/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Kai Nacke - Fix for Bug 202382
 *******************************************************************************/
package org.eclipse.ui.forms.widgets;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.ListenerList;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.FocusListener;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.events.TraverseEvent;
import org.eclipse.swt.events.TraverseListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Layout;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.ui.forms.events.ExpansionEvent;
import org.eclipse.ui.forms.events.HyperlinkAdapter;
import org.eclipse.ui.forms.events.HyperlinkEvent;
import org.eclipse.ui.forms.events.IExpansionListener;
import org.eclipse.ui.internal.forms.widgets.FormUtil;
import org.eclipse.ui.internal.forms.widgets.FormsResources;

/**
 * This composite is capable of expanding or collapsing a single client that is
 * its direct child. The composite renders an expansion toggle affordance
 * (according to the chosen style), and a title that also acts as a hyperlink
 * (can be selected and is traversable). The client is layed out below the title
 * when expanded, or hidden when collapsed.
 * <p>
 * The widget can be instantiated as-is, or subclassed to modify some aspects of
 * it. *
 * <p>
 * Since 3.1, left/right arrow keys can be used to control the expansion state.
 * If several expandable composites are created in the same parent, up/down
 * arrow keys can be used to traverse between them. Expandable text accepts
 * mnemonics and mnemonic activation will toggle the expansion state.
 * 
 * <p>
 * While expandable composite recognize that different styles can be used to
 * render the title bar, and even defines the constants for these styles (<code>TITLE_BAR</code>
 * and <code>SHORT_TITLE_BAR</code> the actual painting is done in the
 * subclasses.
 * 
 * @see Section
 * @since 3.0
 */
public class ExpandableComposite extends Canvas {
    /**
     * If this style is used, a twistie will be used to render the expansion
     * toggle.
     */
    public static final int TWISTIE = 1 << 1;

    /**
     * If this style is used, a tree node with either + or - signs will be used
     * to render the expansion toggle.
     */
    public static final int TREE_NODE = 1 << 2;

    /**
     * If this style is used, the title text will be rendered as a hyperlink
     * that can individually accept focus. Otherwise, it will still act like a
     * hyperlink, but only the toggle control will accept focus.
     */
    public static final int FOCUS_TITLE = 1 << 3;

    /**
     * If this style is used, the client origin will be vertically aligned with
     * the title text. Otherwise, it will start at x = 0.
     */
    public static final int CLIENT_INDENT = 1 << 4;

    /**
     * If this style is used, computed size of the composite will take the
     * client width into consideration only in the expanded state. Otherwise,
     * client width will always be taken into acount.
     */
    public static final int COMPACT = 1 << 5;

    /**
     * If this style is used, the control will be created in the expanded state.
     * This state can later be changed programmatically or by the user if
     * TWISTIE or TREE_NODE style is used.
     */
    public static final int EXPANDED = 1 << 6;

    /**
     * If this style is used, title bar decoration will be painted behind the
     * text.
     */
    public static final int TITLE_BAR = 1 << 8;

    /**
     * If this style is used, a short version of the title bar decoration will
     * be painted behind the text. This style is useful when a more descrete
     * option is needed for the title bar.
     * 
     * @since 3.1
     */
    public static final int SHORT_TITLE_BAR = 1 << 9;

    /**
     * If this style is used, title will not be rendered.
     */
    public static final int NO_TITLE = 1 << 12;

    /**
     * By default, text client is right-aligned. If this style is used, it will
     * be positioned after the text control and vertically centered with it.
     */
    public static final int LEFT_TEXT_CLIENT_ALIGNMENT = 1 << 13;

    /**
     * Width of the margin that will be added around the control (default is 0).
     */
    public int marginWidth = 0;

    /**
     * Height of the margin that will be added around the control (default is
     * 0).
     */
    public int marginHeight = 0;

    /**
     * Vertical spacing between the title area and the composite client control
     * (default is 3).
     */
    public int clientVerticalSpacing = 3;

    /**
     * Vertical spacing between the title area and the description control
     * (default is 0). The description control is normally placed at the new
     * line as defined in the font used to render it. This value will be added
     * to it.
     * 
     * @since 3.3
     */
    public int descriptionVerticalSpacing = 0;

