README.TXT

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.