labelmeWithAI/labelme/app.py

# flake8: noqa
# -*- coding: utf8 -*-
#
# Copyright (C) 2011 Michael Pitidis, Hussein Abdulwahid.
#
# This file is part of Labelme.
#
# Labelme 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.
#
# Labelme 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 Labelme.  If not, see <http://www.gnu.org/licenses/>.
#

import argparse
import os.path
import re
import sys
import subprocess

from functools import partial
from collections import defaultdict

try:
    from PyQt5.QtGui import *
    from PyQt5.QtCore import *
    from PyQt5.QtWidgets import *
    PYQT5 = True
except ImportError:
    from PyQt4.QtGui import *
    from PyQt4.QtCore import *
    PYQT5 = False

from labelme import resources
from labelme.lib import struct, newAction, newIcon, addActions, fmtShortcut
from labelme.shape import Shape, DEFAULT_LINE_COLOR, DEFAULT_FILL_COLOR
from labelme.canvas import Canvas
from labelme.zoomWidget import ZoomWidget
from labelme.labelDialog import LabelDialog
from labelme.colorDialog import ColorDialog
from labelme.labelFile import LabelFile, LabelFileError
from labelme.toolBar import ToolBar


__appname__ = 'labelme'

# FIXME
# - [medium] Set max zoom value to something big enough for FitWidth/Window

# TODO:
# - [high] Automatically add file suffix when saving.
# - [high] Add polygon movement with arrow keys
# - [high] Deselect shape when clicking and already selected(?)
# - [high] Sanitize shortcuts between beginner/advanced mode.
# - [medium] Zoom should keep the image centered.
# - [medium] Add undo button for vertex addition.
# - [low,maybe] Open images with drag & drop.
# - [low,maybe] Preview images on file dialogs.
# - [low,maybe] Sortable label list.
# - Zoom is too "steppy".


### Utility functions and classes.

class WindowMixin(object):
    def menu(self, title, actions=None):
        menu = self.menuBar().addMenu(title)
        if actions:
            addActions(menu, actions)
        return menu

    def toolbar(self, title, actions=None):
        toolbar = ToolBar(title)
        toolbar.setObjectName('%sToolBar' % title)
        #toolbar.setOrientation(Qt.Vertical)
        toolbar.setToolButtonStyle(Qt.ToolButtonTextUnderIcon)
        if actions:
            addActions(toolbar, actions)
        self.addToolBar(Qt.LeftToolBarArea, toolbar)
        return toolbar


class EscapableQListWidget(QListWidget):

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Escape:
            self.clearSelection()


class MainWindow(QMainWindow, WindowMixin):
    FIT_WINDOW, FIT_WIDTH, MANUAL_ZOOM = 0, 1, 2

    def __init__(self, filename=None, output=None, store_data=True,
                 labels=None, sort_labels=True):
        super(MainWindow, self).__init__()
        self.setWindowTitle(__appname__)

        # Whether we need to save or not.
        self.dirty = False

        self._noSelectionSlot = False
        self._beginner = True
        self.screencastViewer = "firefox"
        self.screencast = "screencast.ogv"

        # Main widgets and related state.
        self.labelDialog = LabelDialog(parent=self, labels=labels,
                                       sort_labels=sort_labels)

        self.labelList = QListWidget()
        self.itemsToShapes = []
        self.imageList = []
        self.lastOpenDir = None

        self.labelList.itemActivated.connect(self.labelSelectionChanged)
        self.labelList.itemSelectionChanged.connect(self.labelSelectionChanged)
        self.labelList.itemDoubleClicked.connect(self.editLabel)
        # Connect to itemChanged to detect checkbox changes.
        self.labelList.itemChanged.connect(self.labelItemChanged)

        listLayout = QVBoxLayout()
        listLayout.setContentsMargins(0, 0, 0, 0)
        listLayout.addWidget(self.labelList)
        self.editButton = QToolButton()
        self.editButton.setToolButtonStyle(Qt.ToolButtonTextBesideIcon)
        self.labelListContainer = QWidget()
        self.labelListContainer.setLayout(listLayout)
        listLayout.addWidget(self.editButton)#, 0, Qt.AlignCenter)
        listLayout.addWidget(self.labelList)

        self.uniqLabelList = EscapableQListWidget()
        self.uniqLabelList.setToolTip(
            "Select label to start annotating for it. "
            "Press 'Esc' to deselect.")
        if labels:
            self.uniqLabelList.addItems(labels)
            self.uniqLabelList.sortItems()
        self.labelsdock = QDockWidget(u'Label List', self)
        self.labelsdock.setObjectName(u'Label List')
        self.labelsdock.setWidget(self.uniqLabelList)

        self.dock = QDockWidget('Polygon Labels', self)
        self.dock.setObjectName('Labels')
        self.dock.setWidget(self.labelListContainer)

        self.fileListWidget = QListWidget()
        self.fileListWidget.itemSelectionChanged.connect(self.fileSelectionChanged)
        filelistLayout = QVBoxLayout()
        filelistLayout.setContentsMargins(0, 0, 0, 0)
        filelistLayout.addWidget(self.fileListWidget)
        fileListContainer = QWidget()
        fileListContainer.setLayout(filelistLayout)
        self.filedock = QDockWidget(u'File List', self)
        self.filedock.setObjectName(u'Files')
        self.filedock.setWidget(fileListContainer)

