aewan

aewan(5)                      File Formats Manual                     aewan(5)



NAME
       aewan - 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
       probably 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
       format on your own.


FILE FORMAT
       In the description below, the items in between brackets are NOT
       literal, 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
       understand 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
       foreground 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 ALSO
       aecat(1), aewan(1)




aewan (Aewan Ascii Art Editor)    August 2005                         aewan(5)