1. RE: Win32Lib: drawRectangle question
Brendon,
AFAIK, that's the way it's always been. I remember bringing it to David
Cuny's attention way back when but I don't remember what he said about
it. I think that's just the way Windows does it...
-- Brian
Brendon Sly wrote:
> Hi All,
>
> While messing with something last night I found an interesting effect
> with drawRectangle. If I drew a rectangle (filled or not) then plotted
> the corner points, it wouldn't match up.
>
> I've attached the smallest piece of code that will show you what I'm on
> about.
>
> The top-left dark point is on the yellow rectangle but the other three
> are outside it. I've tried this on my home machine (Win98) and work
> (Win2000) and get the same result.
> I can deal with using 'drawRectangle(A, B, x1, y1, x2+1, y2+1)' but I'm
> just wondering if that's the way it's supposed to be or have I missed
> something in the win32lib docs.
>
> Oh yeah, last thing. I'm using win32lib v0.55.1.
>
> Thanks.
>
>
> Brendon :|
>
> --
>
> include Win32Lib.ew
> without warning
>
> global constant MyWin = create( Window, "MyWin", 0, Default, Default,
> 300, 300, 0)
> setWindowBackColor( MyWin, White )
>
> procedure MyWin_onPaint ( int x1, int y1, int x2, int y2 )
> setPenColor(MyWin, Yellow)
> drawRectangle(MyWin, True, 10, 10, 100, 100)
> setPixel(MyWin, 10, 10, Black)
> setPixel(MyWin, 10, 100, Black)
> setPixel(MyWin, 100, 10, Black)
> setPixel(MyWin, 100, 100, Black)
> end procedure
>
> onPaint[MyWin] = routine_id("MyWin_onPaint")
>
> WinMain( MyWin, Normal )
>
>
>
2. RE: Win32Lib: drawRectangle question
>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
> Unfortunately, that's how the Windows GDI call is supposed to work.=20=
There's
> some sort of logic to it, but the end result is still rather
> counter-intuitive.
> AFAIK, that's the way it's always been. I remember bringing it to Dav=
id
> Cuny's attention way back when but I don't remember what he said about=
> it. I think that's just the way Windows does it...
Thanks David and Brian,
Now I know it behaves that way, I can deal with it. It sure beats going =
over half a dozen or so lines of code 8 or 9 times trying to figure out =
why the boxes and lines don't match.
Brendon :|
3. RE: Win32Lib: drawRectangle question
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
