nuttx/libs/libnx/nxfonts

README
^^^^^^

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

Installing New Fonts
^^^^^^^^^^^^^^^^^^^^

  There is a tool called bdf-converter in the directory tools/.  The bdf-converter
  program be used to convert fonts in Bitmap Distribution Format (BDF)
  into fonts that can be used in the NX graphics system.

  Below are general instructions for creating and installing a new font
  in the NX graphic system:

    1. Locate a font in BDF format,
    2. Use the bdf-converter program to convert the BDF font to the NuttX
       font format.  This will result in a C header file containing
       definitions.  That header file should be installed at, for example,
       graphics/nxfonts/nxfonts_myfont.h.

  Create a new NuttX configuration variable.  For example, suppose
  you define the following variable:  CONFIG_NXFONT_MYFONT.  Then
  you would need to:

    3. Define CONFIG_NXFONT_MYFONT=y in your NuttX configuration file.

  A font ID number has to be assigned for each new font.  The font ID
  is defined in the file include/nuttx/nx/nxfonts.h.  Those definitions
  have to be extended to support your new font.  Look at how the font ID
  enabled by CONFIG_NXFONT_SANS23X27 is defined and add an ID for your
  new font in a similar fashion:

    4. include/nuttx/nx/nxfonts.h. Add you new font as a possible system
       default font:

       #if defined(CONFIG_NXFONT_SANS23X27)
       # define NXFONT_DEFAULT FONTID_SANS23X27
       #elif defined(CONFIG_NXFONT_MYFONT)
       # define NXFONT_DEFAULT FONTID_MYFONT
       #endif

       Then define the actual font ID.  Make sure that the font ID value
       is unique:

       enum nx_fontid_e
       {
         FONTID_DEFAULT     = 0      /* The default font */
       #ifdef CONFIG_NXFONT_SANS23X27
         , FONTID_SANS23X27 = 1      /* The 23x27 sans serif font */
       #endif
       #ifdef CONFIG_NXFONT_MYFONT
         , FONTID_MYFONT    = 2      /* My shiny, new font */
       #endif
       ...

  New Add the font to the NX build system.  There are several files that
  you have to modify to do this.  Look how the build system uses the
  font CONFIG_NXFONT_SANS23X27 for examaples:

    5. nuttx/graphics/Makefile.  This file needs logic to auto-generate
       a C source file from the header file that you generated with the
       the bdf-converter program.  Notice NXFONTS_FONTID=2; this must be
       set to the same font ID value that you defined in the
       include/nuttx/nx/nxfonts.h file.

       genfontsources:
         ifeq ($(CONFIG_NXFONT_SANS23X27),y)
          @$(MAKE) -C nxfonts -f Makefile.sources NXFONTS_FONTID=1 EXTRAFLAGS=$(EXTRAFLAGS)
        endif
         ifeq ($(CONFIG_NXFONT_MYFONT),y)
          @$(MAKE) -C nxfonts -f Makefile.sources NXFONTS_FONTID=2 EXTRAFLAGS=$(EXTRAFLAGS)
        endif

    6. nuttx/graphics/nxfonts/Make.defs.  Set the make variable NXFSET_CSRCS.
       NXFSET_CSRCS determines the name of the font C file to build when
       NXFONTS_FONTID=2:

       ifeq ($(CONFIG_NXFONT_SANS23X27),y)
       NXFSET_CSRCS += nxfonts_bitmaps_sans23x27.c
       endif
       ifeq ($(CONFIG_NXFONT_MYFONT),y)
       NXFSET_CSRCS += nxfonts_bitmaps_myfont.c
       endif

    7. nuttx/graphics/nxfonts/Makefile.sources.  This is the Makefile used
       in step 5 that will actually generate the font C file.  So, given
       your NXFONTS_FONTID=2, it needs to determine a prefix to use for
       auto-generated variable and function names and (again) the name of
       the autogenerated file to create (this must be the same name that
       was used in nuttx/graphics/nxfonts/Make.defs):

       ifeq ($(NXFONTS_FONTID),1)
       NXFONTS_PREFIX := g_sans23x27_
       GEN_CSRC = nxfonts_bitmaps_sans23x27.c
       endif
       ifeq ($(NXFONTS_FONTID),2)
       NXFONTS_PREFIX := g_myfont_
       GEN_CSRC = nxfonts_bitmaps_myfont.c
       endif

    8. graphics/nxfonts/nxfonts_bitmaps.c.  This is the file that contains
       the generic font structures.  It is used as a "template" file by
       nuttx/graphics/nxfonts/Makefile.sources to create your customized
       font data set.

       #if NXFONTS_FONTID == 1
       #  include "nxfonts_sans23x27.h"
       #elif NXFONTS_FONTID == 2
       #  include "nxfonts_myfont.h"
       #else
       #  error "No font ID specified"
       #endif

       Where nxfonts_myfont.h is the NuttX font file that we generated in
       step 2 using the bdf-converter tool.

