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ViewPager that wraps current page's height
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| import android.content.Context; | |
| import android.support.annotation.Nullable; | |
| import android.support.v4.view.PagerAdapter; | |
| import android.support.v4.view.ViewPager; | |
| import android.util.AttributeSet; | |
| import android.view.View; | |
| import android.view.ViewGroup; | |
| /** | |
| * {@link ViewPager} that wraps current page's height | |
| * | |
| * @author Leo | |
| */ | |
| public class WrapContentViewPager extends ViewPager { | |
| private Adapter mAdapter; | |
| public WrapContentViewPager(Context context) { | |
| this(context, null); | |
| } | |
| public WrapContentViewPager(Context context, AttributeSet attrs) { | |
| super(context, attrs); | |
| } | |
| @Override | |
| public void setAdapter(PagerAdapter adapter) { | |
| if (!(adapter instanceof Adapter)) | |
| throw new IllegalArgumentException("Adapter of WrapContentViewPager has to implement WrapContentViewPager.Adapter"); | |
| mAdapter = (Adapter) adapter; | |
| super.setAdapter(adapter); | |
| } | |
| @Override | |
| protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { | |
| int height = 0; | |
| View child = mAdapter == null ? null : mAdapter.getCurrentPageView(getCurrentItem()); | |
| if (child != null) { | |
| child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)); | |
| int h = child.getMeasuredHeight(); | |
| if (h > height) height = h; | |
| } else if (getAdapter() != null && getAdapter().getCount() > 0) { | |
| post(this::requestLayout); // recur until we can get reference to the current page view | |
| } | |
| if (height != 0) { | |
| height += getPaddingTop() + getPaddingBottom(); // take padding into account | |
| heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); | |
| } | |
| super.onMeasure(widthMeasureSpec, heightMeasureSpec); | |
| } | |
| public interface Adapter { | |
| /** | |
| * <p>Get view for currently selected page of the ViewPager. | |
| * <p>Since this method is only called to get the View of current page, so implementation of this method should | |
| * NOT keep references to ALL pages of the ViewPager, but utilize | |
| * {@link PagerAdapter#destroyItem(ViewGroup, int, Object)} to remove unnecessary references instead. | |
| * <p>Or you can override {@link PagerAdapter#setPrimaryItem(ViewGroup, int, Object)} to grab reference to | |
| * current view. | |
| * | |
| * @param currentPosition current page of the ViewPager | |
| * @return {@link View} instance of the current page | |
| */ | |
| @Nullable | |
| View getCurrentPageView(int currentPosition); | |
| } | |
| } |
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