Android: Gallery with sliding skips images and slow loading

Question

Hello guys i am new to android so be gentle with me :),
I have gallery i need to load images i have lot's of them, the performance on image loading i have solved by using AsyncTask.

Now i have the scrolling on gallery problem, it's skips images and it's not looking nice.

Now i have tried to implement my custom Gallery and no success on that, it's just won't work
now i have one more question the

final ScrollableGallery galleryView = (ScrollableGallery)findViewById(R.id.gallery); //always returns null

suddenly , can you explane why please?

Here's the code:

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.Gallery;

public class ScrollableGallery extends Gallery {

    public ScrollableGallery(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public ScrollableGallery(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ScrollableGallery(Context context) {
        super(context);
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {

        // limit the max speed in either direction
        if (velocityX > 1200.0f) {
            velocityX = 1200.0f;
        } else if (velocityX < 1200.0f) {
            velocityX = -1200.0f;
        }
        return super.onFling(e1, e2, velocityX, velocityY);
    }   
}

The XML part:

<ScrollableGallery
        android:id="@+id/gallery"
        android:layout_width="675dp"
        android:layout_height="492dp"
        android:layout_marginLeft="62dp"
        android:layout_marginTop="225dp"
        android:scaleType="fitXY" >
    </ScrollableGallery>

The Actvity Invocation:
The initiation

final ScrollableGallery galleryView = (ScrollableGallery)findViewById(R.id.gallery);

The adapter initiation:

galleryV.setAdapter(new BaseAdapter() {                     
            public int getCount() {             
                return _imageList.size();
            }

            public Object getItem(int position) {
                return _imageList.get(position);
            }

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

            public View getView(final int position, View convertView,final ViewGroup parent) {              
                if (convertView == null) {
                    convertView = new ImageView(Database.this);
                }               
                ImageDispatcher dispatch = new ImageDispatcher(((ImageView) convertView));              
                dispatch.execute(_imageList.get(position));                                     
                ((ImageView) convertView).setScaleType(ImageView.ScaleType.FIT_XY);
                ((ImageView) convertView).setLayoutParams(new ScrollableGallery.LayoutParams(675, 492));

                return convertView;
            }           
        });
<br/>
The image dispatcher:

    import java.lang.ref.WeakReference;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.os.AsyncTask;
    import android.widget.ImageView;

    public class ImageDispatcher extends AsyncTask<String, Void, Bitmap> {

        private final WeakReference<ImageView> imageViewReference;

        public ImageDispatcher(ImageView imageView) {
            imageViewReference = new WeakReference<ImageView>(imageView);
        }

        @Override
        // Actual download method, run in the task thread
        protected Bitmap doInBackground(String... params) { 

            return ShrinkBitmap(params[0], 300 ,300);
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            if (isCancelled()) {
                bitmap = null;
            }

            if (imageViewReference != null) {
                ImageView imageView = imageViewReference.get();
                if (imageView != null) {
                    imageView.setImageBitmap(bitmap);
                }
            }
        }

        /*********************************************************
         * PRIVATE METHODS 
         *********************************************************/
        @SuppressWarnings("unused")
        private Bitmap ShrinkBitmap(String file, int width, int height) {
            BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
            bmpFactoryOptions.inTempStorage = new byte[16 * 1024];
            bmpFactoryOptions.inJustDecodeBounds = true;
            Bitmap bitmap = BitmapFactory.decodeFile(file, bmpFactoryOptions);
            int heightRatio = (int) Math.ceil(bmpFactoryOptions.outHeight / (float) height);
            int widthRatio = (int) Math.ceil(bmpFactoryOptions.outWidth / (float) width);

            bmpFactoryOptions.inSampleSize = heightRatio > 1 || widthRatio > 1 ? heightRatio : widthRatio;                  
            bmpFactoryOptions.inJustDecodeBounds = false;
            bitmap = BitmapFactory.decodeFile(file, bmpFactoryOptions);
            return bitmap;
        }

        @SuppressWarnings("unused")
        private Bitmap ShrinkBitmap(String file) {
            BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
            bmpFactoryOptions.inTempStorage = new byte[16 * 1024];
            bmpFactoryOptions.inJustDecodeBounds = true;

            Bitmap bMap = BitmapFactory.decodeFile(file);       
            Bitmap bMapScaled = Bitmap.createScaledBitmap(bMap,150, 100, true);

            return bMapScaled;
        }
    }

I think it's all the code that i have for this part, now is the question:
How do i make the scroll, one image in time, and how do i show loading indicator like i do in web when i load images ???

Any code fixing would be highly appreciated !

Thank you in advance...

Answer 1

Instead of declaring Gallery in you xml.

Gallery gallery = new  CustomGaller(getActivity());

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams  (LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT);
            params.addRule(RelativeLayout.RIGHT_OF, R.id.left);
            params.addRule(RelativeLayout.LEFT_OF,R.id.right);
            gallery.setLayoutParams(params);
            gallery.setAdapter(new GalleryAdapter(<Pass values>));

You dant have to pass View id to CustomGallery.

Answer 2

In your custom Gallery

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,float velocityY) {
    -->> super.onFling(e1, e2, 20, velocityY); <<--

    return false;
}

Try modifying the 3rd parameter.