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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
<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>
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
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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 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