Joseph M. Newcomer wrote:
See below...
On Mon, 8 Feb 2010 02:13:34 -0800 (PST), Luigino <npuleio@rocketmail.com> wrote:
Hello Steve,
m_MemDC.SetMapMode(MM_ANISOTROPIC);
m_MemDC.SetWindowExt(m_MaxTime, m_nVMaxY);
m_MemDC.SetViewportOrg(0, rect.Height());
m_MemDC.SetWindowOrg(0,0);
m_MemDC.SetViewportExt(rect.Width(),-rect.Height());
m_MemDC.SelectObject(&m_VPen);
m_MemDC.Polyline(&m_VMinPts[0],(int)m_VMinPts.size());
****
I just used Viewport Explorer and verified these settings.
Note that the order of setting the WindowExt before the ViewportExt is important, but you
have that right.
One thing I did when doing complex graphics was to put all the drawing in a *separate*
subroutine. I would pass in a CDC & to it. So what I did was
CPaintDC dc(this);
#ifdef _DEBUG_GRAPHICS
DoDrawing(dc);
#else
CDC memDC;
...create compatible DC and bitmap
DoDrawing(memDC);
... transfer bitmap to surface
#endif
This allowed me to see if I was correctly drawing on the surface, and discover errors in
my drawing logic (especially when I had Z-axis errors). Flickered like crazy, but easy to
debug. Then I would remove the #define _DEBUG_GRAPHICS once I knew it worked.
void CMyClass::DoDrawing(CDC & dc)
{
... do drawing here
}
Because at this point, you don't actually know if the error is in the drawing or in the
transfer of the bitmap to the surface, later. So this technique eliminates the
uncertainty.
****
in the array I'm not using time as X coordinates but just integers
1,2,3,4,...,n which are still consecutive integers as time values...so
in the place of m_MaxTime I use current last X value in the array and
in the place of m_nVMaxY I use rect.bottom since Y values in the array
are actually random with this formula:
myarray[i].y = (LONG)( (double)rand() / (RAND_MAX + 1) * (rect.bottom
- 1) + 1 );
(the array is fixed size to the whole window resolution width where
when I add new value at the last place I rotate before the array to
shift-left it.
The matter is setting SetWindowExt with last myarray[myarray.size() -
1].x and rect.bottom produces an assertion error.
****
Really? I don't suppose you would tell us WHERE this error occurred? Did you check what
routine it was in, what it was asserting for, and check the call to see why? Note that
reporting "an" assertion error only wastes space; the proper report is to say "I got an
assertion error in line XXXXX of file YYYYYY and I'm using VS version N" if you expect any
help. Otherwise we have no idea what went wrong, and only Psychic Vibration Mode can be
used to determine what has gone wrong.
For all we know, your assertion error could be in the array access, which could certainly
happen if the size was 0.
****
Using Newcomer's Viewport example I found on codeproject, i figured to
set the origin at bottom right having axis going back to bottom-left
and top-right it made me setting SetViewportOrg and SetWindowOrg
respectively to 0,0 and rect.BottomRight() so it would start from
bottom-right... and setting SetWindowExt to rect.Width() and
rect.Height() didn't produced any assertion errors but doesn't
repaints rescaled graphic (as you can see in the imageshack
screenshots put before).
****
There's another little glitch you may need to be concerned with: in all versions of
Windows < Vista, the DC for drawing has an area which encompasses the client area of the
parent window (as far as I can tell, this was always a stupid design mistake, and they
finally fixed it); therefore, if you want clipping, you may need to create a clipping
region and select it into the DC if you get "spillover".
****
Maybe I haven't got well in my mind about right settings of those
SetWindowOrg, SetWindowExt, SetViewportOrg, SetViewportExt...
****
One of the reasons I wrote the Viewport Explorer was because I always have trouble with
it, unless I checked with a certain book where I wrote the explanation. But I've
double-checked your settings, and they should scale the drawing to the rectangle, with the
origin in the lower left corner
joe
****
Any suggest?...
thanks
ciao
Luigi
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
Thanks for making things like viewport explorer available. Hopefully,