/Orange/widgets/gui.py

import math
import os
import re
import itertools
from types import LambdaType

import pkg_resources
import numpy

from PyQt4 import QtGui, QtCore, QtWebKit
from PyQt4.QtCore import Qt, pyqtSignal as Signal
from PyQt4.QtGui import QCursor, QApplication

import Orange.data
from Orange.widgets.utils import getdeepattr
from Orange.data import \
    ContinuousVariable, StringVariable, TimeVariable, DiscreteVariable, Variable
from Orange.widgets.utils import vartype
from Orange.widgets.utils.constants import CONTROLLED_ATTRIBUTES, ATTRIBUTE_CONTROLLERS
from Orange.util import namegen

YesNo = NoYes = ("No", "Yes")
_enter_icon = None
__re_label = re.compile(r"(^|[^%])%\((?P<value>[a-zA-Z]\w*)\)")


OrangeUserRole = itertools.count(Qt.UserRole)

LAMBDA_NAME = namegen('_lambda_')


def resource_filename(path):
    """
    Return a resource filename (package data) for path.
    """
    return pkg_resources.resource_filename(__name__, path)


class TableWidget(QtGui.QTableWidget):
    """ An easy to use, row-oriented table widget """

    ROW_DATA_ROLE = QtCore.Qt.UserRole + 1
    ITEM_DATA_ROLE = ROW_DATA_ROLE + 1

    class TableWidgetNumericItem(QtGui.QTableWidgetItem):
        """TableWidgetItem that sorts numbers correctly!"""
        def __lt__(self, other):
            return (self.data(TableWidget.ITEM_DATA_ROLE) <
                    other.data(TableWidget.ITEM_DATA_ROLE))

    def selectionChanged(self, selected:[QtGui.QItemSelectionRange], deselected:[QtGui.QItemSelectionRange]):
        """Override or monkey-patch this method to catch selection changes"""
        super().selectionChanged(selected, deselected)

    def __setattr__(self, attr, value):
        """
        The following selectionChanged magic ensures selectionChanged
        slot, when monkey-patched, always calls the super's selectionChanged
        first (--> avoids Qt quirks), and the user needs not care about that.
        """
        if attr == 'selectionChanged':
            func = value
            @QtCore.pyqtSlot(QtGui.QItemSelection, QtGui.QItemSelection)
            def _f(selected, deselected):
                super(self.__class__, self).selectionChanged(selected, deselected)
                func(selected, deselected)
            value = _f
        self.__dict__[attr] = value

    def _update_headers(func):
        """Decorator to update certain table features after method calls"""
        def _f(self, *args, **kwargs):
            func(self, *args, **kwargs)
            if self.col_labels is not None:
                self.setHorizontalHeaderLabels(self.col_labels)
            if self.row_labels is not None:
                self.setVerticalHeaderLabels(self.row_labels)
            if self.stretch_last_section:
                self.horizontalHeader().setStretchLastSection(True)
        return _f

    @_update_headers
    def __init__(self,
                 parent=None,
                 col_labels=None,
                 row_labels=None,
                 stretch_last_section=True,
                 multi_selection=False,
                 select_rows=False):
        """
        Parameters
        ----------
        parent: QObject
            Parent QObject. If parent has layout(), this widget is added to it.
        col_labels: list of str
            Labels or [] (sequential numbers) or None (no horizontal header)
        row_label: list_of_str
            Labels or [] (sequential numbers) or None (no vertical header)
        stretch_last_section: bool
        multi_selection: bool
            Single selection if False
        select_rows: bool
            If True, select whole rows instead of individual cells.
        """
        super().__init__(parent)
        self._column_filter = {}
        self.col_labels = col_labels
        self.row_labels = row_labels
        self.stretch_last_section = stretch_last_section
        try: parent.layout().addWidget(self)
        except (AttributeError, TypeError): pass
        if col_labels is None:
            self.horizontalHeader().setVisible(False)
        if row_labels is None:
            self.verticalHeader().setVisible(False)
        if multi_selection:
            self.setSelectionMode(self.MultiSelection)
        if select_rows:
            self.setSelectionBehavior(self.SelectRows)
        self.setHorizontalScrollMode(self.ScrollPerPixel)
        self.setVerticalScrollMode(self.ScrollPerPixel)
        self.setEditTriggers(self.NoEditTriggers)
        self.setAlternatingRowColors(True)
        self.setShowGrid(False)
        self.setSortingEnabled(True)

    @_update_headers
    def addRow(self, items:tuple, data=None):
        """
        Appends iterable of `items` as the next row, optionally setting row
        data to `data`. Each item of `items` can be a string or tuple
        (item_name, item_data) if individual, cell-data is required.
        """
        row_data = data
        row = self.rowCount()
        self.insertRow(row)
        col_count = max(len(items), self.columnCount())
        if col_count != self.columnCount():
            self.setColumnCount(col_count)
        for col, item_data in enumerate(items):
            if isinstance(item_data, str):
                name = item_data
            elif hasattr(item_data, '__iter__') and len(item_data) == 2:
                name, item_data = item_data
            elif isinstance(item_data, float):
                name = '{:.4f}'.format(item_data)
            else:
                name = str(item_data)
            if isinstance(item_data, (float, int, numpy.number)):
                item = self.TableWidgetNumericItem(name)
            else:
                item = QtGui.QTableWidgetItem(name)
            item.setData(self.ITEM_DATA_ROLE, item_data)
            if col in self._column_filter:
                item = self._column_filter[col](item) or item
            self.setItem(row, col, item)
        self.resizeColumnsToContents()
        self.resizeRowsToContents()
        if row_data is not None:
            self.setRowData(row, row_data)

