Add examples/contextlost

examples/contextlost/main.go

@@ -0,0 +1,79 @@
+// Copyright 2018 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build example
+
+package main
+
+import (
+	"fmt"
+	_ "image/jpeg"
+	"log"
+	"math"
+
+	"github.com/gopherjs/gopherjs/js"
+
+	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/ebitenutil"
+	"github.com/hajimehoshi/ebiten/inpututil"
+)
+
+const (
+	screenWidth  = 320
+	screenHeight = 240
+)
+
+var (
+	count        = 0
+	gophersImage *ebiten.Image
+)
+
+func update(screen *ebiten.Image) error {
+	if inpututil.IsKeyJustPressed(ebiten.KeySpace) && js.Global != nil {
+		doc := js.Global.Get("document")
+		canvas := doc.Call("getElementsByTagName", "canvas").Index(0)
+		context := canvas.Call("getContext", "webgl")
+		context.Call("getExtension", "WEBGL_lose_context").Call("loseContext")
+		fmt.Println("Context Lost!")
+		return nil
+	}
+
+	count++
+	if ebiten.IsRunningSlowly() {
+		return nil
+	}
+	w, h := gophersImage.Size()
+	op := &ebiten.DrawImageOptions{}
+
+	// For the details, see examples/rotate.
+	op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
+	op.GeoM.Rotate(float64(count%360) * 2 * math.Pi / 360)
+	op.GeoM.Translate(screenWidth/2, screenHeight/2)
+	screen.DrawImage(gophersImage, op)
+
+	ebitenutil.DebugPrint(screen, "Press Space to force GL context lost!\n(Browser only)")
+
+	return nil
+}
+
+func main() {
+	var err error
+	gophersImage, _, err = ebitenutil.NewImageFromFile("_resources/images/gophers.jpg", ebiten.FilterDefault)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Rotate (Ebiten Demo)"); err != nil {
+		log.Fatal(err)
+	}
+}