Flutter 你想知道的Widget可视区域,相对位置,大小

  RevealedOffset getOffsetToReveal(RenderObject target, double alignment, {Rect rect});

  RenderAbstractViewport viewport =
                RenderAbstractViewport.of(renderObject);

            /// Distance between top edge of screen and MyWidget bottom edge
            var offsetToRevealLeading =
                viewport.getOffsetToReveal(renderObject, 0.0);

            /// Distance between bottom edge of screen and MyWidget top edge
            var offsetToRevealTrailingEdge =
                viewport.getOffsetToReveal(renderObject, 1.0);