/*
 * Copyright 2019 Abakkk
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * SPDX-FileCopyrightText: 2019 Abakkk
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

/* jslint esversion: 6 */
/* exported Tool, DrawingArea */

const Cairo = imports.cairo;
const Clutter = imports.gi.Clutter;
const Gio = imports.gi.Gio;
const GLib = imports.gi.GLib;
const GObject = imports.gi.GObject;
const Gtk = imports.gi.Gtk;
const Lang = imports.lang;
const Pango = imports.gi.Pango;
const Shell = imports.gi.Shell;
const St = imports.gi.St;
const System = imports.system;

const ExtensionUtils = imports.misc.extensionUtils;
const Main = imports.ui.main;
const Screenshot = imports.ui.screenshot;

const Me = ExtensionUtils.getCurrentExtension();
const Convenience = ExtensionUtils.getSettings ? ExtensionUtils : Me.imports.convenience;
const Elements = Me.imports.elements;
const Files = Me.imports.files;
const Menu = Me.imports.menu;
const _ = imports.gettext.domain(Me.metadata['gettext-domain']).gettext;
const pgettext = imports.gettext.domain(Me.metadata['gettext-domain']).pgettext;

const MOTION_TIME = 1; // ms, time accuracy for free drawing, max is about 33 ms. The lower it is, the smoother the drawing is.
const TEXT_CURSOR_TIME = 600; // ms
const ELEMENT_GRABBER_TIME = 80; // ms, default is about 16 ms
const TOGGLE_ANIMATION_DURATION = 300; // ms
const GRID_TILES_HORIZONTAL_NUMBER = 30;
const COLOR_PICKER_EXTENSION_UUID = 'color-picker@tuberry'; 
const UUID = Me.uuid.replace(/@/gi, '_at_').replace(/[^a-z0-9+_-]/gi, '_');

const { Shape, TextAlignment, Transformation } = Elements;
const { DisplayStrings } = Menu;

const FontGenericFamilies = ['Sans-Serif', 'Serif', 'Monospace', 'Cursive', 'Fantasy'];
const Manipulation = { MOVE: 100, RESIZE: 101, MIRROR: 102 };
var Tool = Object.assign({
    getNameOf: function(value) {
        return Object.keys(this).find(key => this[key] == value);
    }
}, Shape, Manipulation);
Object.defineProperty(Tool, 'getNameOf', { enumerable: false });

// toJSON provides a string suitable for SVG color attribute whereas
// toString provides a string suitable for displaying the color name to the user.
const getColorFromString = function(string, fallback) {
    let [colorString, displayName] = string.split(':');
    let [success, color] = Clutter.Color.from_string(colorString);
    color.toJSON = () => colorString;
    color.toString = () => displayName || colorString;
    if (success)
        return color;
    
    log(`${Me.metadata.uuid}: "${string}" color cannot be parsed.`);
    color = Clutter.Color.get_static(Clutter.StaticColor[fallback.toUpperCase()]);
    color.toJSON = () => fallback;
    color.toString = () => fallback;
    return color;
};

// Drawing layers are the proper drawing area widgets (painted thanks to Cairo).
const DrawingLayer = new Lang.Class({
    Name: `${UUID}-DrawingLayer`,
    Extends: St.DrawingArea,

    _init: function(repaintFunction, getHasImageFunction) {
        this._repaint = repaintFunction;
        this._getHasImage = getHasImageFunction || (() => false);
        this.parent();
    },
    
    // Bind the size of layers and layer container.
    vfunc_parent_set: function() {
        this.clear_constraints();
        
        if (this.get_parent())
            this.add_constraint(new Clutter.BindConstraint({ coordinate: Clutter.BindCoordinate.SIZE, source: this.get_parent() }));
    },
    
    vfunc_repaint: function() {
        let cr = this.get_context();
        
        try {
            this._repaint(cr);
        } catch(e) {
            logError(e, "An error occured while painting");
        }
        
        cr.$dispose();
        if (this._getHasImage())
            System.gc();
    }
});

// Darwing area is a container that manages drawing elements and drawing layers.
// There is a drawing element for each "brushstroke".
// There is a separated layer for the current element so only the current element is redisplayed when drawing.
// It handles pointer/mouse/(touch?) events and some keyboard events.
var DrawingArea = new Lang.Class({
    Name: `${UUID}-DrawingArea`,
    Extends: St.Widget,
    Signals: { 'show-osd': { param_types: [Gio.Icon.$gtype, GObject.TYPE_STRING, GObject.TYPE_STRING, GObject.TYPE_DOUBLE, GObject.TYPE_BOOLEAN] },
               'pointer-cursor-changed': { param_types: [GObject.TYPE_STRING] },
               'update-action-mode': {},
               'leave-drawing-mode': {} },

    _init: function(params, monitor, helper, areaManagerUtils, loadPersistent) {
        this.parent({ style_class: 'draw-on-your-screen', name: params.name});
        this.monitor = monitor;
        this.helper = helper;
        this.areaManagerUtils = areaManagerUtils;
        
        this.layerContainer = new St.Widget({ width: monitor.width, height: monitor.height });
        this.add_child(this.layerContainer);
        this.add_child(this.helper);
        
        this.backLayer = new DrawingLayer(this._repaintBack.bind(this), this._getHasImageBack.bind(this));
        this.layerContainer.add_child(this.backLayer);
        this.foreLayer = new DrawingLayer(this._repaintFore.bind(this), this._getHasImageFore.bind(this));
        this.layerContainer.add_child(this.foreLayer);
        this.gridLayer = new DrawingLayer(this._repaintGrid.bind(this));
        this.gridLayer.hide();
        this.gridLayer.opacity = 0;
        this.layerContainer.add_child(this.gridLayer);
        
        this.elements = [];
        this.undoneElements = [];
        this.currentElement = null;
        this.currentTool = Shape.NONE;
        this.currentImage = null;
        this.currentTextAlignment = Clutter.get_default_text_direction() == Clutter.TextDirection.RTL ? TextAlignment.RIGHT : TextAlignment.LEFT;
        let fontName = St.Settings && St.Settings.get().font_name || Convenience.getSettings('org.gnome.desktop.interface').get_string('font-name');
        this.currentFont = Pango.FontDescription.from_string(fontName);
        this.currentFont.unset_fields(Pango.FontMask.SIZE);
        this.defaultFontFamily = this.currentFont.get_family();
        this.currentLineWidth = 5;
        this.currentLineJoin = Cairo.LineJoin.ROUND;
        this.currentLineCap = Cairo.LineCap.ROUND;
        this.currentFillRule = Cairo.FillRule.WINDING;
        this.isSquareArea = false;
        this.hasBackground = false;
        this.textHasCursor = false;
        this.dashedLine = false;
        this.fill = false;
        
        this.connect('destroy', this._onDestroy.bind(this));
        this.connect('notify::reactive', this._onReactiveChanged.bind(this));
        this.drawingSettingsChangedHandler = Me.drawingSettings.connect('changed', this._onDrawingSettingsChanged.bind(this));
        this._onDrawingSettingsChanged();
        
