Color alpha channel

[PierreHei]

Everything is in the title, none of the widgets allows to set the alpha field of the color class

[flozz]

To fully support the alpha channel in PhotonUI widget, the following widgets must be modified:

• photonui.Color:
  • setRgbString() must be implemented → done: get/setCssRgbString()
  • setRgbaString() must be implemented → done: get/setCssRgbaString()
  • get|setRgbaHexString() must be implemented → done
  • a fromString() method must be implemented to import color from any format (hex, rgb, rgba, named color,...) → done
• photonui.ColorPicker:
  • must provide an option to enable it to handle the alpha channel (by default it must only allow to update HSB informations)
  • must implement a kind of slider to allow to update the alpha channel (can be disabled)
  • must display a checkerboard on the background of the preview field

• photonui.ColorPalette:
  • must display a checkerboard on the background of the colors that have alpha
• photonui.ColorButton:
  • must display a checkerboard on the background of the colors that have alpha
• photonui.ColorPickerDialog:
  • must provide an option to enable it to handle the alpha channel (by default it must only allow to update HSB and RGB informations)
  • must provide a slider to manipulate the alpha channel