gnome-shell/js/ui/panel.js

/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */

const Cairo = imports.cairo;
const Clutter = imports.gi.Clutter;
const Gio = imports.gi.Gio;
const Lang = imports.lang;
const Mainloop = imports.mainloop;
const Pango = imports.gi.Pango;
const Shell = imports.gi.Shell;
const St = imports.gi.St;
const Signals = imports.signals;

const Config = imports.misc.config;
const CtrlAltTab = imports.ui.ctrlAltTab;
const Layout = imports.ui.layout;
const Overview = imports.ui.overview;
const PopupMenu = imports.ui.popupMenu;
const PanelMenu = imports.ui.panelMenu;
const StatusMenu = imports.ui.statusMenu;
const DateMenu = imports.ui.dateMenu;
const Main = imports.ui.main;
const Tweener = imports.ui.tweener;

const PANEL_ICON_SIZE = 24;

const BUTTON_DND_ACTIVATION_TIMEOUT = 250;

const ANIMATED_ICON_UPDATE_TIMEOUT = 100;
const SPINNER_ANIMATION_TIME = 0.2;

const STANDARD_TRAY_ICON_ORDER = ['a11y', 'keyboard', 'volume', 'bluetooth', 'network', 'battery'];
const STANDARD_TRAY_ICON_SHELL_IMPLEMENTATION = {
    'a11y': imports.ui.status.accessibility.ATIndicator,
    'volume': imports.ui.status.volume.Indicator,
    'battery': imports.ui.status.power.Indicator,
    'keyboard': imports.ui.status.keyboard.XKBIndicator
};

if (Config.HAVE_BLUETOOTH)
    STANDARD_TRAY_ICON_SHELL_IMPLEMENTATION['bluetooth'] = imports.ui.status.bluetooth.Indicator;

try {
    STANDARD_TRAY_ICON_SHELL_IMPLEMENTATION['network'] = imports.ui.status.network.NMApplet;
} catch(e) {
    log('NMApplet is not supported. It is possible that your NetworkManager version is too old');
}

const GDM_TRAY_ICON_ORDER = ['a11y', 'display', 'keyboard', 'volume', 'battery'];
const GDM_TRAY_ICON_SHELL_IMPLEMENTATION = {
    'a11y': imports.ui.status.accessibility.ATIndicator,
    'volume': imports.ui.status.volume.Indicator,
    'battery': imports.ui.status.power.Indicator,
    'keyboard': imports.ui.status.keyboard.XKBIndicator
};

// To make sure the panel corners blend nicely with the panel,
// we draw background and borders the same way, e.g. drawing
// them as filled shapes from the outside inwards instead of
// using cairo stroke(). So in order to give the border the
// appearance of being drawn on top of the background, we need
// to blend border and background color together.
// For that purpose we use the following helper methods, taken
// from st-theme-node-drawing.c
function _norm(x) {
    return Math.round(x / 255);
}

function _over(srcColor, dstColor) {
    let src = _premultiply(srcColor);
    let dst = _premultiply(dstColor);
    let result = new Clutter.Color();

    result.alpha = src.alpha + _norm((255 - src.alpha) * dst.alpha);
    result.red = src.red + _norm((255 - src.alpha) * dst.red);
    result.green = src.green + _norm((255 - src.alpha) * dst.green);
    result.blue = src.blue + _norm((255 - src.alpha) * dst.blue);

    return _unpremultiply(result);
}

function _premultiply(color) {
    return new Clutter.Color({ red: _norm(color.red * color.alpha),
                               green: _norm(color.green * color.alpha),
                               blue: _norm(color.blue * color.alpha),
                               alpha: color.alpha });
};

function _unpremultiply(color) {
    if (color.alpha == 0)
        return new Clutter.Color();

    let red = Math.min((color.red * 255 + 127) / color.alpha, 255);
    let green = Math.min((color.green * 255 + 127) / color.alpha, 255);
    let blue = Math.min((color.blue * 255 + 127) / color.alpha, 255);
    return new Clutter.Color({ red: red, green: green,
                               blue: blue, alpha: color.alpha });
};


function AnimatedIcon(name, size) {
    this._init(name, size);
}

AnimatedIcon.prototype = {
    _init: function(name, size) {
        this.actor = new St.Bin({ visible: false });
        this.actor.connect('destroy', Lang.bind(this, this._onDestroy));
        this.actor.connect('notify::visible', Lang.bind(this, function() {
            if (this.actor.visible) {
                this._timeoutId = Mainloop.timeout_add(ANIMATED_ICON_UPDATE_TIMEOUT, Lang.bind(this, this._update));
            } else {
                if (this._timeoutId)
                    Mainloop.source_remove(this._timeoutId);
                this._timeoutId = 0;
            }
        }));

        this._timeoutId = 0;
        this._i = 0;
        this._animations = St.TextureCache.get_default().load_sliced_image (global.datadir + '/theme/' + name, size, size);
        this.actor.set_child(this._animations);
    },

