def __init__(self, name, a, b, callback):
        QWidget.__init__(self)
        self.name = name
        self.callback = callback
        self.a = a
        self.b = b
        self.manually_triggered = False

        self.slider = QSlider()
        self.slider.setRange(0, 1000)
        self.slider.setValue(500)
        self.slider.valueChanged.connect(self.slider_changed)

        self.name_label = QLabel()
        self.name_label.setText(self.name)
        self.name_label.setAlignment(QtCore.Qt.AlignCenter)

        self.value_label = QLabel()
        self.value_label.setText('%2.2f' % (self.slider.value() * self.a
                                             + self.b))
        self.value_label.setAlignment(QtCore.Qt.AlignCenter)

        self.layout = QGridLayout(self)
        self.layout.addWidget(self.name_label, 0, 0)
        self.layout.addWidget(self.slider, 1, 0, QtCore.Qt.AlignHCenter)
        self.layout.addWidget(self.value_label, 2, 0)

 def rebuild(self):
     """ Clear out all existing widgets, and populate the list using the
     template file and data source."""
     self.clear()
     if (not self.templateFilename) or (not self.data):
         return
     self.setUpdatesEnabled(False)
     
     layout_class = layout_class_for_type[self.layoutType]
     if type(self.layout()) != layout_class:
         if self.layout() is not None:
             # Trick to remove the existing layout by re-parenting it in an empty widget.
             QWidget().setLayout(self.layout())
         l = layout_class(self)
         self.setLayout(l)
     with pydm.data_plugins.connection_queue():
         for i, variables in enumerate(self.data):
             if is_qt_designer() and i > self.countShownInDesigner - 1:
                 break
             w = self.open_template_file(variables)
             if w is None:
                 w = QLabel()
                 w.setText("No Template Loaded.  Data: {}".format(variables))
             w.setParent(self)
             self.layout().addWidget(w)
     self.setUpdatesEnabled(True)

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.uid_label = QLabel()
        self.open_individually_button = QPushButton('Open individually')
        self.open_individually_button.hide()
        self.open_individually_button.clicked.connect(self._open_individually)
        self.open_overplotted_button = QPushButton('Open over-plotted')
        self.open_overplotted_button.hide()
        self.open_overplotted_button.clicked.connect(self._open_overplotted)
        self.open_overplotted_on_button = QPushButton('Add to tab...')
        self.open_overplotted_on_button.hide()
        self.open_overplotted_on_button.setEnabled(False)
        self.open_overplotted_on_button.clicked.connect(self._open_overplotted_on)
        self.copy_uid_button = QPushButton('Copy UID to Clipboard')
        self.copy_uid_button.hide()
        self.copy_uid_button.clicked.connect(self._copy_uid)
        self.streams = QLabel()
        self.entries = []

        uid_layout = QHBoxLayout()
        uid_layout.addWidget(self.uid_label)
        uid_layout.addWidget(self.copy_uid_button)
        layout = QVBoxLayout()
        layout.addWidget(self.open_individually_button)
        layout.addWidget(self.open_overplotted_button)
        layout.addWidget(self.open_overplotted_on_button)
        layout.addLayout(uid_layout)
        layout.addWidget(self.streams)
        self.setLayout(layout)

        self._tab_titles = ()

    def fix_size(self, content, extra=50):
        """
        Adjusts the width and height of the file switcher,
        based on its content.
        """
        # Update size of dialog based on longest shortened path
        strings = []
        if content:
            for rich_text in content:
                label = QLabel(rich_text)
                label.setTextFormat(Qt.PlainText)
                strings.append(label.text())
                fm = label.fontMetrics()

            # Max width
            max_width = max([fm.width(s) * 1.3 for s in strings])
            self.list.setMinimumWidth(max_width + extra)

            # Max height
            if len(strings) < 8:
                max_entries = len(strings)
            else:
                max_entries = 8
            max_height = fm.height() * max_entries * 2.5
            self.list.setMinimumHeight(max_height)

