Text painting operates in two steps:
1. Preparation of a texture that contains all the glyphs required for
text painting, along with metadata that describes the locations of
those glyphs within texture beforehand.
2. Blitting glyphs from the prepared texture onto corresponding glyph
quads.
Users of LibAccelGfx will need to call `prepare_glyphs_texture()`,
passing a set of all unique (font, code_paint) pairs, before painting
any text.
In the upcoming changes, Painter will be used to store the state of
OpenGL context. For example, if Painter is aware of the shader that
have already been loaded, it will be possible to reuse them across
repaints. Also, it would be possible to manage state of loaded textures
and add/remove them depending on which ones are present in the next
sequence of painting commands.
This change introduces a new 2D graphics library that uses OpenGL to
perform painting operations. For now, it has extremely limited
functionality and supports only rectangle painting, but we have to
start somewhere.
Since this library is intended to be used by LibWeb, where the
WebContent process does not have an associated window, painting occurs
in an offscreen buffer created using EGL.
For now it is only possible to compile this library on linux.
Offscreen context creation on SerenityOS and MacOS will have to be
implemented separately in the future.
Co-Authored-By: Andreas Kling <awesomekling@gmail.com>