    _update: function() {
        this._animations.hide_all();
        this._animations.show();
        if (this._i && this._i < this._animations.get_n_children())
            this._animations.get_nth_child(this._i++).show();
        else {
            this._i = 1;
            if (this._animations.get_n_children())
                this._animations.get_nth_child(0).show();
        }
        return true;
    },

    _onDestroy: function() {
        if (this._timeoutId)
            Mainloop.source_remove(this._timeoutId);
    }
};

function TextShadower() {
    this._init();
}

TextShadower.prototype = {
    _init: function() {
        this.actor = new Shell.GenericContainer();
        this.actor.connect('get-preferred-width', Lang.bind(this, this._getPreferredWidth));
        this.actor.connect('get-preferred-height', Lang.bind(this, this._getPreferredHeight));
        this.actor.connect('allocate', Lang.bind(this, this._allocate));

        this._label = new St.Label();
        this.actor.add_actor(this._label);
        for (let i = 0; i < 4; i++) {
            let actor = new St.Label({ style_class: 'label-shadow' });
            actor.clutter_text.ellipsize = Pango.EllipsizeMode.END;
            this.actor.add_actor(actor);
        }
        this._label.raise_top();
    },

    setText: function(text) {
        let children = this.actor.get_children();
        for (let i = 0; i < children.length; i++)
            children[i].set_text(text);
    },

    _getPreferredWidth: function(actor, forHeight, alloc) {
        let [minWidth, natWidth] = this._label.get_preferred_width(forHeight);
        alloc.min_size = minWidth + 2;
        alloc.natural_size = natWidth + 2;
    },

    _getPreferredHeight: function(actor, forWidth, alloc) {
        let [minHeight, natHeight] = this._label.get_preferred_height(forWidth);
        alloc.min_size = minHeight + 2;
        alloc.natural_size = natHeight + 2;
    },

    _allocate: function(actor, box, flags) {
        let children = this.actor.get_children();

        let availWidth = box.x2 - box.x1;
        let availHeight = box.y2 - box.y1;

        let [minChildWidth, minChildHeight, natChildWidth, natChildHeight] =
            this._label.get_preferred_size();

        let childWidth = Math.min(natChildWidth, availWidth - 2);
        let childHeight = Math.min(natChildHeight, availHeight - 2);

        for (let i = 0; i < children.length; i++) {
            let child = children[i];
            let childBox = new Clutter.ActorBox();
            // The order of the labels here is arbitrary, except
            // we know the "real" label is at the end because Clutter.Group
            // sorts by Z order
            switch (i) {
                case 0: // top
                    childBox.x1 = 1;
                    childBox.y1 = 0;
                    break;
                case 1: // right
                    childBox.x1 = 2;
                    childBox.y1 = 1;
                    break;
                case 2: // bottom
                    childBox.x1 = 1;
                    childBox.y1 = 2;
                    break;
                case 3: // left
                    childBox.x1 = 0;
                    childBox.y1 = 1;
                    break;
                case 4: // center
                    childBox.x1 = 1;
                    childBox.y1 = 1;
                    break;
            }
            childBox.x2 = childBox.x1 + childWidth;
            childBox.y2 = childBox.y1 + childHeight;
            child.allocate(childBox, flags);
        }
    }
};

/**
 * AppMenuButton:
 *
 * This class manages the "application menu" component.  It tracks the
 * currently focused application.  However, when an app is launched,
 * this menu also handles startup notification for it.  So when we
 * have an active startup notification, we switch modes to display that.
 */
function AppMenuButton() {
    this._init();
}

AppMenuButton.prototype = {
    __proto__: PanelMenu.Button.prototype,

    _init: function() {
        PanelMenu.Button.prototype._init.call(this, 0.0);
        this._startingApps = [];

        this._targetApp = null;

        let bin = new St.Bin({ name: 'appMenu' });
        this.actor.set_child(bin);

        this.actor.reactive = false;
        this._targetIsCurrent = false;

        this._container = new Shell.GenericContainer();
        bin.set_child(this._container);
        this._container.connect('get-preferred-width', Lang.bind(this, this._getContentPreferredWidth));
        this._container.connect('get-preferred-height', Lang.bind(this, this._getContentPreferredHeight));
        this._container.connect('allocate', Lang.bind(this, this._contentAllocate));

        this._iconBox = new Shell.Slicer({ name: 'appMenuIcon' });
        this._iconBox.connect('style-changed',
                              Lang.bind(this, this._onIconBoxStyleChanged));
        this._iconBox.connect('notify::allocation',
                              Lang.bind(this, this._updateIconBoxClip));
        this._container.add_actor(this._iconBox);
        this._label = new TextShadower();
        this._container.add_actor(this._label.actor);

        this._iconBottomClip = 0;

        this._quitMenu = new PopupMenu.PopupMenuItem('');
        this.menu.addMenuItem(this._quitMenu);
        this._quitMenu.connect('activate', Lang.bind(this, this._onQuit));

