定義在 IDrawing.cs 檔案之第 10 行.
實作於 ShapeObj, ShapeArrow, ShaperightTriangle, ShapeTriangle, ShapeCurve, 及 ShapeRectangle.
實作於 ShapeObj, ShapeText, ShapePencil, eraser, ShapeArrow, ShapeCircle, ShapeCurve, ShapeRectangle, ShaperightTriangle, 及 ShapeTriangle.