docs: public float getScale() {
      if (mDetector.getPointerCount() < 2) {
        return 1;
      } else {
        float startDeltaX = mDetector.getStartX()[1] - mDetector.getStartX()[0];
        float startDeltaY = mDetector.getStartY()[1] - mDetector.getStartY()[0];
        float currentDeltaX = mDetector.getCurrentX()[1] - mDetector.getCurrentX()[0];
        float currentDeltaY = mDetector.getCurrentY()[1] - mDetector.getCurrentY()[0];
        float startDist = (float) Math.hypot(startDeltaX, startDeltaY);
        float currentDist = (float) Math.hypot(currentDeltaX, currentDeltaY);
        return currentDist / startDist;
      }
    }