            # Set position according to size
            self.set_dialog_position()

    def _init_ui(self):
        # LINE 1: Data component drop down
        self.component_prompt = QLabel("Data Component:")
        self.component_prompt.setWordWrap(True)
        # Add the data component labels to the drop down, with the ComponentID
        # set as the userData:
        if self.parent is not None and hasattr(self.parent, 'data_components'):
            self.label_data = [(str(cid), cid) for cid in self.parent.data_components]
        else:
            self.label_data = [(str(cid), cid) for cid in self.data.visible_components]

        default_index = 0
        self.component_combo = QComboBox()
        self.component_combo.setFixedWidth(200)
        update_combobox(self.component_combo, self.label_data, default_index=default_index)
        self.component_combo.currentIndexChanged.connect(self.update_unit_layout)

        # hbl is short for Horizontal Box Layout
        hbl1 = QHBoxLayout()
        hbl1.addWidget(self.component_prompt)
        hbl1.addWidget(self.component_combo)
        hbl1.addStretch(1)

        # LINE 2: Unit conversion layout
        # This layout is filled by CubeVizUnit
        self.unit_layout = QHBoxLayout()  # this is hbl2

        # LINE 3: Message box
        self.message_box = QLabel("")
        hbl3 = QHBoxLayout()
        hbl3.addWidget(self.message_box)
        hbl3.addStretch(1)

        # Line 4: Buttons
        ok_text = "Convert Data" if self.convert_data else "Convert Displayed Units"
        ok_function = self.convert_data_units if self.convert_data else self.convert_displayed_units
        self.okButton = QPushButton(ok_text)
        self.okButton.clicked.connect(ok_function)
        self.okButton.setDefault(True)

        self.cancelButton = QPushButton("Cancel")
        self.cancelButton.clicked.connect(self.cancel)

        hbl4 = QHBoxLayout()
        hbl4.addStretch(1)
        hbl4.addWidget(self.cancelButton)
        hbl4.addWidget(self.okButton)

        vbl = QVBoxLayout()
        vbl.addLayout(hbl1)
        vbl.addLayout(self.unit_layout)
        vbl.addLayout(hbl3)
        vbl.addLayout(hbl4)
        self.setLayout(vbl)
        self.vbl = vbl

        self.update_unit_layout(default_index)

        self.show()

    def setup_page(self):
        # Connections group
        connections_group = QGroupBox(_("Automatic connections"))
        connections_label = QLabel(_("This pane can automatically "
                                     "show an object's help information after "
                                     "a left parenthesis is written next to it. "
                                     "Below you can decide to which plugin "
                                     "you want to connect it to turn on this "
                                     "feature."))
        connections_label.setWordWrap(True)
        editor_box = self.create_checkbox(_("Editor"), 'connect/editor')
        rope_installed = programs.is_module_installed('rope')
        jedi_installed = programs.is_module_installed('jedi', '>=0.8.1')
        editor_box.setEnabled(rope_installed or jedi_installed)
        if not rope_installed and not jedi_installed:
            editor_tip = _("This feature requires the Rope or Jedi libraries.\n"
                           "It seems you don't have either installed.")
            editor_box.setToolTip(editor_tip)
        ipython_box = self.create_checkbox(_("IPython Console"),
                                           'connect/ipython_console')

        connections_layout = QVBoxLayout()
        connections_layout.addWidget(connections_label)
        connections_layout.addWidget(editor_box)
        connections_layout.addWidget(ipython_box)
        connections_group.setLayout(connections_layout)

