- merge `Style` and `StyleDiff` together. `Style` now is used to activate or deactivate certain
style rules not to overidden all of them.
- update all impacted widgets, examples and tests.
* Remove custom Debug implementation of Buffer
* Add `TestBackend::assert_buffer` to compare buffers in integration tests. When
the assertion fails, the output now show the list of differences in addition
of the views of the computed and expected buffers. This effectively replaces
the table of debug code for colors and modifiers as it is easier to read.
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.
Coordinates returned by Buffer::pos_of were interpreted as local coordinates
while they were global. This was resulting in panics due to out of bounds
accesses. Interpreting the coordinates as global and using correct offsets
when computing the new index within the buffer for each cell fix the issue.
- Add tests for this behavior.
- Extend documentation of Buffer::pos_of and Buffer::index_of
- Clarify that the coordinates should be in global coordinate-space
(rather than local).
- Document panics.
- Add examples.