        this._visible = !Main.overview.visible;
        if (!this._visible)
            this.actor.hide();
        Main.overview.connect('hiding', Lang.bind(this, function () {
            this.show();
        }));
        Main.overview.connect('showing', Lang.bind(this, function () {
            this.hide();
        }));

        this._stop = true;

        this._spinner = new AnimatedIcon('process-working.svg',
                                         PANEL_ICON_SIZE);
        this._container.add_actor(this._spinner.actor);
        this._spinner.actor.lower_bottom();

        let tracker = Shell.WindowTracker.get_default();
        tracker.connect('notify::focus-app', Lang.bind(this, this._sync));
        tracker.connect('app-state-changed', Lang.bind(this, this._onAppStateChanged));

        global.window_manager.connect('switch-workspace', Lang.bind(this, this._sync));

        this._sync();
    },

    show: function() {
        if (this._visible)
            return;

        this._visible = true;
        this.actor.show();
        this.actor.reactive = true;

        if (!this._targetIsCurrent)
            return;

        Tweener.removeTweens(this.actor);
        Tweener.addTween(this.actor,
                         { opacity: 255,
                           time: Overview.ANIMATION_TIME,
                           transition: 'easeOutQuad' });
    },

    hide: function() {
        if (!this._visible)
            return;

        this._visible = false;
        this.actor.reactive = false;
        if (!this._targetIsCurrent) {
            this.actor.hide();
            return;
        }

        Tweener.removeTweens(this.actor);
        Tweener.addTween(this.actor,
                         { opacity: 0,
                           time: Overview.ANIMATION_TIME,
                           transition: 'easeOutQuad',
                           onComplete: function() {
                               this.actor.hide();
                           },
                           onCompleteScope: this });
    },

    _onIconBoxStyleChanged: function() {
        let node = this._iconBox.get_theme_node();
        this._iconBottomClip = node.get_length('app-icon-bottom-clip');
        this._updateIconBoxClip();
    },

    _updateIconBoxClip: function() {
        let allocation = this._iconBox.allocation;
        if (this._iconBottomClip > 0)
            this._iconBox.set_clip(0, 0,
                                   allocation.x2 - allocation.x1,
                                   allocation.y2 - allocation.y1 - this._iconBottomClip);
        else
            this._iconBox.remove_clip();
    },

    stopAnimation: function() {
        if (this._stop)
            return;

        this._stop = true;
        Tweener.addTween(this._spinner.actor,
                         { opacity: 0,
                           time: SPINNER_ANIMATION_TIME,
                           transition: "easeOutQuad",
                           onCompleteScope: this,
                           onComplete: function() {
                               this._spinner.actor.opacity = 255;
                               this._spinner.actor.hide();
                           }
                         });
    },

    startAnimation: function() {
        this._stop = false;
        this._spinner.actor.show();
    },

    _getContentPreferredWidth: function(actor, forHeight, alloc) {
        let [minSize, naturalSize] = this._iconBox.get_preferred_width(forHeight);
        alloc.min_size = minSize;
        alloc.natural_size = naturalSize;
        [minSize, naturalSize] = this._label.actor.get_preferred_width(forHeight);
        alloc.min_size = alloc.min_size + Math.max(0, minSize - Math.floor(alloc.min_size / 2));
        alloc.natural_size = alloc.natural_size + Math.max(0, naturalSize - Math.floor(alloc.natural_size / 2));
    },

    _getContentPreferredHeight: function(actor, forWidth, alloc) {
        let [minSize, naturalSize] = this._iconBox.get_preferred_height(forWidth);
        alloc.min_size = minSize;
        alloc.natural_size = naturalSize;
        [minSize, naturalSize] = this._label.actor.get_preferred_height(forWidth);
        if (minSize > alloc.min_size)
            alloc.min_size = minSize;
        if (naturalSize > alloc.natural_size)
            alloc.natural_size = naturalSize;
    },

    _contentAllocate: function(actor, box, flags) {
        let allocWidth = box.x2 - box.x1;
        let allocHeight = box.y2 - box.y1;
        let childBox = new Clutter.ActorBox();

        let [minWidth, minHeight, naturalWidth, naturalHeight] = this._iconBox.get_preferred_size();

        let direction = this.actor.get_direction();

        let yPadding = Math.floor(Math.max(0, allocHeight - naturalHeight) / 2);
        childBox.y1 = yPadding;
        childBox.y2 = childBox.y1 + Math.min(naturalHeight, allocHeight);
        if (direction == St.TextDirection.LTR) {
            childBox.x1 = 0;
            childBox.x2 = childBox.x1 + Math.min(naturalWidth, allocWidth);
        } else {
            childBox.x1 = Math.max(0, allocWidth - naturalWidth);
            childBox.x2 = allocWidth;
        }
        this._iconBox.allocate(childBox, flags);

        let iconWidth = childBox.x2 - childBox.x1;

