public void setCurrentViewport(Viewport viewport) {
        constrainViewport(viewport.left, viewport.top, viewport.right, viewport.bottom);
    }
Set current viewport to the same values as viewport passed in parameter. This method use deep copy so parameter
can be safely modified later. Current viewport must be equal or smaller than maximum viewport.

@param viewport
hellocharts-library/src/lecho/lib/hellocharts/computator/ChartComputator.java