        if (loadPersistent)
            this._loadPersistent();
    },
    
    get menu() {
        if (!this._menu)
            this._menu = new Menu.DrawingMenu(this, this.monitor, Tool, this.areaManagerUtils);
        return this._menu;
    },
    
    closeMenu: function() {
        if (this._menu)
            this._menu.close();
    },
    
    get isWriting() {
        return this.textEntry ? true : false;
    },
    
    get currentTool() {
        return this._currentTool;
    },
    
    set currentTool(tool) {
        this._currentTool = tool;
        if (this.hasManipulationTool)
            this._startElementGrabber();
        else
            this._stopElementGrabber();
    },
    
    get currentPalette() {
        return this._currentPalette;
    },
    
    set currentPalette(palette) {
        this._currentPalette = palette;
        this.colors = palette[1].map(colorString => getColorFromString(colorString, 'White'));
        if (!this.colors[0])
            this.colors.push(Clutter.Color.get_static(Clutter.StaticColor.WHITE));
    },
    
    get currentImage() {
        if (!this._currentImage)
            this._currentImage = Files.Images.getNext(this._currentImage);
        
        return this._currentImage;
    },
    
    set currentImage(image) {
        this._currentImage = image;
    },
    
    get currentFontFamily() {
        return this.currentFont.get_family();
    },
    
    set currentFontFamily(family) {
        this.currentFont.set_family(family);
    },
    
    get currentFontStyle() {
        return this.currentFont.get_style();
    },
    
    set currentFontStyle(style) {
        this.currentFont.set_style(style);
    },
    
    get currentFontWeight() {
        return this.currentFont.get_weight();
    },
    
    set currentFontWeight(weight) {
        this.currentFont.set_weight(weight);
    },
    
    get hasManipulationTool() {
        // No Object.values method in GS 3.24.
        return Object.keys(Manipulation).map(key => Manipulation[key]).indexOf(this.currentTool) != -1;
    },
    
    // Boolean wrapper for switch menu item.
    get currentEvenodd() {
        return this.currentFillRule == Cairo.FillRule.EVEN_ODD;
    },
    
    set currentEvenodd(evenodd) {
        this.currentFillRule = evenodd ? Cairo.FillRule.EVEN_ODD : Cairo.FillRule.WINDING;
    },
    
    get fontFamilies() {
        if (!this._fontFamilies) {
            let otherFontFamilies = Elements.getAllFontFamilies().filter(family => {
                return family != this.defaultFontFamily && FontGenericFamilies.indexOf(family) == -1;
            });
            this._fontFamilies = [this.defaultFontFamily].concat(FontGenericFamilies, otherFontFamilies);
        }
        return this._fontFamilies;
    },
    
    _onDrawingSettingsChanged: function() {
        this.palettes = Me.drawingSettings.get_value('palettes').deep_unpack();
        if (!this.colors) {
            if (this.palettes[0])
                this.currentPalette = this.palettes[0];
            else
                this.currentPalette = ['Palette', ['White']];
        }
        if (!this.currentColor)
            this.currentColor = this.colors[0];
        
        if (Me.drawingSettings.get_boolean('square-area-auto')) {
            this.squareAreaSize = Math.pow(2, 6);
            while (this.squareAreaSize * 2 < Math.min(this.monitor.width, this.monitor.height))
                this.squareAreaSize *= 2;
        } else {
            this.squareAreaSize = Me.drawingSettings.get_uint('square-area-size');
        }
        
        this.areaBackgroundColor = getColorFromString(Me.drawingSettings.get_string('background-color'), 'Black');
        
        this.gridColor = getColorFromString(Me.drawingSettings.get_string('grid-color'), 'Gray');
        if (Me.drawingSettings.get_boolean('grid-line-auto')) {
            this.gridLineSpacing = Math.round(this.monitor.width / (5 * GRID_TILES_HORIZONTAL_NUMBER));
            this.gridLineWidth = this.gridLineSpacing / 20;
        } else {
            this.gridLineSpacing = Me.drawingSettings.get_uint('grid-line-spacing');
            this.gridLineWidth = Math.round(Me.drawingSettings.get_double('grid-line-width') * 100) / 100;
        }
        
        this.dashOffset = Math.round(Me.drawingSettings.get_double('dash-offset') * 100) / 100;
        if (Me.drawingSettings.get_boolean('dash-array-auto')) {
            this.dashArray = [0, 0];
        } else {
            let on = Math.round(Me.drawingSettings.get_double('dash-array-on') * 100) / 100;
            let off = Math.round(Me.drawingSettings.get_double('dash-array-off') * 100) / 100;
            this.dashArray = [on, off];
        }
    },
    
    _repaintBack: function(cr) {
        for (let i = 0; i < this.elements.length; i++) {
            cr.save();
            
            this.elements[i].buildCairo(cr, { showElementBounds: this.grabbedElement && this.grabbedElement == this.elements[i],
                                              drawElementBounds: this.grabPoint ? true : false });
            
            if (this.grabPoint)
                this._searchElementToGrab(cr, this.elements[i]);
            
            if (this.elements[i].fill && !this.elements[i].isStraightLine) {
                cr.fillPreserve();
                if (this.elements[i].shape == Shape.NONE || this.elements[i].shape == Shape.LINE)
                    cr.closePath();
            } 
            
            cr.stroke();
            this.elements[i]._addMarks(cr);
            cr.restore();
        }
        
        if (this.currentElement && this.currentElement.eraser) {
            this.currentElement.buildCairo(cr, { showTextCursor: this.textHasCursor,
                                                 showElementBounds: this.currentElement.shape != Shape.TEXT || !this.isWriting,
                                                 dummyStroke: this.currentElement.fill && this.currentElement.line.lineWidth == 0 });
            cr.stroke();
        }
    },
    
    _repaintFore: function(cr) {
        if (!this.currentElement || this.currentElement.eraser)
            return;
        
        this.currentElement.buildCairo(cr, { showTextCursor: this.textHasCursor,
                                             showElementBounds: this.currentElement.shape != Shape.TEXT || !this.isWriting,
                                             dummyStroke: this.currentElement.fill && this.currentElement.line.lineWidth == 0 });
        cr.stroke();
    },
    
    _repaintGrid: function(cr) {
        if (!this.reactive)
            return;
        
        Clutter.cairo_set_source_color(cr, this.gridColor);
        
        let [gridX, gridY] = [0, 0];
        while (gridX < this.monitor.width / 2) {
            cr.setLineWidth((gridX / this.gridLineSpacing) % 5 ? this.gridLineWidth / 2 : this.gridLineWidth);
            cr.moveTo(this.monitor.width / 2 + gridX, 0);
            cr.lineTo(this.monitor.width / 2 + gridX, this.monitor.height);
            cr.moveTo(this.monitor.width / 2 - gridX, 0);
            cr.lineTo(this.monitor.width / 2 - gridX, this.monitor.height);
            gridX += this.gridLineSpacing;
            cr.stroke();
        }
        while (gridY < this.monitor.height / 2) {
            cr.setLineWidth((gridY / this.gridLineSpacing) % 5 ? this.gridLineWidth / 2 : this.gridLineWidth);
            cr.moveTo(0, this.monitor.height / 2 + gridY);
            cr.lineTo(this.monitor.width, this.monitor.height / 2 + gridY);
            cr.moveTo(0, this.monitor.height / 2 - gridY);
            cr.lineTo(this.monitor.width, this.monitor.height / 2 - gridY);
            gridY += this.gridLineSpacing;
            cr.stroke();
        }
    },
    
