Re: Get Window Pixel

From:
=?Utf-8?B?U2F1bDc3NQ==?= <Saul775@discussions.microsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 8 Mar 2007 16:02:11 -0800
Message-ID:
<4E6B51B6-6CCA-41EF-AB1C-3C422987D4A9@microsoft.com>
Thank you for replying, Joseph.

I tried it the way you suggest, but everytime the return value for GetPixel
is always 0xFFFFFFFF. I can obviously see that the pixel is not white. Do
you know why?

That was my other question relating to this scenario. When I obtain a DC to
the client window. Does it actually copy the pixels of the current client
and use those values to initialize the DC?

"Joseph M. Newcomer" wrote:

This seems a remarkably convoluted way to solve a simple problem

CStatic::OnPaint();
CClientDC dc(this);
COLORREF c = dc.GetPixel(x, y); // for some x,y

Otherwise, to capture an entire screen, see my essay on my MVP TIps site on doing screen
capture to the clipboard. You can omit the steps that manipulate the clipboard.
                    joe

On Thu, 8 Mar 2007 13:03:55 -0800, Saul775 <Saul775@discussions.microsoft.com> wrote:

Hello:

I have a pixel on the screen that I'm trying to obtain the color. The pixel
is found in a static control, which is a class derived from CStatic.

class CReflectColorWnd : public CStatic

I've tried many ways to obtain the pixel, but I cannot attain the COLORREF
of the pixel. I'm wondering if anyone would be kind enough to assist me.

I've tried the following in the paint handler.

void CReflectColorWnd::OnPaint()
{
 CStatic::OnPaint(); // Call original paint

 CClientDC dc(this);

 CBitmap bm;
 bm.CreateCompatibleBitmap(&dc, 100, 100);

 CDC memDC;
 memDC.CreateCompatibleDC(&dc);

 CBitmap *pOrigBM = memDC.SelectObject(&bm);

 this->SendMessage(WM_PRINT, (WPARAM)memDC.GetSafeHdc(), (LPARAM)PRF_CLIENT);

 COLORREF cr = memDC.GetPixel(5, 5);

 memDC.SelectObject(pOrigBM);

 .. // Do something with the color obtained
}

This code, unfortunately, does not seem to work. I've been reading some
articles in the Newsgroups, and they indicate I should just obtain a
CClientDC to the window and just call .GetPixel(). I -- by experience --
perceive this to be a flaw, but I could be wrong. A DC doesn't take the
screen pixels to initialize the DC, does it? That said, I've tried it their
way and still have yet to obtain the pixel colors. Any ideas of what I can
alter or any other methods of obtaining the pixel? Thank you, all.

Saul775

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

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