Break import cycle: use StateReader interface instead of direct State reference

- StateReader interface in ui package (Scale(), ScreenWidth(), ScreenHeight())
- State implements StateReader
- Renderer reads scale/window size via interface, never imports editor
- State fields are private (screenWidth, screenHeight, scale) with accessor methods
- No SetScale/SetWindowSize calls from main.go — Renderer reads from State directly

cmd/pad/main.go

@@ -38,14 +38,15 @@ func run(w *app.Window) error {
 	initialDPW := ui.Dp(390)
 	initialDPH := ui.Dp(844)
 
-	// Track pixel dimensions from ConfigEvent (for resize handling)
-	var pixelW, pixelH int
 	// Track previous scale to detect changes
 	prevScale := float32(1.0)
 
 	// Create logic instance with initial DP size and scale=1.0
 	logic := editor.NewLogic(initialDPW, initialDPH)
 
+	// Set State reference on Renderer — it reads scale/window size from State directly
+	renderer.SetState(logic.State())
+
 	// Shared state protected by mutex
 	var mu sync.Mutex
 	var elems []ui.Element
@@ -62,19 +63,14 @@ func run(w *app.Window) error {
 		case app.DestroyEvent:
 			return e.Err
 		case app.ConfigEvent:
-			// Store pixel dimensions from ConfigEvent
-			pixelW = e.Config.Size.X
-			pixelH = e.Config.Size.Y
-			// Convert to DP using current scale (starts at 1.0)
-			dpW := ui.ToDp(ui.Px(pixelW), 1.0)
-			dpH := ui.ToDp(ui.Px(pixelH), 1.0)
+			// Convert pixel dimensions to DP using current scale (starts at 1.0)
+			dpW := ui.ToDp(ui.Px(e.Config.Size.X), 1.0)
+			dpH := ui.ToDp(ui.Px(e.Config.Size.Y), 1.0)
 			// Send config event to logic goroutine (in DP)
 			logic.ConfigChan() <- editor.ConfigEvent{
 				Width:  dpW,
 				Height: dpH,
 			}
-			// Update renderer with window size from State
-			renderer.SetWindowSize(pixelW, pixelH)
 		case app.FrameEvent:
 			gtx := app.NewContext(&ops, e)
 			newScale := gtx.Metric.PxPerDp
@@ -85,9 +81,6 @@ func run(w *app.Window) error {
 				prevScale = newScale
 			}
 
-			// Update renderer with current scale from State
-			renderer.SetScale(logic.Scale())
-
 			// Acquire mutex, read frame, draw, release mutex
 			mu.Lock()
 			currentElems := elems

internal/editor/logic.go

@@ -25,9 +25,7 @@ type ConfigUpdate interface {
 }
 
 func (e ConfigEvent) apply(s *State) {
-	s.ScreenWidth = e.Width
-	s.ScreenHeight = e.Height
-	s.Elems = EditorLayout(e.Width, e.Height)
+	s.SetSize(e.Width, e.Height)
 }
 
 func (e ScaleEvent) apply(s *State) {
@@ -93,14 +91,14 @@ func (l *Logic) ResultChan() <-chan ResultEvent {
 func (l *Logic) ScreenSize() (ui.Dp, ui.Dp) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	return l.state.ScreenWidth, l.state.ScreenHeight
+	return l.state.ScreenWidth(), l.state.ScreenHeight()
 }
 
 // Scale returns the current scale factor (pixels per DP).
 func (l *Logic) Scale() float32 {
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	return l.state.Scale
+	return l.state.Scale()
 }
 
 // Run runs the logic goroutine loop.

internal/editor/state.go

@@ -7,9 +7,9 @@ import (
 // State holds all application state owned by the logic goroutine.
 // All dimensions are in device-independent pixels (Dp).
 type State struct {
-	ScreenWidth  ui.Dp
-	ScreenHeight ui.Dp
-	Scale        float32 // pixels per DP, default 1.0
+	screenWidth  ui.Dp
+	screenHeight ui.Dp
+	scale        float32 // pixels per DP, default 1.0
 	Elems        []ui.Element
 }
 
