code: private void updateMatrix(int position, float offset) {
          if (mDrawable != null && mScale > 0.0f) {
              if (mPageCount == -1 && mAdapter != null) { // cache page count and translation values
                  mPageCount = mAdapter.getCount();
                  if (mPageCount > 1) {
                      mPageX = (mDrawableWidth * mScale - mViewWidth) / (mPageCount - 1);
                      mPageY = (mDrawableHeight * mScale - mViewHeight) / (mPageCount - 1);
                  }
              }
              mMatrix.setTranslate(-mPageX * position - mPageX * offset,
                      -mPageY * position - mPageY * offset);
              mMatrix.preScale(mScale, mScale);
              mView.setScaleType(MATRIX);
              mView.setImageMatrix(mMatrix);
          }
      }
docs: Scale the image and translate it according to the pager position and offset.