Displaying bitmap image in imageview by simple adapter

Question

I am getting image from an url. I am using imageview in listview. I want to add the list of bitmap images into the each row of the list item. I used SimpleAdapter but the im

Answer 1

The best way to do it is to create a class that extends BaseAdapter and then instanciate an async task for every image (on post execute set the bitmap to the correpondent imageView). Here's a simple function to download an image from web:

private Bitmap loadImageFromNetwork(String url) throws MalformedURLException, IOException {
    HttpURLConnection conn = (HttpURLConnection) (new URL(url)).openConnection();
    conn.connect();
    return BitmapFactory.decodeStream(new FlushedInputStream(conn.getInputStream()));
}

Answer 2

i think is because you are downloading the image from web and you need to do these in ASYNC see painless thrething download image and after that refresh just the imageviews.

Answer 3

Basically the simple adapter automatically bind some ressource id or URI to the imageview of your row layout. But it don't support Bitmap.

That's a problem, because everyone who had to manage bitmap know that we often have to reduce the size of the picture to prevent outOfMemory exceptions. But if you want to add images into a listView, you cannot reduce the image's size if you only provide URI. So here is the solution :

I have modified the simpleAdapter to be able to handle bitmap. Add this class into your project, and use it instead of simpleAdapter. Then instead of passing an URI or a ressourceId for an image, pass a Bitmap !

Hereunder is the code :

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.content.Context;
import android.graphics.Bitmap;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Checkable;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import android.widget.TextView;



public class ExtendedSimpleAdapter extends SimpleAdapter{
    List<? extends Map<String, ?>> map; // if fails to compile, replace with List<HashMap<String, Object>> map
    String[] from;
    int layout;
    int[] to;
    Context context;
    LayoutInflater mInflater;
    public ExtendedSimpleAdapter(Context context, List<? extends Map<String, ?>> data, // if fails to compile, do the same replacement as above on this line
            int resource, String[] from, int[] to) { 
        super(context, data, resource, from, to);
        layout = resource;
        map = data;
        this.from = from;
        this.to = to;
        this.context = context;
    }


@Override
public View getView(int position, View convertView, ViewGroup parent) {
    mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    return this.createViewFromResource(position, convertView, parent, layout);
}

private View createViewFromResource(int position, View convertView,
        ViewGroup parent, int resource) {
    View v;
    if (convertView == null) {
        v = mInflater.inflate(resource, parent, false);
    } else {
        v = convertView;
    }

    this.bindView(position, v);

    return v;
}


private void bindView(int position, View view) {
    final Map dataSet = map.get(position);
    if (dataSet == null) {
        return;
    }

    final ViewBinder binder = super.getViewBinder();
    final int count = to.length;

    for (int i = 0; i < count; i++) {
        final View v = view.findViewById(to[i]);
        if (v != null) {
            final Object data = dataSet.get(from[i]);
            String text = data == null ? "" : data.toString();
            if (text == null) {
                text = "";
            }

            boolean bound = false;
            if (binder != null) {
                bound = binder.setViewValue(v, data, text);
            }

            if (!bound) {
                if (v instanceof Checkable) {
                    if (data instanceof Boolean) {
                        ((Checkable) v).setChecked((Boolean) data);
                    } else if (v instanceof TextView) {
                        // Note: keep the instanceof TextView check at the bottom of these
                        // ifs since a lot of views are TextViews (e.g. CheckBoxes).
                        setViewText((TextView) v, text);
                    } else {
                        throw new IllegalStateException(v.getClass().getName() +
                                " should be bound to a Boolean, not a " +
                                (data == null ? "<unknown type>" : data.getClass()));
                    }
                } else if (v instanceof TextView) {
                    // Note: keep the instanceof TextView check at the bottom of these
                    // ifs since a lot of views are TextViews (e.g. CheckBoxes).
                    setViewText((TextView) v, text);
                } else if (v instanceof ImageView) {
                    if (data instanceof Integer) {
                        setViewImage((ImageView) v, (Integer) data);                            
                    } else if (data instanceof Bitmap){
                        setViewImage((ImageView) v, (Bitmap)data);
                    } else {
                        setViewImage((ImageView) v, text);
                    }
                } else {
                    throw new IllegalStateException(v.getClass().getName() + " is not a " +
                            " view that can be bounds by this SimpleAdapter");
                }
            }
        }
    }
}



private void setViewImage(ImageView v, Bitmap bmp){
    v.setImageBitmap(bmp);
}



}

This class behave exactly like the original class (SimpleAdapter)