Stop the game when the window is not active (#69)

_docs/index.tmpl.html

@@ -41,6 +41,10 @@ pre {
   <li>Works on
     <ul>
       <li>Web browsers (powered by <a href="http://gopherjs.org/">GopherJS</a>)
+        <ul>
+          <li>Supported browsers: Chrome, Firefox, Safari on desktops</li>
+        </ul>
+      </li>
       <li>Mac OS X</li>
       <li>Linux (maybe)</li>
       <li>Windows (possibly)</li>
@@ -111,6 +115,7 @@ pre {
           <li>A lot of keyboard keys have been added. KeyMax and MouseButtonMax were removed.</li>
         </ul>
       </li>
+      <li>The game is stopped when the window is not active.</li>
     </ul>
   </li>
 </ul>

internal/ui/ui_glfw.go

@@ -21,6 +21,7 @@ import (
 	glfw "github.com/go-gl/glfw3"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 	"runtime"
+	"time"
 )
 
 var current *ui
@@ -136,11 +137,19 @@ func Start(width, height, scale int, title string) (actualScale int, err error)
 	return actualScale, nil
 }
 
-func (u *ui) doEvents() {
+func (u *ui) pollEvents() {
 	glfw.PollEvents()
 	u.input.update(u.window, u.scale)
 }
 
+func (u *ui) doEvents() {
+	u.pollEvents()
+	for current.window.GetAttribute(glfw.Focused) == 0 {
+		time.Sleep(time.Second / 60)
+		u.pollEvents()
+	}
+}
+
 func (u *ui) terminate() {
 	glfw.Terminate()
 }

internal/ui/ui_js.go

@@ -26,12 +26,24 @@ import (
 var canvas js.Object
 var context *opengl.Context
 
+var windowIsFocused = true
+
+func init() {
+	// TODO: Check IE
+	window := js.Global.Get("window")
+	window.Set("onfocus", func() {
+		windowIsFocused = true
+	})
+	window.Set("onblur", func() {
+		windowIsFocused = false
+	})
+}
+
 func Use(f func(*opengl.Context)) {
 	f(context)
 }
 
-func DoEvents() {
-	// TODO: requestAnimationFrame is not called when the window is not activated.
+func vsync() {
 	ch := make(chan struct{})
 	js.Global.Get("window").Call("requestAnimationFrame", func() {
 		close(ch)
@@ -39,6 +51,13 @@ func DoEvents() {
 	<-ch
 }
 
+func DoEvents() {
+	vsync()
+	for !windowIsFocused {
+		vsync()
+	}
+}
+
 func Terminate() {
 	// Do nothing.
 }

readme.md

@@ -5,6 +5,7 @@
 * A simple SNES-like 2D game library in Go
 * Works on
   * Web browsers (powered by [GopherJS](http://gopherjs.org/))
+    * Support browsers: Chrome, Firefox, Safari on desktops
   * Mac OS X
   * Linux (maybe)
   * Windows (possibly)

run.go

@@ -47,8 +47,7 @@ func Run(f func(*Image) error, width, height, scale int, title string) error {
 	}
 
 	frames := 0
-	t0 := time.Now().UnixNano()
-	tt0 := t0
+	t := time.Now().UnixNano()
 	for {
 		ui.DoEvents()
 		if ui.IsClosed() {
@@ -74,19 +73,13 @@ func Run(f func(*Image) error, width, height, scale int, title string) error {
 			return err
 		}
 
-		// Wait if the frame is too fast.
-		now := time.Now().UnixNano()
-		d := time.Duration(now - t0)
-		if d < time.Second/90 {
-			time.Sleep(time.Second/60 - d)
-		}
-		t0 = now
-
 		// Calc the current FPS.
+		now := time.Now().UnixNano()
 		frames++
-		if time.Second <= time.Duration(now-tt0) {
-			fps = frames
-			tt0 = now
+		if time.Second <= time.Duration(now-t) {
+			fps = int(int64(frames) * int64(time.Second) / (now - t))
+			// TODO: How to show the current FPS?
+			t = now
 			frames = 0
 		}
 	}