gim: move view code into its own package

gim/main.go

@@ -1,36 +1,30 @@
 package main
 
 import (
-	"fmt"
 	"math/rand"
-	"os"
-	"strings"
 	"time"
 
 	"github.com/mediocregopher/ginger/gg"
 	"github.com/mediocregopher/ginger/gim/geo"
 	"github.com/mediocregopher/ginger/gim/terminal"
+	"github.com/mediocregopher/ginger/gim/view"
 )
 
-// Leave room for:
-// - Changing the "flow" direction
-// - Absolute positioning of some/all vertices
-
 // TODO be able to draw circular graphs
 // TODO audit all steps, make sure everything is deterministic
 // TODO self-edges
 
-const (
-	framerate   = 10
-	frameperiod = time.Second / time.Duration(framerate)
-)
+//const (
+//	framerate   = 10
+//	frameperiod = time.Second / time.Duration(framerate)
+//)
 
-func debugf(str string, args ...interface{}) {
-	if !strings.HasSuffix(str, "\n") {
-		str += "\n"
-	}
-	fmt.Fprintf(os.Stderr, str, args...)
-}
+//func debugf(str string, args ...interface{}) {
+//	if !strings.HasSuffix(str, "\n") {
+//		str += "\n"
+//	}
+//	fmt.Fprintf(os.Stderr, str, args...)
+//}
 
 func mkGraph() (*gg.Graph, gg.Value) {
 	a := gg.NewValue("a")
@@ -83,15 +77,9 @@ func main() {
 	center := geo.Zero.Midpoint(wSize)
 
 	g, start := mkGraph()
-	v := view{
-		g:           g,
-		primFlowDir: geo.Right,
-		secFlowDir:  geo.Down,
-		start:       start,
-	}
-
+	view := view.New(g, start, geo.Right, geo.Down)
 	viewBuf := terminal.NewBuffer()
-	v.draw(viewBuf)
+	view.Draw(viewBuf)
 
 	buf := terminal.NewBuffer()
 	buf.DrawBufferCentered(center, viewBuf)

gim/view/box.go

@@ -1,4 +1,4 @@
-package main
+package view
 
 import (
 	"fmt"

gim/view/line.go

@@ -1,4 +1,4 @@
-package main
+package view
 
 import (
 	"github.com/mediocregopher/ginger/gim/geo"

gim/view/view.go

@@ -1,98 +1,49 @@
-package main
+// Package view implements rendering a graph to a terminal.
+package view
 
 import (
 	"sort"
 
 	"github.com/mediocregopher/ginger/gg"
-	"github.com/mediocregopher/ginger/gim/constraint"
 	"github.com/mediocregopher/ginger/gim/geo"
 	"github.com/mediocregopher/ginger/gim/terminal"
+	"github.com/mediocregopher/ginger/gim/view/constraint"
 )
 
-// "Solves" vertex position by detemining relative positions of vertices in
-// primary and secondary directions (independently), with relative positions
-// being described by "levels", where multiple vertices can occupy one level.
-//
-// Primary determines relative position in the primary direction by trying
-// to place vertices before their outs and after their ins.
-//
-// Secondary determines relative position in the secondary direction by
-// trying to place vertices relative to vertices they share an edge with in
-// the order that the edges appear on the shared node.
-func posSolve(g *gg.Graph) ([][]*gg.Vertex, map[string]int, map[string]int) {
-	primEng := constraint.NewEngine()
-	secEng := constraint.NewEngine()
-
-	strM := g.ByID()
-	for _, v := range strM {
-		var prevIn *gg.Vertex
-		for _, e := range v.In {
-			primEng.AddConstraint(constraint.Constraint{
-				Elem: e.From.ID,
-				LT:   v.ID,
-			})
-			if prevIn != nil {
-				secEng.AddConstraint(constraint.Constraint{
-					Elem: prevIn.ID,
-					LT:   e.From.ID,
-				})
-			}
-			prevIn = e.From
-		}
-
-		var prevOut *gg.Vertex
-		for _, e := range v.Out {
-			if prevOut == nil {
-				continue
-			}
-			secEng.AddConstraint(constraint.Constraint{
-				Elem: prevOut.ID,
-				LT:   e.To.ID,
-			})
-			prevOut = e.To
-		}
-	}
-	prim := primEng.Solve()
-	sec := secEng.Solve()
-
-	// determine maximum primary level
-	var maxPrim int
-	for _, lvl := range prim {
-		if lvl > maxPrim {
-			maxPrim = lvl
-		}
-	}
-
-	outStr := make([][]string, maxPrim+1)
-	for v, lvl := range prim {
-		outStr[lvl] = append(outStr[lvl], v)
-	}
-
-	// sort each primary level
-	for _, vv := range outStr {
-		sort.Slice(vv, func(i, j int) bool {
-			return sec[vv[i]] < sec[vv[j]]
-		})
-	}
-
-	// convert to vertices
-	out := make([][]*gg.Vertex, len(outStr))
-	for i, vv := range outStr {
-		out[i] = make([]*gg.Vertex, len(outStr[i]))
-		for j, v := range vv {
-			out[i][j] = strM[v]
-		}
-	}
-	return out, prim, sec
-}
-
-type view struct {
+// View wraps a single Graph instance and a set of display options for it, and
+// generates renderable terminal output for it.
+type View struct {
 	g     *gg.Graph
-	primFlowDir, secFlowDir geo.XY
 	start gg.Value
+
+	primFlowDir, secFlowDir geo.XY
 }
 
