labelmeWithAI/labelme/app.py

import functools
import io
import os
import os.path as osp
import re
import warnings
import webbrowser

import PIL.Image

from qtpy import QtCore
from qtpy.QtCore import Qt
from qtpy import QtGui
from qtpy import QtWidgets

from labelme import __appname__
from labelme import QT5

from labelme.config import get_config
from labelme.label_file import LabelFile
from labelme.label_file import LabelFileError
from labelme.shape import DEFAULT_FILL_COLOR
from labelme.shape import DEFAULT_LINE_COLOR
from labelme.shape import Shape
from labelme.utils import addActions
from labelme.utils import fmtShortcut
from labelme.utils import newAction
from labelme.utils import newIcon
from labelme.utils import struct
from labelme.widgets import Canvas
from labelme.widgets import ColorDialog
from labelme.widgets import EscapableQListWidget
from labelme.widgets import LabelDialog
from labelme.widgets import LabelQListWidget
from labelme.widgets import ToolBar
from labelme.widgets import ZoomWidget


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

# TODO(unknown):
# - [high] Add polygon movement with arrow keys
# - [high] Deselect shape when clicking and already selected(?)
# - [low,maybe] Open images with drag & drop.
# - [low,maybe] Preview images on file dialogs.
# - Zoom is too "steppy".


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

    def __init__(self, config=None, filename=None, output=None):
        # see labelme/config/default_config.yaml for valid configuration
        if config is None:
            config = get_config()
        self._config = config

        super(MainWindow, self).__init__()
        self.setWindowTitle(__appname__)

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

        self._noSelectionSlot = False

        # Main widgets and related state.
        self.labelDialog = LabelDialog(
            parent=self,
            labels=self._config['labels'],
            sort_labels=self._config['sort_labels'],
            show_text_field=self._config['show_label_text_field'],
            completion=self._config['label_completion'],
            fit_to_content=self._config['fit_to_content'],
        )

        self.labelList = LabelQListWidget()
        self.lastOpenDir = None

        self.flag_dock = self.flag_widget = None
        self.flag_dock = QtWidgets.QDockWidget('Flags', self)
        self.flag_dock.setObjectName('Flags')
        self.flag_widget = QtWidgets.QListWidget()
        if config['flags']:
            self.loadFlags({k: False for k in config['flags']})
        self.flag_dock.setWidget(self.flag_widget)
        self.flag_widget.itemChanged.connect(self.setDirty)

        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)
        self.labelList.setDragDropMode(
            QtWidgets.QAbstractItemView.InternalMove)
        self.labelList.setParent(self)
        self.shape_dock = QtWidgets.QDockWidget('Polygon Labels', self)
        self.shape_dock.setObjectName('Labels')
        self.shape_dock.setWidget(self.labelList)

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

        self.fileSearch = QtWidgets.QLineEdit()
        self.fileSearch.setPlaceholderText('Search Filename')
        self.fileSearch.textChanged.connect(self.fileSearchChanged)
        self.fileListWidget = QtWidgets.QListWidget()
        self.fileListWidget.itemSelectionChanged.connect(
            self.fileSelectionChanged
        )
        fileListLayout = QtWidgets.QVBoxLayout()
        fileListLayout.setContentsMargins(0, 0, 0, 0)
        fileListLayout.setSpacing(0)
        fileListLayout.addWidget(self.fileSearch)
        fileListLayout.addWidget(self.fileListWidget)
        self.file_dock = QtWidgets.QDockWidget(u'File List', self)
        self.file_dock.setObjectName(u'Files')
        fileListWidget = QtWidgets.QWidget()
        fileListWidget.setLayout(fileListLayout)
        self.file_dock.setWidget(fileListWidget)