        # Features group
        features_group = QGroupBox(_("Additional features"))
        math_box = self.create_checkbox(_("Render mathematical equations"),
                                        'math')
        req_sphinx = programs.is_module_installed('sphinx', '>=1.1')
        math_box.setEnabled(req_sphinx)
        if not req_sphinx:
            sphinx_ver = programs.get_module_version('sphinx')
            sphinx_tip = _("This feature requires Sphinx 1.1 or superior.")
            sphinx_tip += "\n" + _("Sphinx %s is currently installed.") % sphinx_ver
            math_box.setToolTip(sphinx_tip)

        features_layout = QVBoxLayout()
        features_layout.addWidget(math_box)
        features_group.setLayout(features_layout)

        # Source code group
        sourcecode_group = QGroupBox(_("Source code"))
        wrap_mode_box = self.create_checkbox(_("Wrap lines"), 'wrap')

        sourcecode_layout = QVBoxLayout()
        sourcecode_layout.addWidget(wrap_mode_box)
        sourcecode_group.setLayout(sourcecode_layout)

        # Final layout
        vlayout = QVBoxLayout()
        vlayout.addWidget(connections_group)
        vlayout.addWidget(features_group)
        vlayout.addWidget(sourcecode_group)
        vlayout.addStretch(1)
        self.setLayout(vlayout)

    def _init_ui(self):
        self.slit_type_label = QLabel('Slit Type')
        self.slit_type_combo = QComboBox()
        self.slit_type_combo.currentIndexChanged.connect(self.update_info)

        hbl1 = QHBoxLayout()
        hbl1.addWidget(self.slit_type_label)
        hbl1.addWidget(self.slit_type_combo)

        self.slit_width_label = QLabel('Slit Width')
        self.slit_width_input = QLineEdit()
        self.slit_width_combo = QComboBox()
        self.slit_width_units = QLabel('arcsec')

        hbl2 = QHBoxLayout()
        hbl2.addWidget(self.slit_width_label)
        hbl2.addWidget(self.slit_width_input)
        hbl2.addWidget(self.slit_width_combo)
        hbl2.addWidget(self.slit_width_units)

        self.slit_length_label = QLabel('Slit Length')
        self.slit_length_input = QLineEdit()
        self.slit_length_combo = QComboBox()
        self.slit_length_units = QLabel('arcsec')

        hbl3 = QHBoxLayout()
        hbl3.addWidget(self.slit_length_label)
        hbl3.addWidget(self.slit_length_input)
        hbl3.addWidget(self.slit_length_combo)
        hbl3.addWidget(self.slit_length_units)

        self.okButton = QPushButton('Apply')
        self.okButton.clicked.connect(self.apply)
        self.okButton.setDefault(True)

        self.cancelButton = QPushButton('Cancel')
        self.cancelButton.clicked.connect(self.cancel)

        hbl4 = QHBoxLayout()
        hbl4.addWidget(self.cancelButton)
        hbl4.addWidget(self.okButton)

        vbl = QVBoxLayout()
        vbl.addLayout(hbl1)
        vbl.addLayout(hbl2)
        vbl.addLayout(hbl3)
        vbl.addLayout(hbl4)
        self.setLayout(vbl)
        self.vbl = vbl

        self._load_selections()
        self._populate_combo()
        self.update_info(0)

        self.show()

 def __init__(self, parent, statusbar):
     StatusBarWidget.__init__(self, parent, statusbar)
     layout = self.layout()
     layout.addWidget(QLabel(_("Line:")))
     self.line = QLabel()
     self.line.setFont(self.label_font)
     layout.addWidget(self.line)
     layout.addWidget(QLabel(_("Column:")))
     self.column = QLabel()
     self.column.setFont(self.label_font)
     layout.addWidget(self.column)
     self.setLayout(layout)

class EncodingStatus(StatusBarWidget):
    def __init__(self, parent, statusbar):
        StatusBarWidget.__init__(self, parent, statusbar)
        layout = self.layout()
        layout.addWidget(QLabel(_("Encoding:")))
        self.encoding = QLabel()
        self.encoding.setFont(self.label_font)
        layout.addWidget(self.encoding)
        layout.addSpacing(20)
        
