Re: Fixing incorrect clip box on multi-monitor machines

I'm using Visual Studio 6.0 (newest SP) on XP SP2.

You seem to be right: Both MFC and direct API calls show the same behaviour.
But it's not quite as simple as that - I've tried a few more things, and the
results confuse me quite a little:

TextOut called directly within the OnPaint event handler will render to the
3rd monitor (both the MFC and API variant). LineTo and DrawClipRect will not
do so.
When calling a function from OnPaint (handing over the dc), even TextOut
will no longer render to the 3rd monitor.
When I restrict my form to use only the middle and right monitors, I can
suddenly draw on the rightmost monitor (but of course, then I can't draw on
the lestmost monitor).

I also have no problems drawing on my leftmost (=negative coordinate)
monitor. I seem to run into trouble only when my client coordinates exceed
the maximum screen coordinate. However, within other applications this seems
to work, so I don't really suspect the graphics drivers.
BTW it's a single graphics card which can manager up to four display
monitors. Each monitor is seen by Windows as a single display (when you go
to display properties / settings).

The application I have is already very trivial. At times it basically only
had an OnPaint handler with the lines and TextOut drawn (and the latter one
only for test purposes).

I can post the current code here...(warning: I haven't worked with C / C++ /
MFC for years, the code might look a bit awkward...)

// clsBackgroundForm.cpp : implementation file
//

#include "stdafx.h"
#include "winuser.h"
#include "WR_MFC_Functions.h"
#include "clsBackgroundForm.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

////////////////////////////////////////////////////////////////////////////
/
// clsBackgroundForm dialog

clsBackgroundForm::clsBackgroundForm(CWnd* pParent /*=NULL*/)
 : CDialog(clsBackgroundForm::IDD, pParent)
{
 //{{AFX_DATA_INIT(clsBackgroundForm)
  // NOTE: the ClassWizard will add member initialization here
 //}}AFX_DATA_INIT
}

void clsBackgroundForm::DoDataExchange(CDataExchange* pDX)
{
 CDialog::DoDataExchange(pDX);
 //{{AFX_DATA_MAP(clsBackgroundForm)
  // NOTE: the ClassWizard will add DDX and DDV calls here
 //}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(clsBackgroundForm, CDialog)
 //{{AFX_MSG_MAP(clsBackgroundForm)
 ON_WM_RBUTTONUP()
 ON_WM_PAINT()
 ON_WM_LBUTTONDOWN()
 ON_WM_LBUTTONUP()
 ON_WM_MOUSEMOVE()
 //}}AFX_MSG_MAP
END_MESSAGE_MAP()

////////////////////////////////////////////////////////////////////////////
/
// clsBackgroundForm message handlers

HDC hMemDC;
HBITMAP hBmp;
HBITMAP hOldBmp;
int x,y,w,h;
int isButtonDown;
CPoint ptStart, ptEnd, ptPrevEnd, ptPrevStart;
CPen myPen;
int isLassoDrawn;
int forceFullRedraw;

void clsBackgroundForm::PaintLines(CPaintDC* dc, CPoint ptFrom, CPoint ptTo)
{
 CRect r;

 if (ptStart == ptTo)
 {
  return;
 }

 dc->SelectObject(myPen);
 int hOldRasterMode = dc->SetROP2(R2_NOT);

 // Only test
 dc->TextOut(2500, 72, "Hello MFC!");
 ::TextOut(*dc,2500,372,"Hello API!",10);

 dc->MoveTo(ptStart.x,ptStart.y);
 dc->LineTo(ptTo.x,ptStart.y);
 dc->LineTo(ptTo.x,ptTo.y);
 dc->LineTo(ptStart.x,ptTo.y);
 dc->LineTo(ptStart.x,ptStart.y);

 isLassoDrawn = !isLassoDrawn;
}

void clsBackgroundForm::OnRButtonUp(UINT nFlags, CPoint point)
{
 // TODO: Add your message handler code here and/or call default
 CDialog::EndDialog(0);
 CDialog::OnRButtonUp(nFlags, point);
}

