public void setTransitionDuration(int durationMs) {
    mDurationMs = durationMs;
    // re-initialize transition if it's running
    if (mTransitionState == TRANSITION_RUNNING) {
      mTransitionState = TRANSITION_STARTING;
    }
  }
Sets the duration of the current transition in milliseconds.
drawee/src/main/java/com/facebook/drawee/drawable/FadeDrawable.java