    def rowData(self, row:int):
        return self.item(row, 0).data(self.ROW_DATA_ROLE)

    def setRowData(self, row:int, data):
        self.item(row, 0).setData(self.ROW_DATA_ROLE, data)

    def setColumnFilter(self, item_filter_func, columns:int or list):
        """
        Pass item(s) at column(s) through `item_filter_func` before
        insertion. Useful for setting specific columns to bold or similar.
        """
        try: iter(columns)
        except TypeError: columns = [columns]
        for i in columns:
            self._column_filter[i] = item_filter_func

    def clear(self):
        super().clear()
        self.setRowCount(0)
        self.setColumnCount(0)

    def selectFirstRow(self):
        if self.rowCount() > 0:
            self.selectRow(0)

    def selectRowsWhere(self, col, value, n_hits=-1,
                        flags=QtCore.Qt.MatchExactly, _select=True):
        """
        Select (also return) at most `n_hits` rows where column `col`
        has value (``data()``) `value`.
        """
        model = self.model()
        matches = model.match(model.index(0, col),
                              self.ITEM_DATA_ROLE,
                              value,
                              n_hits,
                              flags)
        model = self.selectionModel()
        selection_flag = model.Select if _select else model.Deselect
        for index in matches:
            if _select ^ model.isSelected(index):
                model.select(index, selection_flag | model.Rows)
        return matches

    def deselectRowsWhere(self, col, value, n_hits=-1,
                          flags=QtCore.Qt.MatchExactly):
        """
        Deselect (also return) at most `n_hits` rows where column `col`
        has value (``data()``) `value`.
        """
        return self.selectRowsWhere(col, value, n_hits, flags, False)


class WebviewWidget(QtWebKit.QWebView):
    """WebKit window in a window"""
    def __init__(self, parent=None, bridge=None, html=None, debug=None):
        """
        Parameters
        ----------
        parent: QObject
            Parent QObject. If parent has layout(), this widget is added to it.
        bridge: QObject
            The "bridge" object exposed as ``window.pybridge`` in JavaScript.
            Any bridge methods desired to be accessible from JS need to be
            decorated ``@QtCore.pyqtSlot(<*args>, result=<type>)``.
        html: str
            HTML content to set in the webview.
        debug: bool
            If True, enable context menu and webkit inspector.
        """
        super().__init__(parent)
        self.setSizePolicy(QtGui.QSizePolicy(QtGui.QSizePolicy.Expanding,
                                             QtGui.QSizePolicy.Expanding))
        self._bridge = bridge
        try: parent.layout().addWidget(self)
        except (AttributeError, TypeError): pass
        settings = self.settings()
        settings.setAttribute(settings.LocalContentCanAccessFileUrls, True)
        if debug is None:
            import logging
            debug = logging.getLogger().level <= logging.DEBUG
        if debug:
            settings.setAttribute(settings.DeveloperExtrasEnabled, True)
        else:
            self.setContextMenuPolicy(QtCore.Qt.NoContextMenu)
        if html:
            self.setHtml(html)

    def setContent(self, data, mimetype, url=''):
        super().setContent(data, mimetype, QtCore.QUrl(url))
        if self._bridge:
            self.page().mainFrame().addToJavaScriptWindowObject('pybridge', self._bridge)

    def setHtml(self, html, url=''):
        self.setContent(html.encode('utf-8'), 'text/html', url)

    def sizeHint(self):
        return QtCore.QSize(600, 500)

    def evalJS(self, javascript):
        self.page().mainFrame().evaluateJavaScript(javascript)


class ControlledAttributesDict(dict):
    def __init__(self, master):
        super().__init__()
        self.master = master

    def __setitem__(self, key, value):
        if key not in self:
            dict.__setitem__(self, key, [value])
        else:
            dict.__getitem__(self, key).append(value)
        set_controllers(self.master, key, self.master, "")

callbacks = lambda obj: getattr(obj, CONTROLLED_ATTRIBUTES, {})
subcontrollers = lambda obj: getattr(obj, ATTRIBUTE_CONTROLLERS, {})


def notify_changed(obj, name, value):
    if name in callbacks(obj):
        for callback in callbacks(obj)[name]:
            callback(value)
        return

    for controller, prefix in list(subcontrollers(obj)):
        if getdeepattr(controller, prefix, None) != obj:
            del subcontrollers(obj)[(controller, prefix)]
            continue

        full_name = prefix + "." + name
        if full_name in callbacks(controller):
            for callback in callbacks(controller)[full_name]:
                callback(value)
            continue

        prefix = full_name + "."
        prefix_length = len(prefix)
        for controlled in callbacks(controller):
            if controlled[:prefix_length] == prefix:
                set_controllers(value, controlled[prefix_length:], controller, full_name)


def set_controllers(obj, controlled_name, controller, prefix):
    while obj:
        if prefix:
            if hasattr(obj, ATTRIBUTE_CONTROLLERS):
                getattr(obj, ATTRIBUTE_CONTROLLERS)[(controller, prefix)] = True
            else:
                setattr(obj, ATTRIBUTE_CONTROLLERS, {(controller, prefix): True})
        parts = controlled_name.split(".", 1)
        if len(parts) < 2:
            break
        new_prefix, controlled_name = parts
        obj = getattr(obj, new_prefix, None)
        if prefix:
            prefix += '.'
        prefix += new_prefix


class OWComponent:
    def __init__(self, widget):
        setattr(self, CONTROLLED_ATTRIBUTES, ControlledAttributesDict(self))

        if widget.settingsHandler:
            widget.settingsHandler.initialize(self)

    def __setattr__(self, key, value):
        super().__setattr__(key, value)
        notify_changed(self, key, value)


def miscellanea(control, box, parent,
                addToLayout=True, stretch=0, sizePolicy=None, addSpace=False,
                disabled=False, tooltip=None):
    """
    Helper function that sets various properties of the widget using a common
    set of arguments.

