How to use the fabio.app._qt.QCoreApplication.processEvents function in fabio

out = fabio.tifimage.tifimage(data=data, header=header)
        elif format_ == '*.cbf':
            out = fabio.cbfimage.cbfimage(data=data, header=header)
        elif format_ in ['*.mar3450', '*.mar2300']:
            data = self.padd_mar(data, format_)
            out = fabio.mar345image.mar345image(data=data, header=header)
        elif format_ == '*.img':
            out = fabio.OXDimage.OXDimage(data=data, header=header)
        elif format_ == '*.sfrm':
            out = fabio.brukerimage.brukerimage(data=data, header=header)
        else:
            raise Warning("Unknown format: %s" % format_)
        template = 'Writing file %s to %s format, please wait...'
        self.statusBar().showMessage(template % (fname, format_[2:]))
        self.log.appendPlainText('Writing file %s to %s format' % (fname, format_[2:]))
        qt.QCoreApplication.processEvents()
        out.write(fname)
        self.statusBar().clearMessage()

numpy.add(stack, data, stack)
                            self.progressBar.setValue((float(i + 1) / (subtotal)) * 100.)
                            self.log.appendPlainText('File number %d stacked' % i)
                            qt.QCoreApplication.processEvents()
                            if j == thick - 1:
                                self.log.appendPlainText('stack number %d summing up' % k)
                                qt.QCoreApplication.processEvents()
                                if format_ in ['*.mar3450', '*.mar2300']:
                                    self.header_series[i]["PHI_START"] = '%.3f' % (start_angle + step_angle * (i - thick + 1))
                                    self.header_series[i]["PHI_END"] = '%.3f' % (start_angle + step_angle * (i))
                                filename = ('%s_%s%s' % (fname, self.counter_format, format_[1:])) % k
                                self.convert_and_write(filename, format_, stack, self.header_series[i])
                                stack = numpy.zeros_like(data)
                    self.progressBar.setValue(0)
                    self.log.appendPlainText('Downsampling: Complete')
                    qt.QCoreApplication.processEvents()
            else:
                if str(info[0]) != '' and str(info[1]) != '':
                    message = "Could not save image as file if no data have been loaded"
                    qt.QMessageBox.warning(self, 'Warning', message)

self.sequential_file_dict = {}
            self.imagelistWidget.clear()
            self.headerTextEdit.clear()
            with Nexus(fname, 'r') as nxs:
                entry = nxs.get_entries()[0]
                nxdata = nxs.get_class(entry, class_type="NXdata")[0]
                dataset = nxdata.get("data", numpy.zeros(shape=(1, 1, 1)))
                total = dataset.shape[0]
                imgDict = {}
                extract_fname = os.path.basename(os.path.splitext(fname)[0])
                self.images_list.clear()
                safeiid = 0
                for iid in range(total):
                    self.progressBar.setValue(((iid + 1.0) / (total)) * 100.)
                    self.log.appendPlainText('Extracting data from hdf5 archive, image number %d' % iid)
                    qt.QCoreApplication.processEvents()
                    self.data_series.append(dataset[iid])
                    self.header_series += [{'Info': 'No header information available in hdf5 Archive'}]
                    imgDict[extract_fname + str(iid)] = safeiid
                    self.images_list.addItem(extract_fname + str(iid))
                    safeiid += 1
            self.statusBar().clearMessage()
            self.progressBar.setValue(0)
            self.log.appendPlainText('Hdf5 Extraction: Complete')
            self.imgDict = imgDict.copy()
        if self.data_series:
            self.select_new_image(None, imgID=0)

if self.transform_data_series:
                    tmpdata = self.apply_queued_transformations(img.data)
                else:
                    tmpdata = img.data
                filename = ('%s_%s%s' % (fname, self.counter_format, format_[1:])) % ii
                self.convert_and_write(filename, format_, tmpdata, img.header)
                ii += 1
        else:
            total = len(self.data_series)
            for i in range(len(self.data_series)):
                tmpdata = self.data_series[i]
                tmpheader = self.header_series[i]
                tmpfname = ('%s_%s%s' % (fname, self.counter_format, format_[1:])) % i
                self.progressBar.setValue((float(i + 1) / (total)) * 100.)
                self.log.appendPlainText('Converting file %s' % i)
                qt.QCoreApplication.processEvents()
                if self.transform_data_series:
                    tmpdata = self.apply_queued_transformations(tmpdata)
                self.convert_and_write(tmpfname, format_, tmpdata, tmpheader)
        self.progressBar.setValue(0)
        self.log.appendPlainText('Convertion to %s: Complete' % format_[2:])

