Add examples/animation

Fixes #640

examples/animation/main.go

@@ -0,0 +1,82 @@
+// 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 jsgo
+
+package main
+
+import (
+	"bytes"
+	"image"
+	_ "image/png"
+	"log"
+
+	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/examples/resources/images"
+)
+
+const (
+	screenWidth  = 320
+	screenHeight = 240
+
+	frameOX     = 0
+	frameOY     = 32
+	frameWidth  = 32
+	frameHeight = 32
+	frameNum    = 8
+)
+
+var (
+	count       = 0
+	runnerImage *ebiten.Image
+)
+
+func update(screen *ebiten.Image) error {
+	count++
+
+	if ebiten.IsRunningSlowly() {
+		return nil
+	}
+
+	op := &ebiten.DrawImageOptions{}
+	op.GeoM.Translate(-float64(frameWidth)/2, -float64(frameHeight)/2)
+	op.GeoM.Translate(screenWidth/2, screenHeight/2)
+	i := (count / 5) % frameNum
+	sx, sy := frameOX+i*frameWidth, frameOY
+	r := image.Rect(sx, sy, sx+frameWidth, sy+frameHeight)
+	op.SourceRect = &r
+	screen.DrawImage(runnerImage, op)
+	return nil
+}
+
+func main() {
+	// Decode image from a byte slice instead of a file so that
+	// this example works in any working directory.
+	// If you want to use a file, there are some options:
+	// 1) Use os.Open and pass the file to the image decoder.
+	//    This is a very regular way, but doesn't work on browsers.
+	// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
+	//    This works even on browsers.
+	// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
+	//    This also works on browsers.
+	img, _, err := image.Decode(bytes.NewReader(images.Runner_png))
+	if err != nil {
+		log.Fatal(err)
+	}
+	runnerImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
+
+	if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Animation (Ebiten Demo)"); err != nil {
+		log.Fatal(err)
+	}
+}

examples/resources/generate.go

@@ -21,6 +21,7 @@
 //go:generate file2byteslice -package=images -input=./images/fiveyears.jpg -output=./images/fiveyears.go -var=FiveYears_jpg
 //go:generate file2byteslice -package=images -input=./images/gophers.jpg -output=./images/gophers.go -var=Gophers_jpg
 //go:generate file2byteslice -package=images -input=./images/tile.png -output=./images/tile.go -var=Tile_png
+//go:generate file2byteslice -package=images -input=./images/runner.png -output=./images/runner.go -var=Runner_png
 //go:generate file2byteslice -package=images -input=./images/tiles.png -output=./images/tiles.go -var=Tiles_png
 //go:generate file2byteslice -package=images -input=./images/ui.png -output=./images/ui.go -var=UI_png
 //go:generate file2byteslice -package=blocks -input=./images/blocks/background.png -output=./images/blocks/background.go -var=Background_png

examples/resources/images/license.md

@@ -23,6 +23,14 @@ Photograph by Chris Nokleberg
 the Creative Commons Attribution 3.0 License
 ```
 
+## runner.png
+
+```
+https://opengameart.org/content/runner-character
+
+CC0 1.0
+```
+
 ## tile.png
 
 ```