    The function
    - sets the `control`'s attribute `box`, if `box` is given and `control.box`
    is not yet set,
    - attaches a tool tip to the `control` if specified,
    - disables the `control`, if `disabled` is set to `True`,
    - adds the `box` to the `parent`'s layout unless `addToLayout` is set to
    `False`; the stretch factor can be specified,
    - adds the control into the box's layout if the box is given (regardless
    of `addToLayout`!)
    - sets the size policy for the box or the control, if the policy is given,
    - adds space in the `parent`'s layout after the `box` if `addSpace` is set
    and `addToLayout` is not `False`.

    If `box` is the same as `parent` it is set to `None`; this is convenient
    because of the way complex controls are inserted.

    :param control: the control, e.g. a `QCheckBox`
    :type control: PyQt4.QtGui.QWidget
    :param box: the box into which the widget was inserted
    :type box: PyQt4.QtGui.QWidget or None
    :param parent: the parent into whose layout the box or the control will be
        inserted
    :type parent: PyQt4.QtGui.QWidget
    :param addSpace: the amount of space to add after the widget
    :type addSpace: bool or int
    :param disabled: If set to `True`, the widget is initially disabled
    :type disabled: bool
    :param addToLayout: If set to `False` the widget is not added to the layout
    :type addToLayout: bool
    :param stretch: the stretch factor for this widget, used when adding to
        the layout (default: 0)
    :type stretch: int
    :param tooltip: tooltip that is attached to the widget
    :type tooltip: str or None
    :param sizePolicy: the size policy for the box or the control
    :type sizePolicy: PyQt4.QtQui.QSizePolicy
    """
    if disabled:
        # if disabled==False, do nothing; it can be already disabled
        control.setDisabled(disabled)
    if tooltip is not None:
        control.setToolTip(tooltip)
    if box is parent:
        box = None
    elif box and box is not control and not hasattr(control, "box"):
        control.box = box
    if box and box.layout() is not None and \
            isinstance(control, QtGui.QWidget) and \
            box.layout().indexOf(control) == -1:
        box.layout().addWidget(control)
    if sizePolicy is not None:
        (box or control).setSizePolicy(sizePolicy)
    if addToLayout and parent and parent.layout() is not None:
        parent.layout().addWidget(box or control, stretch)
        _addSpace(parent, addSpace)


def setLayout(widget, orientation):
    """
    Set the layout of the widget according to orientation. Argument
    `orientation` can be an instance of :obj:`~PyQt4.QtGui.QLayout`, in which
    case is it used as it is. If `orientation` is `'vertical'` or `True`,
    the layout is set to :obj:`~PyQt4.QtGui.QVBoxLayout`. If it is
    `'horizontal'` or `False`, it is set to :obj:`~PyQt4.QtGui.QVBoxLayout`.

    :param widget: the widget for which the layout is being set
    :type widget: PyQt4.QtGui.QWidget
    :param orientation: orientation for the layout
    :type orientation: str or bool or PyQt4.QtGui.QLayout
    """
    if isinstance(orientation, QtGui.QLayout):
        widget.setLayout(orientation)
    elif orientation == 'horizontal' or not orientation:
        widget.setLayout(QtGui.QHBoxLayout())
    else:
        widget.setLayout(QtGui.QVBoxLayout())


def _enterButton(parent, control, placeholder=True):
    """
    Utility function that returns a button with a symbol for "Enter" and
    optionally a placeholder to show when the enter button is hidden. Both
    are inserted into the parent's layout, if it has one. If placeholder is
    constructed it is shown and the button is hidden.

    The height of the button is the same as the height of the widget passed
    as argument `control`.

    :param parent: parent widget into which the button is inserted
    :type parent: PyQt4.QtGui.QWidget
    :param control: a widget for determining the height of the button
    :type control: PyQt4.QtGui.QWidget
    :param placeholder: a flag telling whether to construct a placeholder
        (default: True)
    :type placeholder: bool
    :return: a tuple with a button and a place holder (or `None`)
    :rtype: PyQt4.QtGui.QToolButton or tuple
    """
    global _enter_icon
    if not _enter_icon:
        _enter_icon = QtGui.QIcon(
            os.path.dirname(__file__) + "/icons/Dlg_enter.png")
    button = QtGui.QPushButton(parent)
    button.setAutoDefault(True)
    button.setDefault(True)
    height = control.sizeHint().height()
    button.setFixedSize(height, height)
    button.setIcon(_enter_icon)
    if parent.layout() is not None:
        parent.layout().addWidget(button)
    if placeholder:
        button.hide()
        holder = QtGui.QWidget(parent)
        holder.setFixedSize(height, height)
        if parent.layout() is not None:
            parent.layout().addWidget(holder)
    else:
        holder = None
    return button, holder


def _addSpace(widget, space):
    """
    A helper function that adds space into the widget, if requested.
    The function is called by functions that have the `addSpace` argument.

    :param widget: Widget into which to insert the space
    :type widget: PyQt4.QtGui.QWidget
    :param space: Amount of space to insert. If False, the function does
        nothing. If the argument is an `int`, the specified space is inserted.
        Otherwise, the default space is inserted by calling a :obj:`separator`.
    :type space: bool or int
    """
    if space:
        if type(space) == int:  # distinguish between int and bool!
            separator(widget, space, space)
        else:
            separator(widget)


def separator(widget, width=4, height=4):
    """
    Add a separator of the given size into the widget.

