ui: Add SetIcon (#386)

examples/windowsize/main.go

@@ -18,15 +18,22 @@ package main
 
 import (
 	"fmt"
+	"image"
 	"image/color"
 	_ "image/jpeg"
 	"log"
 	"math"
+	"math/rand"
+	"time"
 
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/ebitenutil"
 )
 
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
 const (
 	initScreenWidth  = 320
 	initScreenHeight = 240
@@ -44,10 +51,30 @@ var (
 		ebiten.KeyF:     0,
 		ebiten.KeyB:     0,
 		ebiten.KeyC:     0,
+		ebiten.KeyI:     0,
 	}
 	count = 0
 )
 
+func createRandomIconImage() image.Image {
+	const size = 32
+
+	r := uint8(rand.Intn(0x100))
+	g := uint8(rand.Intn(0x100))
+	b := uint8(rand.Intn(0x100))
+	img := image.NewNRGBA(image.Rect(0, 0, size, size))
+	for j := 0; j < size; j++ {
+		for i := 0; i < size; i++ {
+			img.Pix[j*img.Stride+4*i] = r
+			img.Pix[j*img.Stride+4*i+1] = g
+			img.Pix[j*img.Stride+4*i+2] = b
+			img.Pix[j*img.Stride+4*i+3] = uint8(float64(i+j) / float64(2*size) * 0xff)
+		}
+	}
+
+	return img
+}
+
 func update(screen *ebiten.Image) error {
 	for key := range keyStates {
 		if !ebiten.IsKeyPressed(key) {
@@ -106,6 +133,10 @@ func update(screen *ebiten.Image) error {
 	ebiten.SetRunnableInBackground(runnableInBackground)
 	ebiten.SetCursorVisibility(cursorVisible)
 
+	if keyStates[ebiten.KeyI] == 1 {
+		ebiten.SetIcon([]image.Image{createRandomIconImage()})
+	}
+
 	count++
 
 	if ebiten.IsRunningSlowly() {
@@ -128,6 +159,7 @@ Press S key to change the window scale
 Press F key to switch the fullscreen state
 Press B key to switch the run-in-background state
 Press C key to switch the cursor visibility
+Press I key to change the window icon
 Cursor: (%d, %d)
 FPS: %0.2f`, x, y, ebiten.CurrentFPS())
 	ebitenutil.DebugPrint(screen, msg)
@@ -140,6 +172,9 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
+
+	ebiten.SetIcon([]image.Image{createRandomIconImage()})
+
 	if err := ebiten.Run(update, initScreenWidth, initScreenHeight, initScreenScale, "Window Size (Ebiten Demo)"); err != nil {
 		log.Fatal(err)
 	}

internal/ui/ui_glfw.go

@@ -21,6 +21,7 @@ package ui
 
 import (
 	"errors"
+	"image"
 	"runtime"
 	"sync"
 	"time"
@@ -45,6 +46,7 @@ type userInterface struct {
 	origPosY             int
 	initFullscreen       bool
 	initCursorVisible    bool
+	initIconImages       []image.Image
 	runnableInBackground bool
 	m                    sync.Mutex
 }
@@ -87,6 +89,9 @@ func initialize() error {
 	if !currentUI.isInitCursorVisible() {
 		mode = glfw.CursorHidden
 	}
+	if i := currentUI.getInitIconImages(); i != nil {
+		currentUI.window.SetIcon(i)
+	}
 	currentUI.window.SetInputMode(glfw.CursorMode, mode)
 	currentUI.window.SetInputMode(glfw.StickyMouseButtonsMode, glfw.True)
 	currentUI.window.SetInputMode(glfw.StickyKeysMode, glfw.True)
@@ -169,6 +174,19 @@ func (u *userInterface) setRunnableInBackground(runnableInBackground bool) {
 	u.m.Unlock()
 }
 
+func (u *userInterface) getInitIconImages() []image.Image {
+	u.m.Lock()
+	i := u.initIconImages
+	u.m.Unlock()
+	return i
+}
+
+func (u *userInterface) setInitIconImages(iconImages []image.Image) {
+	u.m.Lock()
+	u.initIconImages = iconImages
+	u.m.Unlock()
+}
+
 func (u *userInterface) runOnMainThread(f func() error) error {
 	if u.funcs == nil {
 		// already closed
@@ -259,6 +277,17 @@ func IsRunnableInBackground() bool {
 	return currentUI.isRunnableInBackground()
 }
 
+func SetIcon(iconImages []image.Image) {
+	if !currentUI.isRunning() {
+		currentUI.setInitIconImages(iconImages)
+		return
+	}
+	_ = currentUI.runOnMainThread(func() error {
+		currentUI.window.SetIcon(iconImages)
+		return nil
+	})
+}
+
 func ScreenOffset() (float64, float64) {
 	u := currentUI
 	if !u.isRunning() {

internal/ui/ui_js.go

@@ -17,6 +17,7 @@
 package ui
 
 import (
+	"image"
 	"strconv"
 	"unicode"
 
@@ -97,6 +98,10 @@ func SetCursorVisibility(visibility bool) {
 	}
 }
 
+func SetIcon(iconImages []image.Image) {
+	// Do nothing
+}
+
 func (u *userInterface) getScale() float64 {
 	if !u.fullscreen {
 		return u.scale

internal/ui/ui_mobile.go

@@ -18,6 +18,7 @@ package ui
 
 import (
 	"errors"
+	"image"
 	"runtime"
 	"time"
 
@@ -140,6 +141,10 @@ func IsRunnableInBackground() bool {
 	return false
 }
 
+func SetIcon(iconImages []image.Image) {
+	// Do nothing
+}
+
 func (u *userInterface) actualScreenScale() float64 {
 	return u.scale * deviceScale()
 }

run.go

@@ -15,6 +15,7 @@
 package ebiten
 
 import (
+	"image"
 	"sync/atomic"
 
 	"github.com/hajimehoshi/ebiten/internal/clock"
@@ -245,3 +246,26 @@ func IsRunnableInBackground() bool {
 func SetRunnableInBackground(runnableInBackground bool) {
 	ui.SetRunnableInBackground(runnableInBackground)
 }
+
+// SetIcon sets the icon of the game window.
+//
+// If len(iconImages) is 0, SetIcon reverts the icon to the default one.
+//
+// For desktops, see the document of glfwSetWindowIcon of GLFW 3.2:
+//
+//     This function sets the icon of the specified window.
+//     If passed an array of candidate images, those of or closest to the sizes
+//     desired by the system are selected.
+//     If no images are specified, the window reverts to its default icon.
+//
+//     The desired image sizes varies depending on platform and system settings.
+//     The selected images will be rescaled as needed. Good sizes include 16x16, 32x32 and 48x48.
+//
+// As macOS windows don't have icons, SetIcon doesn't work on macOS.
+//
+// SetIcon doesn't work on browsers or mobiles.
+//
+// This function is concurrent-safe.
+func SetIcon(iconImages []image.Image) {
+	ui.SetIcon(iconImages)
+}