Appendix
graphics/
Directory Structure
The graphics capability consist both of components internal to the RTOS
and of user-callable interfaces. In the NuttX kernel mode build there
are some components of the graphics subsystem are callable in user mode
and other components that are internal to the RTOS. The directory
nuttx/graphics
contains only those components that are internal to
the RTOS. User callable functions must be part of a library that can be
linked against user applications. This user callable interfaces are
provided in sub-directories under nuttx/libnx
.
libnx/nx
Common callable interfaces that are, logically, part of both nxmu and nxsu.
graphics/nxglib
andlibnx/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 or through an LCD driver interface. It has no concept of windows (other than the one, framebuffer or LCD 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
andnxsu
below). It contains most of the important window management logic: clipping, window controls, window drawing, etc.graphics/nxmu
andlibnx/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 ininclude/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.libnx/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
.libnx/nxtk
This is where the NXTOOLKIT implementation resides. This toolkit is built on top of NX and works with the multi-user NX front-end. See
include/nuttx/nx/nxtk.h
.apps/graphics/NxWidgets
The NxWidgets code is provided as a separate package provided in the
apps/
repository.graphics/nxterm
The NxTerm driver is built on top of NX and works with the multi-user NX front-end. See
include/nuttx/nx/nxterm.h
.
NX Configuration Options
General Configuration Settings
CONFIG_NX
Enables overall support for graphics library and NX
CONFIG_NX_RAMBACKED
Enables RAM backed window support. If this option is selected, then windows may be optionally created with a RAM framebuffer backing up the window content. Rending into the window will result in rending into the backup framebuffer, then updating the physical display from the framebuffer.
The advantage of this option is that the application that manages window will no longer receive redraw() callbacks. Those calls normally occur, for example, when a window “above” moves exposing a portion of the window below. If this option is selected, then the system will redraw the exposed portion of the window from the backup framebuffer without intervention of the window applications. This greatly reduces the complexity of the application and performance of the window at the expense of increased memory usage.
An exception is the case when the window is resized to a wider and/or taller size. In that case, the redraw callback will till occur. It is necessary in that case to provide new graphic content for the extended window area.
Redraw requests in other cases are also suppressed: Changes to window position, size, etc.
NXGL Configuration Settings
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
, andCONFIG_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_LCDDRIVER
:By default, NX builds to use a framebuffer driver (see
include/nuttx/video/fb.h
). If this option is defined, NX will build to use an LCD driver (seeinclude/nuttx/lcd/lcd.h
).CONFIG_NX_ANTIALIASING
:Enable support for anti-aliasing when rendering lines as various orientations. This option is only available for use with frame buffer drivers and only with 16-, 24-, or 32-bit RGB color formats.
Configuration Settings
CONFIG_NX_XYINPUT
:Build in support for an X/Y input such as a mouse or a touscreen.
CONFIG_NX_KBD
:Build in support of keypad/keyboard input.
CONFIG_NX_WRITEONLY
:Define if the underlying graphics device does not support read operations. Automatically defined if
CONFIG_NX_LCDDRIVER
andCONFIG_LCD_NOGETRUN
are defined.
NX Server Configuration Settings
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
andCONFIG_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).
NXTK Configuration Settings
CONFIG_NXTK_BORDERWIDTH
:Specifies the width of the border (in pixels) used with framed windows. The default is 4.
CONFIG_NXTK_BORDERCOLOR1
,CONFIG_NXTK_BORDERCOLOR2
, andCONFIG_NXTK_BORDERCOLOR3
:Specify the colors of the border used with framed windows.
CONFIG_NXTK_BORDERCOLOR2
The shadow side color and so is normally darker.
CONFIG_NXTK_BORDERCOLOR3
The shiny side color and so is normally brighter. The default is medium, dark, and light 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.
NXFONTS Configuration Settings
CONFIG_NXFONTS_CHARBITS
:The number of bits in the character set. Current options are only 7 and 8. The default is 7.
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).
NxTerm Configuration Settings
General NxTerm settings.
CONFIG_NXTERM
:Enables building of the NxTerm driver.
NxTerm output text/graphics options:
CONFIG_NXTERM_BPP
:Currently, NxTerm supports only a single pixel depth. This configuration setting must be provided to support that single pixel depth. Default: The smallest enabled pixel depth. (see
CONFIG_NX_DISABLE_*BPP
)CONFIG_NXTERM_CURSORCHAR
:The bitmap code to use as the cursor. Default ‘_’
CONFIG_NXTERM_MXCHARS
:NxTerm needs to remember every character written to the console so that it can redraw the window. This setting determines the size of some internal memory allocations used to hold the character data. Default: 128.
