aewan(5)aewan(5)NAMEaewan - File format documentation
INTRODUCTION
Starting with version 0.9.0, Aewan features an all-new, easier to parse
file format. Prior versions used a binary (largely undocumented) file
format, and relied on a program (ae2aes) to convert it to a readable
format. With the new format, the ae2aes utility became unnecessary and
was deprecated.
An aewan document is a gzipped file. Therefore, you must first gunzip
it in order to be able to parse its contents. On the command line, you
could use zcat or something of the sort. On a program, you will proba‐
bly want to use the zlib library.
In the future it might be better for Aewan to supply a shared library
to enable parsing of aewan files with minimal effort. Such a library
would have to be integrated with the editor in order not to have to
duplicate code (i.e. the editor itself would be just a client of the
library). But for the time being, you have to read and parse the for‐
mat on your own.
FILE FORMAT
In the description below, the items in between brackets are NOT lit‐
eral, they are placeholders. [S] is a placeholder for a string and [N]
is a placeholder for a decimal integer, and [B] is a placeholder for a
boolean value ('true' or 'false'). A line with "..." is not literal
either, it just means that the lines above repeat a certain number of
times.
<Aewan Document v1
layer-count: int: [N]
meta-info: str: [S]
<Layer
name: str: [S]
width: int: [N]
height: int: [N]
visible: bool: [B]
transparent: bool: [B]
layer-line: str: [S]
layer-line: str: [S]
layer-line: str: [S]
(...there are <height> such lines...)
>Layer
(...there are <layer-count> such blocks...)
>Aewan Document v1
Indentation is ignored, but all other whitespace is significant.
In particular, you can't omit the space that immediately follows
the ':' field delimiters, or supply more than one space there.
Notice that the file format does not use any quotation marks
for the values, not even strings.
REPRESENTATION OF STRINGS
Strings are represented almost literally in the file (where the [S]
placeholders are in the blueprint above), and are not put in between
quotes or anything. However, special characters (ASCII codes 1 to 31)
are escaped: the escape code is a backslash, followed by the character
'0' + ch, where ch is the special character. Thus, a newline character
would be represented by "\:", since ":" is '0' + 10.
REPRESENTATION OF INTEGERS AND BOOLEANS
Integers use just the plain old decimal representation. The booleans
are represented as strings: either "true" or "false" (without quotes).
REPRESENTATION OF LAYER LINES
Each layer-line is a string, but it is specially formatted in order to
convey the characters and attibutes in that line. In order to under‐
stand the format of a layer-line string, it is first necessary to
introduce the concept of cells. A cell in an aewan layer is each of the
spaces that can contain a character. A cell has two pieces of data: the
character that is in it, and a color attribute. The character is just
that: an 8-bit value represing the character drawn there. The color
attribute is an 8-bit unsigned value that packs the foreground and
background color of a given cell, as well as standout and blink
attributes.
The following color codes are used: 0=black, 1=red, 2=green, 3=yellow,
4=blue, 5=magenta, 6=cyan, 7=white.
The 8 bits of the attribute have the following meanings: SFFFLBBB.
Where S is the standout bit, FFF is the 3-bit color code for the fore‐
ground color, L is the blink bit, and BBB is the 3-bit color code for
the background color.
The layer-line string is composed of the hexadecimal representation of
layer_width*2 bytes. Each 2 bytes is the information for one cell of
the line: the first byte is the character, and the second is the
attribute. For example, the hex representation for 'A' is 0x41, so a
line with five 'A's each of them in a different foreground color (but
all with black background) would be represented as
41104120413041404150.
LICENSE INFORMATION
Copyright (c) 2004-2005 Bruno Takahashi C. de Oliveira. All rights
reserved.
This program is licensed under the GNU General Public License, version
2 or, at your option, any later version. For full license information,
please refer to the COPYING file that accompanies the program.
SEE ALSOaecat(1), aewan(1)aewan (Aewan Ascii Art Editor) August 2005 aewan(5)