    /**
     * Horizontal margin around the inside of the title bar area when TITLE_BAR
     * or SHORT_TITLE_BAR style is used. This variable is not used otherwise.
     * 
     * @since 3.3
     */
    public int titleBarTextMarginWidth = 6;

    /**
     * The toggle widget used to expand the composite.
     */
    protected ToggleHyperlink toggle;

    /**
     * The text label for the title.
     */
    protected Control textLabel;

    /**
     * @deprecated this variable was left as protected by mistake. It will be
     *             turned into static and hidden in the future versions. Do not
     *             use them and do not change its value.
     */
    protected int VGAP = 3;
    /**
     * @deprecated this variable was left as protected by mistake. It will be
     *             turned into static and hidden in the future versions. Do not
     *             use it and do not change its value.
     */
    protected int GAP = 4;

    static final int IGAP = 4;
    static final int IVGAP = 3;

    private static final Point NULL_SIZE = new Point(0, 0);

    private static final int VSPACE = 3;

    private static final int SEPARATOR_HEIGHT = 2;

    private int expansionStyle = TWISTIE | FOCUS_TITLE | EXPANDED;

    private boolean expanded;

    private Control textClient;

    private Control client;

    private ListenerList listeners = new ListenerList();

    private Color titleBarForeground;

    private class ExpandableLayout extends Layout implements ILayoutExtension {

        private SizeCache toggleCache = new SizeCache();

        private SizeCache textClientCache = new SizeCache();

        private SizeCache textLabelCache = new SizeCache();

        private SizeCache descriptionCache = new SizeCache();

        private SizeCache clientCache = new SizeCache();

        private void initCache(boolean shouldFlush) {
            toggleCache.setControl(toggle);
            textClientCache.setControl(textClient);
            textLabelCache.setControl(textLabel);
            descriptionCache.setControl(getDescriptionControl());
            clientCache.setControl(client);

            if (shouldFlush) {
                toggleCache.flush();
                textClientCache.flush();
                textLabelCache.flush();
                descriptionCache.flush();
                clientCache.flush();
            }
        }

        protected void layout(Composite parent, boolean changed) {
            initCache(changed);

            Rectangle clientArea = parent.getClientArea();
            int thmargin = 0;
            int tvmargin = 0;

