我有一个ScrollView,里面放了一个ViewPager,ViewPager中包含高度不固定的Fragment。由于ScrollView和ViewPager之间滚动处理不太匹配,我使用了这里提供的自定义解决方案。但是,我目前得到了非常异常的结果。ViewPager中的第一个Fragment始终具有0的高度。有时,Fragment可能没有显示其内容,但是当我来回滚动并返回到该Fragment时,内容可能会出现。
自定义 ScrollView:
据我的观察,我发现上面提到的链接中的代码与我正在使用的代码唯一的区别就是该链接中使用了support library v4的FragmentPagerAdapter,而我使用的是v13版(由于其他限制,无法更改为v4)。在我使用它们的方式方面,这两个版本的支持库主要有哪些不同之处?
以下是一些代码:
自定义ViewPager:
import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
/**
* Created by Narayan Acharya on 12/07/2016.
*/
public class DynamicHeightWrappingViewPager extends ViewPager {
private View mCurrentView;
public DynamicHeightWrappingViewPager(Context context) {
super(context);
}
public DynamicHeightWrappingViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (mCurrentView == null) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
return;
}
int height = 0;
mCurrentView.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int h = mCurrentView.getMeasuredHeight();
if (h > height) height = h;
heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
Log.d("ViewPager Measure", h + ":" + heightMeasureSpec);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void measureCurrentView(View currentView) {
mCurrentView = currentView;
requestLayout();
}
}
自定义 ScrollView:
import android.content.Context;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ScrollView;
/**
* Created by Narayan Acharya on 12/07/2016.
*/
public class ChildrenHeightAdaptingScrollView extends ScrollView {
private GestureDetector mGestureDetector;
public ChildrenHeightAdaptingScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
mGestureDetector = new GestureDetector(context, new YScrollDetector());
setFadingEdgeLength(0);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return super.onInterceptTouchEvent(ev)
&& mGestureDetector.onTouchEvent(ev);
}
// Return false if we're scrolling in the x direction
class YScrollDetector extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
return (Math.abs(distanceY) > Math.abs(distanceX));
}
}
}
The PagerAdapter :
import android.app.Fragment;
import android.app.FragmentManager;
import android.support.v13.app.FragmentPagerAdapter;
import android.util.Log;
import android.view.ViewGroup;
/.. Some more project specific imports here../
/**
* Created by Narayan Acharya on 22/06/2016.
*/
public class EventsPagerAdapter extends FragmentPagerAdapter {
private Event event;
private int PAGE_COUNT = 2;
private int mCurrentPosition = -1;
private String tabTitles[] = new String[]{"INFO", "FAQs"};
public EventsPagerAdapter(FragmentManager fm, Event event) {
super(fm);
this.event = event;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return EventInfoFragment.getInstance(event);
case 1:
return EventFAQsFragment.getInstance(event);
default:
return null;
}
}
@Override
public int getCount() {
return PAGE_COUNT;
}
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
super.setPrimaryItem(container, position, object);
if (position != mCurrentPosition) {
Fragment fragment = (Fragment) object;
DynamicHeightWrappingViewPager pager = (DynamicHeightWrappingViewPager) container;
if (fragment != null && fragment.getView() != null) {
mCurrentPosition = position;
pager.measureCurrentView(fragment.getView());
Log.d("Requested Measure for", position + " " + fragment.getClass().getSimpleName());
}
}
}
}
据我的观察,我发现上面提到的链接中的代码与我正在使用的代码唯一的区别就是该链接中使用了support library v4的FragmentPagerAdapter,而我使用的是v13版(由于其他限制,无法更改为v4)。在我使用它们的方式方面,这两个版本的支持库主要有哪些不同之处?