CONFIG_NXTERM_CACHESIZE
:NxTerm supports caching of rendered fonts. This font caching is required for two reasons: (1) First, it improves text performance, but more importantly (2) it preserves the font memory. Since the NX server runs on a separate server thread, it requires that the rendered font memory persist until the server has a chance to render the font. Unfortunately, the font cache would be quite large if all fonts were saved. The
CONFIG_NXTERM_CACHESIZE
setting will control the size of the font cache (in number of glyphs). Only that number of the most recently used glyphs will be retained. Default: 16.NOTE: There can still be a race condition between the NxTerm driver and the NX task. If you every see character corruption (especially when printing a lot of data or scrolling), then increasing the value of
CONFIG_NXTERM_CACHESIZE
is something that you should try. Alternatively, you can reduce the size ofCONFIG_MQ_MAXMSGSIZE
which will force NxTerm task to pace the server task.CONFIG_NXTERM_CACHESIZE
should be larger thanCONFIG_MQ_MAXMSGSIZE
in any event.CONFIG_NXTERM_LINESEPARATION
:This the space (in rows) between each row of test. Default: 0
CONFIG_NXTERM_NOWRAP
:By default, lines will wrap when the test reaches the right hand side of the window. This setting can be defining to change this behavior so that the text is simply truncated until a new line is encountered.
NxTerm input options:
CONFIG_NXTERM_NXKBDIN
:Take input from the NX keyboard input callback. By default, keyboard input is taken from stdin (
/dev/console
). If this option is set, then the interfacenxterm_kdbin()
is enabled. That interface may be driven by window callback functions so that keyboard input only goes to the top window.CONFIG_NXTERM_KBDBUFSIZE
:If
CONFIG_NXTERM_NXKBDIN
is enabled, then this value may be used to define the size of the per-window keyboard input buffer. Default: 16CONFIG_NXTERM_NPOLLWAITERS
:The number of threads that can be waiting for read data available. Default: 4
Installing New Fonts
The BDF Font Converter. 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. The BDF format most well known as a font
format traditionally used for X-11 bitmap fonts.
A Note about Font Copyrights: My understanding is that the underlying bitmap font data for traditional fonts cannot be copyrighted (the same is not true for scalable fonts). This is because a copyright covers only the form of delivery of the font and not the underlying font content and, at least for the traditional typefaces, the underlying font designs are ancient. There could be issues, however, if you convert from modern, trademarked images. However, remember that I am a programmer not an attorney and that my knowledge of font copyright issues is limited to what I glean by Googling.
Font Installation Steps, Below are general instructions for creating and installing a new font in the NX graphic system. The first two steps only apply if you are using the BDF font converter program.
Locate a font in BDF format. There are many good BDF bitmap fonts bundled with X-11. See this link, as an example,
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
.
The remaining steps apply however you managed to create the NuttX C font
header file. After you have your C font header file, the next thing to
do is to create a new NuttX configuration variable to select the font.
For example, suppose you define the following variable:
CONFIG_NXFONT_MYFONT
. Then you would need to:
Define
CONFIG_NXFONT_MYFONT=y
in your NuttX configuration file.
A font ID number has to be assigned for each new font. The font IDs are
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
yournew font in a similar fashion:
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:
#if defined(CONFIG_NXFONT_SANS23X27) # define NXFONT_DEFAULT FONTID_SANS23X27 #elif defined(CONFIG_NXFONT_MYFONT) # define NXFONT_DEFAULT FONTID_MYFONT #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:
nuttx/graphics/Makefile
. This file needs logic to auto-generate a C source file from the header file that you generated with the bdf-converter program. NoticeNXFONTS_FONTID=2
; this must be set to the same font ID value that you defined in theinclude/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
nuttx/graphics/nxfonts/Make.defs
. Set the make variableNXFSET_CSRCS
.NXFSET_CSRCS
determines the name of the font C file to build whenNXFONTS_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
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 innuttx/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
graphics/nxfonts/nxfonts_bitmaps.c
. This is the file that contains the generic font structures. It is used as a “template&qout; file bynuttx/graphics/nxfonts/Makefile.sources
to create your customized font data set at build time.#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.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)
<#nxfgetfonthandle>`__. Note that the lookup is based on the font ID that was defined in step 4. 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 };
NX Test Coverage
apps/examples/nx
. The primary test tool for debugging NX resides
at apps/examples/nx
.