    def encoding_changed(self, encoding):
        self.encoding.setText(str(encoding).upper().ljust(15))

class QLabeledSlider(QWidget):
    """
    A labeled slider widget
    """

    range = None
    integer = None

    def __init__(self, parent=None):

        super(QLabeledSlider, self).__init__(parent)

        self._range = range

        self._slider = QSlider()
        self._slider.setMinimum(0)
        self._slider.setMaximum(100)
        self._slider.setOrientation(Qt.Horizontal)

        self._label = QLabel('')
        self._layout = QHBoxLayout()
        self._layout.setContentsMargins(2, 2, 2, 2)
        self._layout.addWidget(self._slider)
        self._layout.addWidget(self._label)

        self._slider.valueChanged.connect(self._update_label)

        self.setLayout(self._layout)

    def _update_label(self, *args):
        self._label.setText(str(self.value()))

    @property
    def valueChanged(self):
        return self._slider.valueChanged

    def value(self, layer=None, view=None):
        value = self._slider.value() / 100. * (self.range[1] - self.range[0]) + self.range[0]
        if self.integer:
            return int(value)
        else:
            return(value)

    _in_set_value = False

    def setValue(self, value):
        if self._in_set_value:
            return
        self._in_set_value = True
        value = int(100 * (value - self.range[0]) / (self.range[1] - self.range[0]))
        self._slider.setValue(value)
        self._in_set_value = False

class EOLStatus(StatusBarWidget):
    def __init__(self, parent, statusbar):
        StatusBarWidget.__init__(self, parent, statusbar)
        layout = self.layout()
        layout.addWidget(QLabel(_("End-of-lines:")))
        self.eol = QLabel()
        self.eol.setFont(self.label_font)
        layout.addWidget(self.eol)
        layout.addSpacing(20)
        
    def eol_changed(self, os_name):
        os_name = to_text_string(os_name)
        self.eol.setText({"nt": "CRLF", "posix": "LF"}.get(os_name, "CR"))

class ReadWriteStatus(StatusBarWidget):
    def __init__(self, parent, statusbar):
        StatusBarWidget.__init__(self, parent, statusbar)
        layout = self.layout()
        layout.addWidget(QLabel(_("Permissions:")))
        self.readwrite = QLabel()
        self.readwrite.setFont(self.label_font)
        layout.addWidget(self.readwrite)
        layout.addSpacing(20)
        
    def readonly_changed(self, readonly):
        readwrite = "R" if readonly else "RW"
        self.readwrite.setText(readwrite.ljust(3))

 def fix_size(self, content, extra=50):
     """Adjusts the width of the file switcher, based on the content."""
     # Update size of dialog based on longest shortened path
     strings = []
     if content:
         for rich_text in content:
             label = QLabel(rich_text)
             label.setTextFormat(Qt.PlainText)
             strings.append(label.text())
             fm = label.fontMetrics()
         max_width = max([fm.width(s)*1.3 for s in strings])
         self.list.setMinimumWidth(max_width + extra)
         self.set_dialog_position()

class SearchLineEdit(QLineEdit):
    """Line edit search widget with icon and remove all button"""
    def __init__(self, parent=None, icon=True):
        super(SearchLineEdit, self).__init__(parent)
        self.setTextMargins(1, 0, 20, 0)

        if icon:
            self.setTextMargins(18, 0, 20, 0)
            self._label = QLabel(self)
            self._pixmap_icon = QPixmap(get_image_path('conda_search.png'))
            self._label.setPixmap(self._pixmap_icon)
            self._label.setStyleSheet('''border: 0px; padding-bottom: 0px;
                                      padding-left: 2px;''')

        self._pixmap = QPixmap(get_image_path('conda_del.png'))
        self.button_clear = QToolButton(self)
        self.button_clear.setIcon(QIcon(self._pixmap))
        self.button_clear.setIconSize(QSize(18, 18))
        self.button_clear.setCursor(Qt.ArrowCursor)
        self.button_clear.setStyleSheet("""QToolButton
            {background: transparent;
            padding-right: 2px; border: none; margin:0px; }""")
        self.button_clear.setVisible(False)

