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nuttx-bb/nuttx/graphics/README.txt

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README
^^^^^^
This directory contains tiny graphics support for NuttX. The contents of this directory
are only build if CONFIG_NX is defined in the NuttX configuration file.
Contents
^^^^^^^^
Roadmap
Related Header Files
Directories
Installing New Fonts
Configuration Settings
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.
NXFONTS - A set of C graphics tools for present (bitmap) font images.
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/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 built on top of NXGLIB.
Related Header Files
^^^^^^^^^^^^^^^^^^^^
include/nuttx/nx/nxglib.h -- Describes the NXGLIB C interfaces
include/nuttx/nx/nx.h -- Describes the NX C interfaces
include/nuttx/nx/nxtk.h -- Describe the NXTOOLKIT C interfaces
include/nuttx/nx/nxfont.h -- Describe sthe NXFONT C interfaces
include/nuttx/nx/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/nx.h. The
single user front-end is selected when CONFIG_NX_MULTIUSER is not defined in the
NuttX configuration file.
graphics/nxmu
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/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/nxfonts
This is where the NXFONTS implementation resides. This is a relatively low-
level set of charset set/glyph management APIs. See include/nuttx/nx/nxfonts.h
graphics/nxtk
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/nx/nxtk.h
graphics/nxwidgets
At one time, I planned to put NXWIDGETS implementation here, but not anymore.
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
defintions. 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 to 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 TOPDIR=$(TOPDIR) NXFONTS_FONTID=1 EXTRADEFINES=$(EXTRADEFINES)
endif
ifeq ($(CONFIG_NXFONT_MYFONT),y)
@$(MAKE) -C nxfonts -f Makefile.sources TOPDIR=$(TOPDIR) NXFONTS_FONTID=2 EXTRADEFINES=$(EXTRADEFINES)
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
^^^^^^^^^^^^^^^^^^^^^^
CONFIG_NX
Enables overall support for graphics library and NX
CONFIG_NX_MULTIUSER
Configures NX in multi-user mode
CONFIG_NX_NPLANES
Some YUV color formats requires support for multiple planes, one for each
color component. Unless you have such special hardware, this value should be
undefined or set to 1.
CONFIG_NX_DISABLE_1BPP, CONFIG_NX_DISABLE_2BPP,
CONFIG_NX_DISABLE_4BPP, CONFIG_NX_DISABLE_8BPP,
CONFIG_NX_DISABLE_16BPP, CONFIG_NX_DISABLE_24BPP, and
CONFIG_NX_DISABLE_32BPP
NX supports a variety of pixel depths. You can save some memory by disabling
support for unused color depths.
CONFIG_NX_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
CONFIG_NX_MOUSE
Build in support for mouse input.
CONFIG_NX_KBD
Build in support of keypad/keyboard input.
CONFIG_NXTK_BORDERWIDTH
Specifies with with of the border (in pixels) used with framed windows.
The default is 4.
CONFIG_NXTK_BORDERCOLOR1 and CONFIG_NXTK_BORDERCOLOR2
Specify the colors of the border used with framed windows.
CONFIG_NXTK_BORDERCOLOR2 is the shadow side color and so is normally darker.
The default is medium and dark grey, respectively
CONFIG_NXTK_AUTORAISE
If set, a window will be raised to the top if the mouse position is over a
visible portion of the window. Default: A mouse button must be clicked over
a visible portion of the window.
CONFIG_NXFONTS_CHARBITS
The number of bits in the character set. Current options are only 7 and 8.
The default is 7.
CONFIG_NXFONT_SANS23X27
At present, there is only one font, a 23x27 sans serif fount. But if
there were were more, then this option would select that sans serif font.
NX Multi-user only options:
CONFIG_NX_BLOCKING
Open the client message queues in blocking mode. In this case,
nx_eventhandler() will not return until a message is received and processed.
CONFIG_NX_MXSERVERMSGS and CONFIG_NX_MXCLIENTMSGS
Specifies the maximum number of messages that can fit in the message queues.
No additional resources are allocated, but this can be set to prevent
flooding of the client or server with too many messages (CONFIG_PREALLOC_MQ_MSGS
controls how many messages are pre-allocated).
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