Android漂浮背景效果的制作方法

public class FloatText extends FloatObject {
 String text;

 public FloatText(float posX, float posY, String text) {
 super(posX, posY);
 this.text = text;
 setAlpha(88);
 setColor(Color.WHITE);
 }

 @Override
 public void drawFloatObject(Canvas canvas, float x, float y, Paint paint) {
 paint.setTextSize(65);
 canvas.drawText(text, x, y, paint);
 }
}

public void drawFloatItem(Canvas canvas) {

 switch (status) {
  case START:
  // fade in
  if (isFade() && alpha <= ALPHA_LIMIT) {
   paint.setAlpha(alpha);
   alpha += ALPHA_PER_FRAME;
  } else {
   setStatus(MOVE);
  }
  break;
  case MOVE:
  // 更新赛贝尔曲线点
  if (mCurDistance == 0) {
   start = new PointF(x, y);
   end = getRandomPoint((int)start.x, (int)start.y, (int) distance);// 取值范围distance
   c1 = getRandomPoint((int)start.x, (int)start.y, random.nextInt(width / 2)); // 取值范围width/2
   c2 = getRandomPoint(end.x, end.y, random.nextInt(width / 2));// 取值范围width/2
  }

  // 计算塞贝儿曲线的当前点
  PointF bezierPoint = CalculateBezierPoint(mCurDistance / distance, start, c1, c2, end);
  x = bezierPoint.x;
  y = bezierPoint.y;

  // 更新当前路径
  mCurDistance += MOVE_PER_FRAME;

  // 一段画完后重置
  if (mCurDistance >= distance) {
   mCurDistance = 0;
  }
  break;
  case END:
  // fade out
  if (isFade() && alpha > 0) {
   paint.setAlpha(alpha);
   alpha -= ALPHA_PER_FRAME;
  } else {
   setStatus(FINISH);
  }
  break;
 }

 if (status != FINISH) {
  Log.e("drawFloatObject", x+", "+y);
  drawFloatObject(canvas, x ,y, paint);
 }
 }

 private void initFloatObject(int width, int height) {
 for (FloatObject floatObject : floats) {
  int x = (int) (floatObject.posX * width);
  int y = (int) (floatObject.posY * height);
  floatObject.init(x, y, width, height);
 }
 }

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 for (FloatObject floatObject : floats) {
  floatObject.drawFloatItem(canvas);
 }
 // 隔一段时间重绘一次, 动画效果
 getHandler().postDelayed(runnable, DELAY);

 }

 // 重绘线程
 private Runnable runnable = new Runnable() {
 @Override
 public void run() {
  invalidate();
  // 控制帧数
 }
 };

 public void startFloat() {
 for (FloatObject floatObject : floats) {
  floatObject.setStatus(FloatObject.START);
 }
 }

 public void endFloat() {
 for (FloatObject floatObject : floats) {
  floatObject.setStatus(FloatObject.END);
 }
 }

final FloatBackground floatBackground = (FloatBackground) this.findViewById(R.id.float_view);

 Button start = (Button) this.findViewById(R.id.start);
 start.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  floatBackground.startFloat();
  }
 });

 Button end = (Button) this.findViewById(R.id.end);
 end.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  floatBackground.endFloat();
  }
 });

 floatBackground.addFloatView(new FloatRect(0.2f, 0.3f, 30, 40));
 floatBackground.addFloatView(new FloatBitmap( this, 0.2f, 0.3f, R.drawable.gr_ptn_03));
 floatBackground.addFloatView(new FloatCircle( 0.8f, 0.8f));
 floatBackground.addFloatView(new FloatText( 0.3f, 0.6f, "E"));
 floatBackground.addFloatView(new FloatRing( 0.6f, 0.2f, 15 ,20));