private boolean isMatrixIdentity(Matrix transform, float eps) {
    // Checks whether the given matrix is close enough to the identity matrix:
    //   1 0 0
    //   0 1 0
    //   0 0 1
    // Or equivalently to the zero matrix, after subtracting 1.0f from the diagonal elements:
    //   0 0 0
    //   0 0 0
    //   0 0 0
    transform.getValues(mTempValues);
    mTempValues[0] -= 1.0f; // m00
    mTempValues[4] -= 1.0f; // m11
    mTempValues[8] -= 1.0f; // m22
    for (int i = 0; i < 9; i++) {
      if (Math.abs(mTempValues[i]) > eps) {
        return false;
      }
    }
    return true;
  }
Same as {@code Matrix.isIdentity()}, but with tolerance {@code eps}.
samples/zoomable/src/main/java/com/facebook/samples/zoomable/DefaultZoomableController.java