uidriver/glfw: Refactoring: make currentMonitorByOS more explicit

internal/uidriver/glfw/ui.go

@@ -147,7 +147,7 @@ func initialize() error {
 
 	// Create a window and set it: this affects toDeviceIndependentPixel and deviceScaleFactor.
 	theUI.window = w
-	theUI.initMonitor = currentMonitorByOS(w)
+	theUI.initMonitor = currentMonitor(w)
 	v := theUI.initMonitor.GetVideoMode()
 	theUI.initFullscreenWidthInDP = int(theUI.toDeviceIndependentPixel(float64(v.Width)))
 	theUI.initFullscreenHeightInDP = int(theUI.toDeviceIndependentPixel(float64(v.Height)))
@@ -409,7 +409,7 @@ func (u *UserInterface) ScreenSizeInFullscreen() (int, int) {
 
 	var w, h int
 	_ = u.t.Call(func() error {
-		v := u.currentMonitor().GetVideoMode()
+		v := currentMonitor(u.window).GetVideoMode()
 		w = int(u.toDeviceIndependentPixel(float64(v.Width)))
 		h = int(u.toDeviceIndependentPixel(float64(v.Height)))
 		return nil
@@ -587,7 +587,7 @@ func (u *UserInterface) deviceScaleFactor() float64 {
 			return devicescale.GetAt(cm.x, cm.y)
 		}
 	}
-	return devicescale.GetAt(u.currentMonitor().GetPos())
+	return devicescale.GetAt(currentMonitor(u.window).GetPos())
 }
 
 func init() {
@@ -800,7 +800,7 @@ func (u *UserInterface) updateSize() {
 		_ = u.t.Call(func() error {
 			var ww, wh int
 			if u.isFullscreen() {
-				v := u.currentMonitor().GetVideoMode()
+				v := currentMonitor(u.window).GetVideoMode()
 				ww = v.Width
 				wh = v.Height
 			} else {
@@ -961,7 +961,7 @@ func (u *UserInterface) setWindowSize(width, height int, fullscreen bool) {
 			if u.origPosX == invalidPos || u.origPosY == invalidPos {
 				u.origPosX, u.origPosY = u.window.GetPos()
 			}
-			m := u.currentMonitor()
+			m := currentMonitor(u.window)
 			v := m.GetVideoMode()
 			u.window.SetMonitor(m, 0, 0, v.Width, v.Height, v.RefreshRate)
 
@@ -1089,19 +1089,29 @@ func (u *UserInterface) updateVsync() {
 	u.Graphics().SetVsyncEnabled(u.vsync)
 }
 
-// currentMonitor returns the monitor most suitable with the current window.
+// currentMonitor returns the current active monitor.
+//
+// The given window might or might not be used to detect the monitor.
 //
 // currentMonitor must be called on the main thread.
-func (u *UserInterface) currentMonitor() *glfw.Monitor {
+func currentMonitor(window *glfw.Window) *glfw.Monitor {
 	// GetMonitor is available only on fullscreen.
-	if m := u.window.GetMonitor(); m != nil {
+	if m := window.GetMonitor(); m != nil {
 		return m
 	}
 
 	// Getting a monitor from a window position is not reliable in general (e.g., when a window is put across
 	// multiple monitors, or, before SetWindowPosition is called.).
 	// Get the monitor which the current window belongs to. This requires OS API.
-	return currentMonitorByOS(u.window)
+	if m := currentMonitorByOS(); m != nil {
+		return m
+	}
+
+	// As the fallback, detect the monitor from the window.
+	if m := getCachedMonitor(window.GetPos()); m != nil {
+		return m.m
+	}
+	return glfw.GetPrimaryMonitor()
 }
 
 func (u *UserInterface) SetScreenTransparent(transparent bool) {
@@ -1151,7 +1161,7 @@ func (u *UserInterface) SetInitFocused(focused bool) {
 
 func (u *UserInterface) monitorPosition() (int, int) {
 	// TODO: toDeviceIndependentPixel might be required.
-	return u.currentMonitor().GetPos()
+	return currentMonitor(u.window).GetPos()
 }
 
 func (u *UserInterface) Input() driver.Input {

internal/uidriver/glfw/ui_darwin.go

@@ -55,7 +55,7 @@ func (u *UserInterface) adjustWindowPosition(x, y int) (int, int) {
 	return x, y
 }
 
