Android NestedScrollView/ScrollView包裹ViewPager自适应高度

╰+攻爆jí腚メ 2023-10-17 21:22 35阅读 0赞

**Android NestedScrollView/ScrollView包裹ViewPager自适应高度**

当Android的NestedScrollView/ScrollView这类滚动View包裹ViewPager时候，ViewPager中的Fragment包含的又是一系列高度值不固定的View如RecyclerView等等，就会造成ViewPager高度无法自适应子Fragment里面的View的高度，解决方法其中之一就是重新改造ViewPager，让其能自动适应子Fragment里面的View高度，改造后的AutofitHeightViewPager：

import android.content.Context;
    import android.support.v4.view.ViewPager;
    import android.util.AttributeSet;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.ViewGroup;
    
    import java.util.HashMap;
    import java.util.LinkedHashMap;
    
    public class AutofitHeightViewPager extends ViewPager {
        public static final String POSITION = "position";
    
        private int mCurPosition;
        private int mHeight = 0;
    
        private HashMap<Integer, View> mChildrenViews = new LinkedHashMap<Integer, View>();
    
        private boolean scrollble = true;
    
        public AutofitHeightViewPager(Context context) {
            super(context);
        }
    
        public AutofitHeightViewPager(Context context, AttributeSet attrs) {
            super(context, attrs);
        }
    
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            if (mChildrenViews.size() > mCurPosition) {
                View child = mChildrenViews.get(mCurPosition);
                if (child != null) {
                    child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                    mHeight = child.getMeasuredHeight();
                }
            }
    
            if (mHeight != 0) {
                heightMeasureSpec = MeasureSpec.makeMeasureSpec(mHeight, MeasureSpec.EXACTLY);
            }
    
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    
        public void updateHeight(int current) {
            this.mCurPosition = current;
            if (mChildrenViews.size() > current) {
                ViewGroup.LayoutParams layoutParams = getLayoutParams();
                if (layoutParams == null) {
                    layoutParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, mHeight);
                } else {
                    layoutParams.height = mHeight;
                }
    
                setLayoutParams(layoutParams);
            }
        }
    
        public void setViewPosition(View view, int position) {
            mChildrenViews.put(position, view);
        }
    
        @Override
        public boolean onTouchEvent(MotionEvent ev) {
            if (!scrollble) {
                return true;
            }
            return super.onTouchEvent(ev);
        }
    
        public boolean isScrollble() {
            return scrollble;
        }
    
        public void setScrollble(boolean scrollble) {
            this.scrollble = scrollble;
        }
    }

自适应高度的ViewPager思路是每一次切换时候，重新设置ViewPager的高度值。  
使用方法有四点必须实现：  
1，先把AutofitHeightViewPager像Android原生的ViewPager一样写进xml布局。  
2，在上层Java代码的mViewPager添加的切换事件addOnPageChangeListener里面每次updateHeight，例如:

mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                @Override
                public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    
                }
    
                @Override
                public void onPageSelected(int position) {
                    mViewPager.updateHeight(position);
                }
    
                @Override
                public void onPageScrollStateChanged(int state) {
    
                }
            });

3，构建mViewPager肯定要设置FragmentPagerAdapter，在把创建Fragment喂给FragmentPagerAdapter时候，给Fragment把当前Fragment位置position设置进去，例如：

Fragment xxxFragment = new XXXFragment();
            Bundle xxxBunle = new Bundle();
            xxxBunle.putInt(AutofitHeightViewPager.POSITION, 1); //1为当前位置，这里的位置索引即为要传递的值，不同的Fragment按照先后添加顺序添加和传递索引
            xxxFragment.setArguments(xxxBunle);
            mPagerAdapter.addFragment(xxxFragment)

4，然后转入到具体的XXXFragment里面，把当前XXXFragment创建的View高度传回给AutofitHeightViewPager,一般是在onCreateView：

int pos = getArguments().getInt(AutofitHeightViewPager.POSITION);
            (强制转换为ViewPager所在的Activity) getActivity()).mViewPager.setViewPosition(view, pos);