            if (hasTitleBar()) {
                thmargin = titleBarTextMarginWidth;
                tvmargin = IVGAP;
            }
            int x = marginWidth + thmargin;
            int y = marginHeight + tvmargin;
            Point tsize = NULL_SIZE;
            Point tcsize = NULL_SIZE;
            if (toggle != null)
                tsize = toggleCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
            int twidth = clientArea.width - marginWidth - marginWidth
                    - thmargin - thmargin;
            if (tsize.x > 0)
                twidth -= tsize.x + IGAP;
            if (textClient != null) {
                tcsize = textClientCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
            }
            Point size = NULL_SIZE;
            if (textLabel != null) {
                if (tcsize.x > 0 && FormUtil.isWrapControl(textClient)) {
                    size = textLabelCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
                    if (twidth < size.x + IGAP + tcsize.x) {
                        twidth -= IGAP;
                        if (textLabel instanceof Label) {
                            GC gc = new GC(textLabel);
                            size = FormUtil.computeWrapSize(gc, ((Label)textLabel).getText(), Math.round(twidth*(size.x/(float)(size.x+tcsize.x))));
                            gc.dispose();
                        } else
                            size = textLabelCache.computeSize(Math.round(twidth*(size.x/(float)(size.x+tcsize.x))), SWT.DEFAULT);
                        tcsize = textClientCache.computeSize(twidth-size.x, SWT.DEFAULT);
                    }
                }
                else {
                    if (tcsize.x > 0)
                        twidth -= tcsize.x + IGAP;
                    size = textLabelCache.computeSize(twidth, SWT.DEFAULT);
                }
            }
            if (textLabel instanceof Label) {
                Point defSize = textLabelCache.computeSize(SWT.DEFAULT,
                        SWT.DEFAULT);
                if (defSize.y == size.y) {
                    // One line - pick the smaller of the two widths
                    size.x = Math.min(defSize.x, size.x);
                }
            }
            if (toggle != null) {
                GC gc = new GC(ExpandableComposite.this);
                gc.setFont(getFont());
                FontMetrics fm = gc.getFontMetrics();
                int textHeight = fm.getHeight();
                gc.dispose();
                if (textClient != null
                        && (expansionStyle & LEFT_TEXT_CLIENT_ALIGNMENT) != 0) {
                    textHeight = Math.max(textHeight, tcsize.y);
                }
                int ty = textHeight / 2 - tsize.y / 2 + 1;
                ty = Math.max(ty, 0);
                ty += marginHeight + tvmargin;
                toggle.setLocation(x, ty);
                toggle.setSize(tsize);
                x += tsize.x + IGAP;
            }
            if (textLabel != null) {
                int ty = y;
                if (textClient != null
                        && (expansionStyle & LEFT_TEXT_CLIENT_ALIGNMENT) != 0) {
                    if (size.y < tcsize.y)
                        ty = tcsize.y / 2 - size.y / 2 + marginHeight
                                + tvmargin;
                }
                textLabelCache.setBounds(x, ty, size.x, size.y);
            }
            if (textClient != null) {
                int tcx;
                if ((expansionStyle & LEFT_TEXT_CLIENT_ALIGNMENT) != 0) {
                    tcx = x + size.x + GAP;
                } else {
                    tcx = clientArea.width - tcsize.x - marginWidth - thmargin;
                }
                textClientCache.setBounds(tcx, y, tcsize.x, tcsize.y);
            }
            int tbarHeight = 0;
            if (size.y > 0)
                tbarHeight = size.y;
            if (tcsize.y > 0)
                tbarHeight = Math.max(tbarHeight, tcsize.y);
            y += tbarHeight;
            if (hasTitleBar())
                y += tvmargin;
            if (getSeparatorControl() != null) {
                y += VSPACE;
                getSeparatorControl().setBounds(marginWidth, y,
                        clientArea.width - marginWidth - marginWidth,
                        SEPARATOR_HEIGHT);
                y += SEPARATOR_HEIGHT;
                if (expanded)
                    y += VSPACE;
            }
            if (expanded) {
                int areaWidth = clientArea.width - marginWidth - marginWidth
                        - thmargin - thmargin;
                int cx = marginWidth + thmargin;
                if ((expansionStyle & CLIENT_INDENT) != 0) {
                    cx = x;
                    areaWidth -= x;
                }
                if (client != null) {
                    Point dsize = null;
                    Control desc = getDescriptionControl();
                    if (desc != null) {
                        dsize = descriptionCache.computeSize(areaWidth,
                                SWT.DEFAULT);
                        y += descriptionVerticalSpacing;
                        descriptionCache.setBounds(cx, y, areaWidth, dsize.y);
                        y += dsize.y + clientVerticalSpacing;
                    } else {
                        y += clientVerticalSpacing;
                        if (getSeparatorControl() != null)
                            y -= VSPACE;
                    }
                    int cwidth = areaWidth;
                    int cheight = clientArea.height - marginHeight
                            - marginHeight - y;
                    clientCache.setBounds(cx, y, cwidth, cheight);
                }
            }
        }

        protected Point computeSize(Composite parent, int wHint, int hHint,
                boolean changed) {
            initCache(changed);

            int width = 0, height = 0;
            Point tsize = NULL_SIZE;
            int twidth = 0;
            if (toggle != null) {
                tsize = toggleCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
                twidth = tsize.x + IGAP;
            }
            int thmargin = 0;
            int tvmargin = 0;

            if (hasTitleBar()) {
                thmargin = titleBarTextMarginWidth;
                tvmargin = IVGAP;
            }
            int innerwHint = wHint;
            if (innerwHint != SWT.DEFAULT)
                innerwHint -= twidth + marginWidth + marginWidth + thmargin
                        + thmargin;

            int innertHint = innerwHint;