        self.zoomWidget = ZoomWidget()
        self.colorDialog = ColorDialog(parent=self)

        self.canvas = Canvas()
        self.canvas.zoomRequest.connect(self.zoomRequest)

        scroll = QScrollArea()
        scroll.setWidget(self.canvas)
        scroll.setWidgetResizable(True)
        self.scrollBars = {
            Qt.Vertical: scroll.verticalScrollBar(),
            Qt.Horizontal: scroll.horizontalScrollBar()
            }
        self.canvas.scrollRequest.connect(self.scrollRequest)

        self.canvas.newShape.connect(self.newShape)
        self.canvas.shapeMoved.connect(self.setDirty)
        self.canvas.selectionChanged.connect(self.shapeSelectionChanged)
        self.canvas.drawingPolygon.connect(self.toggleDrawingSensitive)

        self.setCentralWidget(scroll)

        self.addDockWidget(Qt.RightDockWidgetArea, self.labelsdock)
        self.addDockWidget(Qt.RightDockWidgetArea, self.dock)
        self.addDockWidget(Qt.RightDockWidgetArea, self.filedock)
        self.filedock.setFeatures(QDockWidget.DockWidgetFloatable)

        self.dockFeatures = QDockWidget.DockWidgetClosable\
                          | QDockWidget.DockWidgetFloatable
        self.dock.setFeatures(self.dock.features() ^ self.dockFeatures)

        # Actions
        action = partial(newAction, self)
        quit = action('&Quit', self.close,
                'Ctrl+Q', 'quit', 'Quit application')
        open = action('&Open', self.openFile,
                'Ctrl+O', 'open', 'Open image or label file')
        opendir = action('&Open Dir', self.openDirDialog,
                         'Ctrl+u', 'open', u'Open Dir')
        openNextImg = action('&Next Image', self.openNextImg,
                             'd', 'next', u'Open Next')

        openPrevImg = action('&Prev Image', self.openPrevImg,
                             'a', 'prev', u'Open Prev')
        save = action('&Save', self.saveFile,
                'Ctrl+S', 'save', 'Save labels to file', enabled=False)
        saveAs = action('&Save As', self.saveFileAs,
                'Ctrl+Shift+S', 'save-as', 'Save labels to a different file',
                enabled=False)
        close = action('&Close', self.closeFile,
                'Ctrl+W', 'close', 'Close current file')
        color1 = action('Polygon &Line Color', self.chooseColor1,
                'Ctrl+L', 'color_line', 'Choose polygon line color')
        color2 = action('Polygon &Fill Color', self.chooseColor2,
                'Ctrl+Shift+L', 'color', 'Choose polygon fill color')

        createMode = action('Create\nPolygo&ns', self.setCreateMode,
                'Ctrl+N', 'new', 'Start drawing polygons', enabled=False)
        editMode = action('&Edit\nPolygons', self.setEditMode,
                'Ctrl+J', 'edit', 'Move and edit polygons', enabled=False)

        create = action('Create\nPolygo&n', self.createShape,
                'Ctrl+N', 'new', 'Draw a new polygon', enabled=False)
        delete = action('Delete\nPolygon', self.deleteSelectedShape,
                'Delete', 'delete', 'Delete', enabled=False)
        copy = action('&Duplicate\nPolygon', self.copySelectedShape,
                'Ctrl+D', 'copy', 'Create a duplicate of the selected polygon',
                enabled=False)

        advancedMode = action('&Advanced Mode', self.toggleAdvancedMode,
                'Ctrl+Shift+A', 'expert', 'Switch to advanced mode',
                checkable=True)

        hideAll = action('&Hide\nPolygons', partial(self.togglePolygons, False),
                'Ctrl+H', 'hide', 'Hide all polygons',
                enabled=False)
        showAll = action('&Show\nPolygons', partial(self.togglePolygons, True),
                'Ctrl+A', 'hide', 'Show all polygons',
                enabled=False)

        help = action('&Tutorial', self.tutorial, 'Ctrl+T', 'help',
                'Show screencast of introductory tutorial')

        zoom = QWidgetAction(self)
        zoom.setDefaultWidget(self.zoomWidget)
        self.zoomWidget.setWhatsThis(
            "Zoom in or out of the image. Also accessible with"\
             " %s and %s from the canvas." % (fmtShortcut("Ctrl+[-+]"),
                 fmtShortcut("Ctrl+Wheel")))
        self.zoomWidget.setEnabled(False)

