public void setMaxViewport(float left, float top, float right, float bottom) {
        this.maxViewport.set(left, top, right, bottom);
        computeMinimumWidthAndHeight();
    }
Set new values for maximum viewport, that will change what part of chart is visible.
hellocharts-library/src/lecho/lib/hellocharts/computator/ChartComputator.java