        # Layout
        self._layout = QHBoxLayout(self)
        self._layout.addWidget(self.button_clear, 0, Qt.AlignRight)
        self._layout.setSpacing(0)
        self._layout.setContentsMargins(0, 2, 2, 0)

        # Signals and slots
        self.button_clear.clicked.connect(self.clear_text)
        self.textChanged.connect(self._toggle_visibility)
        self.textEdited.connect(self._toggle_visibility)

    def _toggle_visibility(self):
        """ """
        if len(self.text()) == 0:
            self.button_clear.setVisible(False)
        else:
            self.button_clear.setVisible(True)

    def sizeHint(self):
        return QSize(200, self._pixmap_icon.height())

    # Public api
    # ----------
    def clear_text(self):
        """ """
        self.setText('')
        self.setFocus()

class CursorPositionStatus(StatusBarWidget):
    """Status bar widget for the current file cursor postion."""

    def __init__(self, parent, statusbar):
        """Status bar widget for the current file cursor postion."""
        super(CursorPositionStatus, self).__init__(parent, statusbar)

        # Widget
        self.label_line = QLabel(_("Line:"))
        self.label_column = QLabel(_("Column:"))
        self.column = QLabel()
        self.line = QLabel()

        # Widget setup
        self.line.setFont(self.label_font)
        self.column.setFont(self.label_font)

        # Layout
        layout = self.layout()
        layout.addWidget(self.label_line)
        layout.addWidget(self.line)
        layout.addWidget(self.label_column)
        layout.addWidget(self.column)
        self.setLayout(layout)
        
    def cursor_position_changed(self, line, index):
        """Update cursos position."""
        self.line.setText("%-6d" % (line+1))
        self.column.setText("%-4d" % (index+1))

    def setup_page(self):
        settings_group = QGroupBox(_("Settings"))
        use_color_box = self.create_checkbox(
            _("Use deterministic colors to differentiate functions"),
            'use_colors', default=True)

        results_group = QGroupBox(_("Results"))
        results_label1 = QLabel(_("Memory profiler plugin results "
                                  "(the output of memory_profiler)\n"
                                  "is stored here:"))
        results_label1.setWordWrap(True)

        # Warning: do not try to regroup the following QLabel contents with
        # widgets above -- this string was isolated here in a single QLabel
        # on purpose: to fix Issue 863 of Profiler plugon
        results_label2 = QLabel(MemoryProfilerWidget.DATAPATH)

        results_label2.setTextInteractionFlags(Qt.TextSelectableByMouse)
        results_label2.setWordWrap(True)

        settings_layout = QVBoxLayout()
        settings_layout.addWidget(use_color_box)
        settings_group.setLayout(settings_layout)

        results_layout = QVBoxLayout()
        results_layout.addWidget(results_label1)
        results_layout.addWidget(results_label2)
        results_group.setLayout(results_layout)

        vlayout = QVBoxLayout()
        vlayout.addWidget(settings_group)
        vlayout.addWidget(results_group)
        vlayout.addStretch(1)
        self.setLayout(vlayout)

    def get_item_size(self, content):
        """
        Get the max size (width and height) for the elements of a list of
        strings as a QLabel.
        """
        strings = []
        if content:
            for rich_text in content:
                label = QLabel(rich_text)
                label.setTextFormat(Qt.PlainText)
                strings.append(label.text())
                fm = label.fontMetrics()

            return (max([fm.width(s) * 1.3 for s in strings]), fm.height())

