public void startZoom(float endZoom) {
        mStartRTC = SystemClock.elapsedRealtime();
        mEndZoom = endZoom;

        mFinished = false;
        mCurrentZoom = 1f;
    }
Starts a zoom from 1.0 to (1.0 + endZoom). That is, to zoom from 100% to 125%, endZoom should by 0.25f.

@see android.widget.Scroller#startScroll(int, int, int, int)
hellocharts-library/src/lecho/lib/hellocharts/gesture/ZoomerCompat.java