Scaling ImageView to device width

Question

In my Android App I have a Activity which show images which have following size 244 x 330. I want to show those images in full device width.

My layout f

Answer 1

I tried really every ScaleType in my ImageView with fill_parent and wrap_content but no of them worked. I also tried everything what I found on Google but nothing worked for me either so came up with something on my own.

It was clear that the ImageView is not scaling my image like I wanted to be scaled so I had to scale it on my own. After scaling the bitmap I would set the new Bitmap as the image source to the ImageView. This works pretty good and looks very good on the G1 and on the Motorola Milestone 2.

And here is all pieces of my code

Layout:

Activity

public class ScalingImages extends Activity {

    private ImageView imageView;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.test_margin);

        this.imageView = (ImageView)findViewById(R.id.news_image);

        // The image is coming from resource folder but it could also 
        // load from the internet or whatever
        Drawable drawable = getResources().getDrawable(R.drawable.img);
        Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();

        // Get scaling factor to fit the max possible width of the ImageView
        float scalingFactor = this.getBitmapScalingFactor(bitmap);

        // Create a new bitmap with the scaling factor
        Bitmap newBitmap = Util.ScaleBitmap(bitmap, scalingFactor);

        // Set the bitmap as the ImageView source
        this.imageView.setImageBitmap(newBitmap);
    }

    private float getBitmapScalingFactor(Bitmap bm) {
        // Get display width from device
        int displayWidth = getWindowManager().getDefaultDisplay().getWidth();

        // Get margin to use it for calculating to max width of the ImageView
        LinearLayout.LayoutParams layoutParams = 
            (LinearLayout.LayoutParams)this.imageView.getLayoutParams();
        int leftMargin = layoutParams.leftMargin;
        int rightMargin = layoutParams.rightMargin;

        // Calculate the max width of the imageView
        int imageViewWidth = displayWidth - (leftMargin + rightMargin);

        // Calculate scaling factor and return it
        return ( (float) imageViewWidth / (float) bm.getWidth() );
    }
}

Util class

public class Util {

    public static Bitmap ScaleBitmap(Bitmap bm, float scalingFactor) {
        int scaleHeight = (int) (bm.getHeight() * scalingFactor);
        int scaleWidth = (int) (bm.getWidth() * scalingFactor);

        return Bitmap.createScaledBitmap(bm, scaleWidth, scaleHeight, true);
    }

}

If there is an better or more accurate way to accomplish the same scaling please let me know because I can't believe that such a trivial thing is so hard to accomplish.

I'm really hoping to see a better way to do this.

Thank you for reading.