Android ImageView which scales the bitmap to fit in a center-bottom manner

CenterBottomImageView.java

import android.content.Context;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.widget.ImageView;

/**
 * This ImageView scales the image to match either the width or height of the
 * ImageView and places in the center-bottom. For eg. if the ImageView is 10x6
 * units and the image is 4x4 units, it will scale the image to 6x6 units and
 * place as follows:
 * 
 * ++------++ <br>
 * ++------++ <br>
 * ++------++ <br>
 * ++------++ <br>
 * ++------++ <br>
 * ++------++ <br>
 * 
 * + denotes the blank space in ImageView <br>
 * - denotes the image itself
 */
public class CenterBottomImageView extends ImageView {

    public CenterBottomImageView(Context context) {
        super(context);
        setup();
    }

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

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

    private void setup() {
        setScaleType(ScaleType.MATRIX);
    }

    @Override
    protected boolean setFrame(int frameLeft, int frameTop, int frameRight, int frameBottom) {
        if (getDrawable() != null) {
            float frameWidth = frameRight - frameLeft;
            float frameHeight = frameBottom - frameTop;

            float originalImageWidth = getDrawable().getIntrinsicWidth();
            float originalImageHeight = getDrawable().getIntrinsicHeight();

            float fitHorizontallyScaleFactor = frameWidth / originalImageWidth;
            float fitVerticallyScaleFactor = frameHeight / originalImageHeight;

            float usedScaleFactor = Math.min(fitHorizontallyScaleFactor, fitVerticallyScaleFactor);

            float newImageWidth = originalImageWidth * usedScaleFactor;
            float newImageHeight = originalImageHeight * usedScaleFactor;

            Matrix matrix = getImageMatrix();
            matrix.setScale(usedScaleFactor, usedScaleFactor, 0, 0);
            matrix.postTranslate((frameWidth - newImageWidth) / 2, frameHeight - newImageHeight);
            setImageMatrix(matrix);
        }

        return super.setFrame(frameLeft, frameTop, frameRight, frameBottom);
    }
}