    9. graphics/nxfonts/nxfonts_getfont.c.  Finally, we need to extend the
       logic that does the run-time font lookups so that can find our new
       font.  The lookup function is NXHANDLE nxf_getfonthandle(enum nx_fontid_e fontid).
       The new font information needs to be added to data structures used by
       that function:

       #ifdef CONFIG_NXFONT_SANS23X27
       extern const struct nx_fontpackage_s g_sans23x27_package;
       #endif
       #ifdef CONFIG_NXFONT_MYFONT
       extern const struct nx_fontpackage_s g_myfont_package;
       #endif

       static FAR const struct nx_fontpackage_s *g_fontpackages[] =
       {
       #ifdef CONFIG_NXFONT_SANS23X27
       &g_sans23x27_package,
       #endif
       #ifdef CONFIG_NXFONT_MYFONT
       &g_myfont_package,
       #endif
       NULL
       };

Configuration Settings
^^^^^^^^^^^^^^^^^^^^^^

NxFonts
-------

CONFIG_NXFONTS
  Enables font support
CONFIG_NXFONTS_CHARBITS
  The number of bits in the character set.  Current options are only 7 and 8.
  The default is 7.
CONFIG_NXFONTS_DISABLE_1BPP, CONFIG_NXFONTS_DISABLE_2BPP,
CONFIG_NXFONTS_DISABLE_4BPP, CONFIG_NXFONTS_DISABLE_8BPP,
CONFIG_NXFONTS_DISABLE_16BPP, CONFIG_NXFONTS_DISABLE_24BPP, and
CONFIG_NXFONTS_DISABLE_32BPP
  NX supports a variety of pixel depths.  You can save some memory by disabling
  support for unused color depths.
CONFIG_NXFONTS_PACKEDMSFIRST
  If a pixel depth of less than 8-bits is used, then NX needs to know if the
  pixels pack from the MS to LS or from LS to MS

Font Selections
---------------

CONFIG_NXFONT_SANS17X22
  This option enables support for a tiny, 17x22 san serif font
  (font ID FONTID_SANS17X22 == 14).
CONFIG_NXFONT_SANS20X26
  This option enables support for a tiny, 20x26 san serif font
  (font ID FONTID_SANS20X26 == 15).
CONFIG_NXFONT_SANS23X27
  This option enables support for a tiny, 23x27 san serif font
  (font ID FONTID_SANS23X27 == 1).
CONFIG_NXFONT_SANS22X29
  This option enables support for a small, 22x29 san serif font
  (font ID FONTID_SANS22X29 == 2).
CONFIG_NXFONT_SANS28X37
  This option enables support for a medium, 28x37 san serif font
  (font ID FONTID_SANS28X37 == 3).
CONFIG_NXFONT_SANS39X48
  This option enables support for a large, 39x48 san serif font
  (font ID FONTID_SANS39X48 == 4).
CONFIG_NXFONT_SANS17X23B
  This option enables support for a tiny, 17x23 san serif bold font
  (font ID FONTID_SANS17X23B == 16).
CONFIG_NXFONT_SANS20X27B
  This option enables support for a tiny, 20x27 san serif bold font
  (font ID FONTID_SANS20X27B == 17).
CONFIG_NXFONT_SANS22X29B
  This option enables support for a small, 22x29 san serif bold font
  (font ID FONTID_SANS22X29B == 5).
CONFIG_NXFONT_SANS28X37B
  This option enables support for a medium, 28x37 san serif bold font
  (font ID FONTID_SANS28X37B == 6).
CONFIG_NXFONT_SANS40X49B
  This option enables support for a large, 40x49 san serif bold font
  (font ID FONTID_SANS40X49B == 7).
CONFIG_NXFONT_SERIF22X29
  This option enables support for a small, 22x29 font (with serifs)
  (font ID FONTID_SERIF22X29 == 8).
CONFIG_NXFONT_SERIF29X37
  This option enables support for a medium, 29x37 font (with serifs)
  (font ID FONTID_SERIF29X37 == 9).
CONFIG_NXFONT_SERIF38X48
  This option enables support for a large, 38x48 font (with serifs)
  (font ID FONTID_SERIF38X48 == 10).
CONFIG_NXFONT_SERIF22X28B
  This option enables support for a small, 27x38 bold font (with serifs)
  (font ID FONTID_SERIF22X28B == 11).
CONFIG_NXFONT_SERIF27X38B
  This option enables support for a medium, 27x38 bold font (with serifs)
  (font ID FONTID_SERIF27X38B == 12).
CONFIG_NXFONT_SERIF38X49B
  This option enables support for a large, 38x49 bold font (with serifs)
  (font ID FONTID_SERIF38X49B == 13).
[REVISIT... this list is not complete]