World Coordinate Transformation


SUMMARY
=======

The WXFORM sample provides a demonstration of the new world-coordinate 
transformation. This sample displays a rectangle in world coordinates and a 
matrix containing the transform values. Users can directly manipulate the 
rectangle and see the effect on the transformation, or they can set the 
transformation and see the effect on the rectangle.

MORE INFORMATION
================

The program begins by setting the viewport origin to the center of the 
client area. It then draws a rectangle in world-coordinate space from the 
point (0, 0) to the point (100, 100). You can directly manipulate this 
rectangle by using the left and right mouse buttons. Specific actions are 
described more fully in the "Direct Manipulation Help" dialog box.

There is a second dialog box titled "World Transform." This shows the values 
of the eM11, eM12, eM21, eM22, eDx, and eDy fields in the XFORM structure 
retrieved by calling the GetWorldTransform function. By choosing the buttons 
on this dialog box, the user can cause the program to call the 
SetWorldTransform function.

There are three coordinate systems of interest in this sample. The first one 
is the world-coordinate system, which is new to Win32. These points are 
ultimately mapped to the second coordinate system, device coordinates, 
before being painted in the window. This program must also use a third 
coordinate system, screen coordinates, for certain interactions with the 
mouse pointer.

There is a third dialog box titled "Mouse Position" that shows the location 
of the cursor in all three coordinate systems. The device coordinates are 
relative to the upper-left corner of the client area. They are not relative 
to the viewport origin.