XML define of View Pager
// create custom view pager and declare into xml as below //
main activity XML
<com.AutoScrollViewPager android:id="@+id/pagerView" android:layout_width="match_parent" android:layout_height="@dimen/dimens150dp" app:layout_constraintStart_toStartOf="parent" app:layout_constraintStart_toEndOf="parent" app:layout_constraintTop_toTopOf="parent" >
main activity java code
viewPager= findViewById(R.id.pagerView);
viewPager.startAutoScroll();
viewPager.setInterval(3000);
viewPager.setCycle(true);
viewPager.setStopScrollWhenTouch(true);
PagerAdapter adapter = new ViewPagerAdapter(HomeActivity.this,imageId,imagesName);
viewPager.setAdapter(adapter);
Custom pager view class
import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.animation.Interpolator;
import androidx.viewpager.widget.PagerAdapter;
import androidx.viewpager.widget.ViewPager;
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
public class AutoScrollViewPager extends ViewPager {
public static final int DEFAULT_INTERVAL = 1500;
public static final int LEFT = 0;
public static final int RIGHT = 1;
/** do nothing when sliding at the last or first item **/ public static final int SLIDE_BORDER_MODE_NONE = 0;
/** cycle when sliding at the last or first item **/ public static final int SLIDE_BORDER_MODE_CYCLE = 1;
/** deliver event to parent when sliding at the last or first item **/ public static final int SLIDE_BORDER_MODE_TO_PARENT = 2;
/** auto scroll time in milliseconds, default is {@link #DEFAULT_INTERVAL} **/ private long interval = DEFAULT_INTERVAL;
/** auto scroll direction, default is {@link #RIGHT} **/ private int direction = RIGHT;
/** whether automatic cycle when auto scroll reaching the last or first item, default is true **/ private boolean isCycle = true;
/** whether stop auto scroll when touching, default is true **/ private boolean stopScrollWhenTouch = true;
/** how to process when sliding at the last or first item, default is {@link #SLIDE_BORDER_MODE_NONE} **/ private int slideBorderMode = SLIDE_BORDER_MODE_NONE;
/** whether animating when auto scroll at the last or first item **/ private boolean isBorderAnimation = true;
/** scroll factor for auto scroll animation, default is 1.0 **/ private double autoScrollFactor = 1.0;
/** scroll factor for swipe scroll animation, default is 1.0 **/ private double swipeScrollFactor = 1.0;
private Handler handler;
private boolean isAutoScroll = false;
private boolean isStopByTouch = false;
private float touchX = 0f, downX = 0f;
private CustomDurationScroller scroller = null;
public static final int SCROLL_WHAT = 0;
public AutoScrollViewPager(Context paramContext) {
super(paramContext);
init();
}
public AutoScrollViewPager(Context paramContext, AttributeSet paramAttributeSet) {
super(paramContext, paramAttributeSet);
init();
}
private void init() {
handler = new MyHandler(this);
setViewPagerScroller();
}
/** * start auto scroll, first scroll delay time is {@link #getInterval()} */ public void startAutoScroll() {
isAutoScroll = true;
sendScrollMessage((long)(interval + scroller.getDuration() / autoScrollFactor * swipeScrollFactor));
}
/** * start auto scroll * * @param delayTimeInMills first scroll delay time */ public void startAutoScroll(int delayTimeInMills) {
isAutoScroll = true;
sendScrollMessage(delayTimeInMills);
}
/** * stop auto scroll */ public void stopAutoScroll() {
isAutoScroll = false;
handler.removeMessages(SCROLL_WHAT);
}
/** * set the factor by which the duration of sliding animation will change while swiping */ public void setSwipeScrollDurationFactor(double scrollFactor) {
swipeScrollFactor = scrollFactor;
}
/** * set the factor by which the duration of sliding animation will change while auto scrolling */ public void setAutoScrollDurationFactor(double scrollFactor) {
autoScrollFactor = scrollFactor;
}
private void sendScrollMessage(long delayTimeInMills) {
/** remove messages before, keeps one message is running at most **/ handler.removeMessages(SCROLL_WHAT);
handler.sendEmptyMessageDelayed(SCROLL_WHAT, delayTimeInMills);
}
/** * set ViewPager scroller to change animation duration when sliding */ private void setViewPagerScroller() {
try {
Field scrollerField = ViewPager.class.getDeclaredField("mScroller");
scrollerField.setAccessible(true);
Field interpolatorField = ViewPager.class.getDeclaredField("sInterpolator");
interpolatorField.setAccessible(true);
scroller = new CustomDurationScroller(getContext(), (Interpolator)interpolatorField.get(null));
scrollerField.set(this, scroller);
} catch (Exception e) {
e.printStackTrace();
}
}
/** * scroll only once */ public void scrollOnce() {
PagerAdapter adapter = getAdapter();
int currentItem = getCurrentItem();
int totalCount;
if (adapter == null || (totalCount = adapter.getCount()) <= 1) {
return;
}
int nextItem = (direction == LEFT) ? --currentItem : ++currentItem;
if (nextItem < 0) {
if (isCycle) {
setCurrentItem(totalCount - 1, isBorderAnimation);
}
} else if (nextItem == totalCount) {
if (isCycle) {
setCurrentItem(0, isBorderAnimation);
}
} else {
setCurrentItem(nextItem, true);
}
}
/** * <ul>
* if stopScrollWhenTouch is true * <li>if event is down, stop auto scroll.</li>
* <li>if event is up, start auto scroll again.</li>
* </ul>
*/ @Override public boolean dispatchTouchEvent(MotionEvent ev) {
int action = ev.getActionMasked();
if (stopScrollWhenTouch) {
