Android實(shí)現(xiàn)跳動的小球加載動畫效果

更新時(shí)間：2016年08月28日 14:31:22 投稿：daisy

Android中有各式各樣的加載動畫，大家多多少少都見過，比如用過美團(tuán)客戶端的用戶對美團(tuán)那個(gè)加載小人的動畫印象很深刻，一個(gè)可愛的小人在那拼命的跑。這樣的動畫實(shí)現(xiàn)其實(shí)還有很多，今天這里就來實(shí)現(xiàn)一個(gè)跳動的小球效果。有需要的可以參考借鑒。

先來看看效果圖

跳動的小球做這個(gè)動畫,需掌握:

1、屬性動畫

2、Path類、Canvas類

3、貝塞爾曲線

4、SurfaceView用法

5、自定義attr屬性

6 、架構(gòu): 狀態(tài)模式,控制器

7 、自由落體,拋物線等概念

不多說了,直接上碼

1.DancingView.java

public class DancingView extends SurfaceView implements SurfaceHolder.Callback {

  public static final int STATE_DOWN = 1;//向下狀態(tài)
  public static final int STATE_UP = 2;//向上狀態(tài)

  public static final int DEFAULT_POINT_RADIUS = 10;
  public static final int DEFAULT_BALL_RADIUS = 13;
  public static final int DEFAULT_LINE_WIDTH = 200;
  public static final int DEFAULT_LINE_HEIGHT = 2;
  public static final int DEFAULT_LINE_COLOR = Color.parseColor("#FF9800");
  public static final int DEFAULT_POINT_COLOR = Color.parseColor("#9C27B0");
  public static final int DEFAULT_BALL_COLOR = Color.parseColor("#FF4081");

  public static final int DEFAULT_DOWN_DURATION = 600;//ms
  public static final int DEFAULT_UP_DURATION = 600;//ms
  public static final int DEFAULT_FREEDOWN_DURATION = 1000;//ms

  public static final int MAX_OFFSET_Y = 50;//水平下降最大偏移距離


  public int PONIT_RADIUS = DEFAULT_POINT_RADIUS;//小球半徑
  public int BALL_RADIUS = DEFAULT_BALL_RADIUS;//小球半徑

  private Paint mPaint;
  private Path mPath;
  private int mLineColor;
  private int mPonitColor;
  private int mBallColor;
  private int mLineWidth;
  private int mLineHeight;

  private float mDownDistance;
  private float mUpDistance;
  private float freeBallDistance;

  private ValueAnimator mDownController;//下落控制器
  private ValueAnimator mUpController;//上彈控制器
  private ValueAnimator mFreeDownController;//自由落體控制器

  private AnimatorSet animatorSet;
  private int state;

  private boolean ismUpControllerDied = false;
  private boolean isAnimationShowing = false;
  private boolean isBounced = false;
  private boolean isBallFreeUp = false;

  public DancingView(Context context) {
    super(context);
    init(context, null);
  }

  public DancingView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context, attrs);
  }


  public DancingView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context, attrs);
  }


  private void init(Context context, AttributeSet attrs) {
    initAttributes(context, attrs);

    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setStrokeWidth(mLineHeight);
    mPaint.setStrokeCap(Paint.Cap.ROUND);

    mPath = new Path();
    getHolder().addCallback(this);

    initController();
  }

  private void initAttributes(Context context, AttributeSet attrs) {
    TypedArray typeArray = context.obtainStyledAttributes(attrs, R.styleable.DancingView);
    mLineColor = typeArray.getColor(R.styleable.DancingView_lineColor, DEFAULT_LINE_COLOR);
    mLineWidth = typeArray.getDimensionPixelOffset(R.styleable.DancingView_lineWidth, DEFAULT_LINE_WIDTH);
    mLineHeight = typeArray.getDimensionPixelOffset(R.styleable.DancingView_lineHeight, DEFAULT_LINE_HEIGHT);
    mPonitColor = typeArray.getColor(R.styleable.DancingView_pointColor, DEFAULT_POINT_COLOR);
    mBallColor = typeArray.getColor(R.styleable.DancingView_ballColor, DEFAULT_BALL_COLOR);
    typeArray.recycle();
  }


