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| author | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
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| committer | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
| commit | 33613a85afc4b1481367fbe92a17ee59c240250b (patch) | |
| tree | 670b842326116b376b505ec2263878912fca97e2 /Master/Agile Software Development/TestApp/dist/lib/graphviz/share/graphviz/doc/addingLayout.txt | |
| download | Studium-master.tar.gz Studium-master.tar.bz2 | |
Diffstat (limited to 'Master/Agile Software Development/TestApp/dist/lib/graphviz/share/graphviz/doc/addingLayout.txt')
| -rw-r--r-- | Master/Agile Software Development/TestApp/dist/lib/graphviz/share/graphviz/doc/addingLayout.txt | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/Master/Agile Software Development/TestApp/dist/lib/graphviz/share/graphviz/doc/addingLayout.txt b/Master/Agile Software Development/TestApp/dist/lib/graphviz/share/graphviz/doc/addingLayout.txt new file mode 100644 index 0000000..777b132 --- /dev/null +++ b/Master/Agile Software Development/TestApp/dist/lib/graphviz/share/graphviz/doc/addingLayout.txt @@ -0,0 +1,200 @@ +New layout: xxx + +Entry points: + +======================== + + void xxx_layout(Agraph_t * g) + + Initialize the graph. + - If the algorithm will use the common edge routing code, it should + call setEdgeType (g, ...); + + - For each node, call common_init_node and gv_nodesize. + + If the algorithm will use spline_edges() to route the edges, the + node coordinates need to be stored in ND_pos, so this should be + allocated here. This, and the two calls mentioned above, are all + handled by a call to neato_init_node(). + + - For each edge, call common_init_edge + + - The algorithm should allocate whatever other data structures it + needs. This can involve fields in the A*info_t fields. In addition, + each of these fields contains a void* alg; subfield that the algorithm + can use the store additional data. + Once we move to cgraph, this will all be replace with + algorithm specific records. + + 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. + + If the algorithm only works with connected components, the code can + use the pack library to get components, lay them out individually, and + pack them together based on user specifications. A typical schema is + given below. One can look at the code for twopi, circo, neato or fdp + for more detailed examples. + + Agraph_t **ccs; + Agraph_t *sg; + Agnode_t *c = NULL; + int ncc; + int i; + + ccs = ccomps(g, &ncc, 0); + if (ncc == 1) { + /* layout nodes of g */ + adjustNodes(g); /* if you need to remove overlaps */ + spline_edges(g); /* generic edge routing code */ + + } else { + pack_info pinfo; + pack_mode pmode = getPackMode(g, l_node); + + for (i = 0; i < ncc; i++) { + sg = ccs[i]; + /* layout sg */ + adjustNodes(sg); /* if you need to remove overlaps */ + } + spline_edges(g); /* generic edge routing */ + + /* initialize packing info, e.g. */ + pinfo.margin = getPack(g, CL_OFFSET, CL_OFFSET); + pinfo.doSplines = 1; + pinfo.mode = pmode; + pinfo.fixed = 0; + packSubgraphs(ncc, ccs, g, &pinfo); + } + for (i = 0; i < ncc; i++) { + agdelete(g, ccs[i]); + } + + free(ccs); + + Be careful in laying of subgraphs if you rely on attributes that have + only been set in the root graph. With connected components, edges can + be added with each component, before packing (as above) or after the + components have been packed (see circo). + + It good to check for trivial cases where the graph has 0 or 1 nodes, + or no edges. + + At the end of xxx_layout, call + + dotneato_postprocess(g); + +====================== + + void xxx_cleanup(Agraph_t * g) + + Free up any resources allocated in the layout. + + Finish with calls to gv_cleanup_node and gv_cleanup_edge for + each node and edge. This cleans up splines labels, ND_pos, shapes + and 0's out the A*info_t, so these have to occur last, but could be + part of explicit xxx_cleanup_node and xxx_cleanup_edge, if desired. + At the end, we usually include + + if (g != g->root) memset(&(g->u), 0, sizeof(Agraphinfo_t)); + + libgvc does a final cleanup to the root graph, freeing any drawing, + freeing its label, and zeroing out Agraphinfo_t of the root graph. + +================== + +Most layouts use auxiliary routines similar to neato, so +the entry points can be added in plugin/neato_layout + +Add to gvlayout_neato_layout.c: + +gvlayout_engine_t xxxgen_engine = { + xxx_layout, + xxx_cleanup, +}; + +and the line + + {LAYOUT_XXX, "xxx", 0, &xxxgen_engine, &neatogen_features}, + +to gvlayout_neato_types and a new emum + + LAYOUT_XXX + +to layout_type in that file. + +The above allows the new layout to piggyback on top of the neato +plugin, but requires rebuilding the plugin. In general, a user +can (and probably should) build a layout plugin totally separately. + +To do this, after writing xxx_layout and xxx_cleanup, it is necessary to: + + - add the types and data structures + +typedef enum { LAYOUT_XXX } layout_type; + +static gvlayout_features_t xxxgen_features = { + 0 +}; +gvlayout_engine_t xxxgen_engine = { + xxx_layout, + xxx_cleanup, +}; +static gvplugin_installed_t gvlayout_xxx_types[] = { + {LAYOUT_XXX, "xxx", 0, &xxxgen_engine, &xxxgen_features}, + {0, NULL, 0, NULL, NULL} +}; +static gvplugin_api_t apis[] = { + {API_layout, &gvlayout_xxx_types}, + {(api_t)0, 0}, +}; +gvplugin_library_t gvplugin_xxx_layout_LTX_library = { "xxx_layout", apis }; + + - combine all of this into a dynamic library whose name contains the + string "gvplugin_" and install the library in the same directory as the + other Graphviz plugins. For example, on Linux systems, the dot layout + plugin is in the library libgvplugin_dot_layout.so. + + - run + dot -C + to regenerate the config file. + +NOTES: + - Additional layouts can be added as extra lines in gvlayout_xxx_types. + - Obviously, most of the names and strings can be arbitrary. One + constraint is that external identifier for the gvplugin_library_t + type must end in "_LTX_library". In addition, the string "xxx" in + each entry of gvlayout_xxx_types is the name used to identify the + layout algorithm, so needs to be distinct from any other layout name. + - The features of a layout algorithm are currently limited to a + flag of bits, and the only flag supported is LAYOUT_USES_RANKDIR, + which enables the layout to the rankdir attribute. + +Changes need to be made to any applications, such as gvedit, that +statically know about layout algorithms. + +================== + +Software configuration - automake + +If you want to integrate your code into the Graphviz software +and use its build system, follow the instructions below. +You can certainly build and install your plugin using your own +build software. + +0. Put your software in lib/xxxgen, and added the hooks describe above +into gvlayout_neato_layout.c +1. In lib/xxxgen, provide a Makefile.am (based on a simple example +like lib/fdpgen/Makefile.am) +3. In lib/Makefile.am, add xxxgen to SUBDIRS +2. In configure.ac, add lib/xxxgen/Makefile to AC_CONFIG_FILES. +4. In lib/plugin/neato_layout/Makefile.am, insert + $(top_builddir)/lib/xxxgen/libxxxgen_C.la + in libgvplugin_neato_layout_C_la_LIBADD +5. Remember to run autogen.sh because on its own configure can guess wrong. + +This also assumes you have a good version of the various automake tools +on your system. + + |
