# Series-Parallel Layout

Series-parallel layout is a layout style that especially suits series-parallel graphs or a collection of series-parallel graphs. Series-parallel graphs are directed graphs with a single source and a single sink that are build recursively using only the following set of rules:

• Series composition: The source of a subgraph is merged with the source of a second subgraph
• Parallel composition: The sources and sinks of two subgraphs are merged

Possible application fields are circuit-diagrams or flowcharts.

## General Tab

### Orientation

Determines the main layout orientation. The algorithm tries to arrange nodes in such a way that all edges point into the main layout direction.

Top to Bottom
The main layout orientation will be from top to bottom.
Bottom to Top
The main layout orientation will be from bottom to top.
Left to Right
The main layout orientation will be from left to right.
Right to Left
The main layout orientation will be from right to left.

### Vertical Alignment

Determines the vertical alignment (with respect to layout orientation Top-to-Bottom) of two parallel subgraphs that share the same source node.

Top
The upper bounds of the parallel subgraphs will be at the same y-coordinate.
Center
The center of the parallel subgraphs will be at the same y-coordinate.
Bottom
The lower bounds of the parallel subgraphs will be at the same y-coordinate.

### Use Drawing As Sketch

If enabled, the current drawing will be interpreted as a sketch of the resulting series-parallel layout, i.e., the algorithm tries to maintain the order of the parallel subgraphs given by the sketch.

### Node to Node Distance

Determines the minimal distance between nodes.

### Node to Edge Distance

Determines the distance between edge segments and nodes.

### Edge to Edge Distance

Determines the distance between adjacent pairs of edge segments. Note that if the edge ports are distributed at the side of a node, this distance might not be kept.

### Consider Node Labels

Determines whether space is reserved for node labels during the layout process.

### Place Edge Labels

Edge labels will be placed by the layouter considering their preferred placement.

## Edges Settings Tab

### Port Style

Centered
All edges connect to the center of their source and target nodes.
Distributed
The ports of the edges will be evenly distributed at the sides of their source and target nodes.

### Minimum First Segment Length

Determines the minimal length of the first edge segment.

### Minimum Last Segment Length

Determines the minimal length of the last edge segment.

### Minimum Length

Determines the minimal length of an edge.

### Routing Style

Orthogonal
Edge paths will be routed in an orthogonal style, i.e., only vertical and horizontal line segments will be used.
Polyline
Edge paths will be routed as a polyline with a certain number of bends.
Octilinear
Edge paths will be routed in an octilinear style, i.e., the routes consist of line segments whose slope is a multiple of 45 degrees.

### Preferred Octilinear Segments Length

Determines the preferred length for all 45-degree segments of the edges. If there is not enough space to add octilinear segments with this length the preferred length can be ignored. This feature is only available for the octilinear routing style.

### Minimum Polyline Distance

Determines the minimal length for the polyline segments. This feature is only available for the polyline routing style.

### Minimum Slope

Determines the minimal slope of the first and last edge segment of polyline edges. This feature is only available for the polyline routing style.

### Route Edges in Flow

Normally, for layout orientation Top-to-Bottom, the edges leave their source at the bottom and enter their target at the top. If this option is disabled, the edges may leave the nodes at the left/right side which reduces the number of bends.