ui/app,apps/gophers,apps/hello: replace CreateWindow with NewWindow

Gio doesn't support multiple windows anyway, so get rid of the
app.Windows channel and use NewWindow call for the mobile platforms
as well.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

apps/go.mod

@@ -2,6 +2,8 @@ module gioui.org/apps
 
 go 1.12
 
+replace gioui.org/ui => ../ui
+
 require (
 	gioui.org/ui v0.0.0-20190331090026-ca5204fcb8b3
 	github.com/google/go-github/v24 v24.0.1

apps/go.sum

@@ -1,6 +1,4 @@
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
-gioui.org/ui v0.0.0-20190331090026-ca5204fcb8b3 h1:+iSMCchOrM75QcNH8czjwCXVbwYLofiPeKHl/8Nxxck=
-gioui.org/ui v0.0.0-20190331090026-ca5204fcb8b3/go.mod h1:FBjAd/bO8PFxAPY49SiMXkF7Mj677k+KYut4glYlhnM=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=

apps/gophers/main.go

@@ -119,14 +119,6 @@ func main() {
 		fmt.Println("The quota for anonymous GitHub API access is very low. Specify a token with -token to avoid quota errors.")
 		fmt.Println("See https://help.github.com/en/articles/creating-a-personal-access-token-for-the-command-line.")
 	}
-	err := app.CreateWindow(app.WindowOptions{
-		Width:  ui.Dp(400),
-		Height: ui.Dp(800),
-		Title:  "Gophers",
-	})
-	if err != nil {
-		log.Fatal(err)
-	}
 	app.Main()
 }
 
@@ -147,13 +139,16 @@ func init() {
 	fonts.italic = mustLoadFont(goitalic.TTF)
 	fonts.mono = mustLoadFont(gomono.TTF)
 	go func() {
-		for w := range app.Windows() {
-			w := w
-			go func() {
-				if err := newApp(w).run(); err != nil {
-					log.Fatal(err)
-				}
-			}()
+		w, err := app.NewWindow(app.WindowOptions{
+			Width:  ui.Dp(400),
+			Height: ui.Dp(800),
+			Title:  "Gophers",
+		})
+		if err != nil {
+			log.Fatal(err)
+		}
+		if err := newApp(w).run(); err != nil {
+			log.Fatal(err)
 		}
 	}()
 }

apps/hello/hello.go

@@ -18,26 +18,10 @@ import (
 )
 
 func main() {
-	err := app.CreateWindow(app.WindowOptions{
-		Width:  ui.Dp(400),
-		Height: ui.Dp(800),
-		Title:  "Hello World",
-	})
-	if err != nil {
-		log.Fatal(err)
-	}
 	app.Main()
 }
 
 func init() {
-	go func() {
-		for w := range app.Windows() {
-			go loop(w)
-		}
-	}()
-}
-
-func loop(w *app.Window) {
 	regular, err := sfnt.Parse(goregular.TTF)
 	if err != nil {
 		panic("failed to load font")
@@ -45,19 +29,29 @@ func loop(w *app.Window) {
 	var faces measure.Faces
 	black := &image.Uniform{color.Black}
 	face := faces.For(regular, ui.Dp(50))
-	for w.IsAlive() {
-		e := <-w.Events()
-		switch e := e.(type) {
-		case app.Draw:
-			faces.Cfg = e.Config
-			cs := layout.ExactConstraints(w.Size())
-			root, _ := (text.Label{Src: black, Face: face, Text: "Hello, World!"}).Layout(cs)
-			w.Draw(root)
-			faces.Frame()
+	go func() {
+		w, err := app.NewWindow(app.WindowOptions{
+			Width:  ui.Dp(400),
+			Height: ui.Dp(800),
+			Title:  "Hello World",
+		})
+		if err != nil {
+			log.Fatal(err)
 		}
-		w.Ack()
-	}
-	if w.Err() != nil {
-		log.Fatal(err)
-	}
+		for w.IsAlive() {
+			e := <-w.Events()
+			switch e := e.(type) {
+			case app.Draw:
+				faces.Cfg = e.Config
+				cs := layout.ExactConstraints(w.Size())
+				root, _ := (text.Label{Src: black, Face: face, Text: "Hello, World!"}).Layout(cs)
+				w.Draw(root)
+				faces.Frame()
+			}
+			w.Ack()
+		}
+		if w.Err() != nil {
+			log.Fatal(err)
+		}
+	}()
 }