            Point tcsize = NULL_SIZE;
            if (textClient != null) {
                tcsize = textClientCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
            }
            Point size = NULL_SIZE;

            if (textLabel != null) {
                if (tcsize.x > 0 && FormUtil.isWrapControl(textClient)) {
                    size = textLabelCache.computeSize(SWT.DEFAULT, SWT.DEFAULT);
                    if (innertHint != SWT.DEFAULT && innertHint < size.x + IGAP + tcsize.x) {
                        innertHint -= IGAP;
                        if (textLabel instanceof Label) {
                            GC gc = new GC(textLabel);
                            size = FormUtil.computeWrapSize(gc, ((Label)textLabel).getText(), Math.round(innertHint*(size.x/(float)(size.x+tcsize.x))));
                            gc.dispose();
                        } else
                            size = textLabelCache.computeSize(Math.round(innertHint*(size.x/(float)(size.x+tcsize.x))), SWT.DEFAULT);
                        tcsize = textClientCache.computeSize(innertHint-size.x, SWT.DEFAULT);
                    }
                } else {
                    if (innertHint != SWT.DEFAULT && tcsize.x > 0)
                        innertHint -= IGAP + tcsize.x;
                    size = textLabelCache.computeSize(innertHint, SWT.DEFAULT);
                }
            }
            if (textLabel instanceof Label) {
                Point defSize = textLabelCache.computeSize(SWT.DEFAULT,
                        SWT.DEFAULT);
                if (defSize.y == size.y) {
                    // One line - pick the smaller of the two widths
                    size.x = Math.min(defSize.x, size.x);
                }
            }
            if (size.x > 0)
                width = size.x;
            if (tcsize.x > 0)
                width += IGAP + tcsize.x;
            if (toggle != null)
                width += twidth;
            height = tcsize.y > 0 ? Math.max(tcsize.y, size.y) : size.y;
            if (getSeparatorControl() != null) {
                height += VSPACE + SEPARATOR_HEIGHT;
                if (expanded && client != null)
                    height += VSPACE;
            }
            // if (hasTitleBar())
            // height += VSPACE;
            if ((expanded || (expansionStyle & COMPACT) == 0) && client != null) {
                int cwHint = wHint;
                int clientIndent = 0;
                if ((expansionStyle & CLIENT_INDENT) != 0)
                    clientIndent = twidth;

                if (cwHint != SWT.DEFAULT) {
                    cwHint -= marginWidth + marginWidth + thmargin + thmargin;
                    if ((expansionStyle & CLIENT_INDENT) != 0)
                        if (tcsize.x > 0)
                            cwHint -= twidth;
                }
                Point dsize = null;
                Point csize = clientCache.computeSize(FormUtil.getWidthHint(
                        cwHint, client), SWT.DEFAULT);
                if (getDescriptionControl() != null) {
                    int dwHint = cwHint;
                    if (dwHint == SWT.DEFAULT) {
                        dwHint = csize.x;
                        if ((expansionStyle & CLIENT_INDENT) != 0)
                            dwHint -= twidth;
                    }
                    dsize = descriptionCache.computeSize(dwHint, SWT.DEFAULT);
                }
                if (dsize != null) {
                    width = Math.max(width, dsize.x + clientIndent);
                    if (expanded)
                        height += descriptionVerticalSpacing + dsize.y
                                + clientVerticalSpacing;
                } else {
                    height += clientVerticalSpacing;
                    if (getSeparatorControl() != null)
                        height -= VSPACE;
                }
                width = Math.max(width, csize.x + clientIndent);
                if (expanded)
                    height += csize.y;
            }
            if (toggle != null)
                height = height - size.y + Math.max(size.y, tsize.y);

            Point result = new Point(width + marginWidth + marginWidth
                    + thmargin + thmargin, height + marginHeight + marginHeight
                    + tvmargin + tvmargin);
            return result;
        }

        public int computeMinimumWidth(Composite parent, boolean changed) {
            return computeSize(parent, 0, SWT.DEFAULT, changed).x;
        }

        /*
         * (non-Javadoc)
         * 
         * @see org.eclipse.ui.forms.parts.ILayoutExtension#computeMinimumWidth(org.eclipse.swt.widgets.Composite,
         *      boolean)
         */
        public int computeMaximumWidth(Composite parent, boolean changed) {
            return computeSize(parent, SWT.DEFAULT, SWT.DEFAULT, changed).x;
        }
    }

