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ViewPager切换滑动速度修改

IP云
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08/27
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ViewPager的setCurrentItem 滑动速度是写死地

下面的方法可以修改，在此以做记录

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public class FixedSpeedScroller extends Scroller {
    private int mDuration = 1500;
 
    public FixedSpeedScroller(Context context) {
        super(context);
    }
 
    public FixedSpeedScroller(Context context, Interpolator interpolator) {
        super(context, interpolator);
    }
 
    @Override
    public void startScroll(int startX, int startY, int dx, int dy, int duration) {
        // Ignore received duration, use fixed one instead
        super.startScroll(startX, startY, dx, dy, mDuration);
    }
 
    @Override
    public void startScroll(int startX, int startY, int dx, int dy) {
        // Ignore received duration, use fixed one instead
        super.startScroll(startX, startY, dx, dy, mDuration);
    }
 
    public void setmDuration(int time) {
        mDuration = time;
    }
 
    public int getmDuration() {
        return mDuration;
    }
}

使用方法：

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try {
                Field field = ViewPager.class.getDeclaredField("mScroller");
                field.setAccessible(true);
                FixedSpeedScroller scroller = new FixedSpeedScroller(mViewPager.getContext(),
                        new AccelerateInterpolator());
                field.set(mViewPager, scroller);
                scroller.setmDuration(2000);
            } catch (Exception e) {
                LogUtils.e(TAG, "", e);
            }

注意点： 
PagerAdapter 的 destroyItem 每次会删除上一个页面，导致，如果做自动切换页面时会看不到动画 .

解决办法:
destoryItem中不做删除view，instantiateItem中对view是否有parent做为判断条件，这种情况适用于，少量的固定的子View，比如一个Banner，banner中做自动循环播放