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

        self.canvas = self.labelList.canvas = Canvas(
            epsilon=self._config['epsilon'],
        )
        self.canvas.zoomRequest.connect(self.zoomRequest)

        scrollArea = QtWidgets.QScrollArea()
        scrollArea.setWidget(self.canvas)
        scrollArea.setWidgetResizable(True)
        self.scrollBars = {
            Qt.Vertical: scrollArea.verticalScrollBar(),
            Qt.Horizontal: scrollArea.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(scrollArea)

        features = QtWidgets.QDockWidget.DockWidgetFeatures()
        for dock in ['flag_dock', 'label_dock', 'shape_dock', 'file_dock']:
            if self._config[dock]['closable']:
                features = features | QtWidgets.QDockWidget.DockWidgetClosable
            if self._config[dock]['floatable']:
                features = features | QtWidgets.QDockWidget.DockWidgetFloatable
            if self._config[dock]['movable']:
                features = features | QtWidgets.QDockWidget.DockWidgetMovable
            getattr(self, dock).setFeatures(features)
            if self._config[dock]['show'] is False:
                getattr(self, dock).setVisible(False)

        self.addDockWidget(Qt.RightDockWidgetArea, self.flag_dock)
        self.addDockWidget(Qt.RightDockWidgetArea, self.label_dock)
        self.addDockWidget(Qt.RightDockWidgetArea, self.shape_dock)
        self.addDockWidget(Qt.RightDockWidgetArea, self.file_dock)

        # Actions
        action = functools.partial(newAction, self)
        shortcuts = self._config['shortcuts']
        quit = action('&Quit', self.close, shortcuts['quit'], 'quit',
                      'Quit application')
        open_ = action('&Open', self.openFile, shortcuts['open'], 'open',
                       'Open image or label file')
        opendir = action('&Open Dir', self.openDirDialog,
                         shortcuts['open_dir'], 'open', u'Open Dir')
        openNextImg = action(
            '&Next Image',
            self.openNextImg,
            shortcuts['open_next'],
            'next',
            u'Open next (hold Ctl+Shift to copy labels)',
            enabled=False,
        )
        openPrevImg = action(
            '&Prev Image',
            self.openPrevImg,
            shortcuts['open_prev'],
            'prev',
            u'Open prev (hold Ctl+Shift to copy labels)',
            enabled=False,
        )
        save = action('&Save', self.saveFile, shortcuts['save'], 'save',
                      'Save labels to file', enabled=False)
        saveAs = action('&Save As', self.saveFileAs, shortcuts['save_as'],
                        'save-as', 'Save labels to a different file',
                        enabled=False)

        saveAuto = action(
            text='Save &Automatically',
            slot=lambda x: self.actions.saveAuto.setChecked(x),
            icon='save',
            tip='Save automatically',
            checkable=True,
            enabled=True,
        )
        saveAuto.setChecked(self._config['auto_save'])

        close = action('&Close', self.closeFile, shortcuts['close'], 'close',
                       'Close current file')
        color1 = action('Polygon &Line Color', self.chooseColor1,
                        shortcuts['edit_line_color'], 'color_line',
                        'Choose polygon line color')
        color2 = action('Polygon &Fill Color', self.chooseColor2,
                        shortcuts['edit_fill_color'], 'color',
                        'Choose polygon fill color')

        createMode = action(
            'Create Polygons',
            lambda: self.toggleDrawMode(False, createMode='polygon'),
            shortcuts['create_polygon'],
            'objects',
            'Start drawing polygons',
            enabled=False,
        )
        createRectangleMode = action(
            'Create Rectangle',
            lambda: self.toggleDrawMode(False, createMode='rectangle'),
            shortcuts['create_rectangle'],
            'objects',
            'Start drawing rectangles',
            enabled=False,
        )
        createCircleMode = action(
            'Create Circle',
            lambda: self.toggleDrawMode(False, createMode='circle'),
            shortcuts['create_circle'],
            'objects',
            'Start drawing circles',
            enabled=False,
        )
        createLineMode = action(
            'Create Line',
            lambda: self.toggleDrawMode(False, createMode='line'),
            shortcuts['create_line'],
            'objects',
            'Start drawing lines',
            enabled=False,
        )
        createPointMode = action(
            'Create Point',
            lambda: self.toggleDrawMode(False, createMode='point'),
            shortcuts['create_point'],
            'objects',
            'Start drawing points',
            enabled=False,
        )
        createLineStripMode = action(
            'Create LineStrip',
            lambda: self.toggleDrawMode(False, createMode='linestrip'),
            shortcuts['create_linestrip'],
            'objects',
            'Start drawing linestrip. Ctrl+LeftClick ends creation.',
            enabled=False,
        )
        editMode = action('Edit Polygons', self.setEditMode,
                          shortcuts['edit_polygon'], 'edit',
                          'Move and edit polygons', enabled=False)

