()
    {
        super.dispose ();
        if ( !defaultFont.isDisposed () )
        {
            defaultFont.dispose ();
        }
    }

    /*
     * @see PaintListener#paintControl(PaintEvent)
     */
    public void paintControl ( PaintEvent e )
    {

        if ( text == null || text.equals ( "" ) || !isVisible )
        {
            return;
        }

        int width = getSize ().x;
        int height = getSize ().y;
        GC gc = e.gc;
        gc.setForeground ( getForeground () );
        gc.setFont ( getFont () );

        if ( isHorizontal () )
        {
            int textWidth = gc.textExtent ( text ).x;
            int x = (int) ( width / 2.0 - textWidth / 2.0 );
            if ( x < 0 )
            {
                // this happens when window size is too small
                x = 0;
            }

            gc.drawString ( text, x, 0, true );
        }
        else
        {

            // create image to draw text
            int textWidth = gc.textExtent ( text ).x;
            int textHeight = gc.textExtent ( text ).y;
            Image image = new Image ( Display.getCurrent (), textWidth, textHeight );
            GC tmpGc = new GC ( image );
            tmpGc.setForeground ( getForeground () );
            tmpGc.setBackground ( getBackground () );
            tmpGc.setFont ( getFont () );
            tmpGc.drawText ( text, 0, 0 );

            // set transform to rotate
            Transform transform = new Transform ( gc.getDevice () );
            transform.translate ( 0, textWidth );
            transform.rotate ( 270 );
            gc.setTransform ( transform );

            // draw the image on the rotated graphics context
            int y = (int) ( height / 2d - textWidth / 2d );
            if ( y < 0 )
            {
                y = 0;
            }
            gc.drawImage ( image, -y, 0 );

            // dispose resources
            tmpGc.dispose ();
            transform.dispose ();
            image.dispose ();
        }
    }
}