This replaces my previous PR which had to be reverted due to an issue…

… with the application not having started. This cleans up some of the init code to avoid calling init multiple times (when starting and when creating a new windows).

Replaces fyne-io#4177

app/app.go

@@ -153,6 +153,11 @@ func newAppWithDriver(d fyne.Driver, id string) fyne.App {
 	repository.Register("http", httpHandler)
 	repository.Register("https", httpHandler)
 
+	// Run .Init() after app has been set up.
+	if driver, ok := d.(interface{ Init() }); ok {
+		driver.Init()
+	}
+
 	return newApp
 }
 

internal/driver/glfw/driver.go

@@ -89,10 +89,6 @@ func (d *gLDriver) AbsolutePositionForObject(co fyne.CanvasObject) fyne.Position
 }
 
 func (d *gLDriver) Device() fyne.Device {
-	if d.device == nil {
-		d.device = &glDevice{}
-	}
-
 	return d.device
 }
 
@@ -177,5 +173,6 @@ func NewGLDriver() *gLDriver {
 		drawDone:     make(chan struct{}),
 		waitForStart: make(chan struct{}),
 		animation:    &animation.Runner{},
+		device:       &glDevice{},
 	}
 }

internal/driver/glfw/loop.go

@@ -2,7 +2,6 @@ package glfw
 
 import (
 	"runtime"
-	"sync"
 	"sync/atomic"
 	"time"
 
@@ -29,7 +28,6 @@ type drawData struct {
 var funcQueue = make(chan funcData)
 var drawFuncQueue = make(chan drawData)
 var running uint32 // atomic bool, 0 or 1
-var initOnce = &sync.Once{}
 
 // Arrange that main.main runs on main thread.
 func init() {
@@ -110,7 +108,6 @@ func (d *gLDriver) runGL() {
 	}
 	close(d.waitForStart) // Signal that execution can continue.
 
-	d.initGLFW()
 	if d.trayStart != nil {
 		d.trayStart()
 	}

internal/driver/glfw/loop_desktop.go

@@ -11,17 +11,16 @@ import (
 	"github.com/go-gl/glfw/v3.3/glfw"
 )
 
-func (d *gLDriver) initGLFW() {
-	initOnce.Do(func() {
-		err := glfw.Init()
-		if err != nil {
-			fyne.LogError("failed to initialise GLFW", err)
-			return
-		}
-
-		initCursors()
-		d.startDrawThread()
-	})
+// Init makes the driver ready to run. Needs to be called after app is created.
+func (d *gLDriver) Init() {
+	err := glfw.Init()
+	if err != nil {
+		fyne.LogError("failed to initialise GLFW", err)
+		return
+	}
+
+	initCursors()
+	d.startDrawThread()
 }
 
 func (d *gLDriver) tryPollEvents() {

internal/driver/glfw/loop_goxjs.go

@@ -12,16 +12,15 @@ import (
 	glfw "github.com/fyne-io/glfw-js"
 )
 
-func (d *gLDriver) initGLFW() {
-	initOnce.Do(func() {
-		err := glfw.Init(gl.ContextWatcher)
-		if err != nil {
-			fyne.LogError("failed to initialise GLFW", err)
-			return
-		}
-
-		d.startDrawThread()
-	})
+// Init makes the driver ready to run. Needs to be called after app is created.
+func (d *gLDriver) Init() {
+	err := glfw.Init(gl.ContextWatcher)
+	if err != nil {
+		fyne.LogError("failed to initialise GLFW", err)
+		return
+	}
+
+	d.startDrawThread()
 }
 
 func (d *gLDriver) tryPollEvents() {

internal/driver/glfw/window.go

@@ -948,13 +948,11 @@ func (d *gLDriver) CreateWindow(title string) fyne.Window {
 }
 
 func (d *gLDriver) createWindow(title string, decorate bool) fyne.Window {
-	var ret *window
 	if title == "" {
 		title = defaultTitle
 	}
+	var ret *window
 	runOnMain(func() {
-		d.initGLFW()
-
 		ret = &window{title: title, decorate: decorate, driver: d}
 		// This queue is destroyed when the window is closed.
 		ret.InitEventQueue()

internal/driver/glfw/window_test.go

@@ -36,7 +36,6 @@ func init() {
 // TestMain makes sure that our driver is running on the main thread.
 // This must be done for some of our tests to function correctly.
 func TestMain(m *testing.M) {
-	d.initGLFW()
 	go func() {
 		// Wait for GLFW loop to be running.
 		// If we try to create windows before the context is created, this will fail with an exception.