DRAKON Editor 1.22 .drn file format

General notes
Tables
Items

General notes

DRAKON Editor relies on SQLite to work with files. A .drn file is an SQLite 3.6 database.

DRAKON files are guaranteed to be backward and forward compatible within the major version. For example, DRAKON Editor 1.4 can use files created with DRAKON Editor 1.5 and vice-versa.

No conversion is needed when a new version of DRAKON Editor comes out.

There are free tools that can be used to read and edit SQLite database files, for example SQLite Database Browser.

The SQL script that creates the database is located in scripts/schema.sql. This script does not create the info table (which serves like a file signature).

info table

General information related to the whole file. A record in this table is a property consisting of a key-value pair.

Field	Data type	Description
key	text, unique	The name of the property.
value	text	The value of the property.

Typical content of the info table:

key field	value field	Comment
type	drakon	This is a DRAKON Editor diagram file.
version	5	The minor version number: 1.5
start_version	1	The major version number: 1.5
language	c++	The diagrams in this file can be used to generate C++ code.

diagrams table

The list of diagrams.

The diagram coordinate space:

X-axis is directed to the right.
Y-axis is direct down.

Field	Data type	Description
diagram_id	integer, unique	The primary key.
name	text, unique	The name of the diagram.
origin	text	The position of the left top corner of the diagram viewport in the diagram coordinate space. Used for scrolling. The origin is stored as a tcl list with two elements. The first element is X, the second element is Y.
description	text	An optional text description of the diagram.
zoom	double	The visible scale of the diagram in percents. 100 means a one-to-one mapping between the screen space and the diagram space. 200 means the coordinate (10, 20) in the diagram transforms to (20, 40) on the screen.

state table

Miscellaneous global information.

This table always contains only one row with the field "row" equal to 1.

Field	Data type	Description
row	integer, unique	Must be equal 1.
current_dia	integer	The currently visible diagram. A reference to the diagrams table.
description	text	An optional text description of the whole file.

diagram_info table

Each diagram owns a list of properties in the form of key-value pairs.

Export parameters are stored as diagram properties.

Field	Data type	Description
diagram_id	integer	References the diagram that owns the property.
name	text	The name of the property.
value	text	The value of the property.

diagram_info table has a composite primary key: diagram_id, name.

items table

Each diagram owns a list of items. An item is an object on the diagram, like an icon or a connector.

Field	Data type	Description
item_id	integer, unique	The primary key of the item.
diagram_id	integer	References the diagram that owns the item.
type	text	The type of the item. For example, action or beginend.
text	text	The text on the icon. Lines and arrows do not have text. Not all items can have text.
text2	text	The secondary text on the icon. For example, the upper text in a shelf item.
selected	integer	1 if the item is selectd, 0 otherwise.
x	integer	The meaning depends on the item type. Usually, it is the X coordinate of the geometric center of the item.
y	integer	The meaning depends on the item type. Usually, it is the Y coordinate of the geometric center of the item.
w	integer	The meaning depends on the item type. Usually, it is a half of the width of the item.
h	integer	The meaning depends on the item type. Usually, it is a half of the height of the item.
a	integer	The meaning depends on the item type.
b	integer	The meaning depends on the item type.
color	text	The color of the item. Format: "fg #000000 bg #aaaa00". fg - foreground and text color bg - background color If empty, the color is set based on the global Editor settings. (See File / Global settings...)
aux_value	text	Reserved.
format	text	Reserved.

tree_nodes table

Each node in the main tree view control of DRAKON Editor is stored as a record in the tree_nodes table.

There are two kinds of nodes: folder nodes and diagram nodes.

There is a one-to-one link between diagram nodes and diagrams.

Field	Data type	Description
node_id	integer, unique	The primary key of the node.
parent	integer	References the node_id of the parent of this node.
type	text	The type of the node. Can be either folder or item.
name	text	For folder nodes, this field contains the text of the tree node. For diagram nodes, the text of the node is taken from diagram name.
diagram_id	integer	For diagram nodes, references the related diagram.

