Qt-Color-Widgets is a color dialog that is more user-friendly than the default
QColorDialog and several other color-related widgets.

The provided widgets are:
* ColorWheel, An analog widget used to select a color
* ColorPreview, A simple widget that displays a color
* GradientSlider, A slider that has a gradient background
* HueSlider, A variant of GradientSlider that has a rainbow background
* ColorSelector, A ColorPreview that shows a ColorDialog when clicked
* ColorDialog, A dialog that uses the above widgets to provide a better user
  experience than QColorDialog
* ColorListWidget, A widget to edit a list of colors
* Swatch, A widget to display a color palette
* ColorPaletteWidget, A widget to use and manage a list of palettes
* Color2DSlider, An analog widget used to select 2 color components
* ColorLineEdit, A widget to manipulate a string representing a color
* HarmonyColorWheel, A ColorWheel which allows defining multiple colors,
  separated by hue
* GradientListModel, A QAbstractListModel used to list gradients (useful for
  comboboxes, list views and the like)

WWW: https://gitlab.com/mattia.basaglia/Qt-Color-Widgets