ui: Add SetWindowPosition(x, y int)

Fixes #936

examples/windowsize/main.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"bytes"
+	"flag"
 	"fmt"
 	"image"
 	"image/color"
@@ -25,6 +26,8 @@ import (
 	"log"
 	"math"
 	"math/rand"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/hajimehoshi/ebiten"
@@ -33,7 +36,12 @@ import (
 	"github.com/hajimehoshi/ebiten/inpututil"
 )
 
+var (
+	flagWindowPosition = flag.String("windowposition", "", "window position (e.g., 100,200)")
+)
+
 func init() {
+	flag.Parse()
 	rand.Seed(time.Now().UnixNano())
 }
 
@@ -77,7 +85,9 @@ func update(screen *ebiten.Image) error {
 	vsyncEnabled := ebiten.IsVsyncEnabled()
 	tps := ebiten.MaxTPS()
 	decorated := ebiten.IsWindowDecorated()
+	positionX, positionY := ebiten.WindowPosition()
 
+	if ebiten.IsKeyPressed(ebiten.KeyShift) {
 		if inpututil.IsKeyJustPressed(ebiten.KeyUp) {
 			screenHeight += d
 		}
@@ -94,6 +104,20 @@ func update(screen *ebiten.Image) error {
 		if inpututil.IsKeyJustPressed(ebiten.KeyRight) {
 			screenWidth += d
 		}
+	} else {
+		if inpututil.IsKeyJustPressed(ebiten.KeyUp) {
+			positionY -= 4
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDown) {
+			positionY += 4
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyLeft) {
+			positionX -= 4
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyRight) {
+			positionX += 4
+		}
+	}
 	if inpututil.IsKeyJustPressed(ebiten.KeyS) {
 		switch screenScale {
 		case 0.75:
@@ -146,6 +170,7 @@ func update(screen *ebiten.Image) error {
 	ebiten.SetVsyncEnabled(vsyncEnabled)
 	ebiten.SetMaxTPS(tps)
 	ebiten.SetWindowDecorated(decorated)
+	ebiten.SetWindowPosition(positionX, positionY)
 
 	if inpututil.IsKeyJustPressed(ebiten.KeyI) {
 		ebiten.SetWindowIcon([]image.Image{createRandomIconImage()})
@@ -173,7 +198,7 @@ func update(screen *ebiten.Image) error {
 	if t := ebiten.MaxTPS(); t != ebiten.UncappedTPS {
 		tpsStr = fmt.Sprintf("%d", t)
 	}
-	msg := fmt.Sprintf(`Press arrow keys to change the window size
+	msg := fmt.Sprintf(`Press shift + arrow keys to change the window size
 Press S key to change the window scale (only for desktops)
 Press F key to switch the fullscreen state (only for desktops)
 Press B key to switch the run-in-background state
@@ -191,6 +216,25 @@ Device Scale Factor: %0.2f`, wx, wy, cx, cy, ebiten.CurrentTPS(), tpsStr, ebiten
 	return nil
 }
 
+func parseWindowPosition() (int, int, bool) {
+	if *flagWindowPosition == "" {
+		return 0, 0, false
+	}
+	tokens := strings.Split(*flagWindowPosition, ",")
+	if len(tokens) != 2 {
+		return 0, 0, false
+	}
+	x, err := strconv.Atoi(tokens[0])
+	if err != nil {
+		return 0, 0, false
+	}
+	y, err := strconv.Atoi(tokens[1])
+	if err != nil {
+		return 0, 0, false
+	}
+	return x, y, true
+}
+
 func main() {
 	fmt.Printf("Device scale factor: %0.2f\n", ebiten.DeviceScaleFactor())
 	w, h := ebiten.ScreenSizeInFullscreen()
@@ -213,6 +257,10 @@ func main() {
 
 	ebiten.SetWindowIcon([]image.Image{createRandomIconImage()})
 
