Today my client wants me to automatically open the next view(next activity) when the user comes to the last page and swipe left. I have searched and found good solutions on SO but they seems to be complex than I thought. So I looked and played with some methods in ViewPager and created an easy solution.
I used OnPageChangeListener in ViewPager class. Here we have 3 methods.
- void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
- void onPageSelected(int position);
- void onPageScrollStateChanged(int state);
It is important to know what are the states in onPageScrollStateChanged() and their sequence of execution.There are 3 states as SCROLL_STATE_IDLE, SCROLL_STATE_DRAGGING and SCROLL_STATE_SETTLING.
This is extracted from android documentation.
/** * Called when the scroll state changes. Useful for discovering when the user
* begins dragging, when the pager is automatically settling to the current page,
* or when it is fully stopped/idle.
* * @param state The new scroll state.
* @see ViewPager#SCROLL_STATE_IDLE
* @see ViewPager#SCROLL_STATE_DRAGGING
* @see ViewPager#SCROLL_STATE_SETTLING */
void onPageScrollStateChanged(int state);
Here is the execution order.
Scroll_state_dragging --> Scroll_state_settling --> onPageSelected() --> Scroll_state_idle
(note: scroll_state_dragging occur multiple times.)
The idea is keeping a flag inside onPageSelected() to record current page number. Then if user in the last page and swipe left scroll_state_dragging called and launch the next view.
private int pagePosition; // keep a class variable
private int[] layouts= new int[]{R.layout.welcome_slide1, R.layout.welcome_slide2, R.layout.welcome_slide3};
Easy as that. Here is my full code implementation. (filter for what you want.)ViewPager.OnPageChangeListener viewPagerPageChangeListener = new ViewPager.OnPageChangeListener() { @Overridepublic void onPageSelected(int position) { addBottomDots(position); pagePosition = position; } @Overridepublic void onPageScrolled(int position, float positionOffset, int arg2) { } @Overridepublic void onPageScrollStateChanged(int state) { if (state == ViewPager.SCROLL_STATE_DRAGGING) { if (pagePosition == layouts.length - 1) { launchHomeScreen(); } } } };private void launchHomeScreen() { startActivity(new Intent(IntroductionActivity.this, MainDockerActivity.class)); finish(); }
package com.YOURAPP.android.app;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.content.res.ResourcesCompat;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.text.Html;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import butterknife.BindView;
public class IntroductionActivity extends BaseActivity {
@BindView(R.id.view_pager_intro)
ViewPager viewPager;
@BindView(R.id.btn_skip)
Button btnSkip;
private LinearLayout dotsLayout;
private int[] layouts;
private Typeface typefaceNormal;
private Typeface typefaceBold;
private int pagePosition;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (Build.VERSION.SDK_INT >= 21) {
getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
}
dotsLayout = findViewById(R.id.layoutDots);
layouts = new int[]{
R.layout.welcome_slide1,
R.layout.welcome_slide2,
R.layout.welcome_slide3};
typefaceNormal = ResourcesCompat.getFont(this, R.font.gill_sans_book);
typefaceBold = ResourcesCompat.getFont(this, R.font.gill_sans_bold);
addBottomDots(0);
// making notification bar transparent
changeStatusBarColor();
MyViewPagerAdapter myViewPagerAdapter = new MyViewPagerAdapter();
viewPager.setAdapter(myViewPagerAdapter);
viewPager.addOnPageChangeListener(viewPagerPageChangeListener);
btnSkip.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
launchHomeScreen();
}
});
}
@Override
protected int getContentView() {
return R.layout.activity_introduction;
}
private void addBottomDots(int currentPage) {
TextView[] dots = new TextView[layouts.length];
int[] colorsActive = getResources().getIntArray(R.array.array_dot_active);
int[] colorsInactive = getResources().getIntArray(R.array.array_dot_inactive);
dotsLayout.removeAllViews();
for (int i = 0; i < dots.length; i++) {
dots[i] = new TextView(this);
dots[i].setText(Html.fromHtml("•"));
dots[i].setTextSize(35);
dots[i].setTextColor(colorsInactive[currentPage]);
dotsLayout.addView(dots[i]);
}
if (dots.length > 0)
dots[currentPage].setTextColor(colorsActive[currentPage]);
}
private int getItem(int i) {
return viewPager.getCurrentItem() + i;
}
private void launchHomeScreen() {
startActivity(new Intent(IntroductionActivity.this, MainDockerActivity.class));
finish();
}
ViewPager.OnPageChangeListener viewPagerPageChangeListener = new ViewPager.OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
addBottomDots(position);
pagePosition = position;
}
@Override
public void onPageScrolled(int position, float positionOffset, int arg2) {
}
@Override
public void onPageScrollStateChanged(int state) {
if (state == ViewPager.SCROLL_STATE_DRAGGING) {
if (pagePosition == layouts.length - 1) {
launchHomeScreen();
}
}
}
};
//Making notification bar transparent
private void changeStatusBarColor() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
Window window = getWindow();
window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
window.setStatusBarColor(Color.TRANSPARENT);
}
}
public class MyViewPagerAdapter extends PagerAdapter {
private LayoutInflater layoutInflater;
public MyViewPagerAdapter() {
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = layoutInflater.inflate(layouts[position], container, false);
TextView mainTitle = view.findViewById(R.id.main_title);
TextView introDescription = view.findViewById(R.id.intro_description);
mainTitle.setTypeface(typefaceBold);
introDescription.setTypeface(typefaceNormal);
container.addView(view);
return view;
}
@Override
public int getCount() {
return layouts.length;
}
@Override
public boolean isViewFromObject(View view, Object obj) {
return view.equals(obj);
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
View view = (View) object;
container.removeView(view);
}
}
}
Hope It will be useful to someone. Happy Coding :-)