Rectangular items

Items of these types have a similar form based on rectangle:

action
beginend
case
commentin
insertion
loopend
loopstart
select
pause
timer

Field	Data type	Description
x	integer	The X coordinate of the geometric center of the item.
y	integer	The Y coordinate of the geometric center of the item.
w	integer	A half of the width of the item.
h	integer	A half of the height of the item.
a	integer	Ignored.
b	integer	Ignored.

Rectangular items with two text fields

Items of these types have two text fields:

input
output
shelf
process

Field	Data type	Description
text2	text	The secondary text. Placed at the upper text field.
x	integer	The X coordinate of the geometric center of the item.
y	integer	The Y coordinate of the geometric center of the item.
w	integer	A half of the width of the item.
h	integer	A half of the height of the item.
a	integer	The distance between the top edge and the horizontal line in the middle.
b	integer	Ignored.

horizontal item

Horizontal line segments:

Plain horizontal line
Left and right arrows
Left and right "transparent" arrows
Left and right paws
parallel line

Field	Data type	Description
x	integer	The X coordinate of the left end.
y	integer	The Y coordinate of the left end.
w	integer	The distance between the left and right ends.
h	integer	Ignored.
a	integer	Line type. See the type codes below.
b	integer	Ignored.

The line type is encoded in the a field:

Line type	a
Plain horizontal line	0
Left arrow	40100
Right arrow	20100
Left "transparent" arrow	40200
Right "transparent" arrow	20200
Left paw	40300
Right paw	20300
Parallel	50100

vertical item

The vertical line.

Vertical line segments:

Plain vertical line
Up and down arrows
Up and down "transparent" arrows
Up and down paws

Field	Data type	Description
x	integer	The X coordinate of the top end.
y	integer	The Y coordinate of the top end.
w	integer	Ignored.
h	integer	The distance between the top and bottom ends.
a	integer	Line type. See the type codes below.
b	integer	Ignored.

The line type is encoded in the a field:

Line type	a
Plain vertical line	0
Up arrow	10100
Down arrow	30100
Up "transparent" arrow	10200
Down "transparent" arrow	30200
Up paw	10300
Down paw	30300

arrow item

The arrow with two angles.

Field	Data type	Description
x	integer	The X coordinate of the top end of the vertical segment.
y	integer	The Y coordinate of the top end of the vertical segment.
w	integer	The length of the upper horizontal segment.
h	integer	The height of the vertical segment.
a	integer	The length of the lower horizontal segment.
b	integer	0 if the arrow points to the left, 1 if to the right.

if item

The if icon.

Field	Data type	Description
x	integer	The X coordinate of the geometric center of the item.
y	integer	The Y coordinate of the geometric center of the item.
w	integer	A half of the width of the item.
h	integer	A half of the height of the item.
a	integer	The length of the horizontal line at the right side.
b	integer	0 means the right exit is YES. 1 means the right exit is NO.

commentout item

A standalone comment icon.

Field	Data type	Description
x	integer	The X coordinate of the geometric center of the item.
y	integer	The Y coordinate of the geometric center of the item.
w	integer	A half of the width of the item.
h	integer	A half of the height of the item.
a	integer	The length of the horizontal line at the side.
b	integer	0 if the horizontal line goes out of the left side, 1 if out of the right side.

branch item

The header of a branch.

Field	Data type	Description
x	integer	The X coordinate of the geometric center of the item.
y	integer	The Y coordinate of the geometric center of the item.
w	integer	A half of the width of the item.
h	integer	A half of the height of the item.
a	integer	Ignored
b	integer	1 if the icon has a cycle mark, 0 if the icon does not have a cycle mark.

address item

The footer of a branch.

Field	Data type	Description
x	integer	The X coordinate of the geometric center of the item.
y	integer	The Y coordinate of the geometric center of the item.
w	integer	A half of the width of the item.
h	integer	A half of the height of the item.
a	integer	Ignored
b	integer	1 if the icon has a cycle mark, 0 if the icon does not have a cycle mark.

Contact: drakon.editor@gmail.com