  private void initController() {
    mDownController = ValueAnimator.ofFloat(0, 1);
    mDownController.setDuration(DEFAULT_DOWN_DURATION);
    mDownController.setInterpolator(new DecelerateInterpolator());
    mDownController.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        mDownDistance = MAX_OFFSET_Y * (float) animation.getAnimatedValue();
        postInvalidate();
      }
    });
    mDownController.addListener(new Animator.AnimatorListener() {
      @Override
      public void onAnimationStart(Animator animation) {
        state = STATE_DOWN;
      }

      @Override
      public void onAnimationEnd(Animator animation) {
      }

      @Override
      public void onAnimationCancel(Animator animation) {
      }

      @Override
      public void onAnimationRepeat(Animator animation) {
      }
    });

    mUpController = ValueAnimator.ofFloat(0, 1);
    mUpController.setDuration(DEFAULT_UP_DURATION);
    mUpController.setInterpolator(new DancingInterpolator());
    mUpController.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        mUpDistance = MAX_OFFSET_Y * (float) animation.getAnimatedValue();
        if (mUpDistance >= MAX_OFFSET_Y) {
          //進(jìn)入自由落體狀態(tài)
          isBounced = true;
          if (!mFreeDownController.isRunning() && !mFreeDownController.isStarted() && !isBallFreeUp) {
            mFreeDownController.start();
          }
        }
        postInvalidate();
      }
    });
    mUpController.addListener(new Animator.AnimatorListener() {
      @Override
      public void onAnimationStart(Animator animation) {
        state = STATE_UP;
      }

      @Override
      public void onAnimationEnd(Animator animation) {
        ismUpControllerDied = true;
      }

      @Override
      public void onAnimationCancel(Animator animation) {
      }

      @Override
      public void onAnimationRepeat(Animator animation) {

      }
    });

    mFreeDownController = ValueAnimator.ofFloat(0, 8f);
    mFreeDownController.setDuration(DEFAULT_FREEDOWN_DURATION);
    mFreeDownController.setInterpolator(new DecelerateInterpolator());
    mFreeDownController.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        //該公式解決上升減速 和 下降加速
        float t = (float) animation.getAnimatedValue();
        freeBallDistance = 40 * t - 5 * t * t;

        if (ismUpControllerDied) {//往上拋,到臨界點(diǎn)
          postInvalidate();
        }
      }
    });
    mFreeDownController.addListener(new Animator.AnimatorListener() {
      @Override
      public void onAnimationStart(Animator animation) {
        isBallFreeUp = true;
      }

      @Override
      public void onAnimationEnd(Animator animation) {
        isAnimationShowing = false;
        //循環(huán)第二次
        startAnimations();
      }

      @Override
      public void onAnimationCancel(Animator animation) {
      }

      @Override
      public void onAnimationRepeat(Animator animation) {
      }
    });

    animatorSet = new AnimatorSet();
    animatorSet.play(mDownController).before(mUpController);
    animatorSet.addListener(new Animator.AnimatorListener() {
      @Override
      public void onAnimationStart(Animator animation) {
        isAnimationShowing = true;
      }

      @Override
      public void onAnimationEnd(Animator animation) {
      }

      @Override
      public void onAnimationCancel(Animator animation) {
      }

      @Override
      public void onAnimationRepeat(Animator animation) {
      }
    });
  }

  /**
   * 啟動動畫,外部調(diào)用
   */
  public void startAnimations() {
    if (isAnimationShowing) {
      return;
    }
    if (animatorSet.isRunning()) {
      animatorSet.end();
      animatorSet.cancel();
    }
    isBounced = false;
    isBallFreeUp = false;
    ismUpControllerDied = false;

    animatorSet.start();
  }


  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);


