An ImageView which can be locked to an aspect ratio.

AspectRatioImageView.java

public class AspectRatioImageView extends ImageView {

    private float widthToHeightRatio;

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

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

    public void setWidthToHeightRatio(float widthToHeightRatio) {
        this.widthToHeightRatio = widthToHeightRatio;
        requestLayout();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (widthToHeightRatio > 0) {
            int originalWidth = MeasureSpec.getSize(widthMeasureSpec);
            int calculatedHeight = (int) (originalWidth / widthToHeightRatio);
            super.onMeasure(
                    MeasureSpec.makeMeasureSpec(originalWidth, MeasureSpec.EXACTLY),
                    MeasureSpec.makeMeasureSpec(calculatedHeight, MeasureSpec.EXACTLY)
            );
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
}