这几天 朋友问我了个问题 有个特别的需求 页面如下
就是当viewpager里面的当前页面内容足够多的时候 要去能滑上去 并且指示器吸顶 但是当内容不多的时候 能滑到哪就停在哪 当时第一反应是用coordinatelayout 结果不行 内容少的时候 也直接滑到顶部了
activity的xml文件
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/main_content" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <com.example.wenlaisu.myapplication.MyScrollview android:id="@+id/scroll" android:layout_width="match_parent" android:layout_height="match_parent" android:fillViewport="true"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <ImageView android:layout_width="match_parent" android:layout_height="200dp" android:background="?attr/colorPrimary" android:scaleType="fitXY" android:id="@+id/iv" android:src="@drawable/tangyan" /> <LinearLayout android:id="@+id/layout" android:layout_width="match_parent" android:layout_height="wrap_content"> <android.support.design.widget.TabLayout android:id="@+id/tabs" android:layout_width="match_parent" android:layout_height="wrap_content" android:background="?attr/colorPrimary" /> </LinearLayout> <com.example.wenlaisu.myapplication.CustomViewPager android:id="@+id/viewpager" android:layout_width="match_parent" android:layout_height="wrap_content" /> </LinearLayout> </com.example.wenlaisu.myapplication.MyScrollview> <RelativeLayout android:id="@+id/rl_layout" android:layout_width="match_parent" android:layout_height="wrap_content" > </RelativeLayout> </RelativeLayout>
后来就直接用scrollView包裹来实现了 自定义scrollView实现滚动监听 用来实现指示器吸顶效果
public class MyScrollview extends ScrollView { private ScrollViewListener scrollViewListener = null; public MyScrollview(Context context) { super(context); } public MyScrollview(Context context, AttributeSet attrs) { super(context, attrs); } public MyScrollview(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } public void setScrollViewListener(ScrollViewListener scrollViewListener) { this.scrollViewListener = scrollViewListener; } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if (scrollViewListener != null) { scrollViewListener.onScrollChanged(this, l, t, oldl, oldt); } } public interface ScrollViewListener { void onScrollChanged(MyScrollview scrollView, int l, int t, int oldl, int oldt); } }
在activity里面设置监听
scroll.setScrollViewListener(new MyScrollview.ScrollViewListener() { @Override public void onScrollChanged(MyScrollview scrollView, int l, int t, int oldl, int oldt) { if (t >iv.getHeight() && mTabLayout.getParent() == layout) { layout.removeView(mTabLayout); rl_layout.addView(mTabLayout); } else if (t < iv.getHeight() && mTabLayout.getParent() == rl_layout) { rl_layout.removeView(mTabLayout); layout.addView(mTabLayout); } } });
然后就是实现viewpager的每个页面的内容高度适配了 从写viewpager
public class CustomViewPager extends ViewPager { private int current; private int height = 0; /** * 保存position与对于的View */ private HashMap<Integer, View> mChildrenViews = new LinkedHashMap<Integer, View>(); private boolean scrollble = true; public CustomViewPager(Context context) { super(context); } public CustomViewPager(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { if (mChildrenViews.size() > current) { View child = mChildrenViews.get(current); if (child != null) { child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)); height = child.getMeasuredHeight(); } } heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); super.onMeasure(widthMeasureSpec, heightMeasureSpec); } public void resetHeight(int current) { this.current = current; if (mChildrenViews.size() > current) { LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) getLayoutParams(); if (layoutParams == null) { layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, height); } else { layoutParams.height = height; } setLayoutParams(layoutParams); } } /** * 保存position与对于的View */ public void setObjectForPosition(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; } }用法是在每个fragment 的onCreatView里面添加一行代码就行
然后在viewpager所在的activity里面设置监听 就可以了
mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { mViewPager.resetHeight(position); } @Override public void onPageScrollStateChanged(int state) { } });
下面是整个activity的代码
package com.example.wenlaisu.myapplication; import android.os.Bundle; import android.support.design.widget.TabLayout; import android.support.v4.app.Fragment; import android.support.v4.view.ViewPager; import android.support.v7.app.AppCompatActivity; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.RelativeLayout; import java.util.ArrayList; import java.util.List; /** * Created by wenlaisu on 2018/4/12. */ public class ViewPagerSample extends AppCompatActivity { CustomViewPager mViewPager; List<Fragment> mFragments; String[] mTitles = new String[]{ "主页", "微博", "相册" }; private TabLayout mTabLayout; private MyScrollview scroll; private LinearLayout layout; private RelativeLayout rl_layout; private ImageView iv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_third); // 第一步,初始化ViewPager和TabLayout mViewPager = (CustomViewPager) findViewById(R.id.viewpager); mTabLayout = (TabLayout) findViewById(R.id.tabs); layout = (LinearLayout) findViewById(R.id.layout); rl_layout = (RelativeLayout) findViewById(R.id.rl_layout); scroll = (MyScrollview) findViewById(R.id.scroll); iv = (ImageView) findViewById(R.id.iv); setupViewPager(); } private void setupViewPager() { mFragments = new ArrayList<>(); ListFragment listFragment = new ListFragment(mViewPager, 0); ListFragment2 listFragment2 = new ListFragment2(mViewPager, 1); ListFragment3 listFragment3 = new ListFragment3(mViewPager, 2); mFragments.add(listFragment); mFragments.add(listFragment2); mFragments.add(listFragment3); // 第二步:为ViewPager设置适配器 BaseFragmentAdapter adapter = new BaseFragmentAdapter(getSupportFragmentManager(), mFragments, mTitles); mViewPager.setAdapter(adapter); // 第三步:将ViewPager与TableLayout 绑定在一起 mTabLayout.setupWithViewPager(mViewPager); mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { mViewPager.resetHeight(position); } @Override public void onPageScrollStateChanged(int state) { } }); scroll.setScrollViewListener(new MyScrollview.ScrollViewListener() { @Override public void onScrollChanged(MyScrollview scrollView, int l, int t, int oldl, int oldt) { if (t >iv.getHeight() && mTabLayout.getParent() == layout) { layout.removeView(mTabLayout); rl_layout.addView(mTabLayout); } else if (t < iv.getHeight() && mTabLayout.getParent() == rl_layout) { rl_layout.removeView(mTabLayout); layout.addView(mTabLayout); } } }); } }就可以了