    // 一條繩子用左右兩部分的二階貝塞爾曲線組成
    mPaint.setColor(mLineColor);
    mPath.reset();
    //起始點(diǎn)
    mPath.moveTo(getWidth() / 2 - mLineWidth / 2, getHeight() / 2);

    if (state == STATE_DOWN) {//下落
      /**************繪制繩子開始*************/
      //左部分 的貝塞爾
      mPath.quadTo((float) (getWidth() / 2 - mLineWidth / 2 + mLineWidth * 0.375), getHeight() / 2 + mDownDistance,
          getWidth() / 2, getHeight() / 2 + mDownDistance);
      //右部分 的貝塞爾
      mPath.quadTo((float) (getWidth() / 2 + mLineWidth / 2 - mLineWidth * 0.375), getHeight() / 2 + mDownDistance,
          getWidth() / 2 + mLineWidth / 2, getHeight() / 2);

      mPaint.setStyle(Paint.Style.STROKE);
      canvas.drawPath(mPath, mPaint);
      /**************繪制繩子結(jié)束*************/


      /**************繪制彈跳小球開始*************/
      mPaint.setStyle(Paint.Style.FILL);
      mPaint.setColor(mBallColor);
      canvas.drawCircle(getWidth() / 2, getHeight() / 2 + mDownDistance - BALL_RADIUS, BALL_RADIUS, mPaint);
      /**************繪制彈跳小球結(jié)束*************/
    } else if (state == STATE_UP) { //向上彈
      /**************繪制繩子開始*************/
      //左部分的貝塞爾
      mPath.quadTo((float) (getWidth() / 2 - mLineWidth / 2 + mLineWidth * 0.375), getHeight() / 2 + 50 - mUpDistance,
          getWidth() / 2,
          getHeight() / 2 + (50 - mUpDistance));

      //右部分的貝塞爾
      mPath.quadTo((float) (getWidth() / 2 + mLineWidth / 2 - mLineWidth * 0.375), getHeight() / 2 + 50 - mUpDistance,
          getWidth() / 2 + mLineWidth / 2,
          getHeight() / 2);

      mPaint.setStyle(Paint.Style.STROKE);
      canvas.drawPath(mPath, mPaint);
      /**************繪制繩子結(jié)束*************/

      mPaint.setStyle(Paint.Style.FILL);
      mPaint.setColor(mBallColor);

      //彈性小球,自由落體
      if (!isBounced) {
        //上升
        canvas.drawCircle(getWidth() / 2, getHeight() / 2 + (MAX_OFFSET_Y - mUpDistance) - BALL_RADIUS, BALL_RADIUS, mPaint);
      } else {
        //自由落體
        canvas.drawCircle(getWidth() / 2, getHeight() / 2 - freeBallDistance - BALL_RADIUS, BALL_RADIUS, mPaint);
      }
    }
    mPaint.setColor(mPonitColor);
    mPaint.setStyle(Paint.Style.FILL);
    canvas.drawCircle(getWidth() / 2 - mLineWidth / 2, getHeight() / 2, PONIT_RADIUS, mPaint);
    canvas.drawCircle(getWidth() / 2 + mLineWidth / 2, getHeight() / 2, PONIT_RADIUS, mPaint);
  }

  @Override
  public void surfaceCreated(SurfaceHolder holder) {
    Canvas canvas = holder.lockCanvas();//鎖定整個(gè)SurfaceView對象,獲取該Surface上的Canvas.
    draw(canvas);
    holder.unlockCanvasAndPost(canvas);//釋放畫布，提交修改
  }

  @Override
  public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
  }

  @Override
  public void surfaceDestroyed(SurfaceHolder holder) {
  }
}

2.DancingInterpolator.java

 public class DancingInterpolator implements Interpolator {
  @Override
  public float getInterpolation(float input) {
    return (float) (1 - Math.exp(-3 * input) * Math.cos(10 * input));
  }
}

3.自定義屬性 styles.xml

<declare-styleable name="DancingView">
    <attr name="lineWidth" format="dimension" />
    <attr name="lineHeight" format="dimension" />
    <attr name="pointColor" format="reference|color" />
    <attr name="lineColor" format="reference|color" />
    <attr name="ballColor" format="reference|color" />
</declare-styleable>

注意：顏色、尺寸、參數(shù)可以自己測試，調(diào)整。

以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)和工作能有所幫助哦。

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