-func (view *view) draw(buf *terminal.Buffer) {
+// New instantiates and returns a view around the given Graph instance, with
+// start indicating the value vertex to consider the "root" of the graph.
+//
+// Drawing is done by aligning the vertices into rows and columns in such a way
+// as to reduce edge crossings. primaryDir indicates the direction edges will
+// primarily be pointed in. For example, if it is geo.Down then adjacent
+// vertices will be arranged into columns.
+//
+// secondaryDir indicates the direction vertices should be arranged when they
+// end up in the same "rank" (e.g. when primaryDir is geo.Down, all vertices on
+// the same row will be the same "rank").
+//
+// A primaryDir/secondaryDir of either geo.Down/geo.Right or geo.Right/geo.Down
+// are recommended, but any combination of perpendicular directions is allowed.
+func New(g *gg.Graph, start gg.Value, primaryDir, secondaryDir geo.XY) *View {
+	return &View{
+		g:           g,
+		start:       start,
+		primFlowDir: primaryDir,
+		secFlowDir:  secondaryDir,
+	}
+}
+
+// Draw renders and draws the View's Graph to the Buffer.
+func (view *View) Draw(buf *terminal.Buffer) {
 	relPos, _, secSol := posSolve(view.g)
 
 	// create boxes
@@ -183,3 +134,80 @@ func (view *view) draw(buf *terminal.Buffer) {
 		line.draw(buf, view.primFlowDir, view.secFlowDir)
 	}
 }
+
+// "Solves" vertex position by detemining relative positions of vertices in
+// primary and secondary directions (independently), with relative positions
+// being described by "levels", where multiple vertices can occupy one level.
+//
+// Primary determines relative position in the primary direction by trying
+// to place vertices before their outs and after their ins.
+//
+// Secondary determines relative position in the secondary direction by
+// trying to place vertices relative to vertices they share an edge with in
+// the order that the edges appear on the shared node.
+func posSolve(g *gg.Graph) ([][]*gg.Vertex, map[string]int, map[string]int) {
+	primEng := constraint.NewEngine()
+	secEng := constraint.NewEngine()
+
+	strM := g.ByID()
+	for _, v := range strM {
+		var prevIn *gg.Vertex
+		for _, e := range v.In {
+			primEng.AddConstraint(constraint.Constraint{
+				Elem: e.From.ID,
+				LT:   v.ID,
+			})
+			if prevIn != nil {
+				secEng.AddConstraint(constraint.Constraint{
+					Elem: prevIn.ID,
+					LT:   e.From.ID,
+				})
+			}
+			prevIn = e.From
+		}
+
+		var prevOut *gg.Vertex
+		for _, e := range v.Out {
+			if prevOut == nil {
+				continue
+			}
+			secEng.AddConstraint(constraint.Constraint{
+				Elem: prevOut.ID,
+				LT:   e.To.ID,
+			})
+			prevOut = e.To
+		}
+	}
+	prim := primEng.Solve()
+	sec := secEng.Solve()
+
+	// determine maximum primary level
+	var maxPrim int
+	for _, lvl := range prim {
+		if lvl > maxPrim {
+			maxPrim = lvl
+		}
+	}
+
+	outStr := make([][]string, maxPrim+1)
+	for v, lvl := range prim {
+		outStr[lvl] = append(outStr[lvl], v)
+	}
+
+	// sort each primary level
+	for _, vv := range outStr {
+		sort.Slice(vv, func(i, j int) bool {
+			return sec[vv[i]] < sec[vv[j]]
+		})
+	}
+
+	// convert to vertices
+	out := make([][]*gg.Vertex, len(outStr))
+	for i, vv := range outStr {
+		out[i] = make([]*gg.Vertex, len(outStr[i]))
+		for j, v := range vv {
+			out[i][j] = strM[v]
+		}
+	}
+	return out, prim, sec
+}