Method dot

internal/driver/webui.go:313–345

dot generates a web page containing an svg diagram.

(w http.ResponseWriter, req *http.Request)

// dot generates a web page containing an svg diagram.
func (ui *webInterface) dot(w http.ResponseWriter, req *http.Request) {
	rpt, errList := ui.makeReport(w, req, []string{"svg"}, nil)
	if rpt == nil {
		return // error already reported
	}

	// Generate dot graph.
	g, config := report.GetDOT(rpt)
	legend := config.Labels
	config.Labels = nil
	dot := &bytes.Buffer{}
	graph.ComposeDot(dot, g, &graph.DotAttributes{}, config)

	// Convert to svg.
	svg, err := dotToSvg(dot.Bytes())
	if err != nil {
		http.Error(w, "Could not execute dot; may need to install graphviz.",
			http.StatusNotImplemented)
		ui.options.UI.PrintErr("Failed to execute dot. Is Graphviz installed?\n", err)
		return
	}

	// Get all node names into an array.
	nodes := []string{""} // dot starts with node numbered 1
	for _, n := range g.Nodes {
		nodes = append(nodes, n.Info.Name)
	}

	ui.render(w, req, "graph", rpt, errList, legend, webArgs{
		HTMLBody: template.HTML(string(svg)),
		Nodes:    nodes,
	})
}

func dotToSvg(dot []byte) ([]byte, error) {
	cmd := exec.Command("dot", "-Tsvg")