    /**
     * Creates an expandable composite using a TWISTIE toggle.
     * 
     * @param parent
     *            the parent composite
     * @param style
     *            SWT style bits
     */
    public ExpandableComposite(Composite parent, int style) {
        this(parent, style, TWISTIE);
    }

    /**
     * Creates the expandable composite in the provided parent.
     * 
     * @param parent
     *            the parent
     * @param style
     *            the control style (as expected by SWT subclass)
     * @param expansionStyle
     *            the style of the expansion widget (TREE_NODE, TWISTIE,
     *            CLIENT_INDENT, COMPACT, FOCUS_TITLE,
     *            LEFT_TEXT_CLIENT_ALIGNMENT, NO_TITLE)
     */
    public ExpandableComposite(Composite parent, int style, int expansionStyle) {
        super(parent, style);
        this.expansionStyle = expansionStyle;
        if ((expansionStyle & TITLE_BAR) != 0)
            setBackgroundMode(SWT.INHERIT_DEFAULT);
        super.setLayout(new ExpandableLayout());
        if (hasTitleBar()) {
            this.addPaintListener(new PaintListener() {
                public void paintControl(PaintEvent e) {
                    onPaint(e);
                }
            });
        }
        if ((expansionStyle & TWISTIE) != 0)
            toggle = new Twistie(this, SWT.NULL);
        else if ((expansionStyle & TREE_NODE) != 0)
            toggle = new TreeNode(this, SWT.NULL);
        else
            expanded = true;
        if ((expansionStyle & EXPANDED) != 0)
            expanded = true;
        if (toggle != null) {
            toggle.setExpanded(expanded);
            toggle.addHyperlinkListener(new HyperlinkAdapter() {
                public void linkActivated(HyperlinkEvent e) {
                    toggleState();
                }
            });
            toggle.addPaintListener(new PaintListener() {
                public void paintControl(PaintEvent e) {
                    if (textLabel instanceof Label && !isFixedStyle())
                        textLabel.setForeground(toggle.hover ? toggle
                                .getHoverDecorationColor()
                                : getTitleBarForeground());
                }
            });
            toggle.addKeyListener(new KeyAdapter() {
                public void keyPressed(KeyEvent e) {
                    if (e.keyCode == SWT.ARROW_UP) {
                        verticalMove(false);
                        e.doit = false;
                    } else if (e.keyCode == SWT.ARROW_DOWN) {
                        verticalMove(true);
                        e.doit = false;
                    }
                }
            });
            if ((getExpansionStyle()&FOCUS_TITLE)==0) {
                toggle.paintFocus=false;
                toggle.addFocusListener(new FocusListener() {
                    public void focusGained(FocusEvent e) {
                        textLabel.redraw();
                    }

                    public void focusLost(FocusEvent e) {
                        textLabel.redraw();
                    }
                });
            }
        }
        if ((expansionStyle & FOCUS_TITLE) != 0) {
            Hyperlink link = new Hyperlink(this, SWT.WRAP);
            link.addHyperlinkListener(new HyperlinkAdapter() {
                public void linkActivated(HyperlinkEvent e) {
                    programmaticToggleState();
                }
            });
            textLabel = link;
        } else if ((expansionStyle & NO_TITLE) == 0) {
            final Label label = new Label(this, SWT.WRAP);
            if (!isFixedStyle()) {
                label.setCursor(FormsResources.getHandCursor());
                Listener listener = new Listener() {
                    public void handleEvent(Event e) {
                        switch (e.type) {
                        case SWT.MouseDown:
                            if (toggle != null)
                                toggle.setFocus();
                            break;
                        case SWT.MouseUp:
                            label.setCursor(FormsResources.getBusyCursor());
                            programmaticToggleState();
                            label.setCursor(FormsResources.getHandCursor());
                            break;
                        case SWT.MouseEnter:
                            if (toggle != null) {
                                label.setForeground(toggle
                                        .getHoverDecorationColor());
                                toggle.hover = true;
                                toggle.redraw();
                            }
                            break;
                        case SWT.MouseExit:
                            if (toggle != null) {
                                label.setForeground(getTitleBarForeground());
                                toggle.hover = false;
                                toggle.redraw();
                            }
                            break;
                        case SWT.Paint:
                            if (toggle != null) {
                                paintTitleFocus(e.gc);
                            }
                            break;
                        }
                    }
                };
                label.addListener(SWT.MouseDown, listener);
                label.addListener(SWT.MouseUp, listener);
                label.addListener(SWT.MouseEnter, listener);
                label.addListener(SWT.MouseExit, listener);
                label.addListener(SWT.Paint, listener);
            }
            textLabel = label;
        }
        if (textLabel != null) {
            textLabel.setMenu(getMenu());
            textLabel.addTraverseListener(new TraverseListener() {
                public void keyTraversed(TraverseEvent e) {
                    if (e.detail == SWT.TRAVERSE_MNEMONIC) {
                        // steal the mnemonic
                        if (!isVisible() || !isEnabled())
                            return;
                        if (FormUtil.mnemonicMatch(getText(), e.character)) {
                            e.doit = false;
                            if (!isFixedStyle()) {
                                programmaticToggleState();
                            }
                            setFocus();
                        }
                    }
                }
            });
        }
    }

