我在我的 android 应用程序中,我需要一个垂直滑动的 viewpager(向上向下的方式)。为此,我制作了一个自定义 viewpager & 在其中我使用传统的 viewpager & 应用 PageTransfirmer 使其垂直而不是水平滑动。除一加 5t(安卓版本 9)外,其他设备一切正常
My code is below:
public class VerticalViewPager extends ViewPager {
private float initialXValue;
private float initialYValue;
private float minXDifference = 200;
private float minYDifference = 100;
public static SwapListener swapListener;
public static String SwipeLeft = "left";
public static String SwipeRight = "right";
public static boolean swipeTriggered = false;
public static boolean verticalSwipeTriggered = false;
private FixedSpeedScroller mScroller = null;
private boolean enabled;
public VerticalViewPager(Context context) {
super(context);
init();
}
public VerticalViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
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);
try {
Class<?> viewpager = ViewPager.class;
Field scroller = viewpager.getDeclaredField("mScroller");
scroller.setAccessible(true);
mScroller = new FixedSpeedScroller(getContext(),
new DecelerateInterpolator());
scroller.set(this, mScroller);
} catch (Exception ignored) {
}
}
/*
* Set the factor by which the duration will change
*/
public void setScrollDuration(int duration) {
mScroller.setScrollDuration(duration);
}
private class FixedSpeedScroller extends Scroller {
private int mDuration = 1000;
public FixedSpeedScroller(Context context) {super(context);}
public FixedSpeedScroller(Context context, Interpolator interpolator) {
super(context, interpolator);
}
public FixedSpeedScroller(Context context, Interpolator interpolator,
boolean flywheel) {super(context, interpolator, flywheel);}
@Override
public void startScroll(int startX, int startY, int dx, int dy, int
duration) {
// Ignore received duration, use fixed one instead
super.startScroll(startX, startY, dx, dy, mDuration);
}
@Override
public void startScroll(int startX, int startY, int dx, int dy) {
// Ignore received duration, use fixed one instead
super.startScroll(startX, startY, dx, dy, mDuration);
}
public void setScrollDuration(int duration) {mDuration = duration;}
}
private class VerticalPageTransformer implements
ViewPager.PageTransformer {
@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 <= 1) {
view.setAlpha(1);
// Counteract the default slide transition
view.setTranslationX(view.getWidth() * -position);
//set Y position to swipe in from top
float yPosition = position * view.getHeight();
view.setTranslationY(yPosition);
}
else {
// This page is way off-screen to the right.
view.setAlpha(0);
}
}
}
/**
* Swaps the X and Y coordinates of your touch event.
*/
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
//IsSwipeAllowed(ev);
return intercepted;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
IsSwipeAllowed(ev);
return super.onTouchEvent(swapXY(ev));
}
private void IsSwipeAllowed(MotionEvent event) {
if(event.getAction() == MotionEvent.ACTION_DOWN) {
initialXValue = event.getX();
initialYValue = event.getY();
}
if(event.getAction()==MotionEvent.ACTION_MOVE) {
try {
float diffX = Math.abs(event.getX() - initialXValue);
float diffy = Math.abs(event.getY() - initialYValue);
if (diffX > diffy && diffX > minXDifference) {
// swipe horizotal
if (!swipeTriggered && event.getX() > initialXValue) {
swapListener.listenSwapEvent(SwipeRight);
swipeTriggered = true;
}
else if (event.getX() < initialXValue) {
if (!HomeScreen.projectName.equals("ABMCPL") &&
CustomViewPager.IsSwipeAllowed(event) && !swipeTriggered) {
swapListener.listenSwapEvent(SwipeLeft); // to webview page
swipeTriggered = true;
}
}
}
else if (diffX < diffy && diffy > minYDifference) {
if (!verticalSwipeTriggered && event.getY() > initialYValue) {
viewPager.setCurrentItem(LandingPage.viewPager.getCurrentItem() - 1);
verticalSwipeTriggered = true;
}
else if (!verticalSwipeTriggered && event.getY() < initialYValue){
verticalSwipeTriggered = true;
}
}
} catch (Exception exception) {
exception.printStackTrace();
}
}
}
public interface SwapListener {
void listenSwapEvent (String direction);
}
}