        delete = action('Delete Polygon', self.deleteSelectedShape,
                        shortcuts['delete_polygon'], 'cancel',
                        'Delete', enabled=False)
        copy = action('Duplicate Polygon', self.copySelectedShape,
                      shortcuts['duplicate_polygon'], 'copy',
                      'Create a duplicate of the selected polygon',
                      enabled=False)
        undoLastPoint = action('Undo last point', self.canvas.undoLastPoint,
                               shortcuts['undo_last_point'], 'undo',
                               'Undo last drawn point', enabled=False)
        addPoint = action('Add Point to Edge', self.canvas.addPointToEdge,
                          None, 'edit', 'Add point to the nearest edge',
                          enabled=False)

        undo = action('Undo', self.undoShapeEdit, shortcuts['undo'], 'undo',
                      'Undo last add and edit of shape', enabled=False)

        hideAll = action('&Hide\nPolygons',
                         functools.partial(self.togglePolygons, False),
                         icon='eye', tip='Hide all polygons', enabled=False)
        showAll = action('&Show\nPolygons',
                         functools.partial(self.togglePolygons, True),
                         icon='eye', tip='Show all polygons', enabled=False)

        help = action('&Tutorial', self.tutorial, icon='help',
                      tip='Show tutorial page')

        zoom = QtWidgets.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('%s,%s' % (shortcuts['zoom_in'],
                                    shortcuts['zoom_out'])),
             fmtShortcut("Ctrl+Wheel")))
        self.zoomWidget.setEnabled(False)

        zoomIn = action('Zoom &In', functools.partial(self.addZoom, 10),
                        shortcuts['zoom_in'], 'zoom-in',
                        'Increase zoom level', enabled=False)
        zoomOut = action('&Zoom Out', functools.partial(self.addZoom, -10),
                         shortcuts['zoom_out'], 'zoom-out',
                         'Decrease zoom level', enabled=False)
        zoomOrg = action('&Original size',
                         functools.partial(self.setZoom, 100),
                         shortcuts['zoom_to_original'], 'zoom',
                         'Zoom to original size', enabled=False)
        fitWindow = action('&Fit Window', self.setFitWindow,
                           shortcuts['fit_window'], 'fit-window',
                           'Zoom follows window size', checkable=True,
                           enabled=False)
        fitWidth = action('Fit &Width', self.setFitWidth,
                          shortcuts['fit_width'], '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.FIT_WINDOW
        fitWindow.setChecked(Qt.Checked)
        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, shortcuts['edit_label'],
                      'edit', 'Modify the label of the selected polygon',
                      enabled=False)

        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)
        fill_drawing = action(
            'Fill Drawing Polygon',
            lambda x: self.canvas.setFillDrawing(x),
            None,
            'color',
            'Fill polygon while drawing',
            checkable=True,
            enabled=True,
        )
        fill_drawing.setChecked(True)

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

        # Store actions for further handling.
        self.actions = struct(
            saveAuto=saveAuto,
            save=save, saveAs=saveAs, open=open_, close=close,
            lineColor=color1, fillColor=color2,
            delete=delete, edit=edit, copy=copy,
            undoLastPoint=undoLastPoint, undo=undo,
            addPoint=addPoint,
            createMode=createMode, editMode=editMode,
            createRectangleMode=createRectangleMode,
            createCircleMode=createCircleMode,
            createLineMode=createLineMode,
            createPointMode=createPointMode,
            createLineStripMode=createLineStripMode,
            shapeLineColor=shapeLineColor, shapeFillColor=shapeFillColor,
            zoom=zoom, zoomIn=zoomIn, zoomOut=zoomOut, zoomOrg=zoomOrg,
            fitWindow=fitWindow, fitWidth=fitWidth,
            zoomActions=zoomActions,
            openNextImg=openNextImg, openPrevImg=openPrevImg,
            fileMenuActions=(open_, opendir, save, saveAs, close, quit),
            tool=(),
            editMenu=(edit, copy, delete, None, undo, undoLastPoint,
                      None, color1, color2),
            # menu shown at right click
            menu=(
                createMode,
                createRectangleMode,
                createCircleMode,
                createLineMode,
                createPointMode,
                createLineStripMode,
                editMode,
                edit,
                copy,
                delete,
                shapeLineColor,
                shapeFillColor,
                undo,
                undoLastPoint,
                addPoint,
            ),
            onLoadActive=(
                close,
                createMode,
                createRectangleMode,
                createCircleMode,
                createLineMode,
                createPointMode,
                createLineStripMode,
                editMode,
            ),
            onShapesPresent=(saveAs, hideAll, showAll),
        )

