Start work on menu interactivity.

With this commit, we get a ui.Interface and ui.Widget type. The
interface monitors hover and mouse click state and tells the widgets
about them; the widgets execute code specified by the application when
events occur.

Next step: have wh40k load the main menu and play sound, etc.

internal/ui/interface.go

@@ -0,0 +1,192 @@
+package ui
+
+import (
+	"fmt"
+	"image"
+	"reflect" // For DeepEqual
+
+	"github.com/hajimehoshi/ebiten"
+
+	"code.ur.gs/lupine/ordoor/internal/assetstore"
+	"code.ur.gs/lupine/ordoor/internal/menus"
+)
+
+// type Interface encapsulates a user interface, providing a means to track UI
+// state, draw the interface, and execute code when the widgets are interacted
+// with.
+//
+// The graphics for UI elements were all created with a 640x480 resolution in
+// mind. The interface transparently scales them all to the current screen size
+// to compensate.
+type Interface struct {
+	menu    *assetstore.Menu
+	static  []*assetstore.Sprite // Static elements in the interface
+	ticks   int
+	widgets []*Widget
+}
+
+func NewInterface(menu *assetstore.Menu) (*Interface, error) {
+	iface := &Interface{
+		menu: menu,
+	}
+
+	for _, record := range menu.Records() {
+		if err := iface.addRecord(record); err != nil {
+			return nil, err
+		}
+	}
+
+	return iface, nil
+}
+
+// Find a widget by its hierarchical ID path
+func (i *Interface) Widget(path ...int) (*Widget, error) {
+	for _, widget := range i.widgets {
+		if reflect.DeepEqual(path, widget.path) {
+			return widget, nil
+		}
+	}
+
+	return nil, fmt.Errorf("Couldn't find widget %#+v", path)
+}
+
+func (i *Interface) Update(screenX, screenY int) error {
+	// Used in animation effects
+	i.ticks += 1
+
+	mousePos := i.getMousePos(screenX, screenY)
+
+	// Iterate through all widgets, update mouse state
+	for _, widget := range i.widgets {
+		mouseIsOver := mousePos.In(widget.Bounds)
+		widget.hovering(mouseIsOver)
+		widget.mouseButton(mouseIsOver && ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft))
+	}
+
+	return nil
+}
+
+func (i *Interface) Draw(screen *ebiten.Image) error {
+	geo := i.scale(screen.Size())
+	do := &ebiten.DrawImageOptions{GeoM: geo}
+
+	for _, sprite := range i.static {
+		do.GeoM.Translate(geo.Apply(float64(sprite.XOffset), float64(sprite.YOffset)))
+		if err := screen.DrawImage(sprite.Image, do); err != nil {
+			return err
+		}
+		do.GeoM = geo
+	}
+
+	for _, widget := range i.widgets {
+		img, err := widget.Image(i.ticks / 2)
+		if err != nil {
+			return err
+		}
+
+		if img == nil {
+			continue
+		}
+
+		do.GeoM.Translate(geo.Apply(float64(widget.Bounds.Min.X), float64(widget.Bounds.Min.Y)))
+		if err := screen.DrawImage(img, do); err != nil {
+			return err
+		}
+		do.GeoM = geo
+	}
+
+	return nil
+}
+
+func (i *Interface) addRecord(record *menus.Record) error {
+	switch record.Type {
+	case menus.TypeStatic: // These are static
+		if sprite, err := i.menu.Sprite(record.SpriteId[0]); err != nil {
+			return err
+		} else {
+			i.static = append(i.static, sprite)
+		}
+	case menus.TypeMenu: // These aren't drawable and can be ignored
+	case menus.TypeOverlay, menus.TypeMainButton: // Widgets \o/
+		if widget, err := i.widgetFromRecord(record); err != nil {
+			return err
+		} else {
+			i.widgets = append(i.widgets, widget)
+		}
+
+	default:
+		return fmt.Errorf("ui.interface: encountered unknown menu record: %#+v", record)
+	}
+
+	// Recursively add all children
+	for _, record := range record.Children {
+		if err := i.addRecord(record); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Works out how much we have to scale the current screen by to draw correctly
+func (i *Interface) scale(w, h int) ebiten.GeoM {
+	var geo ebiten.GeoM
+	geo.Scale(float64(w)/640.0, float64(h)/480.0)
+
+	return geo
+}
+
+func (i *Interface) unscale(w, h int) ebiten.GeoM {
+	geo := i.scale(w, h)
+	geo.Invert()
+
+	return geo
+}
+
+// Returns the current position of the mouse in 640x480 coordinates. Needs the
+// actual size of the screen to do so.
+func (i *Interface) getMousePos(w, h int) image.Point {
+	cX, cY := ebiten.CursorPosition()
+	geo := i.unscale(w, h)
+
+	sX, sY := geo.Apply(float64(cX), float64(cY))
+
+	return image.Pt(int(sX), int(sY))
+}
+
+func (i *Interface) widgetFromRecord(record *menus.Record) (*Widget, error) {
+	// FIXME: we assume that all widgets have a share sprite, but is that true?
+	sprite, err := i.menu.Sprite(record.Share)
+	if err != nil {
+		return nil, err
+	}
+
+	var path []int
+	for r := record; r != nil; r = r.Parent {
+		path = append([]int{r.Id}, path...)
+	}
+
+	widget := &Widget{
+		Bounds: sprite.Rect,
+		path:   path,
+		record: record,
+		sprite: sprite,
+	}
+
+	switch record.Type {
+	case menus.TypeMainButton:
+		hovers, err := i.menu.Images(record.SpriteId[0], record.DrawType)
+		if err != nil {
+			return nil, err
+		}
+		widget.hoverAnimation = hovers
+
+		sprite, err := i.menu.Sprite(record.Share + 1)
+		if err != nil {
+			return nil, err
+		}
+		widget.mouseButtonDownImage = sprite.Image
+	}
+
+	return widget, nil
+}

