- control over the style of each cell and its content using the styling capabilities of Text.
- rows with multiple lines.
- fix panics on small areas.
- less generic type parameters.
Most widgets can be drawn directly based on the input parameters. However, some
features may require some kind of associated state to be implemented.
For example, the `List` widget can highlight the item currently selected. This
can be translated in an offset, which is the number of elements to skip in
order to have the selected item within the viewport currently allocated to this
widget. The widget can therefore only provide the following behavior: whenever
the selected item is out of the viewport scroll to a predefined position (make
the selected item the last viewable item or the one in the middle).
Nonetheless, if the widget has access to the last computed offset then it can
implement a natural scrolling experience where the last offset is reused until
the selected item is out of the viewport.
To allow such behavior within the widgets, this commit introduces the following
changes:
- Add a `StatefulWidget` trait with an associated `State` type. Widgets that
can take advantage of having a "memory" between two draw calls needs to
implement this trait.
- Add a `render_stateful_widget` method on `Frame` where the associated
state is given as a parameter.
The chosen approach is thus to let the developers manage their widgets' states
themselves as they are already responsible for the lifecycle of the wigets
(given that the crate exposes an immediate mode api).
The following changes were also introduced:
- `Widget::render` has been deleted. Developers should use `Frame::render_widget`
instead.
- `Widget::background` has been deleted. Developers should use `Buffer::set_background`
instead.
- `SelectableList` has been deleted. Developers can directly use `List` where
`SelectableList` features have been back-ported.
* Add a generic item object for the list. The item can either be some data
alone or some data and its style
* The List widget now store an Iterator over those element. This should
avoid the need of allocating memory to store its elements
* The List consume the Iterator when it is drawn
The draw function now take a &mut reference to the widget, allowing the
widget to modify itself when drawn. This change the semantic of the draw
call since the widget should now be considered "consumed" after it.
