Update source activity before exit transition

Question

I need help about transition between activities:

I have two activities A and B and both have a ViewPager with the same image list. Every page has an ImageView with the transitionName equals to ​​​​​​​​image_x​​​​ where​​​​​​​​ x is the page index.

A starts activity B calling ActivityOptionsCompat.makeSceneTransitionAnimation and the enter transition is totally fine.

The problem is the following: when I close activity B, the exit transition does not initialize the view pager of activity A at the same position of B.

When user closes B, the latter sets the current page position in the result. In onActivityResult of activity A, I call the setCurrentItem and the behavior is showed in the gif.

Is there a way to update activity A before the exit transition starts?

Nolte

Activity result is the best way of doing this because you do not have the object of activity so activity result is the best way to implement it. – Morello

@PratikGoyal yes but acting this way the exit transition is as showed in the gif, and it is very bad. I would like to see the exit transition just like the start transition (from A to B). – Nolte

What if you eliminate the transition animation in the viewPager when coming back to A (if possible)? If it changes instantly, the user wouldn't notice. – According

@According If I remove the exit transition and the animation of the viewpager when changing the page there are no problems. I wanted to know if there were a way to avoid this solution. – Nolte

Yea I was suggesting to remove it only temporary, so that the ViewPager animations are there when the user interacts with it but not when the system goes back. But I guess the exit page transition will be a problem as well, as there will be some milliseconds the old image is shown – According

@fran: you can use interface between A and B. When you get page change event in B, pass event through interface to A Activity – Bakker

@Nolte I have solved your query... please check my answer... i used interface concept for solution... i hope this will help you – Bakker

Answer 1

You should be able to do achieve that if you use setCurrentItem in the onActivityReenter instead of in onActivityResult (in your ActivityA).

Just be sure you:

1. Before finishing ActivityB, set the result (either with setResult(int resultCode) or setResult(int resultCode, Intent data))
2. Call supportFinishAfterTransition() (or finishAfterTransition()) instead of regular finish() to "close" the ActivityB.

---

To summerize:

in ActivityB:

public void close(){
    Intent data = new Intent();
    data.putExtra(KEY_CURRENT_ITEM, mFullscreenViewPager.getCurrentItem());
    setResult(RESULT_CODE, data);
    supportFinishAfterTransition();
}

in ActivityA:

@Override
public void onActivityReenter(int resultCode, Intent data) {
    super.onActivityReenter(resultCode, data);
    if (data.hasExtra(KEY_CURRENT_ITEM)){
         mViewPager.setCurrentItem(data.getIntExtra(KEY_CURRENT_ITEM, 0), false);
    }
}

Crutchfield

Your answer seems correct but the transition still shows a strange behavior: giphy.com/gifs/d3l2J0f2o84YL0tO – Nolte

Although it didn't solve the problem this is the correct answer. – Celebration

Answer 2

I have got solution.

1. Create Interface class which works between both Activity : demoClass.java

public class demoClass {

public static demoClass instance;
public demoInterface mCallback;

public static demoClass getInstance() {
    if(instance == null) {
        instance = new demoClass();
    }
    return instance;
}

public void setListener(demoInterface callback) {
    this.mCallback = callback;
}

public void changePage(int which) {
    if(this.mCallback != null) {
        this.mCallback.changePage(which);
    }
}


public interface demoInterface {
    public void changePage(int which);
}

}

2. From Activity B , call interface method :

demoClass.getInstance().changePage(mFullscreenViewPager.getCurrentItem());

3. From Activity A , implement interface and register listen to interface :

public class ActivityA extends Activity implements demoClass.demoInterface {
...
} 
---------------------
demoClass.getInstance().setListener(ActivityA.this);

4. Implement changePage(int) method in A :

@Override
public void changePage(int which) {
    mViewPager.setCurrentItem(page);
}

Explaination

When Activity B changes page, report event to interface demoClass.demoInterface thorugh demoClass.getInstance().changePage(index). This will ultimately call method changePage(int) of Activity A and we will change ViewPager content on the go.

Result

You can check output at GIF here

Bakker

Ok, it's a solution. But if the system releases activity A for some reason, will it work? – Nolte

Yes... just you need to save page variable value, you can restore when activity A re-starts. For storing, you can use SharedPreference... – Bakker

Ok, I will try. Thanks! – Nolte

Your solution doesn't solve my issue. The behavior is still this: giphy.com/gifs/d3l2J0f2o84YL0tO Thanks – Nolte

Please post your code... because same solution is working for me... i can share code example if you wish... – Bakker

From gif, i can say you are resetting mViewPager.setCurrentPage from Activity A somewhere... so page 5 is changing to page 3 when going to Activity A... pls post your code so tht i can help – Bakker

I think that trying your code with images instead of text, you'll get the same behavior... – Nolte

No... I have used different texts in different pages... It do not have relation with text or image... code is working :) – Bakker