ui/app/app.go

@@ -59,19 +59,18 @@ const (
 // Set it with the go tool linker flag -X.
 var extraArgs string
 
-var windows = make(chan *Window)
-
-func CreateWindow(opts WindowOptions) error {
+// NewWindow creates a new window for a set of window
+// options. The options are hints; the platform is free to
+// ignore or adjust them.
+// If the current program is running on iOS and Android,
+// NewWindow the window previously created by the platform.
+func NewWindow(opts WindowOptions) (*Window, error) {
 	if opts.Width.V <= 0 || opts.Height.V <= 0 {
 		panic("window width and height must be larger than 0")
 	}
 	return createWindow(opts)
 }
 
-func Windows() <-chan *Window {
-	return windows
-}
-
 func (l Stage) String() string {
 	switch l {
 	case StageDead:

ui/app/os_android.go

@@ -55,6 +55,8 @@ type window struct {
 
 var theJVM *C.JavaVM
 
+var windows = make(chan *Window)
+
 var views = make(map[C.jlong]*window)
 
 func jniGetMethodID(env *C.JNIEnv, class C.jclass, method, sig string) C.jmethodID {
@@ -379,6 +381,6 @@ func Main() {
 	panic("unreachable")
 }
 
-func createWindow(opts WindowOptions) error {
-	return errors.New("createWindow not supported")
+func createWindow(opts WindowOptions) (*Window, error) {
+	return <- windows, nil
 }

ui/app/os_ios.go

@@ -22,10 +22,10 @@ import (
 	"sync/atomic"
 	"time"
 
+	"gioui.org/ui"
 	"gioui.org/ui/f32"
 	"gioui.org/ui/key"
 	"gioui.org/ui/pointer"
-	"gioui.org/ui"
 )
 
 type window struct {
@@ -42,6 +42,8 @@ var layerFactory func() uintptr
 
 var views = make(map[C.CFTypeRef]*window)
 
+var windows = make(chan *Window)
+
 func init() {
 	// Darwin requires UI operations happen on the main thread only.
 	runtime.LockOSThread()
@@ -233,8 +235,8 @@ func (w *window) setTextInput(s key.TextInputState) {
 	}
 }
 
-func createWindow(opts WindowOptions) error {
-	panic("unsupported")
+func createWindow(opts WindowOptions) (*Window, error) {
+	return <-windows, nil
 }
 
 func Main() {

ui/app/os_macos.go

@@ -15,7 +15,6 @@ import (
 	"errors"
 	"image"
 	"runtime"
-	"sync"
 	"time"
 	"unsafe"
 
@@ -36,13 +35,15 @@ type window struct {
 	stage Stage
 }
 
-// Only support one main window for now.
-var singleWindow struct {
-	mu      sync.Mutex
-	hasOpts bool
-	opts    WindowOptions
+type windowError struct {
+	window *Window
+	err    error
 }
 
+var windowOpts = make(chan WindowOptions)
+
+var windows = make(chan windowError)
+
 var viewFactory func() uintptr
 
 var views = make(map[C.CFTypeRef]*window)
@@ -162,7 +163,6 @@ func gio_onTerminate(view C.CFTypeRef) {
 	w := views[view]
 	delete(views, view)
 	w.setStage(StageDead)
-	close(windows)
 }
 
