incubator-nuttx/graphics/README.txt

README
^^^^^^

This directory contains tiny graphics support for NuttX.  The contents of this directory
are only build if CONFIG_NXGRAPHICS is defined in the NuttX configuration file.

Roadmap
^^^^^^^

This directory holds NuttX graphic packages.  Not all of these packages are implemented
at the present, but here is the longer term roadmap:

  NXWIDGETS - I had originally planned a high level, C++, object-oriented library for
              object-oriented access to graphics widgets.  However, because C++ compilers
              are not available for some of the targets supported by NuttX, I have
              decided to implement the entire solution in  C -- that makes the solution
              much uglier, but works fine on all platforms.
  NXTOOLKIT - A set of C graphics tools that provide higher-level window drawing
              operations.  The toolkit can be used for window-oriented graphics
              without NXWIDGETS and is built on top of NX.
  NX        - The tiny NuttX windowing system.  This includes both a small-footprint,
              single user implementaton (NXSU as described below) and a somewhat
              larger multi-user implentation (NXMU as described below).  Both
              conform to the same APIs as defined in include/nuttx/nx.h and, hence,
              are more-or-less interchangable.  NX can be used without NXWIDGETS
              and without NXTOOLKIT for raw access to window memory.
  NXGLIB    - Low level graphics utilities and direct framebuffer rendering logic.
              NX is build on NXGLIB.

Related Header Files
^^^^^^^^^^^^^^^^^^^^

include/nuttx/nxglib.h    -- Describes the NXGLIB C interfaces
include/nuttx/nx.h        -- Describes the NX C interfaces
include/nutt/nxtk.h       -- Describe the NXTOOLKIT C interfaces
include/nuttx/nxwidgets.h -- Will describe the NXWIDGETS classes (no longer planned)

Directories:
^^^^^^^^^^^^

graphics/nxglib
  The NuttX tiny graphics library.  The directory contains generic utilities
  support operations on primitive graphics objects and logic to rasterize directly
  into a framebuffer.  It has no concept of windows (other than the one, framebuffer
  window).

graphics/nxbe
  This is the "back-end" of a tiny windowing system.  It can be used with either of
  two front-ends to complete a windowing system (see nxmu and nxsu below).  It
  contains most of the important window management logic:  clipping, window controls,
  window drawing, etc.

graphics/nxsu
  This is the NX single user "front end".  When combined with the generic "back-end"
  (nxbe), it implements a single thread, single user windowing system.  The files
  in this directory present the window APIs described in include/nuttx/nx.h.  The
  single user front-end is selected when CONFIG_NX_MULTIUSER is not defined in the
  NuttX configuration file.

graphics/nxsu
  This is the NX multi user "front end".  When combined with the generic "back-end"
  (nxbe), it implements a multi-threaded, multi-user windowing system.  The files
  in this directory present the window APIs described in include/nuttx/nx.h.  The
  multi-user front end includes a graphics server that executes on its own thread;
  multiple graphics clients then communicate with the server via a POSIX message
  queue to serialize window operations from many threads. The multi-user front-end
  is selected when CONFIG_NX_MULTIUSER is defined in the NuttX configuration file.

graphics/nxtoolkit
  This is where the NXTOOLKIT implementation resides.  This toolkit is built on
  top of NX and works with either the single-user or multi-user NX version. See
  include/nuttx/nxtk.h

graphics/nxwidgets
  At one time, I planned to put NXWIDGETS implementation here, but not anymore.