internal/ui/widget.go

@@ -0,0 +1,84 @@
+package ui
+
+import (
+	"image"
+
+	"github.com/hajimehoshi/ebiten"
+
+	"code.ur.gs/lupine/ordoor/internal/assetstore"
+	"code.ur.gs/lupine/ordoor/internal/menus"
+)
+
+// Widget represents an interactive area of the screen. Backgrounds and other
+// non-interactive areas are not widgets.
+type Widget struct {
+	// Position on the screen in original (i.e., unscaled) coordinates
+	Bounds image.Rectangle
+	// Tooltip string // TODO: show the tooltip when hovering?
+
+	OnHoverEnter func()
+	OnHoverLeave func()
+
+	// Mouse up can happen without a click taking place if, for instance, the
+	// mouse cursor leaves the bounds while still pressed.
+	OnMouseDown  func()
+	OnMouseClick func()
+	OnMouseUp    func()
+
+	// These are expected to have the same dimensions as the Bounds
+	hoverAnimation []*ebiten.Image
+	hoverState     bool
+
+	// FIXME: We assume right mouse button isn't needed here
+	// TODO: down, up, and click hooks.
+	mouseButtonDownImage *ebiten.Image
+	mouseButtonState     bool
+
+	path   []int
+	record *menus.Record
+	sprite *assetstore.Sprite
+}
+
+func (w *Widget) hovering(value bool) {
+	if w.OnHoverEnter != nil && !w.hoverState && value {
+		w.OnHoverEnter()
+	}
+
+	if w.OnHoverLeave != nil && w.hoverState && !value {
+		w.OnHoverLeave()
+	}
+
+	w.hoverState = value
+
+	return
+}
+
+func (w *Widget) mouseButton(value bool) {
+	if w.OnMouseDown != nil && !w.mouseButtonState && value {
+		w.OnMouseDown()
+	}
+
+	if w.mouseButtonState && !value {
+		if w.OnMouseClick != nil && w.hoverState {
+			w.OnMouseClick()
+		}
+
+		if w.OnMouseUp != nil {
+			w.OnMouseUp()
+		}
+	}
+
+	w.mouseButtonState = value
+}
+
+func (w *Widget) Image(aniStep int) (*ebiten.Image, error) {
+	if w.hoverState && w.mouseButtonState {
+		return w.mouseButtonDownImage, nil
+	}
+
+	if w.hoverState && len(w.hoverAnimation) > 0 {
+		return w.hoverAnimation[(aniStep)%len(w.hoverAnimation)], nil
+	}
+
+	return w.sprite.Image, nil
+}

internal/ui/window.go

@@ -12,6 +12,11 @@ import (
 	"github.com/hajimehoshi/ebiten/inpututil"
 )
 
