The metric mapping model of the Drawing foundation of Windows programming

The logical coordinates are mapped to different display devices, and both x and Y are mapped, so that even if the device is different, x and Y change at the same time, so the shape of the drawing is not changed.

Use GetDeviceCaps to set the viewport and window range.

Set the logical coordinate system in the upper-left corner

Set the logical coordinate system in the lower left corner

Set the logical coordinate system in the middle

Call the Setwindoworgex function to set the logical point.

Pt.x = xclient;

Pt.y = yclient;

Dpthlp (HDC, &PT, 1);

Setwindoworgex (hdc,-PT.X/2,-PT.Y/2, NULL);