        [minWidth, minHeight, naturalWidth, naturalHeight] = this._label.actor.get_preferred_size();

        yPadding = Math.floor(Math.max(0, allocHeight - naturalHeight) / 2);
        childBox.y1 = yPadding;
        childBox.y2 = childBox.y1 + Math.min(naturalHeight, allocHeight);

        if (direction == St.TextDirection.LTR) {
            childBox.x1 = Math.floor(iconWidth / 2);
            childBox.x2 = Math.min(childBox.x1 + naturalWidth, allocWidth);
        } else {
            childBox.x2 = allocWidth - Math.floor(iconWidth / 2);
            childBox.x1 = Math.max(0, childBox.x2 - naturalWidth);
        }
        this._label.actor.allocate(childBox, flags);

        if (direction == St.TextDirection.LTR) {
            childBox.x1 = Math.floor(iconWidth / 2) + this._label.actor.width;
            childBox.x2 = childBox.x1 + this._spinner.actor.width;
            childBox.y1 = box.y1;
            childBox.y2 = box.y2 - 1;
            this._spinner.actor.allocate(childBox, flags);
        } else {
            childBox.x1 = -this._spinner.actor.width;
            childBox.x2 = childBox.x1 + this._spinner.actor.width;
            childBox.y1 = box.y1;
            childBox.y2 = box.y2 - 1;
            this._spinner.actor.allocate(childBox, flags);
        }
    },

    _onQuit: function() {
        if (this._targetApp == null)
            return;
        this._targetApp.request_quit();
    },

    _onAppStateChanged: function(tracker, app) {
        let state = app.state;
        if (state != Shell.AppState.STARTING) {
            this._startingApps = this._startingApps.filter(function(a) {
                return a != app;
            });
        } else if (state == Shell.AppState.STARTING) {
            this._startingApps.push(app);
        }
        // For now just resync on all running state changes; this is mainly to handle
        // cases where the focused window's application changes without the focus
        // changing.  An example case is how we map OpenOffice.org based on the window
        // title which is a dynamic property.
        this._sync();
    },

    _sync: function() {
        let tracker = Shell.WindowTracker.get_default();
        let lastStartedApp = null;
        let workspace = global.screen.get_active_workspace();
        for (let i = 0; i < this._startingApps.length; i++)
            if (this._startingApps[i].is_on_workspace(workspace))
                lastStartedApp = this._startingApps[i];

        let focusedApp = tracker.focus_app;

        if (!focusedApp) {
            // If the app has just lost focus to the panel, pretend
            // nothing happened; otherwise you can't keynav to the
            // app menu.
            if (global.stage_input_mode == Shell.StageInputMode.FOCUSED)
                return;
        }

        let targetApp = focusedApp != null ? focusedApp : lastStartedApp;

        if (targetApp == null) {
            if (!this._targetIsCurrent)
                return;

            this.actor.reactive = false;
            this._targetIsCurrent = false;

            Tweener.removeTweens(this.actor);
            Tweener.addTween(this.actor, { opacity: 0,
                                           time: Overview.ANIMATION_TIME,
                                           transition: 'easeOutQuad' });
            return;
        }

        if (!this._targetIsCurrent) {
            this.actor.reactive = true;
            this._targetIsCurrent = true;

            Tweener.removeTweens(this.actor);
            Tweener.addTween(this.actor, { opacity: 255,
                                           time: Overview.ANIMATION_TIME,
                                           transition: 'easeOutQuad' });
        }

        if (targetApp == this._targetApp) {
            if (targetApp && targetApp.get_state() != Shell.AppState.STARTING)
                this.stopAnimation();
            return;
        }

        this._spinner.actor.hide();
        if (this._iconBox.child != null)
            this._iconBox.child.destroy();
        this._iconBox.hide();
        this._label.setText('');

        this._targetApp = targetApp;
        let icon = targetApp.get_faded_icon(2 * PANEL_ICON_SIZE);

        this._label.setText(targetApp.get_name());
        // TODO - _quit() doesn't really work on apps in state STARTING yet
        this._quitMenu.label.set_text(_("Quit %s").format(targetApp.get_name()));

        this._iconBox.set_child(icon);
        this._iconBox.show();

        if (targetApp.get_state() == Shell.AppState.STARTING)
            this.startAnimation();

        this.emit('changed');
    }
};

Signals.addSignalMethods(AppMenuButton.prototype);

// Activities button. Because everything else in the top bar is a
// PanelMenu.Button, it simplifies some things to make this be one too.
// We just hack it up to not actually have a menu attached to it.
function ActivitiesButton() {
    this._init.apply(this, arguments);
}

ActivitiesButton.prototype = {
    __proto__: PanelMenu.Button.prototype,

    _init: function() {
        PanelMenu.Button.prototype._init.call(this, 0.0);

        let container = new Shell.GenericContainer();
        container.connect('get-preferred-width', Lang.bind(this, this._getPreferredWidth));
        container.connect('get-preferred-height', Lang.bind(this, this._getPreferredHeight));
        container.connect('allocate', Lang.bind(this, this._allocate));
        this.actor.child = container;
        this.actor.name = 'panelActivities';

