In the past, FTXUI switched from std::string to std::wstring to support
fullwidth characters. The reasons was that fullwidth characters can be
stored inside a single wchar_t.
Then FTXUI added support for combining characters. A single glygh
doesn't even fit a wchar_t. Instead, a glyph can be arbitrary large.
The usage of wstring doesn't really fit the new model and have several
drawbacks:
1. It doesn't simplify the implementation of FTXUI, because of combining
characters.
2. It reduces drawing performance by 2x.
3. It increase Screen's memory allocation by 2x.
This patch converts FTXUI to use std::string internally. It now exposes
std::string based API. The std::wstring API remains, but is now
deprecated.
Tests and examples haven't been update to show the breakage is limited.
They will be updated in a second set of patches.
Bug: https://github.com/ArthurSonzogni/FTXUI/issues/153
Co-authored-by: Tushar Maheshwari <tushar27192@gmail.com>
Two new elements:
- flex_grow : Expand the element to occupy free space.
- flex_shrink: Minimize the element leave away missing space.
flex = flex_grow | flex_shrink.
Other changes:
- hbox and vbox are now non flexible by default.
- the vtext element has been added to help writting tests.
- Many new tests.
