Android ImageView scale smaller image to width with flexible height without cropping or distortion

I have solved this by creating a java-class that you include in your layout-file:

public class DynamicImageView extends ImageView {

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

    @Override
    protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) {
        final Drawable d = this.getDrawable();

        if (d != null) {
            // ceil not round - avoid thin vertical gaps along the left/right edges
        final int width = MeasureSpec.getSize(widthMeasureSpec);
        final int height = (int) Math.ceil(width * (float) d.getIntrinsicHeight() / d.getIntrinsicWidth());
            this.setMeasuredDimension(width, height);
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
}

Now, you use this by added your class to your layout-file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <my.package.name.DynamicImageView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:scaleType="centerCrop"
        android:src="https://stackoverflow.com/questions/13992535/@drawable/about_image" />
</RelativeLayout>