        zoomIn = action('Zoom &In', partial(self.addZoom, 10),
                'Ctrl++', 'zoom-in', 'Increase zoom level', enabled=False)
        zoomOut = action('&Zoom Out', partial(self.addZoom, -10),
                'Ctrl+-', 'zoom-out', 'Decrease zoom level', enabled=False)
        zoomOrg = action('&Original size', partial(self.setZoom, 100),
                'Ctrl+=', 'zoom', 'Zoom to original size', enabled=False)
        fitWindow = action('&Fit Window', self.setFitWindow,
                'Ctrl+F', 'fit-window', 'Zoom follows window size',
                checkable=True, enabled=False)
        fitWidth = action('Fit &Width', self.setFitWidth,
                'Ctrl+Shift+F', 'fit-width', 'Zoom follows window width',
                checkable=True, enabled=False)
        # Group zoom controls into a list for easier toggling.
        zoomActions = (self.zoomWidget, zoomIn, zoomOut, zoomOrg, fitWindow, fitWidth)
        self.zoomMode = self.MANUAL_ZOOM
        self.scalers = {
            self.FIT_WINDOW: self.scaleFitWindow,
            self.FIT_WIDTH: self.scaleFitWidth,
            # Set to one to scale to 100% when loading files.
            self.MANUAL_ZOOM: lambda: 1,
        }

        edit = action('&Edit Label', self.editLabel,
                'Ctrl+E', 'edit', 'Modify the label of the selected polygon',
                enabled=False)
        self.editButton.setDefaultAction(edit)

        shapeLineColor = action('Shape &Line Color', self.chshapeLineColor,
                icon='color_line', tip='Change the line color for this specific shape',
                enabled=False)
        shapeFillColor = action('Shape &Fill Color', self.chshapeFillColor,
                icon='color', tip='Change the fill color for this specific shape',
                enabled=False)

        labels = self.dock.toggleViewAction()
        labels.setText('Show/Hide Label Panel')
        labels.setShortcut('Ctrl+Shift+L')

        # Lavel list context menu.
        labelMenu = QMenu()
        addActions(labelMenu, (edit, delete))
        self.labelList.setContextMenuPolicy(Qt.CustomContextMenu)
        self.labelList.customContextMenuRequested.connect(self.popLabelListMenu)

        # Store actions for further handling.
        self.actions = struct(save=save, saveAs=saveAs, open=open, close=close,
                lineColor=color1, fillColor=color2,
                create=create, delete=delete, edit=edit, copy=copy,
                createMode=createMode, editMode=editMode, advancedMode=advancedMode,
                shapeLineColor=shapeLineColor, shapeFillColor=shapeFillColor,
                zoom=zoom, zoomIn=zoomIn, zoomOut=zoomOut, zoomOrg=zoomOrg,
                fitWindow=fitWindow, fitWidth=fitWidth,
                zoomActions=zoomActions,
                fileMenuActions=(open,opendir,save,saveAs,close,quit),
                beginner=(), advanced=(),
                editMenu=(edit, copy, delete, None, color1, color2),
                beginnerContext=(create, edit, copy, delete),
                advancedContext=(createMode, editMode, edit, copy,
                    delete, shapeLineColor, shapeFillColor),
                onLoadActive=(close, create, createMode, editMode),
                onShapesPresent=(saveAs, hideAll, showAll))

        self.menus = struct(
                file=self.menu('&File'),
                edit=self.menu('&Edit'),
                view=self.menu('&View'),
                help=self.menu('&Help'),
                recentFiles=QMenu('Open &Recent'),
                labelList=labelMenu)

        addActions(self.menus.file,
                (open, opendir, self.menus.recentFiles, save, saveAs, close, None, quit))
        addActions(self.menus.help, (help,))
        addActions(self.menus.view, (
            labels, advancedMode, None,
            hideAll, showAll, None,
            zoomIn, zoomOut, zoomOrg, None,
            fitWindow, fitWidth))

        self.menus.file.aboutToShow.connect(self.updateFileMenu)

        # Custom context menu for the canvas widget:
        addActions(self.canvas.menus[0], self.actions.beginnerContext)
        addActions(self.canvas.menus[1], (
            action('&Copy here', self.copyShape),
            action('&Move here', self.moveShape)))

        self.tools = self.toolbar('Tools')
        self.actions.beginner = (
            open, opendir, openNextImg, openPrevImg, save, None, create, copy, delete, None,
            zoomIn, zoom, zoomOut, fitWindow, fitWidth)

        self.actions.advanced = (
            open, opendir, openNextImg, openPrevImg, save, None,
            createMode, editMode, None,
            hideAll, showAll)

        self.statusBar().showMessage('%s started.' % __appname__)
        self.statusBar().show()

        # Application state.
        self.image = QImage()
        self.imagePath = None
        self.labeling_once = output is not None
        self.output = output
        self._store_data = store_data
        self.recentFiles = []
        self.maxRecent = 7
        self.lineColor = None
        self.fillColor = None
        self.zoom_level = 100
        self.fit_window = False

        if filename is not None and os.path.isdir(filename):
            self.importDirImages(filename)
        else:
            self.filename = filename

        # XXX: Could be completely declarative.
        # Restore application settings.
        self.settings = {}
        self.recentFiles = self.settings.get('recentFiles', [])
        size = self.settings.get('window/size', QSize(600, 500))
        position = self.settings.get('window/position', QPoint(0, 0))
        self.resize(size)
        self.move(position)
        # or simply:
        #self.restoreGeometry(settings['window/geometry']
        self.restoreState(self.settings.get('window/state', QByteArray()))
        self.lineColor = QColor(self.settings.get('line/color', Shape.line_color))
        self.fillColor = QColor(self.settings.get('fill/color', Shape.fill_color))
        Shape.line_color = self.lineColor
        Shape.fill_color = self.fillColor

        if self.settings.get('advanced', QVariant()):
            self.actions.advancedMode.setChecked(True)
            self.toggleAdvancedMode()