    _getHasImageBack: function() {
        return this.elements.some(element => element.shape == Shape.IMAGE);
    },
    
    _getHasImageFore: function() {
        return this.currentElement && this.currentElement.shape == Shape.IMAGE || false;
    },
    
    _redisplay: function() {
        // force area to emit 'repaint'
        this.backLayer.queue_repaint();
        this.foreLayer.queue_repaint();
        if (this.hasGrid)
            this.gridLayer.queue_repaint();
    },
    
    _transformStagePoint: function(stageX, stageY) {
        let [s, x, y] = this.transform_stage_point(stageX, stageY);
        if (!s || !this.layerContainer.get_allocation_box().contains(x, y))
            return [false, 0, 0];
        
        return this.layerContainer.transform_stage_point(stageX, stageY);
    },
    
    _onButtonPressed: function(actor, event) {
        if (this.spaceKeyPressed)
            return Clutter.EVENT_PROPAGATE;
        
        let button = event.get_button();
        let [x, y] = event.get_coords();
        let controlPressed = event.has_control_modifier();
        let shiftPressed = event.has_shift_modifier();
        
        if (this.currentElement && this.currentElement.shape == Shape.TEXT && this.isWriting)
            // finish writing
            this._stopWriting();
        
        if (this.helper.visible) {
            // hide helper
            this.toggleHelp();
            return Clutter.EVENT_STOP;
        }
        
        if (button == 1) {
            if (this.hasManipulationTool) {
                if (this.grabbedElement)
                    this._startTransforming(x, y, controlPressed, shiftPressed);
            } else {
                this._startDrawing(x, y, shiftPressed);
            }
            return Clutter.EVENT_STOP;
        } else if (button == 2) {
            this.switchFill();
        } else if (button == 3) {
            this._stopAll();
            
            this.menu.open(x, y);
            return Clutter.EVENT_STOP;
        }

        return Clutter.EVENT_PROPAGATE;
    },
    
    _onKeyboardPopupMenu: function() {
        this._stopAll();
        
        if (this.helper.visible)
            this.toggleHelp();
        this.menu.popup();
        return Clutter.EVENT_STOP;
    },
    
    _onStageKeyPressed: function(actor, event) {
        if (event.get_key_symbol() == Clutter.KEY_Escape) {
            if (this.helper.visible)
                this.toggleHelp();
            else
                this.emit('leave-drawing-mode');
        } else if (event.get_key_symbol() == Clutter.KEY_space) {
            this.spaceKeyPressed = true;
        }
        
        return Clutter.EVENT_PROPAGATE;
    },
    
    _onStageKeyReleased: function(actor, event) {
        if (event.get_key_symbol() == Clutter.KEY_space)
            this.spaceKeyPressed = false;
        
        return Clutter.EVENT_PROPAGATE;
    },
    
    _onKeyPressed: function(actor, event) {
        if (this.currentElement && this.currentElement.shape == Shape.LINE &&
            (event.get_key_symbol() == Clutter.KEY_Return ||
             event.get_key_symbol() == Clutter.KEY_KP_Enter ||
             event.get_key_symbol() == Clutter.KEY_Control_L)) {
            
            if (this.currentElement.points.length == 2)
                // Translators: %s is a key label
                this.emit('show-osd', Files.Icons.ARC, _("Press <i>%s</i> to get\na fourth control point")
                                                       .format(Gtk.accelerator_get_label(Clutter.KEY_Return, 0)), "", -1, true);
            this.currentElement.addPoint();
            this.updatePointerCursor(true);
            this._redisplay();
            return Clutter.EVENT_STOP;
        } else if (this.currentElement &&
                   (this.currentElement.shape == Shape.POLYGON || this.currentElement.shape == Shape.POLYLINE) &&
                   (event.get_key_symbol() == Clutter.KEY_Return || event.get_key_symbol() == Clutter.KEY_KP_Enter)) {
            
            this.currentElement.addPoint();
            return Clutter.EVENT_STOP;
        }
        
        return Clutter.EVENT_PROPAGATE;
    },
    
    _onScroll: function(actor, event) {
        if (this.helper.visible)
            return Clutter.EVENT_PROPAGATE;
        let direction = event.get_scroll_direction();
        if (direction == Clutter.ScrollDirection.UP)
             this.incrementLineWidth(1);
        else if (direction == Clutter.ScrollDirection.DOWN)
            this.incrementLineWidth(-1);
        else
            return Clutter.EVENT_PROPAGATE;
        return Clutter.EVENT_STOP;
    },
    
    _searchElementToGrab: function(cr, element) {
        if (element.getContainsPoint(cr, this.grabPoint[0], this.grabPoint[1]))
            this.grabbedElement = element;
        else if (this.grabbedElement == element)
            this.grabbedElement = null;
        
        if (element == this.elements[this.elements.length - 1])
            // All elements have been tested, the winner is the last.
            this.updatePointerCursor();
    },
    
    _startElementGrabber: function() {
        if (this.elementGrabberHandler)
            return;
        
        this.elementGrabberHandler = this.connect('motion-event', (actor, event) => {
            if (this.motionHandler || this.grabbedElementLocked) {
                this.grabPoint = null;
                return;
            }
            
            // Reduce computing without notable effect.
            if (event.get_time() - (this.elementGrabberTimestamp || 0) < ELEMENT_GRABBER_TIME)
                return;
            this.elementGrabberTimestamp = event.get_time();
            
            let coords = event.get_coords();
            let [s, x, y] = this._transformStagePoint(coords[0], coords[1]);
            if (!s)
                return;
            
            this.grabPoint = [x, y];
            this.grabbedElement = null;
            // this._redisplay calls this._searchElementToGrab.
            this._redisplay();
        });
    },
    
    _stopElementGrabber: function() {
        if (this.elementGrabberHandler) {
            this.disconnect(this.elementGrabberHandler);
            this.grabPoint = null;
            this.elementGrabberHandler = null;
        }
    },
    
