use graphviz lib interface instead of dumping dot file

1 files changed, 23 insertions, 13 deletions

diff --git a/graphviz.lua b/graphviz.lua
index b549696..4d7ed69 100644
--- a/graphviz.lua
+++ b/graphviz.lua
@@ -88,7 +88,7 @@ where `n` is the number of nodes in the graph.
 Coordinates are in the interval [0, 1].
 
 ]]
-function graph.graphvizLayout(g, algorithm)
+function graph.graphvizLayout(g, algorithm, fname)
 	if not graphvizOk or not cgraphOk then
 		error("graphviz library could not be loaded.")
 	end
@@ -98,7 +98,9 @@ function graph.graphvizLayout(g, algorithm)
 	local algorithm = algorithm or "dot"
 	assert(0 == graphviz.gvLayout(context, graphvizGraph, algorithm),
 	       "graphviz layout failed")
-	assert(0 == graphviz.gvRender(context, graphvizGraph, algorithm, nil),
+	-- the algorithm that is passed is a loyout algorithm not a rendering
+	-- format, which is typically like png, svg or dot
+	assert(0 == graphviz.gvRender(context, graphvizGraph, 'dot', nil),
 	       "graphviz render failed")
 
 	-- Extract bounding box.
@@ -117,6 +119,19 @@ function graph.graphvizLayout(g, algorithm)
 		positions[id][2] = y
 	end
 
+	-- if a file name is given, then render to that file
+	if fname then
+		local context = graphviz.gvContext()
+		local graphvizGraph = cgraph.agmemread(g:todot())
+		assert(0 == graphviz.gvLayout(context, graphvizGraph, algorithm),
+		       "graphviz layout failed")
+		assert(0 == graphviz.gvRender(context, graphvizGraph, 'svg', io.open(fname .. '.svg','w')),
+			   "graphviz render failed")
+		graphviz.gvFreeLayout(context, graphvizGraph)
+		cgraph.agclose(graphvizGraph)
+		graphviz.gvFreeContext(context)
+	end
+
 	-- Clean up.
 	graphviz.gvFreeLayout(context, graphvizGraph)
 	cgraph.agclose(graphvizGraph)
@@ -126,20 +141,15 @@ end
 
 
 function graph.dot(g,title,fname)
-	local gv = g:todot(title)
-	local fngv = (fname or os.tmpname()) .. '.dot'
-	local fgv = io.open(fngv,'w')
-	fgv:write(gv)
-	fgv:close()
-	local fnsvg = (fname or os.tmpname()) .. '.svg'
-	os.execute('dot -Tsvg -o ' .. fnsvg .. ' ' .. fngv)
-	if not fname then
+	local qt_display = fname == nil
+	fname = fname or os.tmpname()
+	local fnsvg = fname .. '.svg'
+	graph.graphvizLayout(g, 'dot', fname)
+	if qt_display then
 		require 'qtsvg'
-		local qs = qt.QSvgWidget(fnsvg)
+		local qs = qt.QSvgWidget(fname .. '.svg')
 		qs:show()
-		os.remove(fngv)
 		os.remove(fnsvg)
-		-- print(fngv,fnpng)
 		return qs
 	end
 end