fix #322

    def scaleBy(self, value: float):

        self.scaleImage(value)

    def _set_scene_scale(self, scale: float):

        self.scale_factor = scale

        self.baseLayer.setScale(scale)

        self.setSceneRect(0, 0, self.baseLayer.sceneBoundingRect().width(), self.baseLayer.sceneBoundingRect().height())

    def render_result_img(self):

        scale_before = self.scale_factor

        if scale_before != 1:

            self._set_scene_scale(1)

        self.clearSelection()

        if self.textEditMode() and self.txtblkShapeControl.blk_item is not None:

            if self.txtblkShapeControl.blk_item.is_editting():

        result = QImage(canvas_sz, QImage.Format.Format_ARGB32)

        painter = QPainter(result)

        painter.setRenderHint(QPainter.RenderHint.Antialiasing)

        rect = QRectF(0, 0, canvas_sz.width(), canvas_sz.height())

        self.render(painter, rect, rect)   #  produce blurred result if target/source rect not specified #320

        painter.end()

        self.inpaintLayer.setPixmap(old_ilayer_pixmap)

        if scale_before != 1:

            self._set_scene_scale(scale_before)

        return result

    def updateLayers(self):

        s_f = self.scale_factor * factor

        s_f = np.clip(s_f, CANVAS_SCALE_MIN, CANVAS_SCALE_MAX)

        sbr = self.baseLayer.sceneBoundingRect()

        self.old_size = sbr.size()

        scale_changed = self.scale_factor != s_f

        self.scale_factor = s_f

        self.baseLayer.setScale(self.scale_factor)