    /* (non-Javadoc)
     * @see org.eclipse.swt.widgets.Control#forceFocus()
     */
    public boolean forceFocus() {
        return false;
    }

    /**
     * Overrides 'super' to pass the menu to the text label.
     * 
     * @param menu
     *            the menu from the parent to attach to this control.
     */

    public void setMenu(Menu menu) {
        if (textLabel != null)
            textLabel.setMenu(menu);
        super.setMenu(menu);
    }

    /**
     * Prevents assignment of the layout manager - expandable composite uses its
     * own layout.
     */
    public final void setLayout(Layout layout) {
    }

    /**
     * Sets the background of all the custom controls in the expandable.
     */
    public void setBackground(Color bg) {
        super.setBackground(bg);
        if ((getExpansionStyle() & TITLE_BAR) == 0) {
            if (textLabel != null)
                textLabel.setBackground(bg);
            if (toggle != null)
                toggle.setBackground(bg);
        }
    }

    /**
     * Sets the foreground of all the custom controls in the expandable.
     */
    public void setForeground(Color fg) {
        super.setForeground(fg);
        if (textLabel != null)
            textLabel.setForeground(fg);
        if (toggle != null)
            toggle.setForeground(fg);
    }

    /**
     * Sets the color of the toggle control.
     * 
     * @param c
     *            the color object
     */
    public void setToggleColor(Color c) {
        if (toggle != null)
            toggle.setDecorationColor(c);
    }

    /**
     * Sets the active color of the toggle control (when the mouse enters the
     * toggle area).
     * 
     * @param c
     *            the active color object
     */
    public void setActiveToggleColor(Color c) {
        if (toggle != null)
            toggle.setHoverDecorationColor(c);
    }

    /**
     * Sets the fonts of all the custom controls in the expandable.
     */
    public void setFont(Font font) {
        super.setFont(font);
        if (textLabel != null)
            textLabel.setFont(font);
        if (toggle != null)
            toggle.setFont(font);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.swt.widgets.Control#setEnabled(boolean)
     */

    public void setEnabled(boolean enabled) {
        if (textLabel != null)
            textLabel.setEnabled(enabled);
        if (toggle != null)
            toggle.setEnabled(enabled);
        super.setEnabled(enabled);
    }

    /**
     * Sets the client of this expandable composite. The client must not be
     * <samp>null </samp> and must be a direct child of this container.
     * 
     * @param client
     *            the client that will be expanded or collapsed
     */
    public void setClient(Control client) {
        Assert.isTrue(client != null && client.getParent().equals(this));
        this.client = client;
    }

    /**
     * Returns the current expandable client.
     * 
     * @return the client control
     */
    public Control getClient() {
        return client;
    }

    /**
     * Sets the title of the expandable composite. The title will act as a
     * hyperlink and activating it will toggle the client between expanded and
     * collapsed state.
     * 
     * @param title
     *            the new title string
     * @see #getText()
     */
    public void setText(String title) {
        if (textLabel instanceof Label)
            ((Label) textLabel).setText(title);
        else if (textLabel instanceof Hyperlink)
            ((Hyperlink) textLabel).setText(title);
    }

