Android: Programmatically animate between images i

问题:

Note: As of Jellybean the gallery widget is deprecated. A ViewPager should be used instead.

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I'd like to programmatically move between images in the Gallery widget, with animation.

I can change the currently displaying image using the setSelection(int position) method, however that does not animate. Then there's setSelection(int position, bool animate) but the extra boolean on the end there doesn't appear to do anything.

In the source of Gallery it appears that it can handle DPAD key-presses, so a work-around I thought of was to fake the key-presses. Eg.

dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DPAD_LEFT))

However I can't get this working for some reason. Anyone tried this?

I notice three of the widget's methods I'd love to use moveNext(), movePrevious() and scrollToChild() are all private and unusable.

Does anyone know how I might be able to do this?

回答1:

Just call the key press handler for the gallery directly:

public boolean onKeyDown(int keyCode, KeyEvent event)

i.e

Gallery gallery = ((Gallery) findViewById(R.id.gallery));

gallery.onKeyDown(KeyEvent.KEYCODE_DPAD_LEFT, new KeyEvent(0, 0));

One important thing - this solution works only if child that is on left/right was already created, which means that it has to be 'visible'. If you have your image on fullscreen - consider setting spacing to -1 value.

回答2:

You can Animate using dispatchKeyEvent or calling onFling directly.

Here is sample code for dispatchKeyEvent:

KeyEvent evtKey = new KeyEvent(0, KeyEvent.KEYCODE_DPAD_RIGHT);
dispatchKeyEvent(evtKey);

回答3:

Use gallery.setSelected(int); Here is a simple example.

public class Splash extends Activity {

    ArrayList objects = new ArrayList();
    Gallery g;
    int i = 0;
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.photos);
        g = (Gallery) findViewById(R.id.gallery);
        objects.add(getResources().getDrawable(R.drawable.icon));
        objects.add(getResources().getDrawable(R.drawable.icon));
        objects.add(getResources().getDrawable(R.drawable.icon));
        objects.add(getResources().getDrawable(R.drawable.icon));
        objects.add(getResources().getDrawable(R.drawable.icon));
        objects.add(getResources().getDrawable(R.drawable.icon));
        g.setAdapter(new CustomAdapter(this, objects));
        g.setOnItemSelectedListener(new OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView arg0, View arg1,
                    int arg2, long arg3) {
                Log.i("", "selected " + arg2);
            }

            @Override
            public void onNothingSelected(AdapterView arg0) {}
        });
    }

    @Override
    public void onBackPressed() {
            g.setSelection(i++);
    }

        private class CustomAdapter extends BaseAdapter {

        private Context mCtx;
        private List objects;

        public int getCount() {
            return this.objects.size();
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public CustomAdapter(Context context, ArrayList objects) {
            super();
            mCtx = context;
            this.objects = objects;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView row = (ImageView) convertView;
            if (row == null) {
                row = new ImageView(mCtx);
                row.setBackgroundDrawable(objects.get(position));
            }
            return row;
        }
    }
}

回答4:

In the end I wrote my own version of the Gallery widget with the help of the code at this site.

I then wrote my own method which uses mFlingRunnable.startUsingDistance(distance);

Now I can programmatically animate the gallery between images.

回答5:

Try this

mGallery.onFling(null,null, velocity,0);

http://groups.google.com/group/android-developers/browse_thread/thread/9140fd6af3061cdf#