gistfile1.java

    public final void onMeasure(final int widthMeasureSpec,
                                final int heightMeasureSpec) {
        int mode = View.MeasureSpec.getMode(widthMeasureSpec);
        int width = View.MeasureSpec.getSize(widthMeasureSpec);

        int height = (int) (width / aspect.ratio);
        int heightSpec = MeasureSpec.makeMeasureSpec(height, mode);

        super.onMeasure(widthMeasureSpec, heightSpec);
    }