        /* Translators: If there is no suitable word for "Activities"
           in your language, you can use the word for "Overview". */
        this._label = new St.Label({ text: _("Activities") });
        container.add_actor(this._label);

        this._hotCorner = new Layout.HotCorner();
        container.add_actor(this._hotCorner.actor);

        // Hack up our menu...
        this.menu.open = Lang.bind(this, this._onMenuOpenRequest);
        this.menu.close = Lang.bind(this, this._onMenuCloseRequest);
        this.menu.toggle = Lang.bind(this, this._onMenuToggleRequest);

        this.actor.connect('captured-event', Lang.bind(this, this._onCapturedEvent));
        this.actor.connect_after('button-release-event', Lang.bind(this, this._onButtonRelease));
        this.actor.connect_after('key-release-event', Lang.bind(this, this._onKeyRelease));

        Main.overview.connect('showing', Lang.bind(this, function() {
            this.actor.add_style_pseudo_class('overview');
            this._escapeMenuGrab();
        }));
        Main.overview.connect('hiding', Lang.bind(this, function() {
            this.actor.remove_style_pseudo_class('overview');
            this._escapeMenuGrab();
        }));

        this._xdndTimeOut = 0;
    },

    _getPreferredWidth: function(actor, forHeight, alloc) {
        [alloc.min_size, alloc.natural_size] = this._label.get_preferred_width(forHeight);
    },

    _getPreferredHeight: function(actor, forWidth, alloc) {
        [alloc.min_size, alloc.natural_size] = this._label.get_preferred_height(forWidth);
    },

    _allocate: function(actor, box, flags) {
        this._label.allocate(box, flags);

        // The hot corner needs to be outside any padding/alignment
        // that has been imposed on us
        let primary = Main.layoutManager.primaryMonitor;
        let hotBox = new Clutter.ActorBox();
        let ok, x, y;
        if (actor.get_direction() == St.TextDirection.LTR) {
            [ok, x, y] = actor.transform_stage_point(primary.x, primary.y)
        } else {
            [ok, x, y] = actor.transform_stage_point(primary.x + primary.width, primary.y);
            // hotCorner.actor has northeast gravity, so we don't need
            // to adjust x for its width
        }

        hotBox.x1 = Math.round(x);
        hotBox.x2 = hotBox.x1 + this._hotCorner.actor.width;
        hotBox.y1 = Math.round(y);
        hotBox.y2 = hotBox.y1 + this._hotCorner.actor.height;
        this._hotCorner.actor.allocate(hotBox, flags);
    },

    handleDragOver: function(source, actor, x, y, time) {
        if (source != Main.xdndHandler)
            return;

        if (this._xdndTimeOut != 0)
            Mainloop.source_remove(this._xdndTimeOut);
        this._xdndTimeOut = Mainloop.timeout_add(BUTTON_DND_ACTIVATION_TIMEOUT,
                                                 Lang.bind(this, this._xdndShowOverview, actor));
    },

    _escapeMenuGrab: function() {
        if (this.menu.isOpen)
            this.menu.close();
    },

    _onCapturedEvent: function(actor, event) {
        if (event.type() == Clutter.EventType.BUTTON_PRESS) {
            if (!this._hotCorner.shouldToggleOverviewOnClick())
                return true;
        }
        return false;
    },

    _onMenuOpenRequest: function() {
        this.menu.isOpen = true;
        this.menu.emit('open-state-changed', true);
    },

    _onMenuCloseRequest: function() {
        this.menu.isOpen = false;
        this.menu.emit('open-state-changed', false);
    },

    _onMenuToggleRequest: function() {
        this.menu.isOpen = !this.menu.isOpen;
        this.menu.emit('open-state-changed', this.menu.isOpen);
    },

    _onButtonRelease: function() {
        if (this.menu.isOpen) {
            this.menu.close();
            Main.overview.toggle();
        }
    },

    _onKeyRelease: function(actor, event) {
        let symbol = event.get_key_symbol();
        if (symbol == Clutter.KEY_Return || symbol == Clutter.KEY_space) {
            if (this.menu.isOpen)
                this.menu.close();
            Main.overview.toggle();
        }
    },

    _xdndShowOverview: function(actor) {
        let [x, y, mask] = global.get_pointer();
        let pickedActor = global.stage.get_actor_at_pos(Clutter.PickMode.REACTIVE, x, y);

        if (pickedActor == this.actor) {
            if (!Main.overview.visible && !Main.overview.animationInProgress) {
                Main.overview.showTemporarily();
                Main.overview.beginItemDrag(actor);
            }
        }