        self.canvas.edgeSelected.connect(self.actions.addPoint.setEnabled)

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

        addActions(self.menus.file, (open_, openNextImg, openPrevImg, opendir,
                                     self.menus.recentFiles,
                                     save, saveAs, saveAuto, close,
                                     None,
                                     quit))
        addActions(self.menus.help, (help,))
        addActions(self.menus.view, (
            self.flag_dock.toggleViewAction(),
            self.label_dock.toggleViewAction(),
            self.shape_dock.toggleViewAction(),
            self.file_dock.toggleViewAction(),
            None,
            fill_drawing,
            None,
            hideAll,
            showAll,
            None,
            zoomIn,
            zoomOut,
            zoomOrg,
            None,
            fitWindow,
            fitWidth,
            None,
        ))

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

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

        self.tools = self.toolbar('Tools')
        # Menu buttons on Left
        self.actions.tool = (
            open_,
            opendir,
            openNextImg,
            openPrevImg,
            save,
            None,
            createMode,
            editMode,
            copy,
            delete,
            undo,
            None,
            zoomIn,
            zoom,
            zoomOut,
            fitWindow,
            fitWidth,
        )

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

        # Application state.
        self.image = QtGui.QImage()
        self.imagePath = None
        if self._config['auto_save'] and output is not None:
            warnings.warn('If `auto_save` argument is True, `output` argument '
                          'is ignored and output filename is automatically '
                          'set as IMAGE_BASENAME.json.')
        self.labeling_once = output is not None
        self.output = output
        self.recentFiles = []
        self.maxRecent = 7
        self.lineColor = None
        self.fillColor = None
        self.otherData = None
        self.zoom_level = 100
        self.fit_window = False

        if filename is not None and osp.isdir(filename):
            self.importDirImages(filename, load=False)
        else:
            self.filename = filename

        if config['file_search']:
            self.fileSearch.setText(config['file_search'])
            self.fileSearchChanged()

        # XXX: Could be completely declarative.
        # Restore application settings.
        self.settings = QtCore.QSettings('labelme', 'labelme')
        # FIXME: QSettings.value can return None on PyQt4
        self.recentFiles = self.settings.value('recentFiles', []) or []
        size = self.settings.value('window/size', QtCore.QSize(600, 500))
        position = self.settings.value('window/position', QtCore.QPoint(0, 0))
        self.resize(size)
        self.move(position)
        # or simply:
        # self.restoreGeometry(settings['window/geometry']
        self.restoreState(
            self.settings.value('window/state', QtCore.QByteArray()))
        self.lineColor = QtGui.QColor(
            self.settings.value('line/color', Shape.line_color))
        self.fillColor = QtGui.QColor(
            self.settings.value('fill/color', Shape.fill_color))
        Shape.line_color = self.lineColor
        Shape.fill_color = self.fillColor

        # 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(functools.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.labelList.itemsToShapes

    def populateModeActions(self):
        tool, menu = self.actions.tool, self.actions.menu
        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.createMode,
            self.actions.createRectangleMode,
            self.actions.createCircleMode,
            self.actions.createLineMode,
            self.actions.createPointMode,
            self.actions.createLineStripMode,
            self.actions.editMode,
        )
        addActions(self.menus.edit, actions + self.actions.editMenu)

    def setDirty(self):
        if self._config['auto_save'] or self.actions.saveAuto.isChecked():
            label_file = osp.splitext(self.imagePath)[0] + '.json'
            self.saveLabels(label_file)
            return
        self.dirty = True
        self.actions.save.setEnabled(True)
        self.actions.undo.setEnabled(self.canvas.isShapeRestorable)
        title = __appname__
        if self.filename is not None:
            title = '{} - {}*'.format(title, self.filename)
        self.setWindowTitle(title)