+	if x, y, ok := parseWindowPosition(); ok {
+		ebiten.SetWindowPosition(x, y)
+	}
+
 	if err := ebiten.Run(update, initScreenWidth, initScreenHeight, initScreenScale, "Window Size (Ebiten Demo)"); err != nil {
 		log.Fatal(err)
 	}

internal/driver/ui.go

@@ -57,6 +57,7 @@ type UI interface {
 	SetWindowIcon(iconImages []image.Image)
 	SetWindowResizable(resizable bool)
 	SetWindowTitle(title string)
+	SetWindowPosition(x, y int)
 
 	Input() Input
 }

internal/uidriver/glfw/ui.go

@@ -41,10 +41,6 @@ type UserInterface struct {
 	width           int
 	windowWidth     int
 	height          int
-	initMonitor          *glfw.Monitor
-	initFullscreenWidth  int
-	initFullscreenHeight int
-
 	scale           float64
 	fullscreenScale float64
 
@@ -57,10 +53,15 @@ type UserInterface struct {
 
 	lastActualScale float64
 
+	initMonitor          *glfw.Monitor
+	initFullscreenWidth  int
+	initFullscreenHeight int
 	initFullscreen       bool
 	initCursorVisible    bool
 	initWindowDecorated  bool
 	initWindowResizable  bool
+	initWindowPositionX  *int
+	initWindowPositionY  *int
 	initIconImages       []image.Image
 
 	reqWidth  int
@@ -667,8 +668,14 @@ func (u *UserInterface) run(width, height int, scale float64, title string, cont
 		u.window.SetTitle(title)
 		u.window.Show()
 
-		x := mx + (v.Width-w)/2
+		x, y := 0, 0
-		y := my + (v.Height-h)/3
+		if u.initWindowPositionX != nil && u.initWindowPositionY != nil {
+			x = *u.initWindowPositionX
+			y = *u.initWindowPositionY
+		} else {
+			x = mx + (v.Width-w)/2
+			y = my + (v.Height-h)/3
+		}
 		// Adjusting the position is needed only when the monitor is primary. (#829)
 		if mx == 0 && my == 0 {
 			x, y = adjustWindowPosition(x, y)
@@ -997,6 +1004,24 @@ func (u *UserInterface) currentMonitor() *glfw.Monitor {
 	return u.currentMonitorFromPosition()
 }
 
+func (u *UserInterface) SetWindowPosition(x, y int) {
+	if !u.isRunning() {
+		if u.initWindowPositionX == nil {
+			u.initWindowPositionX = new(int)
+		}
+		if u.initWindowPositionY == nil {
+			u.initWindowPositionY = new(int)
+		}
+		*u.initWindowPositionX = x
+		*u.initWindowPositionY = y
+		return
+	}
+	_ = u.t.Call(func() error {
+		u.window.SetPos(x, y)
+		return nil
+	})
+}
+
 func (u *UserInterface) WindowPosition() (int, int) {
 	if !u.isRunning() {
 		panic("ui: Run is not called yet")

internal/uidriver/js/ui.go

@@ -479,6 +479,10 @@ func (u *UserInterface) updateScreenSize() {
 	u.sizeChanged = true
 }
 
+func (u *UserInterface) SetWindowPosition(x, y int) {
+	// Do nothing
+}
+
 func (u *UserInterface) WindowPosition() (int, int) {
 	return 0, 0
 }

internal/uidriver/mobile/ui.go

@@ -443,6 +443,10 @@ func (u *UserInterface) DeviceScaleFactor() float64 {
 	return deviceScale()
 }
 
+func (u *UserInterface) SetWindowPosition(x, y int) {
+	// Do nothing
+}
+
 func (u *UserInterface) WindowPosition() (int, int) {
 	return 0, 0
 }

window.go

@@ -100,6 +100,15 @@ func SetWindowIcon(iconImages []image.Image) {
 // WindowPosition panics before Run is called.
 //
 // WindowPosition returns (0, 0) on browsers and mobiles.
-func WindowPosition() (int, int) {
+func WindowPosition() (x, y int) {
 	return uiDriver().WindowPosition()
 }
+
+// SetWindowPosition sets the window position.
+//
+// SetWindowPosition works before and after Run is called.
+//
+// SetWindowPosition does nothing on browsers and mobiles.
+func SetWindowPosition(x, y int) {
+	uiDriver().SetWindowPosition(x, y)
+}