    _startTransforming: function(stageX, stageY, controlPressed, duplicate) {
        let [success, startX, startY] = this._transformStagePoint(stageX, stageY);
        
        if (!success)
            return;
        
        if (this.currentTool == Manipulation.MIRROR) {
            this.grabbedElementLocked = !this.grabbedElementLocked;
            if (this.grabbedElementLocked) {
                this.updatePointerCursor();
                let label = controlPressed ? _("Mark a point of symmetry") : _("Draw a line of symmetry");
                this.emit('show-osd', Files.Icons.TOOL_MIRROR, label, "", -1, true);
                return;
            }
        }
        
        this.grabPoint = null;
        
        this.buttonReleasedHandler = this.connect('button-release-event', (actor, event) => {
            this._stopTransforming();
        });
        
        if (duplicate) {
            // deep cloning
            let copy = new this.grabbedElement.constructor(JSON.parse(JSON.stringify(this.grabbedElement)));
            if (this.grabbedElement.color)
                copy.color = this.grabbedElement.color;
            if (this.grabbedElement.font)
                copy.font = this.grabbedElement.font;
            if (this.grabbedElement.image)
                copy.image = this.grabbedElement.image;
            this.elements.push(copy);
            this.grabbedElement = copy;
        }
        
        let undoable = !duplicate;
        
        if (this.currentTool == Manipulation.MOVE)
            this.grabbedElement.startTransformation(startX, startY, controlPressed ? Transformation.ROTATION : Transformation.TRANSLATION, undoable);
        else if (this.currentTool == Manipulation.RESIZE)
            this.grabbedElement.startTransformation(startX, startY, controlPressed ? Transformation.STRETCH : Transformation.SCALE_PRESERVE, undoable);
         else if (this.currentTool == Manipulation.MIRROR) {
            this.grabbedElement.startTransformation(startX, startY, controlPressed ? Transformation.INVERSION : Transformation.REFLECTION, undoable);
            this._redisplay();
        }
        
        this.motionHandler = this.connect('motion-event', (actor, event) => {
            if (this.spaceKeyPressed)
                return;
            
            let coords = event.get_coords();
            let [s, x, y] = this._transformStagePoint(coords[0], coords[1]);
            if (!s)
                return;
            let controlPressed = event.has_control_modifier();
            this._updateTransforming(x, y, controlPressed);
        });
    },
    
    _updateTransforming: function(x, y, controlPressed) {
        let undoable = this.grabbedElement.lastTransformation.undoable || false;
        
        if (controlPressed && this.grabbedElement.lastTransformation.type == Transformation.TRANSLATION) {
            this.grabbedElement.stopTransformation();
            this.grabbedElement.startTransformation(x, y, Transformation.ROTATION, undoable);
        } else if (!controlPressed && this.grabbedElement.lastTransformation.type == Transformation.ROTATION) {
            this.grabbedElement.stopTransformation();
            this.grabbedElement.startTransformation(x, y, Transformation.TRANSLATION, undoable);
        }
        
        if (controlPressed && this.grabbedElement.lastTransformation.type == Transformation.SCALE_PRESERVE) {
            this.grabbedElement.stopTransformation();
            this.grabbedElement.startTransformation(x, y, Transformation.STRETCH, undoable);
        } else if (!controlPressed && this.grabbedElement.lastTransformation.type == Transformation.STRETCH) {
            this.grabbedElement.stopTransformation();
            this.grabbedElement.startTransformation(x, y, Transformation.SCALE_PRESERVE, undoable);
        }
        
        if (controlPressed && this.grabbedElement.lastTransformation.type == Transformation.REFLECTION) {
            this.grabbedElement.transformations.pop();
            this.grabbedElement.startTransformation(x, y, Transformation.INVERSION, undoable);
        } else if (!controlPressed && this.grabbedElement.lastTransformation.type == Transformation.INVERSION) {
            this.grabbedElement.transformations.pop();
            this.grabbedElement.startTransformation(x, y, Transformation.REFLECTION, undoable);
        }
        
        this.grabbedElement.updateTransformation(x, y);
        this._redisplay();
    },
    
    _stopTransforming: function() {
        if (this.motionHandler) {
            this.disconnect(this.motionHandler);
            this.motionHandler = null;
        }
        if (this.buttonReleasedHandler) {
            this.disconnect(this.buttonReleasedHandler);
            this.buttonReleasedHandler = null;
        }
        
        this.grabbedElement.stopTransformation();
        this.grabbedElement = null;
        this.grabbedElementLocked = false;
        this._redisplay();
    },
    
    _startDrawing: function(stageX, stageY, shiftPressed) {
        let [success, startX, startY] = this._transformStagePoint(stageX, stageY);
        if (!success)
            return;
        
        this.buttonReleasedHandler = this.connect('button-release-event', (actor, event) => {
            this._stopDrawing();
        });
        
        if (this.currentTool == Shape.TEXT) {
            this.currentElement = new Elements.DrawingElement({
                shape: this.currentTool,
                color: this.currentColor,
                eraser: shiftPressed,
                font: this.currentFont.copy(),
                // Translators: initial content of the text area
                text: pgettext("text-area-content", "Text"),
                textAlignment: this.currentTextAlignment,
                points: []
            });
        } else if (this.currentTool == Shape.IMAGE) {
            this.currentElement = new Elements.DrawingElement({
                shape: this.currentTool,
                color: this.currentColor,
                colored: shiftPressed,
                image: this.currentImage,
                points: []
            });
        } else {
            this.currentElement = new Elements.DrawingElement({
                shape: this.currentTool,
                color: this.currentColor,
                eraser: shiftPressed,
                fill: this.fill,
                fillRule: this.currentFillRule,
                line: { lineWidth: this.currentLineWidth, lineJoin: this.currentLineJoin, lineCap: this.currentLineCap },
                dash: { active: this.dashedLine, array: this.dashedLine ? [this.dashArray[0] || this.currentLineWidth, this.dashArray[1] || this.currentLineWidth * 3] : [0, 0] , offset: this.dashOffset },
                points: []
            });
        }
        
        this.currentElement.startDrawing(startX, startY);
        
        if (this.currentTool == Shape.POLYGON || this.currentTool == Shape.POLYLINE) {
            let icon = Files.Icons[this.currentTool == Shape.POLYGON ? 'TOOL_POLYGON' : 'TOOL_POLYLINE'];
            // Translators: %s is a key label
            this.emit('show-osd', icon, _("Press <i>%s</i> to mark vertices")
                                        .format(Gtk.accelerator_get_label(Clutter.KEY_Return, 0)), "", -1, true);
        }
        
        this.motionHandler = this.connect('motion-event', (actor, event) => {
            if (this.motionTimeout) {
                GLib.source_remove(this.motionTimeout);
                this.motionTimeout = null;
            }
            
            if (this.spaceKeyPressed)
                return;
            
            let coords = event.get_coords();
            let [s, x, y] = this._transformStagePoint(coords[0], coords[1]);
            if (!s)
                return;
            
            let controlPressed = event.has_control_modifier();
            this._updateDrawing(x, y, controlPressed);
            
            if (this.currentTool == Shape.NONE) {
                let device = event.get_device();
                let sequence = event.get_event_sequence();
                
                // Minimum time between two motion events is about 33 ms.
                // Add intermediate points to make quick free drawings smoother.
                this.motionTimeout = GLib.timeout_add(GLib.PRIORITY_DEFAULT, MOTION_TIME, () => {
                    let success, coords;
                    if (device.get_coords) {
                        [success, coords] = device.get_coords(sequence);
                        if (!success)
                            return GLib.SOURCE_CONTINUE;
                    } else {
                        // GS 40+, device.get_coords() has been removed
                        // and seat.query_state() is unusable with null sequences.
                        let pointer = global.get_pointer();
                        coords = { x: pointer[0], y: pointer[1] };
                    }
                    
                    let [s, x, y] = this._transformStagePoint(coords.x, coords.y);
                    if (!s)
                        return GLib.SOURCE_CONTINUE;
                    