        Mainloop.source_remove(this._xdndTimeOut);
        this._xdndTimeOut = 0;
    }
};

function PanelCorner(panel, side) {
    this._init(panel, side);
}

PanelCorner.prototype = {
    _init: function(box, side) {
        this._side = side;

        this._box = box;
        this._box.connect('style-changed', Lang.bind(this, this._boxStyleChanged));

        this.actor = new St.DrawingArea({ style_class: 'panel-corner' });
        this.actor.connect('style-changed', Lang.bind(this, this._styleChanged));
        this.actor.connect('repaint', Lang.bind(this, this._repaint));
    },

    _findRightmostButton: function(container) {
        if (!container.get_children)
            return null;

        let children = container.get_children();

        if (!children || children.length == 0)
            return null;

        // Start at the back and work backward
        let index = children.length - 1;
        while (!children[index].visible && index >= 0)
            index--;

        if (index < 0)
            return null;

        if (!(children[index].has_style_class_name('panel-menu')) &&
            !(children[index].has_style_class_name('panel-button')))
            return this._findRightmostButton(children[index]);

        return children[index];
    },

    _findLeftmostButton: function(container) {
        if (!container.get_children)
            return null;

        let children = container.get_children();

        if (!children || children.length == 0)
            return null;

        // Start at the front and work forward
        let index = 0;
        while (!children[index].visible && index < children.length)
            index++;

        if (index == children.length)
            return null;

        if (!(children[index].has_style_class_name('panel-menu')) &&
            !(children[index].has_style_class_name('panel-button')))
            return this._findLeftmostButton(children[index]);

        return children[index];
    },

    _boxStyleChanged: function() {
        let button;

        if (this._side == St.Side.LEFT)
            button = this._findLeftmostButton(this._box);
        else if (this._side == St.Side.RIGHT)
            button = this._findRightmostButton(this._box);

        if (button) {
            if (this._button && this._buttonStyleChangedSignalId)
                this._button.disconnect(this._buttonStyleChangedSignalId);

            this._button = button;

            button.connect('destroy', Lang.bind(this,
                function() {
                    if (this._button == button) {
                        this._button = null;
                        this._buttonStyleChangedSignalId = 0;
                    }
                }));

            // Synchronize the locate button's pseudo classes with this corner
            this._buttonStyleChangedSignalId = button.connect('style-changed', Lang.bind(this,
                function(actor) {
                    let pseudoClass = button.get_style_pseudo_class();
                    this.actor.set_style_pseudo_class(pseudoClass);
                }));
        }
    },

    _repaint: function() {
        let node = this.actor.get_theme_node();

        let cornerRadius = node.get_length("-panel-corner-radius");
        let innerBorderWidth = node.get_length('-panel-corner-inner-border-width');
        let outerBorderWidth = node.get_length('-panel-corner-outer-border-width');

        let backgroundColor = node.get_color('-panel-corner-background-color');
        let innerBorderColor = node.get_color('-panel-corner-inner-border-color');
        let outerBorderColor = node.get_color('-panel-corner-outer-border-color');

        let cr = this.actor.get_context();
        cr.setOperator(Cairo.Operator.SOURCE);

        cr.moveTo(0, 0);
        if (this._side == St.Side.LEFT)
            cr.arc(cornerRadius,
                   innerBorderWidth + cornerRadius,
                   cornerRadius, Math.PI, 3 * Math.PI / 2);
        else
            cr.arc(0,
                   innerBorderWidth + cornerRadius,
                   cornerRadius, 3 * Math.PI / 2, 2 * Math.PI);
        cr.lineTo(cornerRadius, 0);
        cr.closePath();

        let savedPath = cr.copyPath();

        let over = _over(innerBorderColor,
                         _over(outerBorderColor, backgroundColor));
        Clutter.cairo_set_source_color(cr, over);
        cr.fill();

        let xOffsetDirection = this._side == St.Side.LEFT ? -1 : 1;
        let offset = outerBorderWidth;
        over = _over(innerBorderColor, backgroundColor);
        Clutter.cairo_set_source_color(cr, over);

        cr.save();
        cr.translate(xOffsetDirection * offset, - offset);
        cr.appendPath(savedPath);
        cr.fill();
        cr.restore();

        if (this._side == St.Side.LEFT)
            cr.rectangle(cornerRadius - offset, 0, offset, outerBorderWidth);
        else
            cr.rectangle(0, 0, offset, outerBorderWidth);
        cr.fill();

        offset = innerBorderWidth;
        Clutter.cairo_set_source_color(cr, backgroundColor);

        cr.save();
        cr.translate(xOffsetDirection * offset, - offset);
        cr.appendPath(savedPath);
        cr.fill();
        cr.restore();
    },

    _styleChanged: function() {
        let node = this.actor.get_theme_node();

        let cornerRadius = node.get_length("-panel-corner-radius");
        let innerBorderWidth = node.get_length('-panel-corner-inner-border-width');

        this.actor.set_size(cornerRadius, innerBorderWidth + cornerRadius);
        this.actor.set_anchor_point(0, innerBorderWidth);
    }
};


function Panel() {
    this._init();
}

Panel.prototype = {
    _init : function() {
        this.actor = new Shell.GenericContainer({ name: 'panel',
                                                  reactive: true });
        this.actor._delegate = this;

        this._statusArea = {};

