Attributes

The following table summarizes the attributes available to the diagram and its components. Where an attribute is applicable, it shows the default value in Python. In the YAML file, you just omit the attribute or leave the value empty. Also, in YAML you can have all values in lowercase. The name of the attribute must be lowercase in both Python and YAML.

Connection label elements inherit default values from the parent connection element.

Attribute	Diagram	Block	Connection	Label
arrow_aspect			1.5
arrow_back			False
arrow_base			3.0
arrow_forward			True
buffer_fill			None
buffer_width			0.0
collapse_connections	False
connection_distance	4.0
entrances			[<all>]
exits			[<all>]
fill	[1.0, 1.0, 1.0]	None
font_family	Arial	Arial	Arial	Inherit
font_size	14.0	10.0	10.0	Inherit
font_style	NORMAL	NORMAL	NORMAL	Inherit
font_weight	NORMAL	NORMAL	NORMAL	Inherit
label	None	None	None	Inherit
label_distance	6.0	6.0	4.0	Inherit
label_position	TOP	CENTER
margin_bottom		24.0
margin_left		24.0
margin_right		24.0
margin_top		24.0
min_height	256.0	48.0
min_width	256.0	96.0
padding_bottom	0.0	8.0
padding_left	0.0	8.0
padding_right	0.0	8.0
padding_top	0.0	8.0
pass_through		False
scale	1.0
stroke_dasharray	None	None	None
stroke_width	0.0	2.0	2.0
stroke	None	[0.0, 0.0, 0.0]	[0.0, 0.0, 0.0]
text_fill	[0.0, 0.0, 0.0]	[0.0, 0.0, 0.0]	[0.0, 0.0, 0.0]	Inherit
text_line_height	1.2	1.2	1.2	Inherit
text_orientation	HORIZONTAL	HORIZONTAL	FOLLOW	Inherit

Basic styling

stroke

• Applies to: Diagram, Blocks and Connections

• Type: Sequence of 3-4 floats

• Default: “none” (D), “black” (B, C)

The stroke attribute defines the color of a line. When used with an area, it applies to the outline. The value must be a sequence of three to four numbers, each number being in the range between 0.0 and 1.0 inclusive. The four numbers correspond to the color components in the RGBA sequence. The value for the A (alpha) component is optional, the default being 1.0 (i.e. fully opaque).

stroke_width

• Applies to: Diagram, Blocks and Connections

• Type: Float

• Default: 0.0 (D), 2.0 (B, C)

The stroke_width attribute defines the width of a connection line or box outline. The value is in device units (i.e. pixels).

stroke_dasharray

• Applies to: Diagram, Blocks and Connections

• Type: Sequence of floats

• Default: None

The stroke_dasharray attribute defines a dash pattern for a line. For example, a value of [6, 3] results in a pattern of dashes six units long separated by gaps three units long.

fill

• Applies to: Diagram and Blocks

• Type: Sequence of 3-4 floats

• Default: None

The fill attribute defines the color to fill areas with.

Text

label

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: String

• Default: None

The label attribute defines the text to draw on a block or near a connection line. It is also used to add a title to the diagram. The value is a string that may consist of several lines separated by newline characters.

Regarding blocks, if the label of a block is not defined, its name is used instead. To have a block without a label, an empty string must be specified in the YAML file.

label_position

• Applies to: Diagram and Blocks

• Type: LabelPosition

• Default: TOP (D), CENTER (B)

The label_position attribute defines the position of the label inside a box. The positions available for labels are:

• BOTTOM

• BOTTOM_LEFT

• BOTTOM_RIGHT

• CENTER

• TOP

• TOP_LEFT

• TOP_RIGHT

label_distance

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: Float

• Default: 6.0 (D, B), 4.0 (C, L)

The label_distance attribute defines the distance of a label from the line relative to which it is drawn. For diagrams and blocks, this is the distance from the outline of the box. For connections, the distance is measured from the connection line.

text_fill

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: Sequence of 3-4 floats

• Default: [0.0, 0.0, 0.0]

The text_fill attribute defines the color in which text is drawn.

text_orientation

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: TextOrientation

• Default: HORIZONTAL (D, B), FOLLOW (C, L)

The text_orientation attribute defines the orientation in which text is drawn. If the value is VERTICAL, the text is rotated 90 degrees anticlockwise.

Regarding connections, text orientation influences the algorithm employed by the program to find an optimal position for the label of a connection. If the orientation of the text is set to HORIZONTAL, the program will attach the label to a horizontal segment, if there is one; VERTICAL works in the same way. However, there is a special value available for the text orientation of connections, which is FOLLOW. This value means that the orientation of the label is the same as the orientation of the segment to which it is attached. The algorithm is free to attach the label to any segment. It is the default value for connections.

text_line_height

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: Float

• Default: 1.2

The text_line_height attribute is used to set the spacing between lines of text. A value of 1.2 means that the distance between two consecutive lines must be 20% of the height of the text itself.

font_family

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: String

• Default: “Arial”

The font_family attribute is used to select a font for the label. It is similar to the font-family property in CSS. The default font family is Arial, which should give similar results in both Windows and Unix systems.