    :param widget: the widget into whose layout the separator is added
    :type widget: PyQt4.QtGui.QWidget
    :param width: width of the separator
    :type width: int
    :param height: height of the separator
    :type height: int
    :return: separator
    :rtype: PyQt4.QtGui.QWidget
    """
    sep = QtGui.QWidget(widget)
    if widget.layout() is not None:
        widget.layout().addWidget(sep)
    sep.setFixedSize(width, height)
    return sep


def rubber(widget):
    """
    Insert a stretch 100 into the widget's layout
    """
    widget.layout().addStretch(100)


def widgetBox(widget, box=None, orientation='vertical', margin=None, spacing=4,
              **misc):
    """
    Construct a box with vertical or horizontal layout, and optionally,
    a border with an optional label.

    If the widget has a frame, the space after the widget is added unless
    explicitly disabled.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param box: tells whether the widget has a border, and its label
    :type box: int or str or None
    :param orientation: orientation for the layout. If the argument is an
        instance of :obj:`~PyQt4.QtGui.QLayout`, it is used as a layout. If
        "horizontal" or false-ish, the layout is horizontal
        (:obj:`~PyQt4.QtGui.QHBoxLayout`), otherwise vertical
        (:obj:`~PyQt4.QtGui.QHBoxLayout`).
    :type orientation: str, int or :obj:`PyQt4.QtGui.QLayout`
    :param sizePolicy: The size policy for the widget (default: None)
    :type sizePolicy: :obj:`~PyQt4.QtGui.QSizePolicy`
    :param margin: The margin for the layout. Default is 7 if the widget has
        a border, and 0 if not.
    :type margin: int
    :param spacing: Spacing within the layout (default: 4)
    :type spacing: int
    :return: Constructed box
    :rtype: PyQt4.QtGui.QGroupBox or PyQt4.QtGui.QWidget
    """
    if box:
        b = QtGui.QGroupBox(widget)
        if isinstance(box, str):
            b.setTitle(" " + box.strip() + " ")
        if margin is None:
            margin = 7
    else:
        b = QtGui.QWidget(widget)
        b.setContentsMargins(0, 0, 0, 0)
        if margin is None:
            margin = 0
    setLayout(b, orientation)
    b.layout().setSpacing(spacing)
    b.layout().setMargin(margin)
    misc.setdefault('addSpace', bool(box))
    miscellanea(b, None, widget, **misc)
    return b


def hBox(*args, **kwargs):
    return widgetBox(orientation="horizontal", *args, **kwargs)


def vBox(*args, **kwargs):
    return widgetBox(orientation="vertical", *args, **kwargs)


def indentedBox(widget, sep=20, orientation="vertical", **misc):
    """
    Creates an indented box. The function can also be used "on the fly"::

        gui.checkBox(gui.indentedBox(box), self, "spam", "Enable spam")

    To align the control with a check box, use :obj:`checkButtonOffsetHint`::

        gui.hSlider(gui.indentedBox(self.interBox), self, "intervals")

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget
    :param sep: Indent size (default: 20)
    :type sep: int
    :param orientation: layout of the inserted box; see :obj:`widgetBox` for
        details
    :type orientation: str, int or PyQt4.QtGui.QLayout
    :return: Constructed box
    :rtype: PyQt4.QtGui.QGroupBox or PyQt4.QtGui.QWidget
    """
    outer = widgetBox(widget, orientation=False, spacing=0)
    separator(outer, sep, 0)
    indented = widgetBox(outer, orientation=orientation)
    miscellanea(indented, outer, widget, **misc)
    return indented


def widgetLabel(widget, label="", labelWidth=None, **misc):
    """
    Construct a simple, constant label.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param label: The text of the label (default: None)
    :type label: str
    :param labelWidth: The width of the label (default: None)
    :type labelWidth: int
    :return: Constructed label
    :rtype: PyQt4.QtGui.QLabel
    """
    lbl = QtGui.QLabel(label, widget)
    if labelWidth:
        lbl.setFixedSize(labelWidth, lbl.sizeHint().height())
    miscellanea(lbl, None, widget, **misc)
    return lbl



def label(widget, master, label, labelWidth=None, box=None,
          orientation="vertical", **misc):
    """
    Construct a label that contains references to the master widget's
    attributes; when their values change, the label is updated.

    Argument :obj:`label` is a format string following Python's syntax
    (see the corresponding Python documentation): the label's content is
    rendered as `label % master.__dict__`. For instance, if the
    :obj:`label` is given as "There are %(mm)i monkeys", the value of
    `master.mm` (which must be an integer) will be inserted in place of
    `%(mm)i`.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param label: The text of the label, including attribute names
    :type label: str
    :param labelWidth: The width of the label (default: None)
    :type labelWidth: int
    :return: label
    :rtype: PyQt4.QtGui.QLabel
    """
    if box:
        b = widgetBox(widget, box, orientation=None, addToLayout=False)
    else:
        b = widget

    lbl = QtGui.QLabel("", b)
    reprint = CallFrontLabel(lbl, label, master)
    for mo in __re_label.finditer(label):
        getattr(master, CONTROLLED_ATTRIBUTES)[mo.group("value")] = reprint
    reprint()
    if labelWidth:
        lbl.setFixedSize(labelWidth, lbl.sizeHint().height())
    miscellanea(lbl, b, widget, **misc)
    return lbl


class SpinBoxWFocusOut(QtGui.QSpinBox):
    """
    A class derived from QtGui.QSpinBox, which postpones the synchronization
    of the control's value with the master's attribute until the user presses
    Enter or clicks an icon that appears beside the spin box when the value
    is changed.