        Main.overview.connect('shown', Lang.bind(this, function () {
            this.actor.add_style_class_name('in-overview');
        }));
        Main.overview.connect('hiding', Lang.bind(this, function () {
            this.actor.remove_style_class_name('in-overview');
        }));

        if (global.session_type == Shell.SessionType.GDM) {
            this._tray_icon_order = GDM_TRAY_ICON_ORDER;
            this._tray_icon_shell_implementation = GDM_TRAY_ICON_SHELL_IMPLEMENTATION;
        } else {
            this._tray_icon_order = STANDARD_TRAY_ICON_ORDER;
            this._tray_icon_shell_implementation = STANDARD_TRAY_ICON_SHELL_IMPLEMENTATION;
        }

        this._menus = new PopupMenu.PopupMenuManager(this);

        this._leftBox = new St.BoxLayout({ name: 'panelLeft' });
        this.actor.add_actor(this._leftBox);
        this._centerBox = new St.BoxLayout({ name: 'panelCenter' });
        this.actor.add_actor(this._centerBox);
        this._rightBox = new St.BoxLayout({ name: 'panelRight' });
        this.actor.add_actor(this._rightBox);

        if (this.actor.get_direction() == St.TextDirection.RTL)
            this._leftCorner = new PanelCorner(this._rightBox, St.Side.LEFT);
        else
            this._leftCorner = new PanelCorner(this._leftBox, St.Side.LEFT);

        this.actor.add_actor(this._leftCorner.actor);

        if (this.actor.get_direction() == St.TextDirection.RTL)
            this._rightCorner = new PanelCorner(this._leftBox, St.Side.RIGHT);
        else
            this._rightCorner = new PanelCorner(this._rightBox, St.Side.RIGHT);
        this.actor.add_actor(this._rightCorner.actor);

        this.actor.connect('get-preferred-width', Lang.bind(this, this._getPreferredWidth));
        this.actor.connect('get-preferred-height', Lang.bind(this, this._getPreferredHeight));
        this.actor.connect('allocate', Lang.bind(this, this._allocate));

        /* Button on the left side of the panel. */
        if (global.session_type == Shell.SessionType.USER) {
            this._activitiesButton = new ActivitiesButton();
            this._activities = this._activitiesButton.actor;
            this._leftBox.add(this._activities);

            // The activities button has a pretend menu, so as to integrate
            // more cleanly with the rest of the panel
            this._menus.addMenu(this._activitiesButton.menu);

            this._appMenu = new AppMenuButton();
            this._leftBox.add(this._appMenu.actor);
            this._menus.addMenu(this._appMenu.menu);
        }

        /* center */
        if (global.session_type == Shell.SessionType.USER)
            this._dateMenu = new DateMenu.DateMenuButton({ showEvents: true });
        else
            this._dateMenu = new DateMenu.DateMenuButton({ showEvents: false });
        this._centerBox.add(this._dateMenu.actor, { y_fill: true });
        this._menus.addMenu(this._dateMenu.menu);

        /* right */

        // System status applets live in statusBox, while legacy tray icons
        // live in trayBox
        // The trayBox is hidden when there are no tray icons.
        this._trayBox = new St.BoxLayout({ name: 'legacyTray' });
        this._statusBox = new St.BoxLayout({ name: 'statusTray' });

        this._trayBox.hide();
        this._rightBox.add(this._trayBox);
        this._rightBox.add(this._statusBox);

        if (global.session_type == Shell.SessionType.USER) {
            this._userMenu = new StatusMenu.StatusMenuButton();
            this._userMenu.actor.name = 'panelStatus';
            this._rightBox.add(this._userMenu.actor);
        }

        Main.statusIconDispatcher.connect('status-icon-added', Lang.bind(this, this._onTrayIconAdded));
        Main.statusIconDispatcher.connect('status-icon-removed', Lang.bind(this, this._onTrayIconRemoved));

        Main.layoutManager.panelBox.add(this.actor);
        Main.ctrlAltTabManager.addGroup(this.actor, _("Top Bar"), 'start-here',
                                        { sortGroup: CtrlAltTab.SortGroup.TOP });
    },

    _getPreferredWidth: function(actor, forHeight, alloc) {
        alloc.min_size = -1;
        alloc.natural_size = Main.layoutManager.primaryMonitor.width;
    },

    _getPreferredHeight: function(actor, forWidth, alloc) {
        // We don't need to implement this; it's forced by the CSS
        alloc.min_size = -1;
        alloc.natural_size = -1;
    },