BOOL clsBackgroundForm::OnInitDialog()
{
 CDialog::OnInitDialog();
 HDC hScreenDC = ::GetDC(NULL);

 x = GetSystemMetrics(SM_XVIRTUALSCREEN);
 y = GetSystemMetrics(SM_YVIRTUALSCREEN);
 w = GetSystemMetrics(SM_CXVIRTUALSCREEN);
 h = GetSystemMetrics(SM_CYVIRTUALSCREEN);

 /*
 // When I do this, I can draw on the rightmost monitor, but no longer on
the leftmost
 x = 0;
 w = 2560;
 */

 CDialog::MoveWindow(x,y,w,h);
 myPen.CreatePen(PS_SOLID | PS_GEOMETRIC,1,RGB(255,0,0));

 hMemDC = CreateCompatibleDC(hScreenDC);
 hBmp = CreateCompatibleBitmap(hScreenDC,w,h);

 static_cast<HBITMAP>(SelectObject(hMemDC,hBmp));

 // Capture the screen
 BitBlt(hMemDC,0,0,w,h,hScreenDC,x,y,SRCCOPY);

 ::ReleaseDC(NULL,hScreenDC);

 return TRUE; // return TRUE unless you set the focus to a control
               // EXCEPTION: OCX Property Pages should return FALSE
}

void clsBackgroundForm::OnPaint()
{
 CRect r,rPrev;
 CRgn rgn;
 CPaintDC dc(this); // device context for painting

 if ((forceFullRedraw) || (!isButtonDown))
 {
  // Paste my screen capture on my window
  StretchBlt(dc,0,0,w,h,hMemDC,0,0,w,h,SRCCOPY);
  isLassoDrawn=0;
 }

 // Only test
 dc.TextOut(2500, 572, "Hello MFC!");
 ::TextOut(dc,2500,772,"Hello API!",10);

 if (isLassoDrawn)
 {
  PaintLines(&dc, ptPrevStart, ptPrevEnd);
 }
 ptPrevEnd = ptEnd;
 ptPrevStart = ptStart;

 PaintLines(&dc, ptStart, ptEnd);

 forceFullRedraw=0;
}

BOOL clsBackgroundForm::DestroyWindow()
{

 myPen.DeleteObject();
 DeleteObject(SelectObject(hMemDC,hOldBmp));
 DeleteDC(hMemDC);

 return CDialog::DestroyWindow();
}

void clsBackgroundForm::OnLButtonDown(UINT nFlags, CPoint point)
{
 CRect r;
 GetWindowRect(&r);

 InvalidateRect(&r,0);

 ptStart = point;
 ptEnd = ptStart;
 isButtonDown=1;
 forceFullRedraw=1;

 CDialog::OnLButtonDown(nFlags, point);
}

void clsBackgroundForm::OnLButtonUp(UINT nFlags, CPoint point)
{
 ptEnd = point;
 isButtonDown=0;

 ptStart.x += x;
 ptStart.y += y;
 ptEnd.x += x;
 ptEnd.y += y;

 CDialog::OnLButtonUp(nFlags, point);
 m_strRange.Format ("%d;%d;%d;%d",ptStart.x, ptStart.y, ptEnd.x, ptEnd.y);
}

void clsBackgroundForm::OnMouseMove(UINT nFlags, CPoint point)
{
 if (isButtonDown)
 {
  ptEnd = point;
  CRect r;
  GetWindowRect(&r);

  InvalidateRect(&r,0);
 }

 CDialog::OnMouseMove(nFlags, point);
}

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:kt1vc2p07erjjdcio9av6hgtoufeohhio1@4ax.com...


e.g., are you using


doesn't create the


trivial example


on my left-hand


a bug in the


the vendor of


have a single


have two cards


Playing Well With


machine


to