    /**
     * Returns the title string.
     * 
     * @return the title string
     * @see #setText(String)
     */
    public String getText() {
        if (textLabel instanceof Label)
            return ((Label) textLabel).getText();
        else if (textLabel instanceof Hyperlink)
            return ((Hyperlink) textLabel).getText();
        else
            return ""; //$NON-NLS-1$
    }

    /**
     * Tests the expanded state of the composite.
     * 
     * @return <samp>true </samp> if expanded, <samp>false </samp> if collapsed.
     */
    public boolean isExpanded() {
        return expanded;
    }

    /**
     * Returns the bitwise-ORed style bits for the expansion control.
     * 
     * @return the bitwise-ORed style bits for the expansion control
     */
    public int getExpansionStyle() {
        return expansionStyle;
    }

    /**
     * Programmatically changes expanded state.
     * 
     * @param expanded
     *            the new expanded state
     */
    public void setExpanded(boolean expanded) {
        internalSetExpanded(expanded);
        if (toggle != null)
            toggle.setExpanded(expanded);
    }

    /**
     * Performs the expansion state change for the expandable control.
     * 
     * @param expanded
     *            the expansion state
     */
    protected void internalSetExpanded(boolean expanded) {
        if (this.expanded != expanded) {
            this.expanded = expanded;
            if (getDescriptionControl() != null)
                getDescriptionControl().setVisible(expanded);
            if (client != null)
                client.setVisible(expanded);
            layout();
        }
    }

    /**
     * Adds the listener that will be notified when the expansion state changes.
     * 
     * @param listener
     *            the listener to add
     */
    public void addExpansionListener(IExpansionListener listener) {
        listeners.add(listener);
    }

    /**
     * Removes the expansion listener.
     * 
     * @param listener
     *            the listner to remove
     */
    public void removeExpansionListener(IExpansionListener listener) {
        listeners.remove(listener);
    }

    /**
     * If TITLE_BAR or SHORT_TITLE_BAR style is used, title bar decoration will
     * be painted behind the text in this method. The default implementation
     * does nothing - subclasses are responsible for rendering the title area.
     * 
     * @param e
     *            the paint event
     */
    protected void onPaint(PaintEvent e) {
    }

    /**
     * Returns description control that will be placed under the title if
     * present.
     * 
     * @return the description control or <samp>null </samp> if not used.
     */
    protected Control getDescriptionControl() {
        return null;
    }

    /**
     * Returns the separator control that will be placed between the title and
     * the description if present.
     * 
     * @return the separator control or <samp>null </samp> if not used.
     */
    protected Control getSeparatorControl() {
        return null;
    }

    /**
     * Computes the size of the expandable composite.
     * 
     * @see org.eclipse.swt.widgets.Composite#computeSize
     */
    public Point computeSize(int wHint, int hHint, boolean changed) {
        checkWidget();
        Point size;
        ExpandableLayout layout = (ExpandableLayout) getLayout();
        if (wHint == SWT.DEFAULT || hHint == SWT.DEFAULT) {
            size = layout.computeSize(this, wHint, hHint, changed);
        } else {
            size = new Point(wHint, hHint);
        }
        Rectangle trim = computeTrim(0, 0, size.x, size.y);
        return new Point(trim.width, trim.height);
    }

    /**
     * Returns <samp>true </samp> if the composite is fixed i.e. cannot be
     * expanded or collapsed. Fixed control will still contain the title,
     * separator and description (if present) as well as the client, but will be
     * in the permanent expanded state and the toggle affordance will not be
     * shown.
     * 
     * @return <samp>true </samp> if the control is fixed in the expanded state,
     *         <samp>false </samp> if it can be collapsed.
     */
    protected boolean isFixedStyle() {
        return (expansionStyle & TWISTIE) == 0
                && (expansionStyle & TREE_NODE) == 0;
    }

    /**
     * Returns the text client control.
     * 
     * @return Returns the text client control if specified, or
     *         <code>null</code> if not.
     */
    public Control getTextClient() {
        return textClient;
    }