-func currentMonitorByOS(w *glfw.Window) *glfw.Monitor {
+func currentMonitorByOS() *glfw.Monitor {
 	x := C.int(0)
 	y := C.int(0)
 	// Note: [NSApp mainWindow] is nil when it doesn't have its border. Use w here.
@@ -67,11 +67,7 @@ func currentMonitorByOS(w *glfw.Window) *glfw.Monitor {
 			return m
 		}
 	}
-
+	return nil
-	if m := getCachedMonitor(w.GetPos()); m != nil {
-		return m.m
-	}
-	return glfw.GetPrimaryMonitor()
 }
 
 func (u *UserInterface) nativeWindow() unsafe.Pointer {

internal/uidriver/glfw/ui_unix.go

@@ -32,12 +32,9 @@ func (u *UserInterface) adjustWindowPosition(x, y int) (int, int) {
 	return x, y
 }
 
-func currentMonitorByOS(w *glfw.Window) *glfw.Monitor {
+func currentMonitorByOS() *glfw.Monitor {
 	// TODO: Implement this correctly. (#1119).
-	if cm := getCachedMonitor(w.GetPos()); cm != nil {
+	return nil
-		return cm.m
-	}
-	return glfw.GetPrimaryMonitor()
 }
 
 func (u *UserInterface) nativeWindow() unsafe.Pointer {

internal/uidriver/glfw/ui_windows.go

@@ -120,19 +120,13 @@ func (u *UserInterface) adjustWindowPosition(x, y int) (int, int) {
 	return x, y
 }
 
-func currentMonitorByOS(glfww *glfw.Window) *glfw.Monitor {
+func currentMonitorByOS() *glfw.Monitor {
-	fallback := func() *glfw.Monitor {
+	// TODO: Should we return nil here?
-		if m := getCachedMonitor(glfww.GetPos()); m != nil {
-			return m.m
-		}
-		return glfw.GetPrimaryMonitor()
-	}
-
-	// TODO: Should we use glfww.GetWin32Window() here?
 	w, err := getActiveWindow()
 	if err != nil {
 		panic(err)
 	}
+
 	if w == 0 {
 		// There is no window at launching, but there is a hidden initialized window.
 		// Get the foreground window, that is common among multiple processes.
@@ -142,7 +136,7 @@ func currentMonitorByOS(glfww *glfw.Window) *glfw.Monitor {
 		}
 		if w == 0 {
 			// GetForegroundWindow can return null according to the document.
-			return fallback()
+			return nil
 		}
 	}
 
@@ -152,7 +146,7 @@ func currentMonitorByOS(glfww *glfw.Window) *glfw.Monitor {
 	m, err := monitorFromWindow(w, monitorDefaultToNearest)
 	if err != nil {
 		// monitorFromWindow can return error on Wine. Ignore this.
-		return fallback()
+		return nil
 	}
 
 	mi := monitorInfo{}
@@ -168,7 +162,7 @@ func currentMonitorByOS(glfww *glfw.Window) *glfw.Monitor {
 			return m
 		}
 	}
-	return fallback()
+	return nil
 }
 
 func (u *UserInterface) nativeWindow() unsafe.Pointer {

internal/uidriver/glfw/window.go

@@ -189,7 +189,7 @@ func (w *window) Position() (int, int) {
 		} else {
 			wx, wy = w.ui.window.GetPos()
 		}
-		mx, my := w.ui.currentMonitor().GetPos()
+		mx, my := currentMonitor(w.ui.window).GetPos()
 		wx -= mx
 		wy -= my
 		xf := w.ui.toDeviceIndependentPixel(float64(wx))
@@ -209,7 +209,7 @@ func (w *window) SetPosition(x, y int) {
 		defer func() {
 			w.setPositionCalled = true
 		}()
-		mx, my := w.ui.currentMonitor().GetPos()
+		mx, my := currentMonitor(w.ui.window).GetPos()
 		xf := w.ui.toDeviceDependentPixel(float64(x))
 		yf := w.ui.toDeviceDependentPixel(float64(y))
 		x, y := w.ui.adjustWindowPosition(mx+int(xf), my+int(yf))