    def setClean(self):
        self.dirty = False
        self.actions.save.setEnabled(False)
        self.actions.createMode.setEnabled(True)
        self.actions.createRectangleMode.setEnabled(True)
        self.actions.createCircleMode.setEnabled(True)
        self.actions.createLineMode.setEnabled(True)
        self.actions.createPointMode.setEnabled(True)
        self.actions.createLineStripMode.setEnabled(True)
        title = __appname__
        if self.filename is not None:
            title = '{} - {}'.format(title, self.filename)
        self.setWindowTitle(title)

    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):
        QtCore.QTimer.singleShot(0, function)

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

    def resetState(self):
        self.labelList.clear()
        self.filename = None
        self.imagePath = None
        self.imageData = None
        self.labelFile = None
        self.otherData = 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)

    # Callbacks

    def undoShapeEdit(self):
        self.canvas.restoreShape()
        self.labelList.clear()
        self.loadShapes(self.canvas.shapes)
        self.actions.undo.setEnabled(self.canvas.isShapeRestorable)

    def tutorial(self):
        url = 'https://github.com/wkentaro/labelme/tree/master/examples/tutorial'  # NOQA
        webbrowser.open(url)

    def toggleAddPointEnabled(self, enabled):
        self.actions.addPoint.setEnabled(enabled)

    def toggleDrawingSensitive(self, drawing=True):
        """Toggle drawing sensitive.

        In the middle of drawing, toggling between modes should be disabled.
        """
        self.actions.editMode.setEnabled(not drawing)
        self.actions.undoLastPoint.setEnabled(drawing)
        self.actions.undo.setEnabled(not drawing)
        self.actions.delete.setEnabled(not drawing)

    def toggleDrawMode(self, edit=True, createMode='polygon'):
        self.canvas.setEditing(edit)
        self.canvas.createMode = createMode
        if edit:
            self.actions.createMode.setEnabled(True)
            self.actions.createRectangleMode.setEnabled(True)
            self.actions.createCircleMode.setEnabled(True)
            self.actions.createLineMode.setEnabled(True)
            self.actions.createPointMode.setEnabled(True)
            self.actions.createLineStripMode.setEnabled(True)
        else:
            if createMode == 'polygon':
                self.actions.createMode.setEnabled(False)
                self.actions.createRectangleMode.setEnabled(True)
                self.actions.createCircleMode.setEnabled(True)
                self.actions.createLineMode.setEnabled(True)
                self.actions.createPointMode.setEnabled(True)
                self.actions.createLineStripMode.setEnabled(True)
            elif createMode == 'rectangle':
                self.actions.createMode.setEnabled(True)
                self.actions.createRectangleMode.setEnabled(False)
                self.actions.createCircleMode.setEnabled(True)
                self.actions.createLineMode.setEnabled(True)
                self.actions.createPointMode.setEnabled(True)
                self.actions.createLineStripMode.setEnabled(True)
            elif createMode == 'line':
                self.actions.createMode.setEnabled(True)
                self.actions.createRectangleMode.setEnabled(True)
                self.actions.createCircleMode.setEnabled(True)
                self.actions.createLineMode.setEnabled(False)
                self.actions.createPointMode.setEnabled(True)
                self.actions.createLineStripMode.setEnabled(True)
            elif createMode == 'point':
                self.actions.createMode.setEnabled(True)
                self.actions.createRectangleMode.setEnabled(True)
                self.actions.createCircleMode.setEnabled(True)
                self.actions.createLineMode.setEnabled(True)
                self.actions.createPointMode.setEnabled(False)
                self.actions.createLineStripMode.setEnabled(True)
            elif createMode == "circle":
                self.actions.createMode.setEnabled(True)
                self.actions.createRectangleMode.setEnabled(True)
                self.actions.createCircleMode.setEnabled(False)
                self.actions.createLineMode.setEnabled(True)
                self.actions.createPointMode.setEnabled(True)
                self.actions.createLineStripMode.setEnabled(True)
            elif createMode == "linestrip":
                self.actions.createMode.setEnabled(True)
                self.actions.createRectangleMode.setEnabled(True)
                self.actions.createCircleMode.setEnabled(True)
                self.actions.createLineMode.setEnabled(True)
                self.actions.createPointMode.setEnabled(True)
                self.actions.createLineStripMode.setEnabled(False)
            else:
                raise ValueError('Unsupported createMode: %s' % createMode)
        self.actions.editMode.setEnabled(not edit)

