OpenEuphoria

RE: Win32Lib: drawRectangle question

• Posted by Derek Parnell <ddparnell at bigpond.com> May 09, 2001
• 482 views

Hi Brendon,
> -----Original Message-----
> From: Brendon Sly [mailto:bwsly at infoscience.otago.ac.nz]
> Sent: Wednesday, 9 May 2001 7:52 AM
> To: EUforum
> Subject: Win32Lib: drawRectangle question

> If I drew a rectangle (filled or not) then plotted the
> corner points, it wouldn't match up.


Here are the Microsoft docs. Take note of the "Remarks" section.
---------------
Rectangle
The Rectangle function draws a rectangle. The rectangle is outlined by using
the current pen and filled by using the current brush.

BOOL Rectangle(
  HDC hdc,         // handle to DC
  int nLeftRect,   // x-coord of upper-left corner of rectangle
  int nTopRect,    // y-coord of upper-left corner of rectangle
  int nRightRect,  // x-coord of lower-right corner of rectangle
  int nBottomRect  // y-coord of lower-right corner of rectangle
);

-------------
Parameters
-------------
hdc
[in] Handle to the device context.

nLeftRect
[in] Specifies the logical x-coordinate of the upper-left corner of the
rectangle.

nTopRect
[in] Specifies the logical y-coordinate of the upper-left corner of the
rectangle.

nRightRect
[in] Specifies the logical x-coordinate of the lower-right corner of the
rectangle.

nBottomRect
[in] Specifies the logical y-coordinate of the lower-right corner of the
rectangle.

-------------
Return Values
-------------
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Windows NT/ 2000: To get extended error information, call GetLastError.

-------------
Remarks
-------------
The current position is neither used nor updated by Rectangle.

The rectangle that is drawn excludes the bottom and right edges.

If a PS_NULL pen is used, the dimensions of the rectangle are 1 pixel less
in height and 1 pixel less in width.

---------------------
As Win32lib uses this GDI function to draw rectangles, it means that the
right and bottom edges are not drawn. This is not intuitive but I'm sure
uncle Bill has a VERY GOOD reason for confusing us all  My guess is that
it was a bug, but to fix it would break so much code they decided to
document it instead.

-----------
cheers,
Derek Parnell