Implement full architecture scaffolding with logic and frame receiver goroutines

- Logic goroutine: receives config events, recomputes layout, sends frames
- Frame receiver goroutine: reads frames, stores under mutex, calls w.Invalidate()
- Main event loop: renders frames under mutex, sends config events to logic
- Proper channel topology: configChan, frameChan, inputChan
- Mutex around elems shared between goroutines
- Window resize triggers layout recomputation in logic goroutine

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

cmd/pad/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"log"
 	"os"
+	"sync"
 
 	"gioui.org/app"
 	"gioui.org/op"
@@ -31,41 +32,81 @@ func run(w *app.Window) error {
 	shaper := text.NewShaper()
 	renderer := ui.New(ui.Theme{FontSize: 14}, shaper)
 
-	// Channel for window configuration events (resize, orientation)
+	// Channels for communication between goroutines
 	configChan := make(chan ui.ConfigEvent)
+	frameChan := make(chan []ui.Element)
+	inputChan := make(chan []ui.InputEvent)
+
+	// Shared state protected by mutex
+	var mu sync.Mutex
+	var elems []ui.Element
 
 	// Initial screen size
 	screenWidth := unit.Dp(390)
 	screenHeight := unit.Dp(844)
 
 	// Compute initial elements
-	elems := ui.EditorLayout(screenWidth, screenHeight)
+	elems = ui.EditorLayout(screenWidth, screenHeight)
 
+	// Start logic goroutine
+	go logic(w, shaper, screenWidth, screenHeight, configChan, frameChan, inputChan)
+
+	// Start frame receiver goroutine
+	go frameReceiver(w, &mu, &elems, frameChan)
+
+	// Main event loop
 	for {
 		switch e := w.Event().(type) {
 		case app.DestroyEvent:
 			return e.Err
 		case app.ConfigEvent:
-			// Send config event to logic goroutine (here, the main goroutine)
+			// Send config event to logic goroutine
 			configChan <- ui.ConfigEvent{
 				Width:  unit.Dp(e.Config.Size.X),
 				Height: unit.Dp(e.Config.Size.Y),
 			}
 		case app.FrameEvent:
-			// Process any pending config events
-			select {
-			case cfg := <-configChan:
-				// Update screen size and recompute layout
-				screenWidth = cfg.Width
-				screenHeight = cfg.Height
-				elems = ui.EditorLayout(screenWidth, screenHeight)
-			default:
-				// No config event, use existing elements
-			}
+			// Acquire mutex, read frame, draw, release mutex
+			mu.Lock()
+			currentElems := elems
+			mu.Unlock()
 
 			gtx := app.NewContext(&ops, e)
-			renderer.Draw(gtx, elems)
+			renderer.Draw(gtx, currentElems)
 			e.Frame(&ops)
 		}
 	}
 }
+
+// logic runs in a separate goroutine and owns all application state.
+func logic(w *app.Window, shaper *text.Shaper, screenWidth, screenHeight unit.Dp,
+	configChan <-chan ui.ConfigEvent, frameChan chan<- []ui.Element, inputChan <-chan []ui.InputEvent) {
+
+	// Initial elements
+	elems := ui.EditorLayout(screenWidth, screenHeight)
+
+	for {
+		select {
+		case cfg := <-configChan:
+			// Update screen size and recompute layout
+			screenWidth = cfg.Width
+			screenHeight = cfg.Height
+			elems = ui.EditorLayout(screenWidth, screenHeight)
+			frameChan <- elems
+		case <-inputChan:
+			// Process input (not implemented in mockup)
+			frameChan <- elems
+		}
+	}
+}
+
+// frameReceiver runs in a separate goroutine and bridges frameChan to the main loop.
+func frameReceiver(w *app.Window, mu *sync.Mutex, elems *[]ui.Element, frameChan <-chan []ui.Element) {
+	for {
+		frame := <-frameChan
+		mu.Lock()
+		*elems = frame
+		w.Invalidate()
+		mu.Unlock()
+	}
+}