android viewpager实现竖屏滑动效果
时间：2020-12-11 20:32:20 | 栏目：Android代码 | 点击：次
Viewpager 横向滑动效果系统就自带了很多种，比如这个
效果
那如果做成竖屏的这种效果呢 。我百度过很多，效果都不是很好，有的代码特别多而且存在很多问题。我结合了以前别人的代码现在来教大家个简单的实现过程。
首先自定义Viewpager 是肯定必不可少的了
public class VerticalViewPager extends ViewPager {
private OnItemClickListener mOnItemClickListener;
public VerticalViewPager(Context context) {
super(context);
init();
}
public VerticalViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
init();
setup();
}
private void init() {
// The majority of the magic happens here
setPageTransformer(true, new VerticalPageTransformer());
// The easiest way to get rid of the overscroll drawing that happens on the left and right
setOverScrollMode(OVER_SCROLL_NEVER);
}
private MotionEvent swapXY(MotionEvent ev) {
float width = getWidth();
float height = getHeight();
float newX = (ev.getY() / height) * width;
float newY = (ev.getX() / width) * height;
ev.setLocation(newX, newY);
return ev;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev){
boolean intercepted = super.onInterceptTouchEvent(swapXY(ev));
swapXY(ev); // return touch coordinates to original reference frame for any child views
return intercepted;
}
private float scaleY ;
@Override
public boolean onTouchEvent(MotionEvent ev) {
System.out.println("----------getY" + ev.getY());
System.out.println("----------scaleY" + scaleY);
if (ev.getAction()==MotionEvent.ACTION_MOVE){
}
if (ev.getAction()==MotionEvent.ACTION_DOWN){
scaleY = ev.getY();
}
if (ev.getAction()==MotionEvent.ACTION_UP){
if (scaleY == ev.getY()){
System.out.println("------------------======");
scaleY= 0;
return false;
}
}
try {
return super.onTouchEvent(swapXY(ev));
}catch (Exception e){
}
return true;
}
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
mOnItemClickListener = onItemClickListener;
}
public interface OnItemClickListener {
void onItemClick(int position);
}
private void setup() {
final GestureDetector tapGestureDetector = new GestureDetector(getContext(), new TapGestureListener());
setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
tapGestureDetector.onTouchEvent(event);
return false;
}
});
}
private class TapGestureListener extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
if(mOnItemClickListener != null) {
mOnItemClickListener.onItemClick(getCurrentItem());
}
return true;
}
}
}
要实现动画效果的核心就在 setPageTransformer(true, new VerticalPageTransformer());，大家都知道这个是设置Viewpager 设置动画的方法 ，那么要实现这个如果用系统自带的切换动画效果的话 肯定是不符合Viewpager 竖屏滑动的效果的。所以自定义PageTransformer 就是必然的趋势了
private class VerticalPageTransformer implements ViewPager.PageTransformer {
private float MIN_SCALE = 0.5f;
@Override
public void transformPage(View view, float position) {
if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left.
view.setAlpha(0);
}else if (position <= 0) { // [-1,1]
view.setAlpha(1 + position);
view.setTranslationX(-view.getWidth() * position);
view.setPivotY( view.getMeasuredHeight());
view.setPivotX( view.getMeasuredWidth()/2);
view.setTranslationY( position * view.getHeight());
float scaleFactor = MIN_SCALE + (1 - MIN_SCALE)
* (1 - Math.abs(position));
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
}
else if (position <= 1) { // [-1,1]
view.setAlpha(1);
view.setTranslationX(-view.getWidth() * position);
view.setTranslationY( position * view.getHeight());
float scaleFactor = MIN_SCALE + (1 - MIN_SCALE)
* (1 - Math.abs(position));
} else { // (1,+Infinity]
view.setAlpha(0);
view.setTranslationY( position * view.getHeight());
}
}
}
重写transformPage 方法。然后得到如上gif 向左旋转90的效果，剩下的代码你们看看也就知道是item点击事件与滑动事件的监听。所以就不细讲了