Perform command and return the appropriate exit code.

        :rtype: int

def perform_command(self):
        """
        Perform command and return the appropriate exit code.

        :rtype: int
        """
        if len(self.actual_arguments) < 2:
            return self.print_help()
        input_file_path = self.actual_arguments[0]
        output_file_path = self.actual_arguments[1]

        if not self.check_input_file(input_file_path):
            return self.ERROR_EXIT_CODE
        if not self.check_output_file(output_file_path):
            return self.ERROR_EXIT_CODE

        fast = self.has_option("--fast")
        fragment_text = self.has_option("--text")
        h_zoom = gf.safe_int(self.has_option_with_value("--hzoom"), 5)
        label = self.has_option_with_value("--label")
        time_step = gf.safe_int(self.has_option_with_value("--time-step"), 0)
        v_zoom = gf.safe_int(self.has_option_with_value("--vzoom"), 30)

        labels = not self.has_option("--no-labels")
        begin_times = not self.has_option("--no-begin-times")
        end_times = not self.has_option("--no-end-times")
        begin_guides = not self.has_option("--no-begin-guides")
        end_guides = not self.has_option("--no-end-guides")

        try:
            # import or ImportError
            from aeneas.plotter import PlotLabelset
            from aeneas.plotter import PlotTimeScale
            from aeneas.plotter import PlotWaveform
            from aeneas.plotter import Plotter

            # create plotter object
            self.print_info(u"Plotting to file...")
            plotter = Plotter(rconf=self.rconf, logger=self.logger)

            # add waveform
            afm = AudioFile(input_file_path, rconf=self.rconf, logger=self.logger)
            afm.read_samples_from_file()
            plotter.add_waveform(PlotWaveform(afm, label=label, fast=fast, rconf=self.rconf, logger=self.logger))

            # add time scale, if requested
            if time_step > 0:
                plotter.add_timescale(PlotTimeScale(afm.audio_length, time_step=time_step, rconf=self.rconf, logger=self.logger))

            # add labelsets, if any
            for i in range(len(self.actual_arguments)):
                if (self.actual_arguments[i] == "-i") and (i + 1 < len(self.actual_arguments)):
                    label_file_path = self.actual_arguments[i + 1]
                    extension = gf.file_extension(label_file_path)
                    if extension == "vad":
                        labelset = self._read_syncmap_file(label_file_path, SyncMapFormat.TSV, False)
                        ls = PlotLabelset(labelset, parameters=None, rconf=self.rconf, logger=self.logger)
                        ls.parameters["labels"] = False
                        ls.parameters["begin_time"] = begin_times
                        ls.parameters["end_time"] = end_times
                        ls.parameters["begin_guide"] = begin_guides
                        ls.parameters["end_guide"] = end_guides
                        plotter.add_labelset(ls)
                    if extension in SyncMapFormat.ALLOWED_VALUES:
                        labelset = self._read_syncmap_file(label_file_path, extension, fragment_text)
                        ls = PlotLabelset(labelset, parameters=None, rconf=self.rconf, logger=self.logger)
                        ls.parameters["labels"] = labels
                        ls.parameters["begin_time"] = begin_times
                        ls.parameters["end_time"] = end_times
                        ls.parameters["begin_guide"] = begin_guides
                        ls.parameters["end_guide"] = end_guides
                        plotter.add_labelset(ls)

            # output to file
            plotter.draw_png(output_file_path, h_zoom=h_zoom, v_zoom=v_zoom)
            self.print_info(u"Plotting to file... done")
            self.print_success(u"Created file '%s'" % output_file_path)
            return self.NO_ERROR_EXIT_CODE
        except ImportError:
            self.print_error(u"You need to install Python module Pillow to output image to file. Run:")
            self.print_error(u"$ pip install Pillow")
            self.print_error(u"or, to install for all users:")
            self.print_error(u"$ sudo pip install Pillow")
        except Exception as exc:
            self.print_error(u"An unexpected error occurred while generating the image file:")
            self.print_error(u"%s" % exc)

        return self.ERROR_EXIT_CODE