Building apps/examples/nx
. NX testing was performed using
apps/examples/nx
with the Linux/Cygwin-based NuttX simulator.
Configuration files for building this test can be found in
boards/sim/sim/sim/configs/nx
and
boards/sim/sim/sim/configs/nx11
. There are two alternative
configurations for building the simulation:
The configuration using the configuration file at
boards/sim/sim/sim/configs/nx/defconfig
. This default configuration exercises the NX logic a 8 BPP but provides no visual feedback. In this configuration, a very simple, simulated framebuffer driver is used that is based upon a simple region of memory posing as video memory. That default configuration can be built as follows:tools/configure.sh sim:nx make ./nuttx
The preferred configuration is at
boards/sim/sim/sim/configs/nx11/defconfig
. This configuration extends the test with a simulated framebuffer driver that uses an X window as a framebuffer. This is a superior test configuration because the X window appears at your desktop and you can see the NX output. This preferred configuration can be built as follows:tools/configure sim:nx11 make ./nuttx
Update: The sim target has suffered some bit-rot over the years and so the following caveats need to be added:
The X target builds under recent Cygwin configurations, but does not execute. (It fails inside of
XOpenDisplay()
.The X target does not build under current (9.09) Ubuntu distributions. I needed to make the following changes:
The build will also fail to locate the X header files unless you install an X11 development package.
Refer to the SIM file for additional information.
Test Coverage. At present, apps/examples/nx
t only exercises a
subset of NX; the remainder is essentially untested. The following table
describes the testing performed on each NX API:
NXGLIB API Test Coverage
Function |
Special Setup/Notes |
Verified |
---|---|---|
|
. |
NO |
|
. |
NO |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
Verified by apps/examples/nxlines. |
YES |
|
. |
NO |
|
Verified by apps/examples/nxlines. |
YES |
|
Verified by apps/examples/nxlines. |
YES |
|
. |
YES |
|
Verified using apps/examples/nxlines Generally works well, but has some accuracy/overflow problems wide lines that are nearly horizontal. There is a “fudge factor” that seems to eliminate the problem, but there could still be issues in some configurations. |
YES |
|
Verified by apps/examples/nxlines. |
YES |
|
Verified by apps/examples/nxlines. |
YES |
NX Server Callbacks Test Coverage
Function |
Special Setup/Notes |
Verified |
---|---|---|
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
NX API Test Coverage
Function |
Special Setup/Notes |
Verified |
---|---|---|
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
This is not used in the current version of apps/examples/nx, was tested in a previous version) |
NO |
|
Change to |
YES |
|
Change to |
YES |
|
Verified by |
YES |
|
Verified by |
YES |
|
. |
NO |
|
Change to |
YES |
|
Change to |
YES |
|
Change to |
YES |
|
Change to |
YES |
|
. |
NO |
|
Exercized using Twm4Nx |
YES, Informally |
|
Exercized using Twm4Nx |
YES, Informally |
|
Change to |
YES |
|
. |
YES |
|
Verified by |
YES |
|
by |
YES |
|
Verified by |
YES |
|
Verified by |
YES |
|
. |
YES |
|
Change to |
YES |
|
Change to |
YES |
|
. |
YES |
|
. |
YES |
NXTK API Test Coverage
Function |
Special Setup/Notes |
Verified |
---|---|---|
|
. |
YES |
|
. |
YES |
|
. |
NO |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
NO |
|
Exercized using Twm4Nx |
YES, informally |
|
Exercized using Twm4Nx |
YES, informally |
|
. |
YES |
|
. |
NO |
|
. |
NO |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
NO |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
NO |
|
. |
NO |
|
. |
NO |
|
. |
NO |
|
. |
NO |
|
. |
NO |
|
. |
NO |
NXFONTS API Test Coverage
Function |
Special Setup/Notes |
Verified |
---|---|---|
|
. |
YES |
|
. |
YES |
|
. |
YES |
|
. |
NO |
|
. |
NO |
|
Use defconfig when building. |
YES |
|
. |
YES |
|
. |
NO |
|
. |
YES |