Add Gio app shells and platform stubs (T-003)

app-modern/cmd/softbox/main.go

@@ -1,11 +1,48 @@
 package main
 
 import (
-	"fmt"
+	"log"
+	"os"
 
+	"gioui.org/app"
+	"gioui.org/op"
+	"gioui.org/unit"
+
+	"softbox.local/app-modern/platform/windows"
+	softboxgio "softbox.local/app-modern/ui/gio"
 	"softbox.local/core"
 )
 
 func main() {
-	fmt.Println(core.ProductName)
+	go func() {
+		if err := run(); err != nil {
+			log.Printf("%s stopped: %v", core.ProductName, err)
+		}
+		os.Exit(0)
+	}()
+	app.Main()
+}
+
+func run() error {
+	platform := windows.New()
+	window := new(app.Window)
+	window.Option(
+		app.Title(core.ProductName),
+		app.Size(unit.Dp(1080), unit.Dp(720)),
+	)
+
+	theme := softboxgio.NewTheme()
+	shell := softboxgio.NewAppShell(string(platform.Edition()))
+	var operations op.Ops
+
+	for {
+		switch event := window.Event().(type) {
+		case app.DestroyEvent:
+			return event.Err
+		case app.FrameEvent:
+			context := app.NewContext(&operations, event)
+			shell.Layout(context, theme)
+			event.Frame(context.Ops)
+		}
+	}
 }