        # Populate the File menu dynamically.
        self.updateFileMenu()
        # Since loading the file may take some time, make sure it runs in the background.
        if self.filename is not None:
            self.queueEvent(partial(self.loadFile, self.filename))

        # Callbacks:
        self.zoomWidget.valueChanged.connect(self.paintCanvas)

        self.populateModeActions()

        #self.firstStart = True
        #if self.firstStart:
        #    QWhatsThis.enterWhatsThisMode()

    ## Support Functions ##

    def noShapes(self):
        return not self.itemsToShapes

    def toggleAdvancedMode(self, value=True):
        self._beginner = not value
        self.canvas.setEditing(True)
        self.populateModeActions()
        self.editButton.setVisible(not value)
        if value:
            self.actions.createMode.setEnabled(True)
            self.actions.editMode.setEnabled(False)
            self.dock.setFeatures(self.dock.features() | self.dockFeatures)
        else:
            self.dock.setFeatures(self.dock.features() ^ self.dockFeatures)

    def populateModeActions(self):
        if self.beginner():
            tool, menu = self.actions.beginner, self.actions.beginnerContext
        else:
            tool, menu = self.actions.advanced, self.actions.advancedContext
        self.tools.clear()
        addActions(self.tools, tool)
        self.canvas.menus[0].clear()
        addActions(self.canvas.menus[0], menu)
        self.menus.edit.clear()
        actions = (self.actions.create,) if self.beginner()\
                else (self.actions.createMode, self.actions.editMode)
        addActions(self.menus.edit, actions + self.actions.editMenu)

    def setBeginner(self):
        self.tools.clear()
        addActions(self.tools, self.actions.beginner)

    def setAdvanced(self):
        self.tools.clear()
        addActions(self.tools, self.actions.advanced)

    def setDirty(self):
        self.dirty = True
        self.actions.save.setEnabled(True)
        self.setWindowTitle('{} - {}*'.format(__appname__, os.path.basename(self.filename)))

    def setClean(self):
        self.dirty = False
        self.actions.save.setEnabled(False)
        self.actions.create.setEnabled(True)
        self.setWindowTitle('{} - {}'.format(__appname__, os.path.basename(self.filename)))

    def toggleActions(self, value=True):
        """Enable/Disable widgets which depend on an opened image."""
        for z in self.actions.zoomActions:
            z.setEnabled(value)
        for action in self.actions.onLoadActive:
            action.setEnabled(value)

    def queueEvent(self, function):
        QTimer.singleShot(0, function)

    def status(self, message, delay=5000):
        self.statusBar().showMessage(message, delay)

    def resetState(self):
        self.itemsToShapes = []
        self.labelList.clear()
        self.filename = None
        self.imageData = None
        self.labelFile = None
        self.canvas.resetState()

    def currentItem(self):
        items = self.labelList.selectedItems()
        if items:
            return items[0]
        return None

    def addRecentFile(self, filename):
        if filename in self.recentFiles:
            self.recentFiles.remove(filename)
        elif len(self.recentFiles) >= self.maxRecent:
            self.recentFiles.pop()
        self.recentFiles.insert(0, filename)

    def beginner(self):
        return self._beginner

    def advanced(self):
        return not self.beginner()

    ## Callbacks ##
    def tutorial(self):
        subprocess.Popen([self.screencastViewer, self.screencast])

    def createShape(self):
        assert self.beginner()
        self.canvas.setEditing(False)
        self.actions.create.setEnabled(False)

    def toggleDrawingSensitive(self, drawing=True):
        """In the middle of drawing, toggling between modes should be disabled."""
        self.actions.editMode.setEnabled(not drawing)
        if not drawing and self.beginner():
            # Cancel creation.
            self.canvas.setEditing(True)
            self.canvas.restoreCursor()
            self.actions.create.setEnabled(True)

    def toggleDrawMode(self, edit=True):
        self.canvas.setEditing(edit)
        self.actions.createMode.setEnabled(edit)
        self.actions.editMode.setEnabled(not edit)

    def setCreateMode(self):
        assert self.advanced()
        self.toggleDrawMode(False)

    def setEditMode(self):
        assert self.advanced()
        self.toggleDrawMode(True)

    def updateFileMenu(self):
        current = self.filename
        def exists(filename):
            return os.path.exists(str(filename))
        menu = self.menus.recentFiles
        menu.clear()
        files = [f for f in self.recentFiles if f != current and exists(f)]
        for i, f in enumerate(files):
            icon = newIcon('labels')
            action = QAction(
                    icon, '&%d %s' % (i+1, QFileInfo(f).fileName()), self)
            action.triggered.connect(partial(self.loadRecent, f))
            menu.addAction(action)

    def popLabelListMenu(self, point):
        self.menus.labelList.exec_(self.labelList.mapToGlobal(point))

    def editLabel(self, item=None):
        if not self.canvas.editing():
            return
        item = item if item else self.currentItem()
        text = self.labelDialog.popUp(item.text())
        if text is None:
            return
        item.setText(text)
        self.setDirty()
        if not self.uniqLabelList.findItems(text, Qt.MatchExactly):
            self.uniqLabelList.addItem(text)
            self.uniqLabelList.sortItems()

    def fileSelectionChanged(self):
        items = self.fileListWidget.selectedItems()
        if not items:
            return
        item = items[0]

        if not self.mayContinue():
            return

        currIndex = self.imageList.index(str(item.text()))
        if currIndex < len(self.imageList):
            filename = self.imageList[currIndex]
            if filename:
                self.loadFile(filename)