    The class overloads :obj:`onChange` event handler to show the commit button,
    and :obj:`onEnter` to commit the change when enter is pressed.

    .. attribute:: enterButton

        A widget (usually an icon) that is shown when the value is changed.

    .. attribute:: placeHolder

        A placeholder which is shown when the button is hidden

    .. attribute:: inSetValue

        A flag that is set when the value is being changed through
        :obj:`setValue` to prevent the programmatic changes from showing the
        commit button.
    """

    def __init__(self, minv, maxv, step, parent=None):
        """
        Construct the object and set the range (`minv`, `maxv`) and the step.
        :param minv: Minimal value
        :type minv: int
        :param maxv: Maximal value
        :type maxv: int
        :param step: Step
        :type step: int
        :param parent: Parent widget
        :type parent: PyQt4.QtGui.QWidget
        """
        super().__init__(parent)
        self.setRange(minv, maxv)
        self.setSingleStep(step)
        self.inSetValue = False
        self.enterButton = None
        self.placeHolder = None

    def onChange(self, _):
        """
        Hides the place holder and shows the commit button unless
        :obj:`inSetValue` is set.
        """
        if not self.inSetValue:
            self.placeHolder.hide()
            self.enterButton.show()

    def onEnter(self):
        """
        If the commit button is visible, the overload event handler commits
        the change by calling the appropriate callbacks. It also hides the
        commit button and shows the placeHolder.
        """
        if self.enterButton.isVisible():
            self.enterButton.hide()
            self.placeHolder.show()
            if self.cback:
                self.cback(int(str(self.text())))
            if self.cfunc:
                self.cfunc()

    # doesn't work: it's probably LineEdit's focusOut that we should
    # (but can't) catch
    def focusOutEvent(self, *e):
        """
        This handler was intended to catch the focus out event and reintepret
        it as if enter was pressed. It does not work, though.
        """
        super().focusOutEvent(*e)
        if self.enterButton and self.enterButton.isVisible():
            self.onEnter()

    def setValue(self, value):
        """
        Set the :obj:`inSetValue` flag and call the inherited method.
        """
        self.inSetValue = True
        super().setValue(value)
        self.inSetValue = False


class DoubleSpinBoxWFocusOut(QtGui.QDoubleSpinBox):
    """
    Same as :obj:`SpinBoxWFocusOut`, except that it is derived from
    :obj:`~PyQt4.QtGui.QDoubleSpinBox`"""
    def __init__(self, minv, maxv, step, parent):
        super().__init__(parent)
        self.setDecimals(math.ceil(-math.log10(step)))
        self.setRange(minv, maxv)
        self.setSingleStep(step)
        self.inSetValue = False
        self.enterButton = None
        self.placeHolder = None

    def onChange(self, _):
        if not self.inSetValue:
            self.placeHolder.hide()
            self.enterButton.show()

    def onEnter(self):
        if self.enterButton.isVisible():
            self.enterButton.hide()
            self.placeHolder.show()
            if self.cback:
                self.cback(float(str(self.text()).replace(",", ".")))
            if self.cfunc:
                self.cfunc()

    # doesn't work: it's probably LineEdit's focusOut that we should
    # (and can't) catch
    def focusOutEvent(self, *e):
        super().focusOutEvent(*e)
        if self.enterButton and self.enterButton.isVisible():
            self.onEnter()

    def setValue(self, value):
        self.inSetValue = True
        super().setValue(value)
        self.inSetValue = False


def spin(widget, master, value, minv, maxv, step=1, box=None, label=None,
         labelWidth=None, orientation=None, callback=None,
         controlWidth=None, callbackOnReturn=False, checked=None,
         checkCallback=None, posttext=None, disabled=False,
         alignment=Qt.AlignLeft, keyboardTracking=True,
         decimals=None, spinType=int, **misc):
    """
    A spinbox with lots of bells and whistles, such as a checkbox and various
    callbacks. It constructs a control of type :obj:`SpinBoxWFocusOut` or
    :obj:`DoubleSpinBoxWFocusOut`.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param value: the master's attribute with which the value is synchronized
    :type value:  str
    :param minv: minimal value
    :type minv: int
    :param maxv: maximal value
    :type maxv: int
    :param step: step (default: 1)
    :type step: int
    :param box: tells whether the widget has a border, and its label
    :type box: int or str or None
    :param label: label that is put in above or to the left of the spin box
    :type label: str
    :param labelWidth: optional label width (default: None)
    :type labelWidth: int
    :param orientation: tells whether to put the label above (`"vertical"` or
        `True`) or to the left (`"horizontal"` or `False`)
    :type orientation: int or bool or str
    :param callback: a function that is called when the value is entered; if
        :obj:`callbackOnReturn` is `True`, the function is called when the
        user commits the value by pressing Enter or clicking the icon
    :type callback: function
    :param controlWidth: the width of the spin box
    :type controlWidth: int
    :param callbackOnReturn: if `True`, the spin box has an associated icon
        that must be clicked to confirm the value (default: False)
    :type callbackOnReturn: bool
    :param checked: if not None, a check box is put in front of the spin box;
        when unchecked, the spin box is disabled. Argument `checked` gives the
        name of the master's attribute given whose value is synchronized with
        the check box's state (default: None).
    :type checked: str
    :param checkCallback: a callback function that is called when the check
        box's state is changed
    :type checkCallback: function
    :param posttext: a text that is put to the right of the spin box
    :type posttext: str
    :param alignment: alignment of the spin box (e.g. `QtCore.Qt.AlignLeft`)
    :type alignment: PyQt4.QtCore.Qt.Alignment
    :param keyboardTracking: If `True`, the valueChanged signal is emitted
        when the user is typing (default: True)
    :type keyboardTracking: bool
    :param spinType: determines whether to use QSpinBox (int) or
        QDoubleSpinBox (float)
    :type spinType: type
    :param decimals: number of decimals (if `spinType` is `float`)
    :type decimals: int
    :return: Tuple `(spin box, check box) if `checked` is `True`, otherwise
        the spin box
    :rtype: tuple or gui.SpinBoxWFocusOut
    """

