text: # coding: utf-8
  # /*##########################################################################
  #
  # Copyright (c) 2016 European Synchrotron Radiation Facility
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  #
  # ###########################################################################*/
  
  from __future__ import absolute_import
  
  __authors__ = ["V. Valls"]
  __license__ = "MIT"
  __date__ = "15/02/2017"
  
  import logging
  from pyFAI.gui import qt
  
  _logger = logging.getLogger(__name__)
  
  
  class FileEdit(qt.QLineEdit):
      """
      QLineEdit connected to a DataModel containing a file or nothing.
  
      It allows to edit a float value which can be nonified (by the use of an
      empty string).
      """
  
      def __init__(self, parent=None):
          super(FileEdit, self).__init__(parent)
          self.__model = None
          self.__applyedWhenFocusOut = True
  
          self.editingFinished.connect(self.__editingFinished)
          self.returnPressed.connect(self.__returnPressed)
  
      def setModel(self, model):
          if self.__model is not None:
              self.__model.changed.disconnect(self.__modelChanged)
          self.__model = model
          if self.__model is not None:
              self.__model.changed.connect(self.__modelChanged)
          self.__modelChanged()
  
      def model(self):
          return self.__model
  
      def keyPressEvent(self, event):
          if event.key() in (qt.Qt.Key_Return, qt.Qt.Key_Enter):
              self.__returnPressed()
              event.accept()
          elif event.key() == qt.Qt.Key_Escape:
              self.__cancelText()
              event.accept()
          else:
              return super(FileEdit, self).keyPressEvent(event)
  
      def __modelChanged(self):
          self.__cancelText()
  
      def __editingFinished(self):
          if self.__applyedWhenFocusOut:
              self.__applyText()
          else:
              self.__cancelText()
  
      def __returnPressed(self):
          self.__applyText()
  
      def __applyText(self):
          text = self.text()
  
          if text.strip() == "":
              value = None
          else:
              value = text
  
          try:
              self.__model.setValue(value)
          except ValueError as e:
              _logger.debug(e, exc_info=True)
              self.__cancelText()
  
      def __cancelText(self):
          """Reset the edited value to the original one"""
          value = self.__model.value()
          if value is None:
              text = ""
          else:
              text = value
          old = self.blockSignals(True)
          self.setText(text)
          self.blockSignals(old)
  
      def isApplyedWhenFocusOut(self):
          return self.__applyedWhenFocusOut
  
      def setApplyedWhenFocusOut(self, isApplyed):
          self.__applyedWhenFocusOut = isApplyed
  
      applyedWhenFocusOut = qt.pyqtProperty(bool, isApplyedWhenFocusOut, setApplyedWhenFocusOut)
      """Apply the current edited value to the widget when it lose the
      focus. By default the previous value is displayed.
      """
  