public void resetContentRect() {
        contentRectMinusAxesMargins.set(maxContentRect);
        contentRectMinusAllMargins.set(maxContentRect);
    }
Calculates available width and height. Should be called when chart dimensions change. ContentRect is relative to
chart view not the device's screen.
hellocharts-library/src/lecho/lib/hellocharts/computator/ChartComputator.java