    # b is the outermost box or the widget if there are no boxes;
    #    b is the widget that is inserted into the layout
    # bi is the box that contains the control or the checkbox and the control;
    #    bi can be the widget itself, if there are no boxes
    # cbox is the checkbox (or None)
    # sbox is the spinbox itself
    if box or label and not checked:
        b = widgetBox(widget, box, orientation, addToLayout=False)
        hasHBox = orientation == 'horizontal' or not orientation
    else:
        b = widget
        hasHBox = False
    if not hasHBox and (checked or callback and callbackOnReturn or posttext):
        bi = widgetBox(b, orientation=0, addToLayout=False)
    else:
        bi = b

    cbox = None
    if checked is not None:
        cbox = checkBox(bi, master, checked, label, labelWidth=labelWidth,
                        callback=checkCallback)
    elif label:
        b.label = widgetLabel(b, label, labelWidth)
    if posttext:
        widgetLabel(bi, posttext)

    isDouble = spinType == float
    sbox = bi.control = \
        (SpinBoxWFocusOut, DoubleSpinBoxWFocusOut)[isDouble](minv, maxv,
                                                             step, bi)
    if bi is not widget:
        bi.setDisabled(disabled)
    else:
        sbox.setDisabled(disabled)

    if decimals is not None:
        sbox.setDecimals(decimals)
    sbox.setAlignment(alignment)
    sbox.setKeyboardTracking(keyboardTracking)
    if controlWidth:
        sbox.setFixedWidth(controlWidth)
    if value:
        sbox.setValue(getdeepattr(master, value))

    cfront, sbox.cback, sbox.cfunc = connectControl(
        master, value, callback,
        not (callback and callbackOnReturn) and
        sbox.valueChanged[(int, float)[isDouble]],
        (CallFrontSpin, CallFrontDoubleSpin)[isDouble](sbox))
    if checked:
        cbox.disables = [sbox]
        cbox.makeConsistent()
    if callback and callbackOnReturn:
        sbox.enterButton, sbox.placeHolder = _enterButton(bi, sbox)
        sbox.valueChanged[str].connect(sbox.onChange)
        sbox.editingFinished.connect(sbox.onEnter)
        sbox.enterButton.clicked.connect(sbox.onEnter)
        if hasattr(sbox, "upButton"):
            sbox.upButton().clicked.connect(
                lambda c=sbox.editor(): c.setFocus())
            sbox.downButton().clicked.connect(
                lambda c=sbox.editor(): c.setFocus())

    miscellanea(sbox, b if b is not widget else bi, widget, **misc)
    if checked:
        if isDouble and b == widget:
            # TODO Backward compatilibity; try to find and eliminate
            sbox.control = b.control
            return sbox
        return cbox, sbox
    else:
        return sbox



# noinspection PyTypeChecker
def doubleSpin(widget, master, value, minv, maxv, step=1, box=None, label=None,
               labelWidth=None, orientation=None, callback=None,
               controlWidth=None, callbackOnReturn=False, checked=None,
               checkCallback=None, posttext=None,
               alignment=Qt.AlignLeft, keyboardTracking=True,
               decimals=None, **misc):
    """
    Backward compatilibity function: calls :obj:`spin` with `spinType=float`.
    """
    return spin(widget, master, value, minv, maxv, step, box=box, label=label,
                labelWidth=labelWidth, orientation=orientation,
                callback=callback, controlWidth=controlWidth,
                callbackOnReturn=callbackOnReturn, checked=checked,
                checkCallback=checkCallback, posttext=posttext,
                alignment=alignment, keyboardTracking=keyboardTracking,
                decimals=decimals, spinType=float, **misc)


def checkBox(widget, master, value, label, box=None,
             callback=None, getwidget=False, id_=None, labelWidth=None,
             disables=None, **misc):
    """
    A simple checkbox.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param value: the master's attribute with which the value is synchronized
    :type value:  str
    :param label: label
    :type label: str
    :param box: tells whether the widget has a border, and its label
    :type box: int or str or None
    :param callback: a function that is called when the check box state is
        changed
    :type callback: function
    :param getwidget: If set `True`, the callback function will get a keyword
        argument `widget` referencing the check box
    :type getwidget: bool
    :param id_: If present, the callback function will get a keyword argument
        `id` with this value
    :type id_: any
    :param labelWidth: the width of the label
    :type labelWidth: int
    :param disables: a list of widgets that are disabled if the check box is
        unchecked
    :type disables: list or PyQt4.QtGui.QWidget or None
    :return: constructed check box; if is is placed within a box, the box is
        return in the attribute `box`
    :rtype: PyQt4.QtGui.QCheckBox
    """
    if box:
        b = widgetBox(widget, box, orientation=None, addToLayout=False)
    else:
        b = widget
    cbox = QtGui.QCheckBox(label, b)

    if labelWidth:
        cbox.setFixedSize(labelWidth, cbox.sizeHint().height())
    cbox.setChecked(getdeepattr(master, value))

    connectControl(master, value, None, cbox.toggled[bool],
                   CallFrontCheckBox(cbox),
                   cfunc=callback and FunctionCallback(
                       master, callback, widget=cbox, getwidget=getwidget,
                       id=id_))
    if isinstance(disables, QtGui.QWidget):
        disables = [disables]
    cbox.disables = disables or []
    cbox.makeConsistent = Disabler(cbox, master, value)
    cbox.toggled[bool].connect(cbox.makeConsistent)
    cbox.makeConsistent(value)
    miscellanea(cbox, b, widget, **misc)
    return cbox


class LineEditWFocusOut(QtGui.QLineEdit):
    """
    A class derived from QtGui.QLineEdit, which postpones the synchronization
    of the control's value with the master's attribute until the user leaves
    the line edit, presses Enter or clicks an icon that appears beside the
    line edit when the value is changed.