    # React to canvas signals.
    def shapeSelectionChanged(self, selected=False):
        if self._noSelectionSlot:
            self._noSelectionSlot = False
        else:
            shape = self.canvas.selectedShape
            if shape:
                index = self._find_item_from_shape(shape)
                item, _ = self.itemsToShapes[index]
                item.setSelected(True)
            else:
                self.labelList.clearSelection()
        self.actions.delete.setEnabled(selected)
        self.actions.copy.setEnabled(selected)
        self.actions.edit.setEnabled(selected)
        self.actions.shapeLineColor.setEnabled(selected)
        self.actions.shapeFillColor.setEnabled(selected)

    def addLabel(self, shape):
        item = QListWidgetItem(shape.label)
        item.setFlags(item.flags() | Qt.ItemIsUserCheckable)
        item.setCheckState(Qt.Checked)
        self.itemsToShapes.append((item, shape))
        self.labelList.addItem(item)
        if not self.uniqLabelList.findItems(shape.label, Qt.MatchExactly):
            self.uniqLabelList.addItem(shape.label)
            self.uniqLabelList.sortItems()
        self.labelDialog.addLabelHistory(item.text())
        for action in self.actions.onShapesPresent:
            action.setEnabled(True)

    def _find_item_from_shape(self, shape):
        for index, (item, shape_) in enumerate(self.itemsToShapes):
            if shape_ == shape:
                return index

    def _find_shape_from_item(self, item):
        for index, (item_, shape) in enumerate(self.itemsToShapes):
            if item_ == item:
                return index

    def remLabel(self, shape):
        index = self._find_item_from_shape(shape)
        item, _ = self.itemsToShapes.pop(index)
        self.labelList.takeItem(self.labelList.row(item))

    def loadLabels(self, shapes):
        s = []
        for label, points, line_color, fill_color in shapes:
            shape = Shape(label=label)
            for x, y in points:
                shape.addPoint(QPointF(x, y))
            shape.close()
            s.append(shape)
            self.addLabel(shape)
            if line_color:
                shape.line_color = QColor(*line_color)
            if fill_color:
                shape.fill_color = QColor(*fill_color)
        self.canvas.loadShapes(s)

    def saveLabels(self, filename):
        lf = LabelFile()
        def format_shape(s):
            return dict(label=str(s.label),
                        line_color=s.line_color.getRgb()\
                                if s.line_color != self.lineColor else None,
                        fill_color=s.fill_color.getRgb()\
                                if s.fill_color != self.fillColor else None,
                        points=[(p.x(), p.y()) for p in s.points])

        shapes = [format_shape(shape) for shape in self.canvas.shapes]
        try:
            imagePath = os.path.relpath(
                self.imagePath, os.path.dirname(filename))
            imageData = self.imageData if self._store_data else None
            lf.save(filename, shapes, imagePath, imageData,
                self.lineColor.getRgb(), self.fillColor.getRgb())
            self.labelFile = lf
            # self.filename = filename # disable allows next and previous image to proceed
            return True
        except LabelFileError as e:
            self.errorMessage('Error saving label data',
                    '<b>%s</b>' % e)
            return False

    def copySelectedShape(self):
        self.addLabel(self.canvas.copySelectedShape())
        #fix copy and delete
        self.shapeSelectionChanged(True)

    def labelSelectionChanged(self):
        item = self.currentItem()
        if item and self.canvas.editing():
            self._noSelectionSlot = True
            index = self._find_shape_from_item(item)
            _, shape = self.itemsToShapes[index]
            self.canvas.selectShape(shape)

    def labelItemChanged(self, item):
        index = self._find_shape_from_item(item)
        _, shape = self.itemsToShapes[index]
        label = str(item.text())
        if label != shape.label:
            shape.label = str(item.text())
            self.setDirty()
        else: # User probably changed item visibility
            self.canvas.setShapeVisible(shape, item.checkState() == Qt.Checked)

    ## Callback functions:
    def newShape(self):
        """Pop-up and give focus to the label editor.

        position MUST be in global coordinates.
        """
        items = self.uniqLabelList.selectedItems()
        text = None
        if items:
            text = items[0].text()
        text = self.labelDialog.popUp(text)
        if text is not None:
            self.addLabel(self.canvas.setLastLabel(text))
            if self.beginner(): # Switch to edit mode.
                self.canvas.setEditing(True)
                self.actions.create.setEnabled(True)
            else:
                self.actions.editMode.setEnabled(True)
            self.setDirty()
        else:
            self.canvas.undoLastLine()

    def scrollRequest(self, delta, orientation):
        units = - delta * 0.1 # natural scroll
        bar = self.scrollBars[orientation]
        bar.setValue(bar.value() + bar.singleStep() * units)