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

    def updateFileMenu(self):
        current = self.filename

        def exists(filename):
            return osp.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 = QtWidgets.QAction(
                icon, '&%d %s' % (i + 1, QtCore.QFileInfo(f).fileName()), self)
            action.triggered.connect(functools.partial(self.loadRecent, f))
            menu.addAction(action)

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

    def validateLabel(self, label):
        # no validation
        if self._config['validate_label'] is None:
            return True

        for i in range(self.uniqLabelList.count()):
            label_i = self.uniqLabelList.item(i).text()
            if self._config['validate_label'] in ['exact', 'instance']:
                if label_i == label:
                    return True
            if self._config['validate_label'] == 'instance':
                m = re.match(r'^{}-[0-9]*$'.format(label_i), label)
                if m:
                    return True
        return False

    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
        if not self.validateLabel(text):
            self.errorMessage('Invalid label',
                              "Invalid label '{}' with validation type '{}'"
                              .format(text, self._config['validate_label']))
            return
        item.setText(text)
        self.setDirty()
        if not self.uniqLabelList.findItems(text, Qt.MatchExactly):
            self.uniqLabelList.addItem(text)
            self.uniqLabelList.sortItems()

    def fileSearchChanged(self):
        self.importDirImages(
            self.lastOpenDir,
            pattern=self.fileSearch.text(),
            load=False,
        )

    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:
                item = self.labelList.get_item_from_shape(shape)
                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 = QtWidgets.QListWidgetItem(shape.label)
        item.setFlags(item.flags() | Qt.ItemIsUserCheckable)
        item.setCheckState(Qt.Checked)
        self.labelList.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 remLabel(self, shape):
        item = self.labelList.get_item_from_shape(shape)
        self.labelList.takeItem(self.labelList.row(item))

    def loadShapes(self, shapes):
        for shape in shapes:
            self.addLabel(shape)
        self.canvas.loadShapes(shapes)

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

    def loadFlags(self, flags):
        self.flag_widget.clear()
        for key, flag in flags.items():
            item = QtWidgets.QListWidgetItem(key)
            item.setFlags(item.flags() | Qt.ItemIsUserCheckable)
            item.setCheckState(Qt.Checked if flag else Qt.Unchecked)
            self.flag_widget.addItem(item)

    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],
                        shape_type=s.shape_type)

        shapes = [format_shape(shape) for shape in self.labelList.shapes]
        flags = {}
        for i in range(self.flag_widget.count()):
            item = self.flag_widget.item(i)
            key = item.text()
            flag = item.checkState() == Qt.Checked
            flags[key] = flag
        try:
            imagePath = osp.relpath(
                self.imagePath, osp.dirname(filename))
            imageData = self.imageData if self._config['store_data'] else None
            lf.save(
                filename=filename,
                shapes=shapes,
                imagePath=imagePath,
                imageData=imageData,
                imageHeight=self.image.height(),
                imageWidth=self.image.width(),
                lineColor=self.lineColor.getRgb(),
                fillColor=self.fillColor.getRgb(),
                otherData=self.otherData,
                flags=flags,
            )
            self.labelFile = lf
            items = self.fileListWidget.findItems(
                self.imagePath, Qt.MatchExactly
            )
            if len(items) > 0:
                if len(items) != 1:
                    raise RuntimeError('There are duplicate files.')
                items[0].setCheckState(Qt.Checked)
            # disable allows next and previous image to proceed
            # self.filename = filename
            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
            shape = self.labelList.get_shape_from_item(item)
            self.canvas.selectShape(shape)

    def labelItemChanged(self, item):
        shape = self.labelList.get_shape_from_item(item)
        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 and not self.validateLabel(text):
            self.errorMessage('Invalid label',
                              "Invalid label '{}' with validation type '{}'"
                              .format(text, self._config['validate_label']))
            text = None
        if text is None:
            self.canvas.undoLastLine()
            self.canvas.shapesBackups.pop()
        else:
            self.addLabel(self.canvas.setLastLabel(text))
            self.actions.editMode.setEnabled(True)
            self.actions.undoLastPoint.setEnabled(False)
            self.actions.undo.setEnabled(True)
            self.setDirty()