+type Game interface {
+	Update(screenX, screenY int) error
+	Draw(*ebiten.Image) error
+}
+
 var (
 	screenScale = flag.Float64("screen-scale", 1.0, "Scale the window by this factor")
 
@@ -26,9 +31,8 @@ type Window struct {
 	KeyUpHandlers     map[ebiten.Key]func()
 	MouseWheelHandler func(float64, float64)
 
-	// User-provided update actions
-	updateFn func() error
-	drawFn   func(*ebiten.Image) error
+	// Allow the "game" to be switched out at any time
+	game Game
 
 	debug    bool
 	firstRun bool
@@ -37,7 +41,7 @@ type Window struct {
 // 0,0 is the *top left* of the window
 //
 // ebiten assumes a single window, so only call this once...
-func NewWindow(title string) (*Window, error) {
+func NewWindow(game Game, title string) (*Window, error) {
 	ebiten.SetRunnableInBackground(true)
 
 	return &Window{
@@ -45,6 +49,7 @@ func NewWindow(title string) (*Window, error) {
 		KeyUpHandlers: make(map[ebiten.Key]func()),
 		debug:         true,
 		firstRun:      true,
+		game:          game,
 	}, nil
 }
 
@@ -57,13 +62,12 @@ func (w *Window) OnMouseWheel(f func(x, y float64)) {
 	w.MouseWheelHandler = f
 }
 
-func (w *Window) run(screen *ebiten.Image) error {
-	if w.firstRun {
-		ebiten.SetScreenScale(*screenScale)
-		w.firstRun = false
-	}
+func (w *Window) Layout(_, _ int) (int, int) {
+	return *winX, *winY
+}
 
-	if err := w.updateFn(); err != nil {
+func (w *Window) Update(screen *ebiten.Image) error {
+	if err := w.game.Update(screen.Size()); err != nil {
 		return err
 	}
 
@@ -83,16 +87,18 @@ func (w *Window) run(screen *ebiten.Image) error {
 		}
 	}
 
-	if !ebiten.IsDrawingSkipped() {
-		if err := w.drawFn(screen); err != nil {
-			return err
-		}
+	if ebiten.IsDrawingSkipped() {
+		return nil
+	}
 
-		if w.debug {
-			// Draw FPS, etc, to the screen
-			msg := fmt.Sprintf("tps=%0.2f fps=%0.2f", ebiten.CurrentTPS(), ebiten.CurrentFPS())
-			ebitenutil.DebugPrint(screen, msg)
-		}
+	if err := w.game.Draw(screen); err != nil {
+		return err
+	}
+
+	if w.debug {
+		// Draw FPS, etc, to the screen
+		msg := fmt.Sprintf("tps=%0.2f fps=%0.2f", ebiten.CurrentTPS(), ebiten.CurrentFPS())
+		ebitenutil.DebugPrint(screen, msg)
 	}
 
 	return nil
@@ -101,10 +107,7 @@ func (w *Window) run(screen *ebiten.Image) error {
 // TODO: a stop or other cancellation mechanism
 //
 // Note that this must be called on the main OS thread
-func (w *Window) Run(updateFn func() error, drawFn func(*ebiten.Image) error) error {
-	w.updateFn = updateFn
-	w.drawFn = drawFn
-
+func (w *Window) Run() error {
 	if *cpuprofile != "" {
 		f, err := os.Create(*cpuprofile)
 		if err != nil {
@@ -117,5 +120,7 @@ func (w *Window) Run(updateFn func() error, drawFn func(*ebiten.Image) error) er
 		defer pprof.StopCPUProfile()
 	}
 
-	return ebiten.Run(w.run, *winX, *winY, 1, w.Title) // Native game resolution: 640x480
+	ebiten.SetWindowSize(int(float64(*winX)**screenScale), int(float64(*winY)**screenScale))
+	ebiten.SetWindowTitle(w.Title)
+	return ebiten.RunGame(w) // Native game resolution: 640x480
 }