ViewPager可能包含无限数量的页面

Question

I am currently using a ViewPager object to create a gallery of dynamically loaded photos (from a remote server). I noticed that a ViewPager object relies heavily on knowing the number of pages (or pictures in my case) in advance, while in my situation I don't know.

Am I right? And if I am, is there an alternative that will make sliding between pictures very easy (that's what I like about ViewPager)?

Thanks in advance

Answer 1

Am I right?

Well, you need to have a getCount() method on your PagerAdapter that returns something. If you wish to define that as "relies heavily", then, use, it "relies heavily".

And if I am, is there an alternative that will make sliding between pictures very easy (that's what I like about ViewPager)?

Use ViewPager .

While your images may be loaded dynamically, probably the count of images is knowable in advance. In that case, retrieve that value, then use that for getCount() .

Otherwise, have getCount() return 1000000 or something similarly huge. If you find you reach the end of your available pictures, call notifyDataSetChanged() and have your PagerAdapter return the right value from getCount() (since you know it now). Or, have the remaining pages show some placeholder.

Answer 2

For Infinite Scrolling , I figured out one solution to it.

Here's how I am doing it:

No looping is required in this case. No matter what your getCount() is.

After setting the pager adapter, I am setting a setOnPageChangeListener to the view pager like this:

myPager.setOnPageChangeListener(new OnPageChangeListener() {

                @Override
                public void onPageSelected(int position) {
//Define the focused page before your onCreate()..private int focusedPage = 0;
                    focusedPage = position;
                }
                //We don't have to do anything here.
                @Override
                public void onPageScrolled(int arg0, float arg1, int arg2) {
                    // TODO Auto-generated method stub

                }
                //Here's where the magic is. After you reach the end of the page, you can scroll again and it will move your view to position you desire to put. In my case it's 0.
                @Override
                public void onPageScrollStateChanged(int arg0) {

                    myPager.setCurrentItem(0,false);

                }
            });

I know it's too late to answer this question but this was the solution I found out. Maybe helpful for other users.

It's working perfect for me...Any suggestions to make this answer better will really help me too.