if ((action == MotionEvent.ACTION_DOWN) && isAutoScroll) {
isStopByTouch = true;
stopAutoScroll();
} else if (ev.getAction() == MotionEvent.ACTION_UP && isStopByTouch) {
startAutoScroll();
}
}
if (slideBorderMode == SLIDE_BORDER_MODE_TO_PARENT || slideBorderMode == SLIDE_BORDER_MODE_CYCLE) {
touchX = ev.getX();
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
downX = touchX;
}
int currentItem = getCurrentItem();
PagerAdapter adapter = getAdapter();
int pageCount = adapter == null ? 0 : adapter.getCount();
/** * current index is first one and slide to right or current index is last one and slide to left.<br/>
* if slide border mode is to parent, then requestDisallowInterceptTouchEvent false.<br/>
* else scroll to last one when current item is first one, scroll to first one when current item is last * one. */ if ((currentItem == 0 && downX <= touchX) || (currentItem == pageCount - 1 && downX >= touchX)) {
if (slideBorderMode == SLIDE_BORDER_MODE_TO_PARENT) {
getParent().requestDisallowInterceptTouchEvent(false);
} else {
if (pageCount > 1) {
setCurrentItem(pageCount - currentItem - 1, isBorderAnimation);
}
getParent().requestDisallowInterceptTouchEvent(true);
}
return super.dispatchTouchEvent(ev);
}
}
getParent().requestDisallowInterceptTouchEvent(true);
return super.dispatchTouchEvent(ev);
}
private static class MyHandler extends Handler {
private final WeakReference<AutoScrollViewPager> autoScrollViewPager;
public MyHandler(AutoScrollViewPager autoScrollViewPager) {
this.autoScrollViewPager = new WeakReference<AutoScrollViewPager>(autoScrollViewPager);
}
@Override public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case SCROLL_WHAT:
AutoScrollViewPager pager = this.autoScrollViewPager.get();
if (pager != null) {
pager.scroller.setScrollDurationFactor(pager.autoScrollFactor);
pager.scrollOnce();
pager.scroller.setScrollDurationFactor(pager.swipeScrollFactor);
pager.sendScrollMessage(pager.interval + pager.scroller.getDuration());
}
default:
break;
}
}
}
/** * get auto scroll time in milliseconds, default is {@link #DEFAULT_INTERVAL} * * @return the interval */ public long getInterval() {
return interval;
}
/** * set auto scroll time in milliseconds, default is {@link #DEFAULT_INTERVAL} * * @param interval the interval to set */ public void setInterval(long interval) {
this.interval = interval;
}
/** * get auto scroll direction * * @return {@link #LEFT} or {@link #RIGHT}, default is {@link #RIGHT} */ public int getDirection() {
return (direction == LEFT) ? LEFT : RIGHT;
}
/** * set auto scroll direction * * @param direction {@link #LEFT} or {@link #RIGHT}, default is {@link #RIGHT} */ public void setDirection(int direction) {
this.direction = direction;
}
/** * whether automatic cycle when auto scroll reaching the last or first item, default is true * * @return the isCycle */ public boolean isCycle() {
return isCycle;
}
/** * set whether automatic cycle when auto scroll reaching the last or first item, default is true * * @param isCycle the isCycle to set */ public void setCycle(boolean isCycle) {
this.isCycle = isCycle;
}
/** * whether stop auto scroll when touching, default is true * * @return the stopScrollWhenTouch */ public boolean isStopScrollWhenTouch() {
return stopScrollWhenTouch;
}
/** * set whether stop auto scroll when touching, default is true * * @param stopScrollWhenTouch */ public void setStopScrollWhenTouch(boolean stopScrollWhenTouch) {
this.stopScrollWhenTouch = stopScrollWhenTouch;
}
/** * get how to process when sliding at the last or first item * * @return the slideBorderMode {@link #SLIDE_BORDER_MODE_NONE}, {@link #SLIDE_BORDER_MODE_TO_PARENT}, * {@link #SLIDE_BORDER_MODE_CYCLE}, default is {@link #SLIDE_BORDER_MODE_NONE} */ public int getSlideBorderMode() {
return slideBorderMode;
}
/** * set how to process when sliding at the last or first item * * @param slideBorderMode {@link #SLIDE_BORDER_MODE_NONE}, {@link #SLIDE_BORDER_MODE_TO_PARENT}, * {@link #SLIDE_BORDER_MODE_CYCLE}, default is {@link #SLIDE_BORDER_MODE_NONE} */ public void setSlideBorderMode(int slideBorderMode) {
this.slideBorderMode = slideBorderMode;
}
/** * whether animating when auto scroll at the last or first item, default is true * * @return */ public boolean isBorderAnimation() {
return isBorderAnimation;
}
/** * set whether animating when auto scroll at the last or first item, default is true * * @param isBorderAnimation */ public void setBorderAnimation(boolean isBorderAnimation) {
this.isBorderAnimation = isBorderAnimation;
}
}
//------------------------------------------------------------------------------------//
class CustomDurationScroller below details
import android.content.Context;
import android.view.animation.Interpolator;
import android.widget.Scroller;
public class CustomDurationScroller extends Scroller {
private double scrollFactor = 1;
public CustomDurationScroller(Context context) {
super(context);
}
public CustomDurationScroller(Context context, Interpolator interpolator) {
super(context, interpolator);
}
public void setScrollDurationFactor(double scrollFactor) {
this.scrollFactor = scrollFactor;
}
@Override public void startScroll(int startX, int startY, int dx, int dy, int duration) {
super.startScroll(startX, startY, dx, dy, (int)(duration * scrollFactor));
}
}
//----------------------------------------------------------------------------//