                    // Important: do not call this._updateDrawing because the area MUST NOT BE REDISPLAYED at this step.
                    // It would lead to critical issues (bad performances and shell crashes).
                    // The area will be redisplayed, including the intermediate points, at the next motion event.
                    this.currentElement.addIntermediatePoint(x, y, controlPressed);
                    
                    return GLib.SOURCE_CONTINUE;
                });
            }
        });
    },
    
    _updateDrawing: function(x, y, controlPressed) {
        if (!this.currentElement)
            return;
        
        this.currentElement.updateDrawing(x, y, controlPressed);
        
        if (this.currentElement.eraser)
            this._redisplay();
        else
            this.foreLayer.queue_repaint();
        this.updatePointerCursor(controlPressed);
    },
    
    _stopDrawing: function() {
        if (this.motionTimeout) {
            GLib.source_remove(this.motionTimeout);
            this.motionTimeout = null;
        }
        if (this.motionHandler) {
            this.disconnect(this.motionHandler);
            this.motionHandler = null;
        }
        if (this.buttonReleasedHandler) {
            this.disconnect(this.buttonReleasedHandler);
            this.buttonReleasedHandler = null;
        }
        
        // skip when a polygon has not at least 3 points
        if (this.currentElement && this.currentElement.shape == Shape.POLYGON && this.currentElement.points.length < 3)
            this.currentElement = null;
        
        if (this.currentElement)
            this.currentElement.stopDrawing();
        
        if (this.currentElement && this.currentElement.points.length >= 2) {
            if (this.currentElement.shape == Shape.TEXT && !this.isWriting) {
                this._startWriting();
                return;
            }
        
            this.elements.push(this.currentElement);
        }
        
        this.currentElement = null;
        this._redisplay();
        this.updatePointerCursor();
    },
    
    _startWriting: function() {
        let [stageX, stageY] = this.get_transformed_position();
        let [x, y] = [this.currentElement.x, this.currentElement.y];
        this.currentElement.text = '';
        this.currentElement.cursorPosition = 0;
        // Translators: %s is a key label
        this.emit('show-osd', Files.Icons.TOOL_TEXT, _("Press <i>%s</i>\nto start a new line")
                                                     .format(Gtk.accelerator_get_label(Clutter.KEY_Return, 0)), "", -1, true);
        this._updateTextCursorTimeout();
        this.textHasCursor = true;
        this._redisplay();
        
        // Do not hide and do not set opacity to 0 because:
        // 1. ibusCandidatePopup need a mapped text entry to init correctly its position.
        // 2. 'cursor-changed' signal is no emitted if the text entry is not visible.
        this.textEntry = new St.Entry({ opacity: 1, x: stageX + x, y: stageY + y });
        this.insert_child_below(this.textEntry, null);
        this.textEntry.grab_key_focus();
        this.updateActionMode();
        this.updatePointerCursor();
        
        let ibusCandidatePopup = Main.layoutManager.uiGroup.get_children().find(child =>
            child.has_style_class_name && child.has_style_class_name('candidate-popup-boxpointer'));
        if (ibusCandidatePopup) {
            this.ibusHandler = ibusCandidatePopup.connect('notify::visible', () => {
                if (ibusCandidatePopup.visible) {
                    this.set_child_above_sibling(this.textEntry, null);
                    this.textEntry.opacity = 255;
                }
            });
            this.textEntry.connect('destroy', () => ibusCandidatePopup.disconnect(this.ibusHandler));
        }
        
        this.textEntry.clutterText.set_single_line_mode(false);
        this.textEntry.clutterText.set_activatable(false);
        
        let showCursorOnPositionChanged = true;
        this.textEntry.clutterText.connect('text-changed', clutterText => {
            this.textEntry.y = stageY + y + (this.textEntry.clutterText.get_layout().get_line_count() - 1) * this.currentElement.height;
            this.currentElement.text = clutterText.text;
            showCursorOnPositionChanged = false;
            this._redisplay();
        });
        
        this.textEntry.clutterText.connect('cursor-changed', clutterText => {
            this.currentElement.cursorPosition = clutterText.cursorPosition;
            this._updateTextCursorTimeout();
            let cursorPosition = clutterText.cursorPosition == -1 ? clutterText.text.length : clutterText.cursorPosition;
            this.textHasCursor = showCursorOnPositionChanged || GLib.unichar_isspace(clutterText.text.charAt(cursorPosition - 1));
            showCursorOnPositionChanged = true;
            this._redisplay();
        });
        
        this.textEntry.clutterText.connect('key-press-event', (clutterText, event) => {
            if (event.get_key_symbol() == Clutter.KEY_Escape) {
                this._stopWriting();
                return Clutter.EVENT_STOP;
            }
            
            return Clutter.EVENT_PROPAGATE;
        });
    },
    
    _stopWriting: function() {
        if (this.currentElement.text.length > 0)
            this.elements.push(this.currentElement);
            
        this.currentElement = null;
        this._stopTextCursorTimeout();
        this.textEntry.destroy();
        delete this.textEntry;
        this.grab_key_focus();
        this.updateActionMode();
        this.updatePointerCursor();
        
        this._redisplay();
    },
    
    setPointerCursor: function(pointerCursorName) {
        if (!this.currentPointerCursorName || this.currentPointerCursorName != pointerCursorName) {
            this.currentPointerCursorName = pointerCursorName;
            this.emit('pointer-cursor-changed', pointerCursorName);
        }
    },
    
    updatePointerCursor: function(controlPressed) {
        if (this.currentTool == Manipulation.MIRROR && this.grabbedElementLocked)
            this.setPointerCursor('CROSSHAIR');
        else if (this.hasManipulationTool)
            this.setPointerCursor(this.grabbedElement ? 'MOVE_OR_RESIZE_WINDOW' : 'DEFAULT');
        else if (this.currentElement && this.currentElement.shape == Shape.TEXT && this.isWriting)
            this.setPointerCursor('IBEAM');
        else if (!this.currentElement)
            this.setPointerCursor(this.currentTool == Shape.NONE ? 'POINTING_HAND' : 'CROSSHAIR');
        else if (this.currentElement.shape != Shape.NONE && controlPressed)
            this.setPointerCursor('MOVE_OR_RESIZE_WINDOW');
    },
    
    initPointerCursor: function() {
        this.currentPointerCursorName = null;
        this.updatePointerCursor();
    },
    
    _stopTextCursorTimeout: function() {
        if (this.textCursorTimeoutId) {
            GLib.source_remove(this.textCursorTimeoutId);
            this.textCursorTimeoutId = null;
        }
        this.textHasCursor = false;
    },
    
    _updateTextCursorTimeout: function() {
        this._stopTextCursorTimeout();
        this.textCursorTimeoutId = GLib.timeout_add(GLib.PRIORITY_DEFAULT, TEXT_CURSOR_TIME, () => {
            this.textHasCursor = !this.textHasCursor;
            this._redisplay();
            return GLib.SOURCE_CONTINUE;
        });
    },
    