    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, pos):
        canvas_width_old = self.canvas.width()

        units = delta * 0.1
        self.addZoom(units)

        canvas_width_new = self.canvas.width()
        if canvas_width_old != canvas_width_new:
            canvas_scale_factor = canvas_width_new / canvas_width_old

            x_shift = round(pos.x() * canvas_scale_factor) - pos.x()
            y_shift = round(pos.y() * canvas_scale_factor) - pos.y()

            self.scrollBars[Qt.Horizontal].setValue(
                self.scrollBars[Qt.Horizontal].value() + x_shift)
            self.scrollBars[Qt.Vertical].setValue(
                self.scrollBars[Qt.Vertical].value() + y_shift)

    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.labelList.itemsToShapes:
            item.setCheckState(Qt.Checked if value else Qt.Unchecked)

    def convertImageDataToPng(self, imageData):
        if imageData is None:
            return
        img = PIL.Image.open(io.BytesIO(imageData))
        with io.BytesIO() as imgBytesIO:
            img.save(imgBytesIO, "PNG")
            imgBytesIO.seek(0)
            data = imgBytesIO.read()
        return data

    def loadFile(self, filename=None):
        """Load the specified file, or the last opened file if None."""
        # changing fileListWidget loads file
        if (filename in self.imageList and
                self.fileListWidget.currentRow() !=
                self.imageList.index(filename)):
            self.fileListWidget.setCurrentRow(self.imageList.index(filename))
            self.fileListWidget.repaint()
            return

        self.resetState()
        self.canvas.setEnabled(False)
        if filename is None:
            filename = self.settings.value('filename', '')
        filename = str(filename)
        if not QtCore.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..." % osp.basename(str(filename)))
        label_file = osp.splitext(filename)[0] + '.json'
        if QtCore.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 QtGui.QImage.fromData(self.labelFile.imageData).isNull():
                    # tries to read image with PIL and convert it to PNG
                    self.labelFile.imageData = self.convertImageDataToPng(
                        self.labelFile.imageData)
                if QtGui.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 = osp.join(
                osp.dirname(label_file),
                self.labelFile.imagePath,
            )
            self.lineColor = QtGui.QColor(*self.labelFile.lineColor)
            self.fillColor = QtGui.QColor(*self.labelFile.fillColor)
            self.otherData = self.labelFile.otherData
        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
                if QtGui.QImage.fromData(self.imageData).isNull():
                    self.imageData = self.convertImageDataToPng(self.imageData)
            self.labelFile = None
        image = QtGui.QImage.fromData(self.imageData)
        if image.isNull():
            formats = ['*.{}'.format(fmt.data().decode())
                       for fmt in QtGui.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
        if self._config['keep_prev']:
            prev_shapes = self.canvas.shapes
        self.canvas.loadPixmap(QtGui.QPixmap.fromImage(image))
        if self._config['flags']:
            self.loadFlags({k: False for k in self._config['flags']})
        if self._config['keep_prev']:
            self.loadShapes(prev_shapes)
        if self.labelFile:
            self.loadLabels(self.labelFile.shapes)
            if self.labelFile.flags is not None:
                self.loadFlags(self.labelFile.flags)
        self.setClean()
        self.canvas.setEnabled(True)
        self.adjustScale(initial=True)
        self.paintCanvas()
        self.addRecentFile(self.filename)
        self.toggleActions(True)
        self.status("Loaded %s" % osp.basename(str(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 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()
        self.settings.setValue(
            'filename', self.filename if self.filename else '')
        self.settings.setValue('window/size', self.size())
        self.settings.setValue('window/position', self.pos())
        self.settings.setValue('window/state', self.saveState())
        self.settings.setValue('line/color', self.lineColor)
        self.settings.setValue('fill/color', self.fillColor)
        self.settings.setValue('recentFiles', self.recentFiles)
        # ask the use for where to save the labels
        # self.settings.setValue('window/geometry', self.saveGeometry())