def rotation_90(self):
        if self.transform_data_series:
            if self.sequential_file_mode:
                self.transformation_queue.addItem('rotation(+90)')
                self.transform_list += ['rotation(+90)']
                self.log.appendPlainText('Add + 90 rotation to transformations queue')
                qt.QCoreApplication.processEvents()
            else:
                total = len(self.data_series)
                if not total:
                    message = "Could not transform image if no data have been loaded"
                    qt.QMessageBox.warning(self, 'Warning', message)
                    return
                for i in range(len(self.data_series)):
                    self.data_series[i] = numpy.rot90(self.data_series[i])[:]
                    self.progressBar.setValue((float(i + 1) / (total)) * 100.)
                    self.log.appendPlainText('Applying + 90 rotation to data series: image %d' % i)
                    qt.QCoreApplication.processEvents()
                iid = self.imgDict[str(self.images_list.currentText())]
                self.select_new_image(None, imgID=iid)
        else:
            if self.data.any():
                self.data = numpy.rot90(self.data)[:]

def on_draw(self):
        """ Redraws the figure"""
        self.statusBar().showMessage('Loading display...')
        qt.QCoreApplication.processEvents()
        # clear the axes and redraw a new plot
        self.axes.clear()
        # self.axes.imshow(numpy.log(numpy.clip(self.data,1.0e-12,1.0e260) ),interpolation = 'nearest')
        self.axes.imshow(numpy.log(self.data), interpolation='nearest')

        self.axes.set_visible(True)
        if self.axes.get_ylim()[0] < self.axes.get_ylim()[1]:
            self.axes.set_ylim(self.axes.get_ylim()[::-1])
        self.canvas.draw()
        self.statusBar().clearMessage()

if self.sequential_file_mode:
                self.transformation_queue.addItem('horizontal_mirror')
                self.transform_list += ['horizontal_mirror']
                self.log.appendPlainText('Add horizontal mirror to transformations queue')
                qt.QCoreApplication.processEvents()
            else:
                total = len(self.data_series)
                if not total:
                    message = "Could not transform image if no data have been loaded"
                    qt.QMessageBox.warning(self, 'Warning', message)
                    return
                for i in range(len(self.data_series)):
                    self.data_series[i] = numpy.flipud(self.data_series[i])[:]
                    self.progressBar.setValue((float(i + 1) / (total)) * 100.)
                    self.log.appendPlainText('Applying horizontal mirror to data series: image %d' % i)
                    qt.QCoreApplication.processEvents()
                iid = self.imgDict[str(self.images_list.currentText())]
                self.select_new_image(None, imgID=iid)
        else:

            if self.data.any():
                self.data = numpy.flipud(self.data)[:]
                iid = self.imgDict[str(self.images_list.currentText())]
                self.data_series[iid] = self.data[:]
                self.log.appendPlainText('Applying horizontal mirror to current data')
                self.on_draw()
            else:
                message = "Could not transform image if no data have been loaded"
                qt.QMessageBox.warning(self, 'Warning', message)
        self.progressBar.setValue(0)

def vertical_mirror(self):
        if self.transform_data_series:
            if self.sequential_file_mode:
                self.transformation_queue.addItem('vertical_mirror')
                self.transform_list += ['vertical_mirror']
                self.log.appendPlainText('Add vertical mirror to transformations queue')
                qt.QCoreApplication.processEvents()
            else:
                total = len(self.data_series)
                if not total:
                    message = "Could not transform image if no data have been loaded"
                    qt.QMessageBox.warning(self, 'Warning', message)
                    return
                for i in range(len(self.data_series)):
                    self.data_series[i] = numpy.fliplr(self.data_series[i])[:]
                    self.progressBar.setValue((float(i + 1) / (total)) * 100.)
                    self.log.appendPlainText('Applying vertical mirror to data series: image %d' % i)
                    qt.QCoreApplication.processEvents()
                iid = self.imgDict[str(self.images_list.currentText())]
                self.select_new_image(None, imgID=iid)
        else:
            if self.data.any():
                self.data = numpy.fliplr(self.data)[:]