    The class also allows specifying a callback function for focus-in event.

    .. attribute:: enterButton

        A widget (usually an icon) that is shown when the value is changed.

    .. attribute:: placeHolder

        A placeholder which is shown when the button is hidden

    .. attribute:: inSetValue

        A flag that is set when the value is being changed through
        :obj:`setValue` to prevent the programmatic changes from showing the
        commit button.

    .. attribute:: callback

        Callback that is called when the change is confirmed

    .. attribute:: focusInCallback

        Callback that is called on the focus-in event
    """

    def __init__(self, parent, callback, focusInCallback=None,
                 placeholder=False):
        super().__init__(parent)
        if parent.layout() is not None:
            parent.layout().addWidget(self)
        self.callback = callback
        self.focusInCallback = focusInCallback
        self.enterButton, self.placeHolder = \
            _enterButton(parent, self, placeholder)
        self.enterButton.clicked.connect(self.returnPressedHandler)
        self.textChanged[str].connect(self.markChanged)
        self.returnPressed.connect(self.returnPressedHandler)

    def markChanged(self, *_):
        if self.placeHolder:
            self.placeHolder.hide()
        self.enterButton.show()

    def markUnchanged(self, *_):
        self.enterButton.hide()
        if self.placeHolder:
            self.placeHolder.show()

    def returnPressedHandler(self):
        if self.enterButton.isVisible():
            self.markUnchanged()
            if hasattr(self, "cback") and self.cback:
                self.cback(self.text())
            if self.callback:
                self.callback()

    def setText(self, t):
        super().setText(t)
        if self.enterButton:
            self.markUnchanged()

    def focusOutEvent(self, *e):
        super().focusOutEvent(*e)
        self.returnPressedHandler()

    def focusInEvent(self, *e):
        if self.focusInCallback:
            self.focusInCallback()
        return super().focusInEvent(*e)


def lineEdit(widget, master, value, label=None, labelWidth=None,
             orientation='vertical', box=None, callback=None,
             valueType=str, validator=None, controlWidth=None,
             callbackOnType=False, focusInCallback=None,
             enterPlaceholder=False, **misc):
    """
    Insert a line edit.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param value: the master's attribute with which the value is synchronized
    :type value:  str
    :param label: label
    :type label: str
    :param labelWidth: the width of the label
    :type labelWidth: int
    :param orientation: tells whether to put the label above (`"vertical"` or
        `True`) or to the left (`"horizontal"` or `False`)
    :type orientation: int or bool or str
    :param box: tells whether the widget has a border, and its label
    :type box: int or str or None
    :param callback: a function that is called when the check box state is
        changed
    :type callback: function
    :param valueType: the type into which the entered string is converted
        when synchronizing to `value`
    :type valueType: type
    :param validator: the validator for the input
    :type validator: PyQt4.QtGui.QValidator
    :param controlWidth: the width of the line edit
    :type controlWidth: int
    :param callbackOnType: if set to `True`, the callback is called at each
        key press (default: `False`)
    :type callbackOnType: bool
    :param focusInCallback: a function that is called when the line edit
        receives focus
    :type focusInCallback: function
    :param enterPlaceholder: if set to `True`, space of appropriate width is
        left empty to the right for the icon that shows that the value is
        changed but has not been committed yet
    :type enterPlaceholder: bool
    :rtype: PyQt4.QtGui.QLineEdit or a box
    """
    if box or label:
        b = widgetBox(widget, box, orientation, addToLayout=False)
        if label is not None:
            widgetLabel(b, label, labelWidth)
        hasHBox = orientation == 'horizontal' or not orientation
    else:
        b = widget
        hasHBox = False

    baseClass = misc.pop("baseClass", None)
    if baseClass:
        ledit = baseClass(b)
        ledit.enterButton = None
        if b is not widget:
            b.layout().addWidget(ledit)
    elif focusInCallback or callback and not callbackOnType:
        if not hasHBox:
            outer = widgetBox(b, "", 0, addToLayout=(b is not widget))
        else:
            outer = b
        ledit = LineEditWFocusOut(outer, callback, focusInCallback,
                                  enterPlaceholder)
    else:
        ledit = QtGui.QLineEdit(b)
        ledit.enterButton = None
        if b is not widget:
            b.layout().addWidget(ledit)

    if value:
        ledit.setText(str(getdeepattr(master, value)))
    if controlWidth:
        ledit.setFixedWidth(controlWidth)
    if validator:
        ledit.setValidator(validator)
    if value:
        ledit.cback = connectControl(
            master, value,
            callbackOnType and callback, ledit.textChanged[str],
            CallFrontLineEdit(ledit), fvcb=value and valueType)[1]

    miscellanea(ledit, b, widget, **misc)
    return ledit


def button(widget, master, label, callback=None, width=None, height=None,
           toggleButton=False, value="", default=False, autoDefault=True,
           buttonType=QtGui.QPushButton, **misc):
    """
    Insert a button (QPushButton, by default)