class ConnectionInspector(QWidget):
    def __init__(self, parent=None):
        super(ConnectionInspector, self).__init__(parent, Qt.Window)
        connections = self.fetch_data()
        self.table_view = ConnectionTableView(connections, self)
        self.setLayout(QVBoxLayout(self))
        self.layout().addWidget(self.table_view)
        button_layout = QHBoxLayout()
        self.layout().addItem(button_layout)
        self.save_status_label = QLabel(self)
        button_layout.addWidget(self.save_status_label)
        button_layout.addStretch()
        self.save_button = QPushButton(self)
        self.save_button.setText("Save list to file...")
        self.save_button.clicked.connect(self.save_list_to_file)
        button_layout.addWidget(self.save_button)
        self.update_timer = QTimer(parent=self)
        self.update_timer.setInterval(1500)
        self.update_timer.timeout.connect(self.update_data)
        self.update_timer.start()

    def update_data(self):
        self.table_view.model().connections = self.fetch_data()

    def fetch_data(self):
        plugins = data_plugins.plugin_modules
        return [connection
                for p in plugins.values()
                for connection in p.connections.values()
                ]

    @Slot()
    def save_list_to_file(self):
        filename, filters = QFileDialog.getSaveFileName(self,
                                                        "Save connection list",
                                                        "",
                                                        "Text Files (*.txt)")
        try:
            with open(filename, "w") as f:
                for conn in self.table_view.model().connections:
                    f.write(
                        "{p}://{a}\n".format(p=conn.protocol, a=conn.address))
            self.save_status_label.setText("File saved to {}".format(filename))
        except Exception as e:
            msgBox = QMessageBox()
            msgBox.setText("Couldn't save connection list to file.")
            msgBox.setInformativeText("Error: {}".format(str(e)))
            msgBox.setStandardButtons(QMessageBox.Ok)
            msgBox.exec_()

class StatusBarWidget(QWidget):
    """Status bar widget base."""
    TIP = None

    def __init__(self, parent, statusbar, icon=None):
        """Status bar widget base."""
        super(StatusBarWidget, self).__init__(parent)

        # Variables
        self.value = None

        # Widget
        self._icon = icon
        self._pixmap = icon.pixmap(QSize(16, 16)) if icon is not None else None
        self.label_icon = QLabel() if icon is not None else None
        self.label_value = QLabel()

        # Widget setup
        if icon is not None:
            self.label_icon.setPixmap(self._pixmap)
        self.text_font = QFont(get_font(option='font'))  # See Issue #9044
        self.text_font.setPointSize(self.font().pointSize())
        self.text_font.setBold(True)
        self.label_value.setAlignment(Qt.AlignRight)
        self.label_value.setFont(self.text_font)

        if self.TIP:
            self.setToolTip(self.TIP)
            self.label_value.setToolTip(self.TIP)

        # Layout
        layout = QHBoxLayout()
        if icon is not None:
            layout.addWidget(self.label_icon)
        layout.addWidget(self.label_value)
        layout.addSpacing(20)

        # Layout setup
        layout.setContentsMargins(0, 0, 0, 0)
        self.setLayout(layout)

        # Setup
        statusbar.addPermanentWidget(self)

    def set_value(self, value):
        """Set formatted text value."""
        self.value = value
        if self.isVisible():
            self.label_value.setText(value)

 def __init__(self, parent=None, init_channel=None):
     QLabel.__init__(self, parent)
     PyDMWidget.__init__(self, init_channel=init_channel)
     if 'Text' not in PyDMLabel.RULE_PROPERTIES:
         PyDMLabel.RULE_PROPERTIES = PyDMWidget.RULE_PROPERTIES.copy()
         PyDMLabel.RULE_PROPERTIES.update(
             {'Text': ['value_changed', str]})
     self.app = QApplication.instance()
     self.setTextFormat(Qt.PlainText)
     self.setTextInteractionFlags(Qt.NoTextInteraction)
     self.setText("PyDMLabel")
     self._display_format_type = self.DisplayFormat.Default
     self._string_encoding = "utf_8"
     if is_pydm_app():
         self._string_encoding = self.app.get_string_encoding()