    _allocate: function(actor, box, flags) {
        let allocWidth = box.x2 - box.x1;
        let allocHeight = box.y2 - box.y1;

        let [leftMinWidth, leftNaturalWidth] = this._leftBox.get_preferred_width(-1);
        let [centerMinWidth, centerNaturalWidth] = this._centerBox.get_preferred_width(-1);
        let [rightMinWidth, rightNaturalWidth] = this._rightBox.get_preferred_width(-1);

        let sideWidth, centerWidth;
        centerWidth = centerNaturalWidth;
        sideWidth = (allocWidth - centerWidth) / 2;

        let childBox = new Clutter.ActorBox();

        childBox.y1 = 0;
        childBox.y2 = allocHeight;
        if (this.actor.get_direction() == St.TextDirection.RTL) {
            childBox.x1 = allocWidth - Math.min(Math.floor(sideWidth),
                                                leftNaturalWidth);
            childBox.x2 = allocWidth;
        } else {
            childBox.x1 = 0;
            childBox.x2 = Math.min(Math.floor(sideWidth),
                                   leftNaturalWidth);
        }
        this._leftBox.allocate(childBox, flags);

        childBox.x1 = Math.ceil(sideWidth);
        childBox.y1 = 0;
        childBox.x2 = childBox.x1 + centerWidth;
        childBox.y2 = allocHeight;
        this._centerBox.allocate(childBox, flags);

        childBox.y1 = 0;
        childBox.y2 = allocHeight;
        if (this.actor.get_direction() == St.TextDirection.RTL) {
            childBox.x1 = 0;
            childBox.x2 = Math.min(Math.floor(sideWidth),
                                   rightNaturalWidth);
        } else {
            childBox.x1 = allocWidth - Math.min(Math.floor(sideWidth),
                                                rightNaturalWidth);
            childBox.x2 = allocWidth;
        }
        this._rightBox.allocate(childBox, flags);

        let [cornerMinWidth, cornerWidth] = this._leftCorner.actor.get_preferred_width(-1);
        let [cornerMinHeight, cornerHeight] = this._leftCorner.actor.get_preferred_width(-1);
        childBox.x1 = 0;
        childBox.x2 = cornerWidth;
        childBox.y1 = allocHeight;
        childBox.y2 = allocHeight + cornerHeight;
        this._leftCorner.actor.allocate(childBox, flags);

        let [cornerMinWidth, cornerWidth] = this._rightCorner.actor.get_preferred_width(-1);
        let [cornerMinHeight, cornerHeight] = this._rightCorner.actor.get_preferred_width(-1);
        childBox.x1 = allocWidth - cornerWidth;
        childBox.x2 = allocWidth;
        childBox.y1 = allocHeight;
        childBox.y2 = allocHeight + cornerHeight;
        this._rightCorner.actor.allocate(childBox, flags);
    },

    startStatusArea: function() {
        for (let i = 0; i < this._tray_icon_order.length; i++) {
            let role = this._tray_icon_order[i];
            let constructor = this._tray_icon_shell_implementation[role];
            if (!constructor) {
                // This icon is not implemented (this is a bug)
                continue;
            }

            let indicator = new constructor();
            this.addToStatusArea(role, indicator, i);
        }

        // PopupMenuManager depends on menus being added in order for
        // keyboard navigation
        if (this._userMenu)
            this._menus.addMenu(this._userMenu.menu);
    },

    addToStatusArea: function(role, indicator, position) {
        if (this._statusArea[role])
            throw new Error('Extension point conflict: there is already a status indicator for role ' + role);

        if (!(indicator instanceof PanelMenu.Button))
            throw new TypeError('Status indicator must be an instance of PanelMenu.Button');

        if (!position)
            position = 0;

        this._statusBox.insert_actor(indicator.actor, position);
        this._menus.addMenu(indicator.menu);

        this._statusArea[role] = indicator;
        let destroyId = indicator.connect('destroy', Lang.bind(this, function(emitter) {
            this._statusArea[role] = null;
            emitter.disconnect(destroyId);
        }));

        return indicator;
    },

    _onTrayIconAdded: function(o, icon, role) {
        icon.height = PANEL_ICON_SIZE;

        if (this._tray_icon_shell_implementation[role]) {
            // This icon is legacy, and replaced by a Shell version
            // Hide it
            return;
        }
        // Figure out the index in our well-known order for this icon
        let position = this._tray_icon_order.indexOf(role);
        icon._rolePosition = position;
        let children = this._trayBox.get_children();
        let i;
        // Walk children backwards, until we find one that isn't
        // well-known, or one where we should follow
        for (i = children.length - 1; i >= 0; i--) {
            let rolePosition = children[i]._rolePosition;
            if (!rolePosition || position > rolePosition) {
                this._trayBox.insert_actor(icon, i + 1);
                break;
            }
        }
        if (i == -1) {
            // If we didn't find a position, we must be first
            this._trayBox.insert_actor(icon, 0);
        }

        // Make sure the trayBox is shown.
        this._trayBox.show();
    },

    _onTrayIconRemoved: function(o, icon) {
        if (icon.get_parent() != null)
            this._trayBox.remove_actor(icon);
    },

};