本文实例讲述了android开发通过Scroller实现过渡滑动效果。分享给大家供大家参考，具体如下：

主要介绍一下Scroller这个类，它可以实现过渡滑动的效果，使滑动看起来不是那么生硬，当然它用大量的重绘来实现，invalidate();通过源码看：

看构造方法

 /**
   * Create a Scroller with the default duration and interpolator.
   */
  public Scroller(Context context) {
    this(context, null);
  }
  /**
   * Create a Scroller with the specified interpolator. If the interpolator is
   * null, the default (viscous) interpolator will be used. "Flywheel" behavior will
   * be in effect for apps targeting Honeycomb or newer.
   */
  public Scroller(Context context, Interpolator interpolator) {
    this(context, interpolator,
        context.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.HONEYCOMB);
  }
  /**
   * Create a Scroller with the specified interpolator. If the interpolator is
   * null, the default (viscous) interpolator will be used. Specify whether or
   * not to support progressive "flywheel" behavior in flinging.
   */
  public Scroller(Context context, Interpolator interpolator, boolean flywheel) {
    mFinished = true;
    if (interpolator == null) {
      mInterpolator = new ViscousFluidInterpolator();
    } else {
      mInterpolator = interpolator;
    }
    mPpi = context.getResources().getDisplayMetrics().density * 160.0f;
    mDeceleration = computeDeceleration(ViewConfiguration.getScrollFriction());
    mFlywheel = flywheel;
    mPhysicalCoeff = computeDeceleration(0.84f); // look and feel tuning
  }

我们用默认的就行，传个context就行了，其他的什么差值器，先不管了

然后调用startScroll，传递我们歧视滑动位置和滑动的偏移量，还有可选的默认持续时间，默认为250毫秒
这个方法是用来赋值的，接下来会调用invalidate()进行重新绘制，然后就会onDraw()，这时候会调用
computeScroll()这个方法，我们重写这个方法，computeScrollOffset()是判断动画有没有结束的一个方法，没结束的时候，我们根据滑动的偏移位置进行移动也就是scrollto到scroller的当前位置，再次调用invalidate()，由此无数的重回进行拼接形成了平滑的滑动

/**
   * Call this when you want to know the new location. If it returns true,
   * the animation is not yet finished.
   */
  public boolean computeScrollOffset() {
    if (mFinished) {
      return false;
    }
    int timePassed = (int)(AnimationUtils.currentAnimationTimeMillis() - mStartTime);
    if (timePassed < mDuration) {
      switch (mMode) {
      case SCROLL_MODE:
        final float x = mInterpolator.getInterpolation(timePassed * mDurationReciprocal);
        mCurrX = mStartX + Math.round(x * mDeltaX);
        mCurrY = mStartY + Math.round(x * mDeltaY);
        break;
      case FLING_MODE:
        final float t = (float) timePassed / mDuration;
        final int index = (int) (NB_SAMPLES * t);
        float distanceCoef = 1.f;
        float velocityCoef = 0.f;
        if (index < NB_SAMPLES) {
          final float t_inf = (float) index / NB_SAMPLES;
          final float t_sup = (float) (index + 1) / NB_SAMPLES;
          final float d_inf = SPLINE_POSITION[index];
          final float d_sup = SPLINE_POSITION[index + 1];
          velocityCoef = (d_sup - d_inf) / (t_sup - t_inf);
          distanceCoef = d_inf + (t - t_inf) * velocityCoef;
        }
        mCurrVelocity = velocityCoef * mDistance / mDuration * 1000.0f;
        mCurrX = mStartX + Math.round(distanceCoef * (mFinalX - mStartX));
        // Pin to mMinX <= mCurrX <= mMaxX
        mCurrX = Math.min(mCurrX, mMaxX);
        mCurrX = Math.max(mCurrX, mMinX);
        mCurrY = mStartY + Math.round(distanceCoef * (mFinalY - mStartY));
        // Pin to mMinY <= mCurrY <= mMaxY
        mCurrY = Math.min(mCurrY, mMaxY);
        mCurrY = Math.max(mCurrY, mMinY);
        if (mCurrX == mFinalX && mCurrY == mFinalY) {
          mFinished = true;
        }
        break;
      }
    }
    else {
      mCurrX = mFinalX;
      mCurrY = mFinalY;
      mFinished = true;
    }
    return true;
  }