doc: Update examples

docs/examples/audio.html

@@ -27,6 +27,9 @@
   <iframe src="audio.content.html" width="640" height="480"></iframe>
   <pre><code class="language-go">// &#43;build example
 
+// This is an example to implement an audio player.
+// See examples/wav for a simpler example to play a sound file.
+
 package main
 
 import (
@@ -71,7 +74,7 @@ type Input struct {
 }
 
 func (i *Input) update() {
-        for _, key := range []ebiten.Key{ebiten.KeyP, ebiten.KeyS, ebiten.KeyX, ebiten.KeyZ} {
+        for _, key := range []ebiten.Key{ebiten.KeyP, ebiten.KeyS, ebiten.KeyX, ebiten.KeyZ, ebiten.KeyB} {
                 if !ebiten.IsKeyPressed(key) {
                         i.keyStates[key] = 0
                 } else {
@@ -183,6 +186,10 @@ func (p *Player) update() error {
         p.updatePlayPause()
         p.updateSE()
         p.updateVolume()
+        if p.input.isKeyTriggered(ebiten.KeyB) {
+                b := ebiten.IsRunnableInBackground()
+                ebiten.SetRunnableInBackground(!b)
+        }
         if err := p.audioContext.Update(); err != nil {
                 return err
         }
@@ -275,6 +282,7 @@ func (p *Player) draw(screen *ebiten.Image) {
 Press S to toggle Play/Pause
 Press P to play SE
 Press Z or X to change volume of the music
+Press B to switch the run-in-background state
 %s`, ebiten.CurrentFPS(), currentTimeStr)
         ebitenutil.DebugPrint(screen, msg)
 }

docs/examples/piano.html

@@ -165,8 +165,6 @@ var (
 )
 
 func init() {
-        imageEmpty, _ := ebiten.NewImage(16, 16, ebiten.FilterNearest)
-        imageEmpty.Fill(color.White)
         imagePiano, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
         whiteKeys := []string{"A", "S", "D", "F", "G", "H", "J", "K", "L"}
         width := 24
@@ -174,12 +172,7 @@ func init() {
         for i, k := range whiteKeys {
                 x := i*width + 36
                 height := 112
-                op := &ebiten.DrawImageOptions{}
+                ebitenutil.DrawRect(imagePiano, float64(x), float64(y), float64(width-1), float64(height), color.White)
-                w, h := imageEmpty.Size()
-                op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
-                op.GeoM.Translate(float64(x), float64(y))
-                op.ColorM.Scale(1, 1, 1, 1)
-                imagePiano.DrawImage(imageEmpty, op)
                 common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.Black)
         }
 
@@ -190,12 +183,7 @@ func init() {
                 }
                 x := i*width + 24
                 height := 64
-                op := &ebiten.DrawImageOptions{}
+                ebitenutil.DrawRect(imagePiano, float64(x), float64(y), float64(width-1), float64(height), color.Black)
-                w, h := imageEmpty.Size()
-                op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
-                op.GeoM.Translate(float64(x), float64(y))
-                op.ColorM.Scale(0, 0, 0, 1)
-                imagePiano.DrawImage(imageEmpty, op)
                 common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.White)
         }
 }