我有 LiveWallpaper，事实上是秋天的雪。以什么方式添加背景？我想插入一张图片。
public class SnowService extends WallpaperService {
private final static int[] windCurve = {1,3,5,6,6,6,7,7,6,5,4,2,1,1};
public Engine onCreateEngine() {
return new SnowEngine();
}
public class SnowEngine extends WallpaperService.Engine {
private SnowThread thread;
private Random random = new Random();
private SurfaceHolder holder;
private Bitmap flakeImage;
private Set<Snowflake> flakes = new HashSet<Snowflake>();
private Set<Snowflake> oobFlakes = new HashSet<Snowflake>();
private int wind = 0;
public SnowEngine() {
flakeImage = BitmapFactory.decodeResource(getResources(), R.drawable.square3x3);
}
public class SnowThread extends Thread {
private boolean isSnowing = true;
private long lastWindUpdate = System.currentTimeMillis();
private int windCurveIndex = 0;
private void update(Canvas c) {
c.drawRGB(0, 0, 0);
flakes.add(new Snowflake(random.nextFloat() * c.getWidth(), -flakeImage.getWidth(), flakeImage));
long nowTime = System.currentTimeMillis();
if (wind == 0) {
if (nowTime - lastWindUpdate > 20000) {
wind = windCurve[++windCurveIndex];
lastWindUpdate = nowTime;
}
} else if (nowTime - lastWindUpdate > 1000) {
if (windCurveIndex < windCurve.length -1) {
wind = windCurve[++windCurveIndex];
lastWindUpdate = nowTime;
} else {
windCurveIndex = 0;
wind = 0;
lastWindUpdate = nowTime;
}
}
for (Snowflake flake : flakes) {
flake.update(wind);
c.drawBitmap(flake.bitmap, flake.x, flake.y, null);
if (flake.x > c.getWidth() || flake.x < -flake.bitmap.getWidth() ||
flake.y > c.getHeight()) {
oobFlakes.add(flake);
}
}
flakes.removeAll(oobFlakes);
oobFlakes.clear();
}
@Override
public void run() {
Log.d("snow", "SnowThread started");
while (isSnowing) {
Canvas canvas = null;
try {
Thread.sleep(30);
canvas = holder.lockCanvas();
update(canvas);
} catch (InterruptedException e) {
} finally {
if (canvas != null) {
holder.unlockCanvasAndPost(canvas);
}
}
}
}
public boolean isSnowing() {
return isSnowing;
}
public void stopSnowing() {
isSnowing = false;
}
}
@Override
public void onVisibilityChanged(boolean visible) {
super.onVisibilityChanged(visible);
Log.d("snow", "visibilityChanged to " + visible);
if (visible) {
thread = new SnowThread();
thread.start();
} else {
thread.stopSnowing();
}
}
@Override
public void onSurfaceCreated(SurfaceHolder holder) {
Log.d("snow", "surfaceCreated");
this.holder = holder;
}
@Override
public void onSurfaceDestroyed(SurfaceHolder holder) {
// usual case is onVisibilityChanged(false) has been called
// and the thread is shutting down
Log.d("snow", "surfaceDestroyed");
boolean retry = true;
while (retry) {
try {
thread.stopSnowing(); // just in case
thread.join();
Log.d("snow", "snowThread died");
retry = false;
} catch (InterruptedException e) {
}
}
}
class Snowflake {
public Bitmap bitmap;
float x;
float y;
int bias = 0;
int biasTime = 0;
boolean interBias = false;
Snowflake(float x, float y, Bitmap bitmap) {
this.x = x;
this.y = y;
this.bitmap = bitmap;
}
void update(int wind) {
if (biasTime < 0) {
if (interBias) {
bias = ((Integer) random.nextInt(3)).compareTo(1);
interBias = false;
} else {
bias = 0;
interBias = true;
}
biasTime = random.nextInt(30);
}
biasTime--;
x += bias + wind;
y += 4;
}
}
}
}