A very commonly used function, a ViewPager will automatically scroll, and there are a row of small dots black and white to indicate the current scrolling progress.
First write a ViewPager adapter. Here, for the convenience of all the elements inside this adapter are ImageView
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/**
* Created by Administrator on 2016/2/24.
*/
public class HomeHomeBannerAdapter extends PagerAdapter{
private Context context;
private ImageView[] eventImageViews;
private String[] eventUrls;
int destWidth,destHeight;
public HomeHomeBannerAdapter(Context context, String[] eventUrls,int destWidth,int destHeight) {
= context;
= eventUrls;
= destHeight;
= destWidth;
initImageViews();
}
/**
* Initialize several pictures in the viewPager
*/
private void initImageViews(){
if(eventUrls==null)return;
eventImageViews = new ImageView[];
for (int i=0;i<;i++) {
eventImageViews[i] = new ImageView(context);
eventImageViews[i].setLayoutParams(new (destWidth, destHeight));
eventImageViews[i].setPadding(0, 0, 0, 0);
eventImageViews[i].setScaleType(.FIT_XY);
(context,eventImageViews[i],eventUrls[i]);
}//Show pictures }
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (eventImageViews != null && > position && position >= 0)
(eventImageViews[position]);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
(eventImageViews[position], 0);
return eventImageViews[position];
}
@Override
public int getCount() {return eventUrls==null?0:;}
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == arg1;
}
//ViewPager listener is integrated into internal class static public class EventViewPagerChangeListener implements {
LinearLayout llGuideGroup;
int oldEventPosition;
int currentItem;
public EventViewPagerChangeListener(LinearLayout llGuideGroup){
= llGuideGroup;
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
/**
* Control the display of white or black for small dots
* @param position
*/
public void onPageSelected(int position) {
(oldEventPosition).setBackgroundResource(.dot_normal);//Black dot (position).setBackgroundResource(.dot_focused);//White dots oldEventPosition = position;
currentItem = position;
}
@Override
public void onPageScrollStateChanged(int state) {
}
}
/**
* Timed tasks that control the automatic sliding of viewpager
*/
public static class ScrollTask implements Runnable {
EventViewPagerChangeListener listener;
ViewPager vpEvent;
int eventSize;
Handler handler;
public ScrollTask(EventViewPagerChangeListener listener,final ViewPager vpEvent, int eventSize){
= listener;
= vpEvent;
= eventSize;
handler = new Handler();
}
public void run() {
if(listener==null||vpEvent==null||eventSize==0)return;
= ( + 1) % eventSize;
("Alex","currentItem is"+);
(new Runnable() {
@Override
public void run() {
(); // Switch pictures through Handler }
});
}
}
public static class FixedSpeedScroller extends Scroller {
private static final int mDuration = 400;
private int eventCount;
public FixedSpeedScroller(Context context, Interpolator interpolator,int eventCount) {
super(context, interpolator);
= eventCount;
}
@Override
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
if (duration % 100 == 0 && duration > 0) {
//"It's automatic stroke now" if (duration / 100 == eventCount) (startX, startY, dx, dy, 1);//If it's the last one else (startX, startY, dx, dy, mDuration);
} else {
// "Now it's manual stroke" (startX, startY, dx, dy, 80);
}
}
}
}
There is a listener in the inner class of the above adapter. This listener has a member LinearLayout llGuideGroup. This linear layout contains several small dots. The following is the definition of this layout:
<RelativeLayout
android:
android:layout_width="match_parent"
android:layout_height="200dp"
android:visibility="gone">
<.
android:
android:layout_width="match_parent"
android:layout_height="200dp"
android:background="@color/black666666" />
<LinearLayout
android:
android:layout_width="match_parent"
android:layout_height="10dp"
android:layout_alignParentBottom="true"
android:layout_marginBottom="10dp"
android:layout_centerHorizontal="true"
android:gravity="center"
android:orientation="horizontal" >
</LinearLayout>
</RelativeLayout>
Set the number of small dots and initialize the listener
/**
* Add small dots to a linear layout, and the specific control logic is in the listener
* @param llGuideGroup
* @param count How many small dots to add
*/
public EventViewPagerChangeListener addViewPagerDots(LinearLayout llGuideGroup,ViewPager vpEvents,int count){
if(llGuideGroup==null||vpEvents==null||count<1)return null;
lp = new (15, 15);
= 5;
= 5;
for(int i=0;i<count;i++){
ImageView imageView = new ImageView(());
(lp);
(i==0?.dot_focused:.dot_normal);
(imageView);
}
//The monitor that controls the display of small dots EventViewPagerChangeListener listener = new EventViewPagerChangeListener(llGuideGroup);
(listener);
return listener;
}
Timed page switching through multithreading
listener = (,,);//Add small dots for indication // When the Activity is displayed, switch the image display every 3 seconds ScheduledExecutorService scheduledExecutorService = ();
(new (listener,,), 3, 3, );
Setting a custom scroller to reduce the switching speed of viewPager
/**
* Set a custom scroller for ViewPager to reduce the default scrolling speed
* @param vpEvent
*/
public void setViewPagerScroller(ViewPager vpEvent){
if(vpEvent==null)return;
Field mField;
Scroller mScroller;
try {
mField = ("mScroller");
(true);
mScroller = new ((), new AccelerateInterpolator(),());
try {
(vpEvent, mScroller);
} catch (IllegalAccessException e) {
();
}
} catch (NoSuchFieldException e) {
();
}
}
The above is all the content of this article. I hope it will be helpful to everyone's study and I hope everyone will support me more.