要制作视差动画,可以使用 Android 的视差库,例如 ParallaxViewPager 或 ParallaxRecyclerView。以下是一个示例代码,演示如何使用 ParallaxViewPager 实现视差动画:
implementation 'com.ogaclejapan:smarttablayout:1.6.1@aar'
implementation 'com.ogaclejapan.smarttablayout:utils-v4:1.6.1@aar'
implementation 'com.ogaclejapan.smarttablayout:utils-v13:1.6.1@aar'
implementation 'com.nineoldandroids:library:2.4.0'
import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.View;
public class ParallaxViewPager extends ViewPager implements ViewPager.OnPageChangeListener {
private ParallaxPagerAdapter mAdapter;
public ParallaxViewPager(Context context) {
super(context);
init();
}
public ParallaxViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
addOnPageChangeListener(this);
}
public void setAdapter(ParallaxPagerAdapter adapter) {
super.setAdapter(adapter);
mAdapter = adapter;
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (mAdapter != null) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
ParallaxViewPagerItem parallaxItem = mAdapter.getParallaxItem(child);
if (parallaxItem != null) {
parallaxItem.animate(child, getPositionOffset(position, positionOffset));
}
}
}
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
}
private float getPositionOffset(int position, float positionOffset) {
if (positionOffset < 0 || positionOffset > 1) {
return 0;
}
return positionOffset;
}
}
import android.view.View;
public abstract class ParallaxViewPagerItem {
private final View mView;
public ParallaxViewPagerItem(View view) {
mView = view;
}
public abstract void animate(View view, float positionOffset);
public View getView() {
return mView;
}
}
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;
public class ParallaxPagerAdapter extends PagerAdapter {
private List mItems = new ArrayList<>();
public void addItem(ParallaxViewPagerItem item) {
mItems.add(item);
}
public ParallaxViewPagerItem getParallaxItem(View view) {
for (ParallaxViewPagerItem item : mItems) {
if (item.getView() == view) {
return item;
}
}
return null;
}
@Override
public int getCount() {
return mItems.size();
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
View view = mItems.get(position).getView();
container.addView(view);
return view;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
}
ParallaxViewPager viewPager = findViewById(R.id.viewPager);
ParallaxPagerAdapter adapter = new ParallaxPagerAdapter();
adapter.addItem(new ParallaxViewPagerItem(view1) {
@Override
public void animate(View view, float positionOffset) {
// 处理视差动画