    // A priori there is nothing to stop, except transformations, if there is no current element.
    // 'force' argument is passed when leaving drawing mode to ensure all is clean, as a workaround for possible bugs.
    _stopAll: function(force) {
        if (this.grabbedElement) {
            this._stopTransforming();
            this.grabbedElement = null;
            this.grabbedElementLocked = null;
            this.updatePointerCursor();
        }
            
        if (!this.currentElement && !force)
            return;
        
        if (this.isWriting)
            this._stopWriting();
        
        this._stopDrawing();
    },
    
    erase: function() {
        this.deleteLastElement();
        this.elements = [];
        this.undoneElements = [];
        this._redisplay();
    },
    
    deleteLastElement: function() {
        this._stopAll();
        this.elements.pop();
        
        if (this.elements.length)
            this.elements[this.elements.length - 1].resetUndoneTransformations();
        
        this._redisplay();
    },
    
    undo: function() {
        if (!this.elements.length)
            return;
        
        let success = this.elements[this.elements.length - 1].undoTransformation();
        if (!success) {
            this.undoneElements.push(this.elements.pop());
            if (this.elements.length)
                this.elements[this.elements.length - 1].resetUndoneTransformations();
        }
        
        this._redisplay();
    },
    
    redo: function() {
        let success = false;
        
        if (this.elements.length)
            success = this.elements[this.elements.length - 1].redoTransformation();
            
        if (!success && this.undoneElements.length > 0)
            this.elements.push(this.undoneElements.pop());
        
        this._redisplay();
    },
    
    smoothLastElement: function() {
        if (this.elements.length > 0 && this.elements[this.elements.length - 1].shape == Shape.NONE) {
            this.elements[this.elements.length - 1].smoothAll();
            this._redisplay();
        }
    },
    
    toggleBackground: function() {
        this.hasBackground = !this.hasBackground;
        let backgroundColor = this.hasBackground ? this.areaBackgroundColor : Clutter.Color.get_static(Clutter.StaticColor.TRANSPARENT);
        
        if (this.ease) {
            this.remove_all_transitions();
            this.ease({ backgroundColor,
                        duration: TOGGLE_ANIMATION_DURATION,
                        transition: Clutter.AnimationMode.EASE_IN_OUT_QUAD });
        } else {
            this.set_background_color(backgroundColor);
        }
    },
    
    get hasGrid() {
        return this.gridLayer.visible;
    },
    
    toggleGrid: function() {
        // The grid layer is repainted when the visibility changes.
        if (this.gridLayer.ease) {
            this.gridLayer.remove_all_transitions();
            let visible = !this.gridLayer.visible;
            this.gridLayer.visible = true;
            this.gridLayer.ease({ opacity: visible ? 255 : 0,
                                  duration: TOGGLE_ANIMATION_DURATION,
                                  transition: Clutter.AnimationMode.EASE_IN_OUT_QUAD,
                                  onStopped: () => this.gridLayer.visible = visible });
        } else {
            this.gridLayer.visible = !this.gridLayer.visible;
        }
    },
    
    toggleSquareArea: function() {
        this.isSquareArea = !this.isSquareArea;
        let x, y, width, height, onComplete;
        
        if (this.isSquareArea) {
            this.layerContainer.add_style_class_name('draw-on-your-screen-square-area');
            [x, y] = [(this.monitor.width - this.squareAreaSize) / 2, (this.monitor.height - this.squareAreaSize) / 2];
            width = height = this.squareAreaSize;
            onComplete = () => {};
        } else {
            x = y = 0;
            [width, height] = [this.monitor.width, this.monitor.height];
            onComplete = () => this.layerContainer.remove_style_class_name('draw-on-your-screen-square-area');
        }
        
        if (this.layerContainer.ease) {
            this.layerContainer.remove_all_transitions();
            this.layerContainer.ease({ x, y, width, height, onComplete,
                                       duration: TOGGLE_ANIMATION_DURATION,
                                       transition: Clutter.AnimationMode.EASE_OUT_QUAD });
        } else {
            this.layerContainer.set_position(x, y);
            this.layerContainer.set_size(width, height);
            onComplete();
        }
    },
    
    selectColor: function(index) {
        if (!this.colors[index])
            return;
        
        this.currentColor = this.colors[index];
        if (this.currentElement) {
            this.currentElement.color = this.currentColor;
            this._redisplay();
        }
        // Foreground color markup is not displayed since 3.36, use style instead but the transparency is lost.
        this.emit('show-osd', Files.Icons.COLOR, String(this.currentColor), this.currentColor.to_string().slice(0, 7), -1, false);
    },
    
    selectTool: function(tool) {
        this.currentTool = tool;
        this.emit('show-osd', Files.Icons[`TOOL_${Tool.getNameOf(tool)}`] || null, DisplayStrings.Tool[tool], "", -1, false);
        this.updatePointerCursor();
    },
    
    switchFill: function() {
        this.fill = !this.fill;
        let icon = Files.Icons[this.fill ? 'FILL' : 'STROKE'];
        this.emit('show-osd', icon, DisplayStrings.getFill(this.fill), "", -1, false);
    },
    
    switchFillRule: function() {
        this.currentFillRule = this.currentFillRule == 1 ? 0 : this.currentFillRule + 1;
        let icon = Files.Icons[this.currentEvenodd ? 'FILLRULE_EVENODD' : 'FILLRULE_NONZERO'];
        this.emit('show-osd', icon, DisplayStrings.FillRule[this.currentFillRule], "", -1, false);
    },
    
    switchColorPalette: function(reverse) {
        let index = this.palettes.indexOf(this.currentPalette);
        if (reverse)
            this.currentPalette = index <= 0 ? this.palettes[this.palettes.length - 1] : this.palettes[index - 1];
        else
            this.currentPalette = index == this.palettes.length - 1 ? this.palettes[0] : this.palettes[index + 1];
        this.emit('show-osd', Files.Icons.PALETTE, this.currentPalette[0], "", -1, false);
    },
    
    switchDash: function() {
        this.dashedLine = !this.dashedLine;
        let icon = Files.Icons[this.dashedLine ? 'DASHED_LINE' : 'FULL_LINE'];
        this.emit('show-osd', icon, DisplayStrings.getDashedLine(this.dashedLine), "", -1, false);
    },
    
    incrementLineWidth: function(increment) {
        this.currentLineWidth = Math.max(this.currentLineWidth + increment, 0);
        this.emit('show-osd', null, DisplayStrings.getPixels(this.currentLineWidth), "", 2 * this.currentLineWidth, false);
    },
    
    switchLineJoin: function() {
        this.currentLineJoin = this.currentLineJoin == 2 ? 0 : this.currentLineJoin + 1;
        this.emit('show-osd', Files.Icons.LINEJOIN, DisplayStrings.LineJoin[this.currentLineJoin], "", -1, false);
    },
    
    switchLineCap: function() {
        this.currentLineCap = this.currentLineCap == 2 ? 0 : this.currentLineCap + 1;
        this.emit('show-osd', Files.Icons.LINECAP, DisplayStrings.LineCap[this.currentLineCap], "", -1, false);
    },
    