    def setZoom(self, value):
        self.actions.fitWidth.setChecked(False)
        self.actions.fitWindow.setChecked(False)
        self.zoomMode = self.MANUAL_ZOOM
        self.zoomWidget.setValue(value)

    def addZoom(self, increment=10):
        self.setZoom(self.zoomWidget.value() + increment)

    def zoomRequest(self, delta):
        units = delta * 0.1
        self.addZoom(units)

    def setFitWindow(self, value=True):
        if value:
            self.actions.fitWidth.setChecked(False)
        self.zoomMode = self.FIT_WINDOW if value else self.MANUAL_ZOOM
        self.adjustScale()

    def setFitWidth(self, value=True):
        if value:
            self.actions.fitWindow.setChecked(False)
        self.zoomMode = self.FIT_WIDTH if value else self.MANUAL_ZOOM
        self.adjustScale()

    def togglePolygons(self, value):
        for item, shape in self.itemsToShapes:
            item.setCheckState(Qt.Checked if value else Qt.Unchecked)

    def loadFile(self, filename=None):
        """Load the specified file, or the last opened file if None."""
        self.resetState()
        self.canvas.setEnabled(False)
        if filename is None:
            filename = self.settings.get('filename', '')
        filename = str(filename)
        if not QFile.exists(filename):
            self.errorMessage(
                'Error opening file', 'No such file: <b>%s</b>' % filename)
            return False
        # assumes same name, but json extension
        self.status("Loading %s..." % os.path.basename(str(filename)))
        label_file = os.path.splitext(filename)[0] + '.json'
        if QFile.exists(label_file) and LabelFile.isLabelFile(label_file):
            try:
                self.labelFile = LabelFile(label_file)
                # FIXME: PyQt4 installed via Anaconda fails to load JPEG
                # and JSON encoded images.
                # https://github.com/ContinuumIO/anaconda-issues/issues/131
                if QImage.fromData(self.labelFile.imageData).isNull():
                    raise LabelFileError(
                        'Failed loading image data from label file.\n'
                        'Maybe this is a known issue of PyQt4 built on'
                        ' Anaconda, and may be fixed by installing PyQt5.')
            except LabelFileError as e:
                self.errorMessage('Error opening file',
                        ("<p><b>%s</b></p>"
                            "<p>Make sure <i>%s</i> is a valid label file.")\
                        % (e, label_file))
                self.status("Error reading %s" % label_file)
                return False
            self.imageData = self.labelFile.imageData
            self.imagePath = os.path.join(os.path.dirname(label_file),
                                            self.labelFile.imagePath)
            self.lineColor = QColor(*self.labelFile.lineColor)
            self.fillColor = QColor(*self.labelFile.fillColor)
        else:
            # Load image:
            # read data first and store for saving into label file.
            self.imageData = read(filename, None)
            if self.imageData is not None:
                # the filename is image not JSON
                self.imagePath = filename
            self.labelFile = None
        image = QImage.fromData(self.imageData)
        if image.isNull():
            formats = ['*.{}'.format(fmt.data().decode())
                        for fmt in QImageReader.supportedImageFormats()]
            self.errorMessage(
                'Error opening file',
                '<p>Make sure <i>{0}</i> is a valid image file.<br/>'
                'Supported image formats: {1}</p>'
                .format(filename, ','.join(formats)))
            self.status("Error reading %s" % filename)
            return False
        self.image = image
        self.filename = filename
        self.canvas.loadPixmap(QPixmap.fromImage(image))
        if self.labelFile:
            self.loadLabels(self.labelFile.shapes)
        self.setClean()
        self.canvas.setEnabled(True)
        self.adjustScale(initial=True)
        self.paintCanvas()
        self.addRecentFile(self.filename)
        self.toggleActions(True)
        self.status("Loaded %s" % os.path.basename(str(filename)))
        if filename in self.imageList:
            self.fileListWidget.setCurrentRow(self.imageList.index(filename))
        return True

    def resizeEvent(self, event):
        if self.canvas and not self.image.isNull()\
           and self.zoomMode != self.MANUAL_ZOOM:
            self.adjustScale()
        super(MainWindow, self).resizeEvent(event)

    def paintCanvas(self):
        assert not self.image.isNull(), "cannot paint null image"
        self.canvas.scale = 0.01 * self.zoomWidget.value()
        self.canvas.adjustSize()
        self.canvas.update()

    def adjustScale(self, initial=False):
        value = self.scalers[self.FIT_WINDOW if initial else self.zoomMode]()
        self.zoomWidget.setValue(int(100 * value))

    def scaleFitWindow(self):
        """Figure out the size of the pixmap in order to fit the main widget."""
        e = 2.0 # So that no scrollbars are generated.
        w1 = self.centralWidget().width() - e
        h1 = self.centralWidget().height() - e
        a1 = w1/ h1
        # Calculate a new scale value based on the pixmap's aspect ratio.
        w2 = self.canvas.pixmap.width() - 0.0
        h2 = self.canvas.pixmap.height() - 0.0
        a2 = w2 / h2
        return w1 / w2 if a2 >= a1 else h1 / h2

    def scaleFitWidth(self):
        # The epsilon does not seem to work too well here.
        w = self.centralWidget().width() - 2.0
        return w / self.canvas.pixmap.width()

    def closeEvent(self, event):
        if not self.mayContinue():
            event.ignore()
        s = self.settings
        s['filename'] = self.filename if self.filename else ''
        s['window/size'] = self.size()
        s['window/position'] = self.pos()
        s['window/state'] = self.saveState()
        s['line/color'] = self.lineColor
        s['fill/color'] = self.fillColor
        s['recentFiles'] = self.recentFiles
        s['advanced'] = not self._beginner
        # ask the use for where to save the labels
        #s['window/geometry'] = self.saveGeometry()