    # User Dialogs #

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

    def openPrevImg(self, _value=False):
        keep_prev = self._config['keep_prev']
        if QtGui.QGuiApplication.keyboardModifiers() == \
                (QtCore.Qt.ControlModifier | QtCore.Qt.ShiftModifier):
            self._config['keep_prev'] = True

        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)

        self._config['keep_prev'] = keep_prev

    def openNextImg(self, _value=False, load=True):
        keep_prev = self._config['keep_prev']
        if QtGui.QGuiApplication.keyboardModifiers() == \
                (QtCore.Qt.ControlModifier | QtCore.Qt.ShiftModifier):
            self._config['keep_prev'] = True

        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]
            else:
                filename = self.imageList[-1]
        self.filename = filename

        if self.filename and load:
            self.loadFile(self.filename)

        self._config['keep_prev'] = keep_prev

    def openFile(self, _value=False):
        if not self.mayContinue():
            return
        path = osp.dirname(str(self.filename)) if self.filename else '.'
        formats = ['*.{}'.format(fmt.data().decode())
                   for fmt in QtGui.QImageReader.supportedImageFormats()]
        filters = "Image & Label files (%s)" % ' '.join(
            formats + ['*%s' % LabelFile.suffix])
        filename = QtWidgets.QFileDialog.getOpenFileName(
            self, '%s - Choose Image or Label file' % __appname__,
            path, filters)
        if QT5:
            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._config['flags'] or 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 = QtWidgets.QFileDialog(self, caption, self.currentPath(), filters)
        dlg.setDefaultSuffix(LabelFile.suffix[1:])
        dlg.setAcceptMode(QtWidgets.QFileDialog.AcceptSave)
        dlg.setOption(QtWidgets.QFileDialog.DontConfirmOverwrite, False)
        dlg.setOption(QtWidgets.QFileDialog.DontUseNativeDialog, False)
        basename = osp.splitext(self.filename)[0]
        default_labelfile_name = osp.join(
            self.currentPath(), basename + LabelFile.suffix)
        filename = dlg.getSaveFileName(
            self, 'Choose File', default_labelfile_name,
            'Label files (*%s)' % LabelFile.suffix)
        if QT5:
            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.labelList.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 = QtWidgets.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 QtWidgets.QMessageBox.critical(
            self, title, '<p><b>%s</b></p>%s' % (title, message))

    def currentPath(self):
        return osp.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 = QtWidgets.QMessageBox.Yes, QtWidgets.QMessageBox.No
        msg = 'You are about to permanently delete this polygon, ' \
              'proceed anyway?'
        if yes == QtWidgets.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 osp.exists(self.lastOpenDir):
            defaultOpenDirPath = self.lastOpenDir
        else:
            defaultOpenDirPath = osp.dirname(self.filename) \
                if self.filename else '.'

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

    @property
    def imageList(self):
        lst = []
        for i in range(self.fileListWidget.count()):
            item = self.fileListWidget.item(i)
            lst.append(item.text())
        return lst

    def importDirImages(self, dirpath, pattern=None, load=True):
        self.actions.openNextImg.setEnabled(True)
        self.actions.openPrevImg.setEnabled(True)

        if not self.mayContinue() or not dirpath:
            return

        self.lastOpenDir = dirpath
        self.filename = None
        self.fileListWidget.clear()
        for filename in self.scanAllImages(dirpath):
            if pattern and pattern not in filename:
                continue
            label_file = osp.splitext(filename)[0] + '.json'
            item = QtWidgets.QListWidgetItem(filename)
            item.setFlags(Qt.ItemIsEnabled | Qt.ItemIsSelectable)
            if QtCore.QFile.exists(label_file) and \
                    LabelFile.isLabelFile(label_file):
                item.setCheckState(Qt.Checked)
            else:
                item.setCheckState(Qt.Unchecked)
            self.fileListWidget.addItem(item)
        self.openNextImg(load=load)

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

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


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