    :param widget: the widget into which the button is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param label: label
    :type label: str
    :param callback: a function that is called when the button is pressed
    :type callback: function
    :param width: the width of the button
    :type width: int
    :param height: the height of the button
    :type height: int
    :param toggleButton: if set to `True`, the button is checkable, but it is
        not synchronized with any attribute unless the `value` is given
    :type toggleButton: bool
    :param value: the master's attribute with which the value is synchronized
        (the argument is optional; if present, it makes the button "checkable",
        even if `toggleButton` is not set)
    :type value: str
    :param default: if `True` it makes the button the default button; this is
        the button that is activated when the user presses Enter unless some
        auto default button has current focus
    :type default: bool
    :param autoDefault: all buttons are auto default: they are activated if
        they have focus (or are the next in the focus chain) when the user
        presses enter. By setting `autoDefault` to `False`, the button is not
        activated on pressing Return.
    :type autoDefault: bool
    :param buttonType: the button type (default: `QPushButton`)
    :type buttonType: PyQt4.QtGui.QAbstractButton
    :rtype: PyQt4.QtGui.QAbstractButton
    """
    button = buttonType(widget)
    if label:
        button.setText(label)
    if width:
        button.setFixedWidth(width)
    if height:
        button.setFixedHeight(height)
    if toggleButton or value:
        button.setCheckable(True)
    if buttonType == QtGui.QPushButton:
        button.setDefault(default)
        button.setAutoDefault(autoDefault)

    if value:
        button.setChecked(getdeepattr(master, value))
        connectControl(
            master, value, None, button.toggled[bool],
            CallFrontButton(button),
            cfunc=callback and FunctionCallback(master, callback,
                                                widget=button))
    elif callback:
        button.clicked.connect(callback)

    miscellanea(button, None, widget, **misc)
    return button


def toolButton(widget, master, label="", callback=None,
               width=None, height=None, tooltip=None):
    """
    Insert a tool button. Calls :obj:`button`

    :param widget: the widget into which the button is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param label: label
    :type label: str
    :param callback: a function that is called when the button is pressed
    :type callback: function
    :param width: the width of the button
    :type width: int
    :param height: the height of the button
    :type height: int
    :rtype: PyQt4.QtGui.QToolButton
    """
    return button(widget, master, label, callback, width, height,
                  buttonType=QtGui.QToolButton, tooltip=tooltip)


def createAttributePixmap(char, background=Qt.black, color=Qt.white):
    """
    Create a QIcon with a given character. The icon is 13 pixels high and wide.

    :param char: The character that is printed in the icon
    :type char: str
    :param background: the background color (default: black)
    :type background: PyQt4.QtGui.QColor
    :param color: the character color (default: white)
    :type color: PyQt4.QtGui.QColor
    :rtype: PyQt4.QtGui.QIcon
    """
    pixmap = QtGui.QPixmap(13, 13)
    pixmap.fill(QtGui.QColor(0, 0, 0, 0))
    painter = QtGui.QPainter()
    painter.begin(pixmap)
    painter.setRenderHints(painter.Antialiasing | painter.TextAntialiasing |
                           painter.SmoothPixmapTransform)
    painter.setPen(background)
    painter.setBrush(background)
    rect = QtCore.QRectF(0, 0, 13, 13)
    painter.drawRoundedRect(rect, 4, 4)
    painter.setPen(color)
    painter.drawText(2, 11, char)
    painter.end()
    return QtGui.QIcon(pixmap)


class __AttributeIconDict(dict):
    def __getitem__(self, key):
        if not self:
            for tpe, char, col in ((vartype(ContinuousVariable()),
                                    "C", (202, 0, 32)),
                                   (vartype(DiscreteVariable()),
                                    "D", (26, 150, 65)),
                                   (vartype(StringVariable()),
                                    "S", (0, 0, 0)),
                                   (vartype(TimeVariable()),
                                    "T", (68, 170, 255)),
                                   (-1, "?", (128, 128, 128))):
                self[tpe] = createAttributePixmap(char, QtGui.QColor(*col))
        if key not in self:
            key = vartype(key) if isinstance(key, Variable) else -1
        return super().__getitem__(key)

#: A dict that returns icons for different attribute types. The dict is
#: constructed on first use since icons cannot be created before initializing
#: the application.
#:
#: Accepted keys are variable type codes and instances
#: of :obj:`Orange.data.variable`: `attributeIconDict[var]` will give the
#: appropriate icon for variable `var` or a question mark if the type is not
#: recognized
attributeIconDict = __AttributeIconDict()


def attributeItem(var):
    """
    Construct a pair (icon, name) for inserting a variable into a combo or
    list box

    :param var: variable
    :type var: Orange.data.Variable
    :rtype: tuple with PyQt4.QtGui.QIcon and str
    """
    return attributeIconDict[var], var.name


def listBox(widget, master, value=None, labels=None, box=None, callback=None,
            selectionMode=QtGui.QListWidget.SingleSelection,
            enableDragDrop=False, dragDropCallback=None,
            dataValidityCallback=None, sizeHint=None, **misc):
    """
    Insert a list box.

    The value with which the box's value synchronizes (`master.<value>`)
    is a list of indices of selected items.

    :param widget: the widget into which the box is inserted
    :type widget: PyQt4.QtGui.QWidget or None
    :param master: master widget
    :type master: OWWidget or OWComponent
    :param value: the name of the master's attribute with which the value is
        synchronized (list of ints - indices of selected items)
    :type value: str
    :param labels: the name of the master's attribute with the list of items
        (as strings or tuples with icon and string)
    :type labels: str
    :param box: tells whether the widget has a border, and its label
    :type box: int or str or None
    :param callback: a f