是否可以在没有子级的简单寻呼机适配器上使用viewpager wrap_content

Question

我想知道是否可以在不使用getChildCount((和getChildAt(I(的情况下使用wrap_content的PagerAdapter？我已经检查了下面的答案，但由于我的适配器没有孩子，所以它不起作用。

https://stackoverflow.com/a/20784791/10020799

有人知道在这种情况下如何制作包装式适配器吗？我的PagerAdapter代码是：

public class SectionsPagerAdapter extends PagerAdapter {
private Integer pagerTotal = 10;
public SectionsPagerAdapter(Context c) {
super();
inflater = (LayoutInflater) c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public void setPagerTotal(Integer item) {
pagerTotal = item;
}
@Override
public int getCount() {
return pagerTotal;
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
LinearLayout layout = (LinearLayout) inflater.inflate(R.layout.home_top_page, null);
container.addView(layout);
topMain = (ImageView) layout.findViewById(R.id.top_main);
if(imageBitmapArray != null && imageBitmapArray.length > 0){
topMain.setImageBitmap(imageBitmapArray[position]);
}else{
if(intImageArray != null) {
topMain.setImageResource(R.drawable.top_main_01);
}
}
return layout;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((View) object);
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view.equals(object);
}
}

Answer 1

您可以根据此答案在页面滑动时将ViewPager调整为当前页面大小。

您可以使用以下代码：

public class WrapContentViewPager extends ViewPager {
private int mCurrentPagePosition = 0;
public WrapContentViewPager(Context context) {
super(context);
}
public WrapContentViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
try {
boolean wrapHeight = MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.AT_MOST;
if (wrapHeight) {
View child = getChildAt(mCurrentPagePosition);
if (child != null) {
child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int h = child.getMeasuredHeight();
heightMeasureSpec = MeasureSpec.makeMeasureSpec(h, MeasureSpec.EXACTLY);
}
}
} catch (Exception e) {
e.printStackTrace();
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void reMeasureCurrentPage(int position) {
mCurrentPagePosition = position;
requestLayout();
}
}

在xml:中使用

<your.package.name.WrapContentViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</your.package.name.WrapContentViewPager>

之后调用页面上的reMeasureCurrentpage功能。

final WrapContentViewPager wrapContentViewPager = (WrapContentViewPager) findViewById(R.id.view_pager);
wrapContentViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
wrapContentViewPager.reMeasureCurrentPage(wrapContentViewPager.getCurrentItem());
}
@Override
public void onPageScrollStateChanged(int state) {
}
});

注意一个列表可能有数百个项目，那么使用此wrap_contentViewPager是不好的。

Answer 2

即使使用不可扩展的适配器，也可以使用getChildCount((和getChildAt(i(函数。根据Khemraj的回答和这篇文章的回答，我用以下代码解决了这个问题：

类别：

public class WrapContentViewPager extends ViewPager {
public WrapContentViewPager(Context context) {
super(context);
}
public WrapContentViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int height = 0;
for(int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int h = child.getMeasuredHeight();
if(h > height) height = h;
}
if (height != 0) {
heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}

xml:

<your.package.name.WrapContentViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</your.package.name.WrapContentViewPager>

页面滑动：

final WrapContentViewPager wrapContentViewPager = (WrapContentViewPager) findViewById(R.id.view_pager);
wrapContentViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
}
});