How to use the silx.gui.colors.rgba function in silx

def getCurrentStyle(self):
        """Returns the current curve style.

        Curve style depends on curve highlighting

        :rtype: CurveStyle
        """
        baseColor = rgba(self.getColor())
        if isinstance(self, core.LineMixIn):
            baseLinestyle = self.getLineStyle()
            baseLinewidth = self.getLineWidth()
        else:
            baseLinestyle = self._DEFAULT_LINESTYLE
            baseLinewidth = self._DEFAULT_LINEWIDTH
        if isinstance(self, core.SymbolMixIn):
            baseSymbol = self.getSymbol()
            baseSymbolsize = self.getSymbolSize()
        else:
            baseSymbol = 'o'
            baseSymbolsize = 1

        if self.isHighlighted():
            style = self.getHighlightedStyle()
            color = style.getColor()

def strokeColor(self, color):
        color = rgba(color)
        if color != self.strokeColor:
            self._stroke.setAttribute('color', color)
            # Fully transparent = hidden
            self._stroke.visible = color[-1] != 0.
            self.notify()

def background(self, color):
        if color is not None:
            color = rgba(color)
        if self._background != color:
            self._background = color
            self._changed()

def _setOverlayColorForImage(self, image):
        """Set the color of overlay adapted to image

        :param image: :class:`.items.ImageBase` object to set color for.
        """
        if isinstance(image, items.ColormapMixIn):
            colormap = image.getColormap()
            self._defaultOverlayColor = rgba(
                cursorColorForColormap(colormap['name']))
        else:
            self._defaultOverlayColor = rgba('black')

def addHandle(self, item=None, role="default"):
        """
        Add a new handle to the ROI.

        Dragging handles while affect the position or the shape of the
        ROI.

        :param Union[None,silx.gui.plot.items.Marker] item: The new marker to
            add, else None to create a default marker.
        :rtype: silx.gui.plot.items.Marker
        """
        if item is None:
            item = items.Marker()
            color = rgba(self.getColor())
            color = self._computeHandleColor(color)
            item.setColor(color)
            if role == "default":
                item.setSymbol("s")
            elif role == "user":
                pass
            elif role == "translate":
                item.setSymbol("+")
            elif role == "label":
                item.setSymbol("")

        if role == "user":
            pass
        elif role == "label":
            item._setSelectable(False)
            item._setDraggable(False)

def _adjustColorAndBrushSize(self, activeScatter):
        colormap = activeScatter.getColormap()
        self._defaultOverlayColor = rgba(cursorColorForColormap(colormap['name']))
        self._setMaskColors(self.levelSpinBox.value(),
                            self.transparencySlider.value() /
                            self.transparencySlider.maximum())
        self._z = activeScatter.getZValue() + 1
        self._data_scatter = activeScatter

        # Adjust brush size to data range
        xData = self._data_scatter.getXData(copy=False)
        yData = self._data_scatter.getYData(copy=False)
        # Adjust brush size to data range
        if xData.size > 0 and yData.size > 0:
            xMin, xMax = min_max(xData)
            yMin, yMax = min_max(yData)
            self._data_extent = max(xMax - xMin, yMax - yMin)
        else:
            self._data_extent = None

def __updateMaskColor(self, color):
        maskTool = self.getMaskTool()
        # TODO: Not anymore needed for silx >= 0.10
        color = colors.rgba(color)[0:3]
        maskTool.setMaskColors(color)

if not isinstance(destination, (list, tuple)):
            destination = [destination]
        if event == items.ItemChangedType.NAME:
            value = source.getName()
            for d in destination:
                d.setName(value)
        elif event == items.ItemChangedType.EDITABLE:
            value = source.isEditable()
            for d in destination:
                d.setEditable(value)
        elif event == items.ItemChangedType.SELECTABLE:
            value = source.isSelectable()
            for d in destination:
                d._setSelectable(value)
        elif event == items.ItemChangedType.COLOR:
            value = rgba(source.getColor())
            for d in destination:
                d.setColor(value)
        elif event == items.ItemChangedType.LINE_STYLE:
            value = self.getLineStyle()
            for d in destination:
                d.setLineStyle(value)
        elif event == items.ItemChangedType.LINE_WIDTH:
            value = self.getLineWidth()
            for d in destination:
                d.setLineWidth(value)
        elif event == items.ItemChangedType.SYMBOL:
            value = self.getSymbol()
            for d in destination:
                d.setSymbol(value)
        elif event == items.ItemChangedType.SYMBOL_SIZE:
            value = self.getSymbolSize()