    ## User Dialogs ##

    def loadRecent(self, filename):
        if self.mayContinue():
            self.loadFile(filename)

    def openPrevImg(self, _value=False):
        if not self.mayContinue():
            return

        if len(self.imageList) <= 0:
            return

        if self.filename is None:
            return

        currIndex = self.imageList.index(self.filename)
        if currIndex - 1 >= 0:
            filename = self.imageList[currIndex - 1]
            if filename:
                self.loadFile(filename)

    def openNextImg(self, _value=False):
        if not self.mayContinue():
            return

        if len(self.imageList) <= 0:
            return

        filename = None
        if self.filename is None:
            filename = self.imageList[0]
        else:
            currIndex = self.imageList.index(self.filename)
            if currIndex + 1 < len(self.imageList):
                filename = self.imageList[currIndex + 1]

        if filename:
            self.loadFile(filename)

    def openFile(self, _value=False):
        if not self.mayContinue():
            return
        path = os.path.dirname(str(self.filename))\
                if self.filename else '.'
        formats = ['*.{}'.format(fmt.data().decode())
                   for fmt in QImageReader.supportedImageFormats()]
        filters = "Image & Label files (%s)" % \
                ' '.join(formats + ['*%s' % LabelFile.suffix])
        filename = QFileDialog.getOpenFileName(self,
            '%s - Choose Image or Label file' % __appname__, path, filters)
        if PYQT5:
            filename, _ = filename
        filename = str(filename)
        if filename:
            self.loadFile(filename)

    def saveFile(self, _value=False):
        assert not self.image.isNull(), "cannot save empty image"
        if self.hasLabels():
            if self.labelFile:
                # DL20180323 - overwrite when in directory
                self._saveFile(self.labelFile.filename)
            elif self.output:
                self._saveFile(self.output)
            else:
                self._saveFile(self.saveFileDialog())

    def saveFileAs(self, _value=False):
        assert not self.image.isNull(), "cannot save empty image"
        if self.hasLabels():
            self._saveFile(self.saveFileDialog())

    def saveFileDialog(self):
        caption = '%s - Choose File' % __appname__
        filters = 'Label files (*%s)' % LabelFile.suffix
        dlg = QFileDialog(self, caption, self.currentPath(), filters)
        dlg.setDefaultSuffix(LabelFile.suffix[1:])
        dlg.setAcceptMode(QFileDialog.AcceptSave)
        dlg.setOption(QFileDialog.DontConfirmOverwrite, False)
        dlg.setOption(QFileDialog.DontUseNativeDialog, False)
        basename = os.path.splitext(self.filename)[0]
        default_labelfile_name = os.path.join(self.currentPath(),
                                              basename + LabelFile.suffix)
        filename = dlg.getSaveFileName(
            self, 'Choose File', default_labelfile_name,
            'Label files (*%s)' % LabelFile.suffix)
        if PYQT5:
            filename, _ = filename
        filename = str(filename)
        return filename

    def _saveFile(self, filename):
        if filename and self.saveLabels(filename):
            self.addRecentFile(filename)
            self.setClean()
            if self.labeling_once:
                self.close()

    def closeFile(self, _value=False):
        if not self.mayContinue():
            return
        self.resetState()
        self.setClean()
        self.toggleActions(False)
        self.canvas.setEnabled(False)
        self.actions.saveAs.setEnabled(False)

    # Message Dialogs. #
    def hasLabels(self):
        if not self.itemsToShapes:
            self.errorMessage('No objects labeled',
                    'You must label at least one object to save the file.')
            return False
        return True

    def mayContinue(self):
        if not self.dirty:
            return True
        mb = QMessageBox
        msg = 'Save annotations to "{}" before closing?'.format(self.filename)
        answer = mb.question(self,
                             'Save annotations?',
                             msg,
                             mb.Save | mb.Discard | mb.Cancel,
                             mb.Save)
        if answer == mb.Discard:
            return True
        elif answer == mb.Save:
            self.saveFile()
            return True
        else: # answer == mb.Cancel
            return False

    def errorMessage(self, title, message):
        return QMessageBox.critical(self, title,
                '<p><b>%s</b></p>%s' % (title, message))

    def currentPath(self):
        return os.path.dirname(str(self.filename)) if self.filename else '.'

