SetPixel not working on Vista
Paul
SetPixel on Vista is acting strange. Certain areas it cannot draw on.
If I draw the entire window, then we can see the areas it can draw to,
which is vertical areas/bars that are a few hundred pixels wide. The
code works fine on my XP PC. So I thought there might be some window
app behind it preventing it from drawing in certain areas, but found
nothing. Changing the desktop to a solid color did nothing. Any ideas
what could be causing this? Here's the code,
void CTest1View::OnPaint()
{
CPaintDC dc(this); // device context for painting
if(IsIconic()){
return;
}
long x,y;
for(y=0; y < 1024; y++) {
for(x=0; x < 1024; x++) {
dc.SetPixel(x,y,0xff);
}
}
}
and another example,
void CTest2View::OnPaint()
{
CPaintDC dc(this); // device context for painting
if(IsIconic()){
return;
}
long x,y;
PAINTSTRUCT ps;
BeginPaint(&ps);
for(y=0; y < 1024; y++) {
for(x=0; x < 1024; x++) {
dc.SetPixel(x,y,0xff);
}
}
EndPaint(&ps);
}
Also I tried dc,
int save = dc.SaveDC(); // place this near start of code
...
dc.RestoreDC(save); // place this near end of code
Also I tried calling OnDraw the common way within OnPaint-- same
results.
I've tried everything I know. Change the window size. Regardless, the
above code always draws vertical bars that are black, white, black,
white, about ~ 200 pixels per bar.
Thanks for any suggestions.
Paul
Paul
Ha ha, would you believe it, after search for hours how to solve this
issue, just moments after my above post I found some info on this
Vista issue,
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=452578
Well, looks like it's a Windows Vista issue. Okay, I'll stay away from
SetPixel, as it was used only to see if a function was working, but
being a bit stuborn I wanted to dig down and get the SetPixel to work.
Regards,
Paul
Joseph M. Newcomer
On Tue, 20 Oct 2009 09:09:44 -0700 (PDT), Paul <energ...@gmail.com> wrote:
>Hi,
>
>SetPixel on Vista is acting strange. Certain areas it cannot draw on.
>If I draw the entire window, then we can see the areas it can draw to,
>which is vertical areas/bars that are a few hundred pixels wide. The
>code works fine on my XP PC. So I thought there might be some window
>app behind it preventing it from drawing in certain areas, but found
>nothing. Changing the desktop to a solid color did nothing. Any ideas
>what could be causing this? Here's the code,
>
>void CTest1View::OnPaint()
>{
> CPaintDC dc(this); // device context for painting
> if(IsIconic()){
> return;
> }
> long x,y;
> for(y=0; y < 1024; y++) {
> for(x=0; x < 1024; x++) {
> dc.SetPixel(x,y,0xff);
> }
> }
>}
***
I gather this is a test case to show the problem. This would be less than ideal in
practice. (besides, 0xff is not a color value; you should use the RGB macro). But in any
case, I just ran this on Vista and got a solid rectangle.
****
>
>
>and another example,
>
>void CTest2View::OnPaint()
>{
> CPaintDC dc(this); // device context for painting
> if(IsIconic()){
> return;
> }
> long x,y;
> PAINTSTRUCT ps;
> BeginPaint(&ps);
****
This code is erroneous. You already have a PAINTSTRUCT which has been set, and the second
BeginPaint is nonsensical. What do you think CPaintDC is doing?
****
> for(y=0; y < 1024; y++) {
> for(x=0; x < 1024; x++) {
> dc.SetPixel(x,y,0xff);
> }
> }
> EndPaint(&ps);
****
Of course, since the BeginPaint is wrong, the EndPaint is also wrong.
****
>}
>
>Also I tried dc,
>int save = dc.SaveDC(); // place this near start of code
>...
>dc.RestoreDC(save); // place this near end of code
***
Irrelevant.
****
>
>Also I tried calling OnDraw the common way within OnPaint-- same
>results.
****
Actually, you should not be doing any drawing in the OnPaint of a view; you should be
doing it exclusively in the OnDraw.
****
>
>
>I've tried everything I know. Change the window size. Regardless, the
>above code always draws vertical bars that are black, white, black,
>white, about ~ 200 pixels per bar.
****
There's something missing in your description, because I was able to use the code you
wrote and I get a solid rectangle (I used RGB(255, 0, 0) and got a solid red rectangle)
joe
****
>
>Thanks for any suggestions.
>Paul
Joseph M. Newcomer [MVP]
email: newc...@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
David Ching
news:02e2d860-1112-4155...@z4g2000prh.googlegroups.com...
> Ha ha, would you believe it, after search for hours how to solve this
> issue, just moments after my above post I found some info on this
> Vista issue,
>
> https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=452578
>
Don't you just love it when they say "Closed as Fixed" without telling you
what version the fix is in?
-- David
Paul
As the other guy stated, it occurs in certain Vista packages, and only
when in certain theme modes.
Paul
Paul
> "Paul" <energymo...@gmail.com> wrote in message
>
> news:02e2d860-1112-4155...@z4g2000prh.googlegroups.com...
>
> > Ha ha, would you believe it, after search for hours how to solve this
> > issue, just moments after my above post I found some info on this
> > Vista issue,
>
>
> Don't you just love it when they say "Closed as Fixed" without telling you
> what version the fix is in?
>
> -- David
Good point. Maybe it's a future version.
Paul
João Neto
Try this... works fine for me !
/* SetPixel problem with Vista:
(found here : http://www.codeproject.com/Messages/2515738/Re-Strange-bug-in-SetPixel-in-Visual-Cplusplus-pro.aspx)
I have hacked a temporary solution, thus, but I would prefer a proper
permanent solution:
*/
void Set_Pixel(HDC dc,int x,int y,COLORREF c);
#define SetPixel(dc,x,y,c) Set_Pixel(dc,x,y,c)
/*-----*/
void Set_Pixel(HDC dc,int x,int y,COLORREF c)
{
HPEN p=CreatePen(PS_SOLID,1,c),q;
q=(HPEN)SelectObject(dc,p);
MoveToEx(dc,x,y,0);
LineTo(dc,x,y+1);
SelectObject(dc,q);
DeleteObject(p);
}
Paul
> I have hacked a temporary solution, thus, but I would prefer a proper
> permanent solution:
> */
> void Set_Pixel(HDC dc,int x,int y,COLORREF c);
> #define SetPixel(dc,x,y,c) Set_Pixel(dc,x,y,c)
>
> /*-----*/
> void Set_Pixel(HDC dc,int x,int y,COLORREF c)
> {
> HPEN p=CreatePen(PS_SOLID,1,c),q;
> q=(HPEN)SelectObject(dc,p);
> MoveToEx(dc,x,y,0);
> LineTo(dc,x,y+1);
> SelectObject(dc,q);
> DeleteObject(p);
>
> }
Nice! Thanks, I see no reason why that would not work. :-)
Regards,
Paul