 //export gio_onHide
@@ -185,28 +185,23 @@ func gio_onCreate(view C.CFTypeRef) {
 	ow := newWindow(w)
 	w.w = ow
 	views[view] = w
-	windows <- ow
+	windows <- windowError{window: ow}
 }
 
-func createWindow(opts WindowOptions) error {
-	singleWindow.mu.Lock()
-	defer singleWindow.mu.Unlock()
-	if singleWindow.hasOpts {
-		panic("only one window supported")
-	}
-	singleWindow.opts = opts
-	singleWindow.hasOpts = true
-	return nil
+func createWindow(opts WindowOptions) (*Window, error) {
+	windowOpts <- opts
+	werr := <-windows
+	return werr.window, werr.err
 }
 
 func Main() {
 	view := C.CFTypeRef(viewFactory())
 	if view == 0 {
-		// TODO: return this error from CreateWindow.
-		panic(errors.New("CreateWindow: failed to create view"))
+		windows <- windowError{err: errors.New("CreateWindow: failed to create view")}
+		return
 	}
 	cfg := getConfig()
-	opts := singleWindow.opts
+	opts := <-windowOpts
 	w := cfg.Pixels(opts.Width)
 	h := cfg.Pixels(opts.Height)
 	title := C.CString(opts.Title)

ui/app/os_wayland.go

@@ -141,30 +141,28 @@ func Main() {
 	<-mainDone
 }
 
-func createWindow(opts WindowOptions) error {
+func createWindow(opts WindowOptions) (*Window, error) {
 	connMu.Lock()
 	defer connMu.Unlock()
 	if len(winMap) > 0 {
 		panic("multiple windows are not supported")
 	}
 	if err := waylandConnect(); err != nil {
-		return err
+		return nil, err
 	}
 	w, err := createNativeWindow(opts)
 	if err != nil {
 		conn.destroy()
-		return err
+		return nil, err
 	}
 	go func() {
-		windows <- w.w
 		w.setStage(StageVisible)
 		w.loop()
 		w.destroy()
 		conn.destroy()
-		close(windows)
 		close(mainDone)
 	}()
-	return nil
+	return w.w, nil
 }
 
 func createNativeWindow(opts WindowOptions) (*window, error) {

ui/app/os_windows.go

@@ -13,10 +13,10 @@ import (
 
 	syscall "golang.org/x/sys/windows"
 
+	"gioui.org/ui"
 	"gioui.org/ui/f32"
 	"gioui.org/ui/key"
 	"gioui.org/ui/pointer"
-	"gioui.org/ui"
 )
 
 var winMap = make(map[syscall.Handle]*window)
@@ -157,34 +157,37 @@ func Main() {
 	<-mainDone
 }
 
-func createWindow(opts WindowOptions) error {
+func createWindow(opts WindowOptions) (*Window, error) {
 	onceMu.Lock()
 	defer onceMu.Unlock()
 	if len(winMap) > 0 {
 		panic("multiple windows are not supported")
 	}
-	cerr := make(chan error, 1)
+	type windowError struct {
+		window *Window
+		err    error
+	}
+	cerr := make(chan windowError)
 	go func() {
 		// Call win32 API from a single OS thread.
 		runtime.LockOSThread()
 		w, err := createNativeWindow(opts)
 		if err != nil {
-			cerr <- err
+			cerr <- windowError{err: err}
 			return
 		}
 		defer w.destroy()
-		cerr <- nil
-		windows <- w.w
+		cerr <- windowError{w.w, nil}
 		showWindow(w.hwnd, _SW_SHOWDEFAULT)
 		setForegroundWindow(w.hwnd)
 		setFocus(w.hwnd)
 		if err := w.loop(); err != nil {
 			panic(err)
 		}
-		close(windows)
 		close(mainDone)
 	}()
-	return <-cerr
+	werr := <-cerr
+	return werr.window, werr.err
 }
 
 func createNativeWindow(opts WindowOptions) (*window, error) {