使用viewpager滑动图像（而不是布局）

Question

What my code does:

Here's my code which for viewpager that swipes between xml layouts (named left.xml, right.xml and center.xml).

What I want it to do

I want to swipe between images (stored in the drawable folder). When I replace R.layout.xml with R.drawable.image, my app crashes down. Can anybody help me figure it out?

public class MainActivity extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    MyPagerAdapter adapter = new MyPagerAdapter();
    ViewPager myPager = (ViewPager) findViewById(R.id.myfivepanelpager);
    myPager.setAdapter(adapter);
    myPager.setCurrentItem(0);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

class MyPagerAdapter extends PagerAdapter {

    public int getCount() {
        return 3;
    }

    public Object instantiateItem(View collection, int position) {

        LayoutInflater inflater = (LayoutInflater) collection.getContext()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        int resId = 0;
        switch (position) {
        case 0:
            resId = R.layout.left;
            break;
        case 1:
            resId = R.layout.center;
            break;
        case 2:
            resId = R.layout.right;
            break;
        }

        View view = inflater.inflate(resId, null);

        ((ViewPager) collection).addView(view, 0);

        return view;
    }

    @Override
    public void destroyItem(View arg0, int arg1, Object arg2) {
        ((ViewPager) arg0).removeView((View) arg2);

    }

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        return arg0 == ((View) arg1);

    }

    @Override
    public Parcelable saveState() {
        return null;
    }
}

}

Answer 1

If you are using the same implementation and just adding R.drawable.XXX instead of R.layout.YYY then the problem is right there. You are using LayoutInflater to inflate ImageView s, the layout inflater as it states by itself it inflates a whole layout in a single View .

Instead of doing that try to create ImageView objects through code and then in the return return the newly created ImageView . Some sample code would be:

public Object instantiateItem(View collection, int position) {

    ImageView img = new ImageView(context); //this is a variable that stores the context of the activity
    //set properties for the image like width, height, gravity etc...

    int resId = 0;
    switch (position) {
        case 0:
            resId = R.drawable.img1;
            break;
        case 1:
            resId = R.drawable.img2;
            break;
        case 2:
            resId = R.drawable.img3;
            break;
    }

    img.setImageResource(resId); //setting the source of the image
    return img;
}

If you are just using a specific amount of images or pages you should consider adding them in the xml that contains the ViewPager rather than dynamically creating the ViewPager .

Answer 2

我认为一种选择是使用ImageView将每个图像插入到自己的布局中，然后使图像所在的布局膨胀而不是图像本身。