font_size

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: Float

• Default: 14.0 (D), 10.0 (B, C, L)

The font_size attribute defines the size of the font in points. It is equivalent to the font-size property in CSS. Orthogram uses a factor of 1.25 internally to convert points to device units (i.e. one point equals 1.25 pixels).

font_style

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: FontStyle

• Default: NORMAL

The font_style attribute defines the style of the font used to render text. It is similar to the font-style property in CSS. The following font styles are available:

• NORMAL

• ITALIC

• OBLIQUE

font_weight

• Applies to: Diagram, Blocks, Connections and Connection Labels

• Type: FontWeight

• Default: NORMAL

The font_weight attribute defines the weight of the font used to render text. It is similar to the font-weight property in CSS. The value of the attribute may be one of the following:

• NORMAL

• BOLD

Arrows

arrow_forward

• Applies to: Connections

• Type: Boolean

• Default: True

If arrow_forward is true for a connection, the program draws an arrow head at the end of the connection line. This is the default. This attribute is similar to the arrowforward attribute in Graphviz.

arrow_back

• Applies to: Connections

• Type: Boolean

• Default: False

If arrow_back is true for a connection, the program draws an arrow head at the start of the connection line. By default, the program does not draw a back arrow. This attribute is similar to the arrowback attribute in Graphviz.

arrow_base

• Applies to: Connections

• Type: Float

• Default: 3.0

Attribute arrow_base controls the width of the arrow relative to the width of the line. The width of the base of the arrow is equal to arrow_base * stroke_width.

arrow_aspect

• Applies to: Connections

• Type: Float

• Default: 1.5

Attribute arrow_aspect controls the length of the arrow, which is equal to arrow_aspect * arrow_base * stroke_width.

Buffering

buffer_width

• Applies to: Connections

• Type: Float

• Default: 0.0

The buffer_width attribute defines the width of the buffer around a connection line. The default width is zero, i.e. no buffer is drawn.

buffer_fill

• Applies to: Connections

• Type: Sequence of 3-4 floats

• Default: None

The buffer_fill attribute defines the color of the buffer around a connection line. The default color is None, i.e. no buffer is visible.

Maintaining distances

connection_distance

• Applies to: Diagram

• Type: Float

• Default: 4.0

The connection_distance attribute is used to define the minimum distance between connection lines.

margin_top

• Applies to: Blocks

• Type: Float

• Default: 24.0

margin_bottom

• Applies to: Blocks

• Type: Float

• Default: 24.0

margin_left

• Applies to: Blocks

• Type: Float

• Default: 24.0

margin_right

• Applies to: Blocks

• Type: Float

• Default: 24.0

The margin_* attributes are used to define the space around blocks. They are similar to the margin-* properties of CSS, though they are used in a slightly different way. In Orthogram they are additive, i.e. if one block has a 12 unit right margin and the block next to it has a 10 unit left margin, the distance between them will be equal to 22 units.

padding_top

• Applies to: Diagram and Blocks

• Type: Float

• Default: 0.0 (D), 8.0 (B)

padding_bottom

• Applies to: Diagram and Blocks

• Type: Float

• Default: 0.0 (D), 8.0 (B)

padding_left

• Applies to: Diagram and Blocks

• Type: Float

• Default: 0.0 (D), 8.0 (B)

padding_right

• Applies to: Diagram and Blocks

• Type: Float

• Default: 0.0 (D), 8.0 (B)

The padding_* attributes define the distance between the border of a box and its contents. They are similar to the padding-* properties in CSS.

Sizing

min_width

• Applies to: Diagram and Blocks

• Type: Float

• Default: 256.0 (D), 96.0 (B)

min_height

• Applies to: Diagram and Blocks

• Type: Float

• Default: 256.0 (D), 48.0 (B)

The min_width and min_height attributes define lower limits for the dimensions of boxes. Note that Orthogram will make the size of the diagram large enough to fit all the elements inside it, and will also enlarge blocks as needed for the connections attached to them. These attributes are analogous to the minwidth and minheight attributes in Graphviz.

scale

• Applies to: Diagram

• Type: Float

• Default: 1.0

The scale attribute causes the image to be drawn scaled by the specified factor.

Routing

exits

• Applies to: Connections

• Type: Set of Side

• Default: All possible values

entrances

• Applies to: Connections

• Type: Set of Side

• Default: All possible values

The exits and entrances attributes control the routing of a connection at the start and end points, respectively. By default, the program is free to start routing a connection from any side of the source block, as well as end at any side of the destination block. Using the aforementioned attributes, one can restrict the exit and entrance sides. The value is a set that may contain any of the following values:

• BOTTOM

• LEFT

• RIGHT

• TOP

pass_through

• Applies to: Blocks

• Type: Boolean

• Default: False

By default, a block does not permit connections to pass through it unless they start or end within the block itself. Setting pass_through to false makes a block permeable to all connections.

Grouping

collapse_connections

• Applies to: Diagram

• Type: Boolean

• Default: False

If the value of the collapse_connections diagram attribute is true, parallel segments of connections in the same group are drawn on top of each other.