    switchFontWeight: function() {
        let fontWeights = Object.keys(DisplayStrings.FontWeight).map(key => Number(key));
        let index = fontWeights.indexOf(this.currentFontWeight);
        this.currentFontWeight = index == fontWeights.length - 1 ? fontWeights[0] : fontWeights[index + 1];
        if (this.currentElement && this.currentElement.font) {
            this.currentElement.font.set_weight(this.currentFontWeight);
            this._redisplay();
        }
        this.emit('show-osd', Files.Icons.FONT_WEIGHT, `<span font_weight="${this.currentFontWeight}">` +
                                    `${DisplayStrings.FontWeight[this.currentFontWeight]}</span>`, "", -1, false);
    },
    
    switchFontStyle: function() {
        this.currentFontStyle = this.currentFontStyle == 2 ? 0 : this.currentFontStyle + 1;
        if (this.currentElement && this.currentElement.font) {
            this.currentElement.font.set_style(this.currentFontStyle);
            this._redisplay();
        }
        this.emit('show-osd', Files.Icons.FONT_STYLE, `<span font_style="${DisplayStrings.FontStyleMarkup[this.currentFontStyle]}">` + 
                                    `${DisplayStrings.FontStyle[this.currentFontStyle]}</span>`, "", -1, false);
    },
    
    switchFontFamily: function(reverse) {
        let index = Math.max(0, this.fontFamilies.indexOf(this.currentFontFamily));
        if (reverse)
            this.currentFontFamily = (index == 0) ? this.fontFamilies[this.fontFamilies.length - 1] : this.fontFamilies[index - 1];
        else
            this.currentFontFamily = (index == this.fontFamilies.length - 1) ? this.fontFamilies[0] : this.fontFamilies[index + 1];
        if (this.currentElement && this.currentElement.font) {
            this.currentElement.font.set_family(this.currentFontFamily);
            this._redisplay();
        }
        this.emit('show-osd', Files.Icons.FONT_FAMILY, `<span font_family="${this.currentFontFamily}">${DisplayStrings.getFontFamily(this.currentFontFamily)}</span>`, "", -1, false);
    },
    
    switchTextAlignment: function() {
        this.currentTextAlignment = this.currentTextAlignment == 2 ? 0 : this.currentTextAlignment + 1;
        if (this.currentElement && this.currentElement.textAlignment != this.currentTextAlignment) {
            this.currentElement.textAlignment = this.currentTextAlignment;
            this._redisplay();
        }
        let icon = Files.Icons[this.currentTextAlignment == TextAlignment.RIGHT ? 'RIGHT_ALIGNED' : this.currentTextAlignment == TextAlignment.CENTER ? 'CENTERED' : 'LEFT_ALIGNED'];
        this.emit('show-osd', icon, DisplayStrings.TextAlignment[this.currentTextAlignment], "", -1, false);
    },
    
    switchImageFile: function(reverse) {
        this.currentImage = Files.Images[reverse ? 'getPrevious' : 'getNext'](this.currentImage);
        if (this.currentImage)
            this.emit('show-osd', this.currentImage.gicon, this.currentImage.toString(), "", -1, false);
    },
    
    pasteImageFiles: function() {
        Files.Images.addImagesFromClipboard(lastImage => {
            this.currentImage = lastImage;
            this.currentTool = Shape.IMAGE;
            this.updatePointerCursor();
            this.emit('show-osd', this.currentImage.gicon, this.currentImage.toString(), "", -1, false);
        });
    },
    
    _onColorPicked: function(color) {
        if (color instanceof Clutter.Color)
            color = color.to_string().slice(0, -2);
        
        this.currentColor = getColorFromString(color);
        if (this.currentElement) {
            this.currentElement.color = this.currentColor;
            this._redisplay();
        }
        this.emit('show-osd', Files.Icons.COLOR, String(this.currentColor), this.currentColor.to_string().slice(0, 7), -1, false);
        this.initPointerCursor();
    },
    
    pickColor: function() {
        if (!Screenshot.PickPixel)
            // GS 3.28-
            return;
        
        // Translators: It is displayed in an OSD notification to ask the user to start picking, so it should use the imperative mood.
        this.emit('show-osd', Files.Icons.COLOR_PICKER, pgettext("osd-notification", "Pick a color"), "", -1, false);
        
        let extension = Main.extensionManager && Main.extensionManager.lookup(COLOR_PICKER_EXTENSION_UUID);
        if (extension && extension.state == ExtensionUtils.ExtensionState.ENABLED && extension.stateObj && extension.stateObj.pickAsync) {
            extension.stateObj.pickAsync().then(result => {
                if (typeof result == 'string')
                    this._onColorPicked(result);
                else
                    this.initPointerCursor();
            }).catch(e => {
                this.initPointerCursor();
            });
            
            return;
        }
        
        try {
            let screenshot = new Shell.Screenshot();
            let pickPixel = new Screenshot.PickPixel(screenshot);
            
            if (pickPixel.pickAsync) {
                pickPixel.pickAsync().then(result => {
                    if (result instanceof Clutter.Color) {
                        // GS 3.38+
                        this._onColorPicked(result);
                    } else {
                        // GS 3.36
                        let graphenePoint = result;
                        screenshot.pick_color(graphenePoint.x, graphenePoint.y, (o, res) => {
                            let [, color] = screenshot.pick_color_finish(res);
                            this._onColorPicked(color);
                        });
                    }
                }).catch(() => this.initPointerCursor());
            } else {
                // GS 3.34-
                pickPixel.show();
                pickPixel.connect('finished', (pickPixel, coords) => {
                    if (coords)
                        screenshot.pick_color(...coords, (o, res) => {
                            let [, color] = screenshot.pick_color_finish(res);
                            this._onColorPicked(color);
                        });
                    else
                        this.initPointerCursor();
                });
            }
        } catch(e) {
            log(`${Me.metadata.uuid}: color picker failed: ${e.message}`);
            this.initPointerCursor();
        }
    },
    
    toggleHelp: function() {
        if (this.helper.visible) {
            this.helper.hideHelp();
            if (this.textEntry)
                this.textEntry.grab_key_focus();
        } else {
            this.helper.showHelp();
            this.grab_key_focus();
        }
        
    },
    
    // The area is reactive when it is modal.
    _onReactiveChanged: function() {
        if (this.hasGrid)
            this._redisplay();
        if (this.helper.visible)
            this.toggleHelp();
        if (this.textEntry && this.reactive)
            this.textEntry.grab_key_focus();
        
        if (this.reactive) {
            this.stageKeyPressedHandler = global.stage.connect('key-press-event', this._onStageKeyPressed.bind(this));
            this.stageKeyReleasedHandler = global.stage.connect('key-release-event', this._onStageKeyReleased.bind(this));
        } else {
            if (this.stageKeyPressedHandler) {
                global.stage.disconnect(this.stageKeyPressedHandler);
                this.stageKeyPressedHandler = null;
            }
            if (this.stageKeyReleasedHandler) {
                global.stage.disconnect(this.stageKeyReleasedHandler);
                this.stageKeyReleasedHandler = null;
            }
            this.spaceKeyPressed = false;
        }
    },
    
