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Q27585: INFO: Specifying Windows "Bounding Box" Coordinates

Article: Q27585
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1,95; winnt:3.5,3.51,4.0
Operating System(s): 
Keyword(s): kbOSWinNT350 kbOSWinNT351 kbOSWinNT400 kbOSWin95 kbSDKWin16
Last Modified: 11-MAY-2001

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
- Microsoft Win32 Application Programming Interface (API), used with:
   - Microsoft Windows NT Server versions 3.5, 3.51, 4.0 
   - Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0 
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SUMMARY
=======

GDI functions, such as Rectangle, Ellipse, RoundRect, Chord, and Pie, have
parameters that specify the coordinates of a "bounding box" into which the
figure is drawn. Windows draws the figure up to, but not including, the right
and bottom coordinates.

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

Suppose the following call is made:

     Rectangle(hDC, 1, 1, 5, 3)

Assuming that the device context is using the MM_TEXT mapping mode (in which case
logical units map directly to physical pixels), the resulting rectangle will be
4 pixels wide and 2 pixels tall. The following diagram shows which pixels are
affected:

           ---0-----1-----2-----3-----4-----5-----6-
           |     |     |     |     |     |     |
           0     |     |     |     |     |     |
           |-----|-----|-----|-----|-----|-----|----
           |     |     |     |     |     |     |
           1     |  X  |  X  |  X  |  X  |     |
           |-----|-----|-----|-----|-----|-----|----
           |     |     |     |     |     |     |
           2     |  X  |  X  |  X  |  X  |     |
           |-----|-----|-----|-----|-----|-----|----
           |     |     |     |     |     |     |
           3     |     |     |     |     |     |
           |-----|-----|-----|-----|-----|-----|----
           |     |     |     |     |     |     |
           4     |     |     |     |     |     |

It may be helpful to think of the display as a grid, with each pixel contained in
a grid cell. The X1, Y1, X2, and Y2 parameters to the Rectangle function specify
an imaginary "bounding box" drawn on the grid. The rectangle is drawn within the
bounding box.

The height, width, and area of the resulting rectangle have the following useful
properties:

  Height = X2 - X1
  Width  = Y2 - Y1
  Area   = Height * Width

Additional query words: 3.00 3.10 3.50 4.00 win16sdk

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Keywords          : kbOSWinNT350 kbOSWinNT351 kbOSWinNT400 kbOSWin95 kbSDKWin16 
Technology        : kbAudDeveloper kbSDKSearch kbWin32sSearch kbWin32API kbWinSDKSearch
Version           : WINDOWS:3.1,95; winnt:3.5,3.51,4.0
Issue type        : kbinfo

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