Some applications provide features that reflect (or mirror) objects which were drawn in the client area. If your application requires reflection capabilities, you can use the SetWorldTransform function to set the appropriate values in the world-space to page-space transformation. This function receives a pointer to an XFORM data structure which contains the appropriate values. The member eM11 contains the horizontal reflection component and the member eM22 contains the vertical reflection component.
The following illustration shows a rendering of the house after it was reflected about an imaginary horizontal-axis drawn through its midpoint:
Reflected Front-View of House