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#
# $Id: README.Raster,v 1.3 2001/03/04 15:01:12 ltoetsch Exp $
#
This is the README file for the Raster display driver for lcd4linux
This driver is intended to create various raster formats, at the moment
there is support for binary PPM (portable pixmap) and PNG.
The driver creates the output file(s) specified with the -o switch. The
parameter is used as a format string for sprintf(), if you specify '%d'
in the output file, files with a sequence number will be created.
The output file is first created with a '.tmp' extension, this temporary
file will be written and closed, and finally (atomically) renamed. This way
you can be shure that you will always get a complete file, but its contents
changes every 'tick' milliseconds.
Configuration:
The driver needs/supports the following entries in lcd4linux.conf:
Display: must be either "PPM" or "PNG"
size: [columns]x[rows], e.g. "20x4"
font: [xrex]x[yres], at the moment only "5x8" and "6x8" supported.
pixel: [pixelsize]+[pixelgap], e.g. "5+1"
gap: [row gap]x[column gap], e.g. "3x3"
border: border width
foreground: color of an active LCD Pixel, must be #rrggbb
halfground: color of an inactive LCD Pixel, must be #rrggbb
background: backlight color, must be #rrggbb
This may look weird, but it is weird. Let's explain this a bit further:
The raster driver tries to emulate a real LC display. A real LCD has a
size of columns*rows characters. Each character consists of xres*yres
LCD cells. One single cell will be represented by a rectangle of
pixelsize*pixelsize pixels. If you want to, you can emulate the gap
between this lcd cells by specifying a pixelgap greater than zero.
Sometimes there's a gap between characters, too. You can specify this
gap (in pixels again) horizontally and vertically. Usually this gap
is the same size as a cell (which is pixelsize+pixelgap). If you specify
either the row gap or the column gap as -1, this cell size will be used
instead.
If you use a font of 5x8, some characters may use the first and the last
pixel. So you should specify a column gap, otherwise the caracters may
touch. On the other hand, the 6x8 font never uses the first pixel. So you
can omit the column gap, and will get the same text layout, but
uninterupted bars!
After all: don't try to understand this unless you have tried it out!
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