    _onDestroy: function() {
        Me.drawingSettings.disconnect(this.drawingSettingsChangedHandler);
        this.erase();
        if (this._menu)
            this._menu.disable();
        delete this.areaManagerUtils;
    },
    
    updateActionMode: function() {
        this.emit('update-action-mode');
    },
    
    enterDrawingMode: function() {
        this.keyPressedHandler = this.connect('key-press-event', this._onKeyPressed.bind(this));
        this.buttonPressedHandler = this.connect('button-press-event', this._onButtonPressed.bind(this));
        this.keyboardPopupMenuHandler = this.connect('popup-menu', this._onKeyboardPopupMenu.bind(this));
        this.scrollHandler = this.connect('scroll-event', this._onScroll.bind(this));
        this.set_background_color(this.reactive && this.hasBackground ? this.areaBackgroundColor : null);
    },
    
    leaveDrawingMode: function(save, erase) {
        if (this.keyPressedHandler) {
            this.disconnect(this.keyPressedHandler);
            this.keyPressedHandler = null;
        }
        if (this.buttonPressedHandler) {
            this.disconnect(this.buttonPressedHandler);
            this.buttonPressedHandler = null;
        }
        if (this.keyboardPopupMenuHandler) {
            this.disconnect(this.keyboardPopupMenuHandler);
            this.keyboardPopupMenuHandler = null;
        }
        if (this.scrollHandler) {
            this.disconnect(this.scrollHandler);
            this.scrollHandler = null;
        }
        
        this._stopAll(true);
        
        if (erase)
            this.erase();
        
        this.closeMenu();
        this.set_background_color(null);
        Files.Images.reset();
        if (save)
            this.savePersistent();
    },
    
    // Used by the menu.
    getSvgContentsForJson(json) {
        let elements = [];
        let elementsContent = '';
        
        elements.push(...JSON.parse(json.contents).map(object => {
            if (object.color)
                object.color = getColorFromString(object.color, 'White');
            if (object.font && typeof object.font == 'string')
                object.font = Pango.FontDescription.from_string(object.font);
            if (object.image)
                object.image = new Files.Image(object.image);
            return new Elements.DrawingElement(object);
        }));
        elements.forEach(element => elementsContent += element.buildSVG('transparent'));
        
        let prefixes = 'xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"';
        
        let getGiconSvgContent = () => {
            let size = Math.min(this.monitor.width, this.monitor.height);
            let [x, y] = [(this.monitor.width - size) / 2, (this.monitor.height - size) / 2];
            return `<svg viewBox="${x} ${y} ${size} ${size}" ${prefixes}>${elementsContent}\n</svg>`;
        };
        
        let getImageSvgContent = () => {
            return `<svg viewBox="0 0 ${this.layerContainer.width} ${this.layerContainer.height}" ${prefixes}>${elementsContent}\n</svg>`;
        };
        
        return [getGiconSvgContent, getImageSvgContent];
    },
    
    exportToSvg: function() {
        this._stopAll();
        
        let prefixes = 'xmlns="http://www.w3.org/2000/svg"';
        if (this.elements.some(element => element.shape == Shape.IMAGE))
            prefixes += ' xmlns:xlink="http://www.w3.org/1999/xlink"';
        let content = `<svg viewBox="0 0 ${this.layerContainer.width} ${this.layerContainer.height}" ${prefixes}>`;
        let backgroundColorString = this.hasBackground ? String(this.areaBackgroundColor) : 'transparent';
        if (backgroundColorString != 'transparent')
            content += `\n  <rect id="background" width="100%" height="100%" fill="${backgroundColorString}"/>`;
        this.elements.forEach(element => content += element.buildSVG(backgroundColorString));
        content += "\n</svg>";
        
        if (Files.saveSvg(content)) {
            let flashspot = new Screenshot.Flashspot(this);
            flashspot.fire();
            if (global.play_theme_sound) {
                global.play_theme_sound(0, 'screen-capture', "Save as SVG", null);
            } else if (global.display && global.display.get_sound_player) {
                let player = global.display.get_sound_player();
                player.play_from_theme('screen-capture', "Save as SVG", null);
            }
        }
    },
    
    _saveAsJson: function(json, notify, callback) {
        this._stopAll();
        
        // do not use "content = JSON.stringify(this.elements, null, 2);", neither "content = JSON.stringify(this.elements);"
        // do compromise between disk usage and human readability
        let contents = this.elements.length ? `[\n  ` + new Array(...this.elements.map(element => JSON.stringify(element))).join(`,\n\n  `) + `\n]` : '[]';
        
        GLib.idle_add(GLib.PRIORITY_DEFAULT_IDLE, () => {
            json.contents = contents;
            if (notify)
                this.emit('show-osd', Files.Icons.SAVE, json.name, "", -1, false);
            if (!json.isPersistent)
                this.currentJson = json;
            if (callback)
                callback();
        });
    },
    
    saveAsJsonWithName: function(name, callback) {
        this._saveAsJson(Files.Jsons.getNamed(name), false, callback);
    },
    
    saveAsJson: function(notify, callback) {
        this._saveAsJson(Files.Jsons.getDated(), notify, callback);
    },
    
    savePersistent: function() {
        this._saveAsJson(Files.Jsons.getPersistent());
    },
    
    syncPersistent: function() {
        // do not override peristent.json with an empty drawing when changing persistency setting
        if (!this.elements.length)
            this._loadPersistent();
        else
            this.savePersistent();
            
    },
    
    _loadJson: function(json, notify) {
        this._stopAll();
        
        this.elements = [];
        this.currentElement = null;
        
        if (!json.contents)
            return;
        
        this.elements.push(...JSON.parse(json.contents).map(object => {
            if (object.color)
                object.color = getColorFromString(object.color, 'White');
            if (object.font && typeof object.font == 'string')
                object.font = Pango.FontDescription.from_string(object.font);
            if (object.image)
                object.image = new Files.Image(object.image);
            return new Elements.DrawingElement(object);
        }));
        
        if (notify)
            this.emit('show-osd', Files.Icons.OPEN, json.name, "", -1, false);
        if (!json.isPersistent)
            this.currentJson = json;
    },
    
    _loadPersistent: function() {
        this._loadJson(Files.Jsons.getPersistent());
    },
    
    loadJson: function(json, notify) {
        this._loadJson(json, notify);
        this._redisplay();
    },
    
    loadPreviousJson: function() {
        let json = Files.Jsons.getPrevious(this.currentJson || null);
        if (json)
            this.loadJson(json, true);
    },
    
    loadNextJson: function() {
        let json = Files.Jsons.getNext(this.currentJson || null);
        if (json)
            this.loadJson(json, true);
    },
    
    get drawingContentsHasChanged() {
        let contents = `[\n  ` + new Array(...this.elements.map(element => JSON.stringify(element))).join(`,\n\n  `) + `\n]`;
        return contents != (this.currentJson && this.currentJson.contents);
    }
});