    /**
     * Sets the text client control. Text client is a control that is a child of
     * the expandable composite and is placed to the right of the text. It can
     * be used to place small image hyperlinks. If more than one control is
     * needed, use Composite to hold them. Care should be taken that the height
     * of the control is comparable to the height of the text.
     * 
     * @param textClient
     *            the textClient to set or <code>null</code> if not needed any
     *            more.
     */
    public void setTextClient(Control textClient) {
        if (this.textClient != null)
            this.textClient.dispose();
        this.textClient = textClient;
    }

    /**
     * Returns the difference in height between the text and the text client (if
     * set). This difference can cause vertical alignment problems when two
     * expandable composites are placed side by side, one with and one without
     * the text client. Use this method obtain the value to add to either
     * <code>descriptionVerticalSpacing</code> (if you have description) or
     * <code>clientVerticalSpacing</code> to correct the alignment of the
     * expandable without the text client.
     * 
     * @return the difference in height between the text and the text client or
     *         0 if no corrective action is needed.
     * @since 3.3
     */
    public int getTextClientHeightDifference() {
        if (textClient == null || textLabel == null)
            return 0;
        int theight = textLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
        int tcheight = textClient.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
        return Math.max(tcheight - theight, 0);
    }

    /**
     * Tests if this expandable composite renders a title bar around the text.
     * 
     * @return <code>true</code> for <code>TITLE_BAR</code> or
     *         <code>SHORT_TITLE_BAR</code> styles, <code>false</code>
     *         otherwise.
     */
    protected boolean hasTitleBar() {
        return (getExpansionStyle() & TITLE_BAR) != 0
                || (getExpansionStyle() & SHORT_TITLE_BAR) != 0;
    }

    /**
     * Sets the color of the title bar foreground when TITLE_BAR style is used.
     * 
     * @param color
     *            the title bar foreground
     */
    public void setTitleBarForeground(Color color) {
        if (hasTitleBar())
            titleBarForeground = color;
        if (textLabel != null)
            textLabel.setForeground(color);
    }

    /**
     * Returns the title bar foreground when TITLE_BAR style is used.
     * 
     * @return the title bar foreground
     */
    public Color getTitleBarForeground() {
        return titleBarForeground;
    }

    // end of APIs

    private void toggleState() {
        boolean newState = !isExpanded();
        fireExpanding(newState, true);
        internalSetExpanded(newState);
        fireExpanding(newState, false);
        if (newState)
            FormUtil.ensureVisible(this);
    }

    private void fireExpanding(boolean state, boolean before) {
        int size = listeners.size();
        if (size == 0)
            return;
        ExpansionEvent e = new ExpansionEvent(this, state);
        Object [] listenerList = listeners.getListeners();
        for (int i = 0; i < size; i++) {
            IExpansionListener listener = (IExpansionListener) listenerList[i];
            if (before)
                listener.expansionStateChanging(e);
            else
                listener.expansionStateChanged(e);
        }
    }

    private void verticalMove(boolean down) {
        Composite parent = getParent();
        Control[] children = parent.getChildren();
        for (int i = 0; i < children.length; i++) {
            Control child = children[i];
            if (child == this) {
                ExpandableComposite sibling = getSibling(children, i, down);
                if (sibling != null && sibling.toggle != null) {
                    sibling.setFocus();
                }
                break;
            }
        }
    }

    private ExpandableComposite getSibling(Control[] children, int index,
            boolean down) {
        int loc = down ? index + 1 : index - 1;
        while (loc >= 0 && loc < children.length) {
            Control c = children[loc];
            if (c instanceof ExpandableComposite && c.isVisible())
                return (ExpandableComposite) c;
            loc = down ? loc + 1 : loc - 1;
        }
        return null;
    }

    private void programmaticToggleState() {
        if (toggle != null)
            toggle.setExpanded(!toggle.isExpanded());
        toggleState();
    }
    
    private void paintTitleFocus(GC gc) {
        Point size = textLabel.getSize();
        gc.setBackground(textLabel.getBackground());
        gc.setForeground(textLabel.getForeground());
        if (toggle.isFocusControl())
            gc.drawFocus(0, 0, size.x, size.y);
    }
}