SetWindowOrgEx 与 SetViewportOrgEx

SetWindowOrgEx specifies
which logical point maps to the device point (0,0). It has the effect of shifting the axes so that the logical point (0,0) no longer refers to the upper-left corner.

Generally, you will use one function or the other, but not both. Regardless of your use of SetWindowOrgEx and SetViewportOrgEx,
the device point (0,0) is always the upper-left corner.

//map the logical point (xWinOrg, yWinOrg) to the device point (0,0)
SetWindowOrgEx (hdc, xWinOrg, yWinOrg, NULL)

SetViewportOrgEx specifies
which device point maps to the logical point (0,0). It has the effect of shifting the axes so that the logical point (0,0) no longer refers to the upper-left corner.

//map the logical point (0,0) to the device point (xViewOrg, yViewOrg)
SetViewportOrgEx (hdc, xViewOrg, yViewOrg, NULL)

Regardless of your use of SetWindowOrgEx and SetViewportOrgEx, the device point (0,0) is always the upper-left corner.

The viewport refers
to the device coordinate system of the device space（与之对应的是window对应逻辑坐标点）[b].[/b]The extent is
the maximum value of an axis. This function sets the maximum values for the horizontal and vertical axes of the viewport in device coordinates (or pixels). When mapping between page space and device space, SetWindowExtEx andSetViewportExtEx determine
the scaling factor between the window and the viewport.

BOOL SetViewportExtEx(
_In_   HDC hdc,
_In_   int nXExtent,
_In_   int nYExtent,
_Out_  LPSIZE lpSize
);

如果 nYExtent为负数，则表示Y轴方向反转