* Update the `Shape` trait. Instead of returning an iterator of point, all
shapes are now aware of the surface they will be drawn to through a `Painter`.
In order to draw themselves, they paint points of the "braille grid".
* Rewrite how lines are drawn using a common line drawing algorithm (Bresenham).
* Clean redundant generics params in Table
It is possible to use associated types the same way as generics parameters. In fact associated types are nothing more than better organized generics params. For example, there is no need to introduce another param to constraint iterator item to be Display, you can just say `where I::Iterator, I::Item: Display`. This allows to drop type params for Table from 5 to 2.
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.
* removed flush calls because execute already calls flush under the hood.
* moved some static functions into From traits
* removed useless clone in demo
* upgrade to crossterm 0.13
* map all errors
