Libnetpbm PPM Drawing Function Manual
Updated: September 2005
Table Of Contents
This reference manual covers functions in the libnetpbm li‐
brary for drawing
images, using the PPM image format and the libnetpbm in‐mem‐
ory image
formats.
We actually have very little information here; this is mainly
a framework
for adding documentation later if someone becomes interested
in this
facility.
The Functions
The functions are all declared in the ppmdraw.h header file.
ppmd_point_drawproc
ppmd_setlinetype
ppmd_setlineclip
ppmd_line
ppmd_spline3
ppmd_polyspline
ppmd_circle
ppmd_filledrectangle
ppmd_fill_init
ppmd_fill_drawproc
ppmd_fill
ppmd_text
ppmd_text_box
Fonts
The ppmd_text and ppmd_text_box functions use fonts. You con‐
trol the fonts
using functions described in this section. There is one font
that comes with
Netpbm, called "standard". It is built into the function li‐
brary and is the
default font. You can create additional fonts and use them in‐
stead.
In a program that uses Netpbm drawing facilities, there is a
"current font."
all drawing of text uses the current font. When the program
starts, the
current font is "standard"; you can change it after that by
calling the
ppmd_setfont function.
Other than a built‐in font, a font lives in file in a format
special to
Netpbm called Ppmdfont. The file typically has a name that
ends in
".ppmdfont".
Use the ppmddumpfont program to dump the contents of a Ppmd‐
font file in
human readable format.
Use the ppmdmkfont program to generate the "standard" font as
a Ppmdfont
file. You don’t normally need to do this, becuase "standard"
is built into
libnetpbm.
Use the ppmdcfont program to turn a Ppmdfont file into a C
source file that
you can compile into a program as a built‐in font. Though we
don’t give full
instructions here on how to do that, libnetpbm’s built‐in
"standard" font is
a good example. In Netpbm source code, you will find the C
source file
standardppmdfont.c, which was generated from the file stan‐
dard.ppmdfont by
ppmdcfont. You simply use a pointer to the structure that the
C file defines
as a font handle, just like one you would get from ppmd_read‐
font.Font File Format
The font file starts with the characters "ppmdfont" (without
the quotation
marks) in ASCII.
The rest of the format is not yet documented, but it generally
describes,
for each code point, a sequence of straight line plotting com‐
mands to form
the glyph for the indicated character. I.e. it is a vector,
not raster,
font.
Font Control Functions
These functions are declared in the header file ppmdfont.h.
ppmd_readfont
This function associates a Ppmdfont file, which you identify
by naming the
Ppmdfont file, with a handle that you can use to identify the
font to other
functions. Technically, this function reads the font into mem‐
ory.
ppmd_freefont
This function releases the handle that you get from ppmd_read‐
font. It frees
resources associated with it; you can’t use the handle after
this.
ppmd_getfont
This function returns the handle of the currently selected
font.
ppmd_setfont
This function sets the currently selected font. You identify
the font to
which to set it with a handle such as you get from pp‐
md_readfont or
ppmd_getfont.
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Table Of Contents
* The Functions
* Fonts