@@ -18,17 +18,33 @@ type State struct {
 // scale defaults to 1.0 until updated by ScaleEvent.
 func NewState(screenWidth, screenHeight ui.Dp) *State {
 	return &State{
-		ScreenWidth:  screenWidth,
-		ScreenHeight: screenHeight,
-		Scale:        1.0,
+		screenWidth:  screenWidth,
+		screenHeight: screenHeight,
+		scale:        1.0,
 		Elems:        EditorLayout(screenWidth, screenHeight),
 	}
 }
 
+// Scale returns the current scale factor (pixels per DP).
+func (s *State) Scale() float32 { return s.scale }
+
+// ScreenWidth returns the current screen width in Dp.
+func (s *State) ScreenWidth() ui.Dp { return s.screenWidth }
+
+// ScreenHeight returns the current screen height in Dp.
+func (s *State) ScreenHeight() ui.Dp { return s.screenHeight }
+
 // SetScale updates the scale factor and recomputes layout.
 func (s *State) SetScale(scale float32) {
-	s.Scale = scale
-	s.Elems = EditorLayout(s.ScreenWidth, s.ScreenHeight)
+	s.scale = scale
+	s.Elems = EditorLayout(s.screenWidth, s.screenHeight)
+}
+
+// SetSize updates the screen dimensions and recomputes layout.
+func (s *State) SetSize(width, height ui.Dp) {
+	s.screenWidth = width
+	s.screenHeight = height
+	s.Elems = EditorLayout(width, height)
 }
 
 // EditorLayout computes regions for the editor page.

internal/ui/render.go

@@ -15,50 +15,52 @@ import (
 	"golang.org/x/image/math/fixed"
 )
 
+// StateReader provides access to scale and window dimensions from State.
+// Implemented by editor.State to avoid import cycles.
+type StateReader interface {
+	Scale() float32
+	ScreenWidth() Dp
+	ScreenHeight() Dp
+}
+
 // Renderer consumes a slice of elements and draws them.
 type Renderer struct {
 	theme Theme
 	shp   *text.Shaper
-	scale float32 // pixels per DP, from State.Scale
-	// Window dimensions in physical pixels, from State
-	windowW int
-	windowH int
+	state StateReader // read-only access to State for scale/window size
 }
 
 // New creates a new Renderer.
 func New(th Theme, shp *text.Shaper) *Renderer {
-	return &Renderer{theme: th, shp: shp, scale: 1.0}
+	return &Renderer{theme: th, shp: shp}
 }
 
-// SetScale updates the renderer's scale factor from State.Scale.
-func (r *Renderer) SetScale(scale float32) {
-	r.scale = scale
+// SetState sets the State reference for the Renderer.
+// The Renderer reads scale and window size from State directly.
+func (r *Renderer) SetState(state StateReader) {
+	r.state = state
 }
 
-// SetWindowSize updates the window dimensions in physical pixels from State.
-func (r *Renderer) SetWindowSize(w, h int) {
-	r.windowW = w
-	r.windowH = h
-}
-
-// toPx converts Dp to physical pixels using the renderer's scale.
+// toPx converts Dp to physical pixels using the scale from State.
 func (r *Renderer) toPx(dp Dp) Px {
-	return ToPx(dp, r.scale)
+	return ToPx(dp, r.state.Scale())
 }
 
-// toDp converts physical pixels to Dp using the renderer's scale.
+// toDp converts physical pixels to Dp using the scale from State.
 func (r *Renderer) toDp(px Px) Dp {
-	return ToDp(px, r.scale)
+	return ToDp(px, r.state.Scale())
 }
 
 // Draw iterates elements and draws each in slice order (back-to-front).
-// Window constraints come from State (set via SetWindowSize), not from gtx.
-// Scale comes from State (set via SetScale), not from gtx.Metric.PxPerDp.
+// All scale and window size values come from State, never from gtx.
 func (r *Renderer) Draw(gtx layout.Context, elems []Element) {
-	// Use window dimensions from State — never from gtx.Constraints
+	// Use window dimensions from State — convert DP to pixels using State.Scale
+	state := r.state
+	windowWPx := int(r.toPx(state.ScreenWidth()))
+	windowHPx := int(r.toPx(state.ScreenHeight()))
 	initialConstraints := WindowConstraints{
 		Min: image.Point{X: 0, Y: 0},
-		Max: image.Point{X: r.windowW, Y: r.windowH},
+		Max: image.Point{X: windowWPx, Y: windowHPx},
 	}
 
 	for _, e := range elems {