    def chooseColor1(self):
        color = self.colorDialog.getColor(self.lineColor, 'Choose line color',
                default=DEFAULT_LINE_COLOR)
        if color:
            self.lineColor = color
            # Change the color for all shape lines:
            Shape.line_color = self.lineColor
            self.canvas.update()
            self.setDirty()

    def chooseColor2(self):
       color = self.colorDialog.getColor(self.fillColor, 'Choose fill color',
                default=DEFAULT_FILL_COLOR)
       if color:
            self.fillColor = color
            Shape.fill_color = self.fillColor
            self.canvas.update()
            self.setDirty()

    def deleteSelectedShape(self):
        yes, no = QMessageBox.Yes, QMessageBox.No
        msg = 'You are about to permanently delete this polygon, proceed anyway?'
        if yes == QMessageBox.warning(self, 'Attention', msg, yes|no):
            self.remLabel(self.canvas.deleteSelected())
            self.setDirty()
            if self.noShapes():
                for action in self.actions.onShapesPresent:
                    action.setEnabled(False)

    def chshapeLineColor(self):
        color = self.colorDialog.getColor(self.lineColor, 'Choose line color',
                default=DEFAULT_LINE_COLOR)
        if color:
            self.canvas.selectedShape.line_color = color
            self.canvas.update()
            self.setDirty()

    def chshapeFillColor(self):
        color = self.colorDialog.getColor(self.fillColor, 'Choose fill color',
                default=DEFAULT_FILL_COLOR)
        if color:
            self.canvas.selectedShape.fill_color = color
            self.canvas.update()
            self.setDirty()

    def copyShape(self):
        self.canvas.endMove(copy=True)
        self.addLabel(self.canvas.selectedShape)
        self.setDirty()

    def moveShape(self):
        self.canvas.endMove(copy=False)
        self.setDirty()

    def openDirDialog(self, _value=False, dirpath=None):
        if not self.mayContinue():
            return

        defaultOpenDirPath = dirpath if dirpath else '.'
        if self.lastOpenDir and os.path.exists(self.lastOpenDir):
            defaultOpenDirPath = self.lastOpenDir
        else:
            defaultOpenDirPath = os.path.dirname(self.filename) if self.filename else '.'

        targetDirPath = str(QFileDialog.getExistingDirectory(self,
                                                     '%s - Open Directory' % __appname__, defaultOpenDirPath,
                                                     QFileDialog.ShowDirsOnly | QFileDialog.DontResolveSymlinks))
        self.importDirImages(targetDirPath)

    def importDirImages(self, dirpath):
        if not self.mayContinue() or not dirpath:
            return

        self.lastOpenDir = dirpath
        self.filename = None
        self.fileListWidget.clear()
        self.imageList = self.scanAllImages(dirpath)
        self.openNextImg()
        for imgPath in self.imageList:
            item = QListWidgetItem(imgPath)
            self.fileListWidget.addItem(item)

    def scanAllImages(self, folderPath):
        extensions = ['.%s' % fmt.data().decode("ascii").lower() for fmt in QImageReader.supportedImageFormats()]
        images = []

        for root, dirs, files in os.walk(folderPath):
            for file in files:
                if file.lower().endswith(tuple(extensions)):
                    relativePath = os.path.join(root, file)
                    images.append(relativePath)
        images.sort(key=lambda x: x.lower())
        return images


class Settings(object):
    """Convenience dict-like wrapper around QSettings."""
    def __init__(self, types=None):
        self.data = QSettings()
        self.types = defaultdict(lambda: QVariant, types if types else {})

    def __setitem__(self, key, value):
        t = self.types[key]
        self.data.setValue(key,
                t(value) if not isinstance(value, t) else value)

    def __getitem__(self, key):
        return self._cast(key, self.data.value(key))

    def get(self, key, default=None):
        return self._cast(key, self.data.value(key, default))

    def _cast(self, key, value):
        # XXX: Very nasty way of converting types to QVariant methods :P
        t = self.types[key]
        if t != QVariant:
            method = getattr(QVariant, re.sub('^Q', 'to', t.__name__, count=1))
            return method(value)
        return value


def inverted(color):
    return QColor(*[255 - v for v in color.getRgb()])


def read(filename, default=None):
    try:
        with open(filename, 'rb') as f:
            return f.read()
    except:
        return default


def main():
    """Standard boilerplate Qt application code."""
    parser = argparse.ArgumentParser()
    parser.add_argument('filename', nargs='?', help='image or label filename')
    parser.add_argument('--output', '-O', '-o', help='output label name')
    parser.add_argument('--nodata', dest='store_data', action='store_false',
                        help='stop storing image data to JSON file')
    parser.add_argument('--labels',
                        help='comma separated list of labels OR file '
                        'containing one label per line')
    parser.add_argument('--nosortlabels', dest='sort_labels',
                        action='store_false', help='stop sorting labels')
    args = parser.parse_args()

    if args.labels is not None:
        if os.path.isfile(args.labels):
            args.labels = [l.strip() for l in open(args.labels, 'r')
                           if l.strip()]
        else:
            args.labels = [l for l in args.labels.split(',') if l]

    app = QApplication(sys.argv)
    app.setApplicationName(__appname__)
    app.setWindowIcon(newIcon("app"))
    win = MainWindow(
        filename=args.filename,
        output=args.output,
        store_data=args.store_data,
        labels=args.labels,
        sort_labels=args.sort_labels,
    )
    win.show()
    win.raise_()
    sys.exit(app.exec_())