-New layout: xxx
-
-Entry points:
+To create a new layout plugin called xxx, you first need
+to provide two functions: xxx_layout and xxx_cleanup. The
+semantics of these are described below.
========================
Layout the graph. When finished, each node should have its coordinates
stored in points in ND_coord_i(n), each edge should have its layout
- described in ED_spl(e). Note: If spline_edges() is used, the coordinates
- in ND_pos will be correctly copied into ND_coord_i.
+ described in ED_spl(e).
+ (N.B. As of version 2.21, ND_coord_i has been replaced by ND_coord,
+ which are now floating point coordinates.)
+
+ To add edges, there are 3 functions available:
+
+ - spline_edges1 (Agraph_t*, int edgeType)
+ Assumes the node coordinates are stored in ND_coord_i, and that
+ GD_bb is set. For each edge, this function constructs the appropriate
+ data and stores it in ED_spl.
+ - spline_edges0 (Agraph_t*)
+ Assumes the node coordinates are stored in ND_pos, and that
+ GD_bb is set. This function uses the ratio attribute if set,
+ copies the values in ND_pos to ND_coord_i (converting from
+ inches to points); and calls spline_edges1 using the edge type
+ specified by setEdgeType().
+ - spline_edges (Agraph_t*)
+ Assumes the node coordinates are stored in ND_pos. This
+ function calculates the bounding box of g and stores it in GD_bb,
+ then calls spline_edges0().
If the algorithm only works with connected components, the code can
use the pack library to get components, lay them out individually, and
dotneato_postprocess(g);
+ The following template will work in most cases, ignoring the problems of
+ handling disconnected graphs and removing node overlaps:
+
+ static void
+ xxx_init_node(node_t * n)
+ {
+ neato_init_node(n);
+ /* add algorithm-specific data, if desired */
+ }
+
+ static void
+ xxx_init_edge(edge_t * e)
+ {
+ common_init_edge(e);
+ /* add algorithm-specific data, if desired */
+ }
+
+ static void
+ xxx_init_node_edge(graph_t * g)
+ {
+ node_t *n;
+ edge_t *e;
+
+ for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
+ xxx_init_node(n);
+ }
+ for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
+ for (e = agfstout(g, n); e; e = agnxtout(g, e)){
+ xxx_init_edge(e);
+ }
+ }
+ }
+
+ void
+ xxx_layout (Agraph_t* g)
+ {
+ xxx_init_node_edge(g);
+ /* Set ND_pos(n) for each node n */
+ spline_edges(g);
+ dotneato_postprocess(g);
+ }
+
======================
void xxx_cleanup(Agraph_t * g)
libgvc does a final cleanup to the root graph, freeing any drawing,
freeing its label, and zeroing out Agraphinfo_t of the root graph.
+ The following template will work in most cases:
+
+ static void xxx_cleanup_graph(Agraph_t * g)
+ {
+ /* Free any algorithm-specific data attached to the graph */
+ if (g != g->root) memset(&(g->u), 0, sizeof(Agraphinfo_t));
+ }
+
+ static void xxx_cleanup_edge (Agedge_t* e)
+ {
+ /* Free any algorithm-specific data attached to the edge */
+ gv_cleanup_edge(e);
+ }
+
+ static void xxx_cleanup_node (Agnode_t* n)
+ {
+ /* Free any algorithm-specific data attached to the node */
+ gv_cleanup_node(e);
+ }
+
+ void xxx_cleanup(Agraph_t * g)
+ {
+ Agnode_t *n;
+ Agedge_t *e;
+
+ for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
+ for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
+ xxx_cleanup_edge(e);
+ }
+ xxx_cleanup_node(n);
+ }
+ xxx_cleanup_graph(g);
+ }
+
==================
Most layouts use auxiliary routines similar to neato, so
To allow for changes in the format, Graphviz attaches the attribute
<TT>xdotversion</TT> to the graph.
<P>
-At present, additional drawing attributes are only attached to nodes
-and edges. There are six new attributes:
+Additional drawing attributes can appear on nodes, edges, clusters and
+on the graph itself. There are six new attributes:
<SPACER TYPE=VERTICAL size=10>
<TABLE border bgcolor=beige>
<TR><TD>_draw_<TD colspan=2>Drawing operations
<TR><TD>_tldraw_<TD>Tail label<TD>Edge only
</TABLE>
<P>
+For a given graph object, one will typically a draw directive before the
+label directive. For example, for a node, one would first use the commands
+in <B>_draw_</B> followed by the commands in <B>_ldraw_</B>.
+<P>
The value of these attributes consists of the concatenation of some
-(multi-)set of the following 12 rendering or attribute operations.
+(multi-)set of the following 13 rendering or attribute operations.
(The number is parentheses gives the xdot version when the operation
was added to the format. If no version number is given, the operation
was in the original specification.)
To allow for changes in the format, Graphviz attaches the attribute
<TT>xdotversion</TT> to the graph.
<P>
-At present, additional drawing attributes are only attached to nodes
-and edges. There are six new attributes:
+Additional drawing attributes can appear on nodes, edges, clusters and
+on the graph itself. There are six new attributes:
<SPACER TYPE=VERTICAL size=10>
<TABLE border bgcolor=beige>
<TR><TD>_draw_<TD colspan=2>Drawing operations
<TR><TD>_tldraw_<TD>Tail label<TD>Edge only
</TABLE>
<P>
+For a given graph object, one will typically a draw directive before the
+label directive. For example, for a node, one would first use the commands
+in <B>_draw_</B> followed by the commands in <B>_ldraw_</B>.
+<P>
The value of these attributes consists of the concatenation of some
-(multi-)set of the following 12 rendering or attribute operations.
+(multi-)set of the following 13 rendering or attribute operations.
(The number is parentheses gives the xdot version when the operation
was added to the format. If no version number is given, the operation
was in the original specification.)
projects / graphviz / commitdiff