Link Tool UX

* On the Doodads tab is the Link button to enter the Link Tool.
* Click Link, then click the 1st doodad on the level, then click the 2nd
  doodad to complete the link.
* The actors struct in the Level holds the link IDs for each actor.

pkg/editor_ui.go

@@ -267,6 +267,17 @@ func (u *EditorUI) SetupCanvas(d *Doodle) *uix.Canvas {
 		u.startDragActor(doodad)
 	}
 
+	// A link event to connect two actors together.
+	drawing.OnLinkActors = func(a, b *level.Actor) {
+		d.Flash("Link %s and %s", a.Filename, b.Filename)
+		idA, idB := a.ID(), b.ID()
+		a.AddLink(idB)
+		b.AddLink(idA)
+
+		// Reset the Link tool.
+		drawing.Tool = uix.ActorTool
+	}
+
 	// Set up the drop handler for draggable doodads.
 	// NOTE: The drag event begins at editor_ui_doodad.go when configuring the
 	// Doodad Palette buttons.

pkg/editor_ui_doodad.go

@@ -57,7 +57,7 @@ func (u *EditorUI) setupDoodadFrame(e render.Engine, window *ui.Window) (*ui.Fra
 		Background:  render.Grey,
 		BorderSize:  2,
 		BorderStyle: ui.BorderRaised,
-		Height:      20,
+		Height:      24,
 	})
 	{
 		// Link button.
@@ -65,7 +65,8 @@ func (u *EditorUI) setupDoodadFrame(e render.Engine, window *ui.Window) (*ui.Fra
 			Text: "Link Doodads",
 		}))
 		linkButton.Handle(ui.Click, func(p render.Point) {
-			u.d.Flash("Hello world")
+			u.Canvas.LinkStart()
+			u.d.Flash("Click on the first Doodad to link to another one.")
 		})
 		u.Supervisor.Add(linkButton)
 
@@ -81,6 +82,9 @@ func (u *EditorUI) setupDoodadFrame(e render.Engine, window *ui.Window) (*ui.Fra
 
 	// Pager buttons on top of the doodad list.
 	pager := ui.NewFrame("Doodad Pager")
+	pager.SetBackground(render.RGBA(255, 0, 0, 20)) // TODO: if I don't set a background color,
+	// this frame will light up the same color as the Link button on mouse
+	// over. somewhere some memory might be shared between the recent widgets
 	{
 		leftBtn := ui.NewButton("Prev Page", ui.NewLabel(ui.Label{
 			Text: "<",
@@ -109,6 +113,7 @@ func (u *EditorUI) setupDoodadFrame(e render.Engine, window *ui.Window) (*ui.Fra
 	frame.Pack(pager, ui.Pack{
 		Anchor: ui.N,
 		Fill:   true,
+		PadY:   5,
 	})
 
 	doodadsAvailable, err := doodads.ListDoodads()

pkg/level/actors.go

@@ -39,9 +39,21 @@ type Actor struct {
 	id       string       // NOTE: read only, use ID() to access.
 	Filename string       `json:"filename"` // like "exit.doodad"
 	Point    render.Point `json:"point"`
+	Links    []string     `json:"links,omitempty"` // IDs of linked actors
 }
 
 // ID returns the actor's ID.
 func (a *Actor) ID() string {
 	return a.id
 }
+
+// AddLink adds a linked Actor to an Actor. Add the linked actor by its ID.
+func (a *Actor) AddLink(id string) {
+	// Don't add a duplicate ID to the links array.
+	for _, exist := range a.Links {
+		if exist == id {
+			return
+		}
+	}
+	a.Links = append(a.Links, id)
+}

pkg/uix/canvas.go

@@ -65,9 +65,11 @@ type Canvas struct {
 	OnDeleteActors func([]*level.Actor)
 	OnDragStart    func(filename string)
 
+	// -- WHEN Canvas.Tool is "Link" --
 	// When the Canvas wants to link two actors together. Arguments are the IDs
 	// of the two actors.
-	OnLinkActors func(a, b string)
+	OnLinkActors func(a, b *level.Actor)
+	linkFirst    *Actor
 
 	// Tracking pixels while editing. TODO: get rid of pixelHistory?
 	pixelHistory []*level.Pixel

pkg/uix/canvas_editable.go

@@ -58,7 +58,6 @@ func (w *Canvas) loopEditable(ev *events.State) error {
 	case ActorTool:
 		// See if any of the actors are below the mouse cursor.
 		var WP = w.WorldIndexAt(cursor)
-		_ = WP
 
 		var deleteActors = []*level.Actor{}
 		for _, actor := range w.actors {
@@ -100,6 +99,47 @@ func (w *Canvas) loopEditable(ev *events.State) error {
 		if len(deleteActors) > 0 && w.OnDeleteActors != nil {
 			w.OnDeleteActors(deleteActors)
 		}
+	case LinkTool:
+		// See if any of the actors are below the mouse cursor.
+		var WP = w.WorldIndexAt(cursor)
+
+		for _, actor := range w.actors {
+			// Permanently color the actor if it's the current subject of the
+			// Link Tool (after 1st click, until 2nd click of other actor)
+			if w.linkFirst == actor {
+				actor.Canvas.Configure(ui.Config{
+					Background: render.RGBA(255, 153, 255, 153),
+				})
+				continue
+			}
+
+			box := render.Rect{
+				X: actor.Actor.Point.X - P.X - w.Scroll.X,
+				Y: actor.Actor.Point.Y - P.Y - w.Scroll.Y,
+				W: actor.Canvas.Size().W,
+				H: actor.Canvas.Size().H,
+			}
+
+			if WP.Inside(box) {
+				actor.Canvas.Configure(ui.Config{
+					BorderSize:  1,
+					BorderColor: render.RGBA(255, 153, 255, 255),
+					BorderStyle: ui.BorderSolid,
+					Background:  render.White, // TODO: cuz the border draws a bgcolor
+				})
+
+				// Click handler to start linking this actor.
+				if ev.Button1.Read() {
+					if err := w.LinkAdd(actor); err != nil {
+						return err
+					}
+					break
+				}
+			} else {
+				actor.Canvas.SetBorderSize(0)
+				actor.Canvas.SetBackground(render.RGBA(0, 0, 1, 0)) // TODO
+			}
+		}
 	}
 
 	return nil

pkg/uix/canvas_link_tool.go

@@ -0,0 +1,28 @@
+package uix
+
+import "errors"
+
+// LinkStart initializes the Link tool.
+func (w *Canvas) LinkStart() {
+	w.Tool = LinkTool
+	w.linkFirst = nil
+}
+
+// LinkAdd adds an actor to be linked in the Link tool.
+func (w *Canvas) LinkAdd(a *Actor) error {
+	if w.linkFirst == nil {
+		// First click, hold onto this actor.
+		w.linkFirst = a
+	} else {
+		// Second click, call the OnLinkActors handler with the two actors.
+		if w.OnLinkActors != nil {
+			w.OnLinkActors(w.linkFirst.Actor, a.Actor)
+		} else {
+			return errors.New("Canvas.LinkAdd: no OnLinkActors handler is ready")
+		}
+
+		// Reset the link state.
+		w.linkFirst = nil
+	}
+	return nil
+}