|
Hi,
What you do is that you create a compatible device context (CreateComaptibleDC), and you create a bitmap, the size of your original bitmap (CreateCompatibleBitmap). You select this bitmap into your compatible DC.
Now, you have an area in which you can save your original background.
First, you copy the information on the screen (from the original device context) into your compatible device context, using BitBlt.
Then you draw your circle. When you act on a mouse-move event, you restore the original background again (using BitBlt, copying from your compatible DC to your original DC) and then you re-draw the circle on its new location.
If you need some more info on the subject, I could probably cut and paste some sample code from an existing project.
Have fun!
William.
|
|
|
|
|
Hi Edinburg,
Please help me out. I am sending the code what i have written to draw the Circle.
//========================================================================
void CPaintingView::OnLButtonDown(UINT nFlags, CPoint point)
{
Anchor.x = point.x;
Anchor.y = point.y;
OldPoint.x = Anchor.x;
OldPoint.y = Anchor.y;
CScrollView::OnLButtonDown(nFlags, point);
}
void CPaintingView::OnLButtonUp(UINT nFlags, CPoint point)
{
DrawTo.x = point.x;
DrawTo.y = point.y;
CClientDC dc(this);
if(bEllipseFlag)
{
SetCursor(AfxGetApp()->LoadCursor(IDC_CURSOR1));
dc.SelectStockObject(NULL_BRUSH);
dc.Ellipse(Anchor.x, Anchor.y, DrawTo.x, DrawTo.y);
}
CScrollView::OnLButtonUp(nFlags, point);
}
void CPaintingView::OnMouseMove(UINT nFlags, CPoint point)
{
int nOldMode;
CClientDC* pDC = new CClientDC(this);
if((nFlags && MK_LBUTTON) && bEllipseFlag)
{
SetCursor(AfxGetApp()->LoadCursor(IDC_CURSOR1));
nOldMode = pDC->GetROP2();
pDC->SetROP2(R2_NOT);
pDC->SelectStockObject(NULL_BRUSH);
pDC->Ellipse(OldPoint.x, OldPoint.y, Anchor.x, Anchor.y);
pDC->Ellipse(Anchor.x, Anchor.y, point.x, point.y);
OldPoint.x = point.x;
OldPoint.y = point.y;
pDC->SetROP2(nOldMode);
szPosx.Format("%d",point.x);
szPosy.Format("%d",point.y);
Res = "x=";
Res += szPosx;
Res += ",";
Res += "y=";
Res += szPosy;
CMainFrame* pFrameParent = (CMainFrame *)GetParentFrame();
pFrameParent->m_wndStatusBar.SetPaneText(4,Res);
}
delete pDC;
CScrollView::OnMouseMove(nFlags, point);
}
void CPaintingView::OnLButtonDblClk(UINT nFlags, CPoint point)
{
if(bEllipseFlag == true)
{
CRect rect;
ClientToScreen(&rect);
GetClientRect(&rect);
InvalidateRect(rect,TRUE);
}
CScrollView::OnLButtonDblClk(nFlags, point);
}
//===========================================================================
Please help me out.
uday
|
|
|
|
|
Hi Uday,
I would be thinking along the following lines:
//=======================================================
// Existing variables:
CDC * m_pDC;
CDC m_CompatibleDC;
CBitmap * m_pBitmap;
RECT m_Rect;
// constructor initialization:
m_pDC = (CDC *)NULL;
m_pBitmap = (CBitmap *)NULL;
// OnLButtonDown (draw the first circle)
void CPaintingView::OnLButtonDown(UINT nFlags, CPoint point)
{
if (m_pDC == (CDC *)NULL) // first time?
{
m_pDC = GetDC (); // create the device context
m_CompatibleDC.CreateCompatibleDC (m_pDC); // and a helper context
}
GetClientRect (&m_Rect); // get the required size
if (m_pBitmap != (CBitmap *)NULL) // we want a fresh bitmap
delete m_pBitmap; // so delete any old stuff
m_pBitmap = new CBitmap; // and create the new one
m_pBitmap->CreateCompatibleBitmap (m_pDC, m_Rect.right, m_Rect.bottom);// create the helper bitmap with the correct size
m_CompatibleDC.SelectObject (m_pBitmap); // and select it into the DC
m_CompatibleDC.BitBlt (0,0,m_Rect.right,m_Rect.bottom,m_pDC, // copy the current screen content
0,
0,
SRCCOPY);
Anchor.x = point.x;
Anchor.y = point.y;
CScrollView::OnLButtonDown(nFlags, point);
}
void CPaintingView::OnMouseMove(UINT nFlags, CPoint point)
{
m_pDC->BitBlt (0,0,m_Rect.right,m_Rect.bottom, // restore original screen content
&m_CompatibleDC,
0,
0,
SRCCOPY);
m_pDC->Ellipse(Anchor.x, Anchor.y, point.x, point.y); // and redraw the circle
}
void CPaintingView::OnLButtonUp(UINT nFlags, CPoint point)
{
// Draw definitive circle
m_pDC->BitBlt (0,0,m_Rect.right,m_Rect.bottom, // restore original screen content
&m_CompatibleDC,
0,
0,
SRCCOPY);
DrawTo.x = point.x;
DrawTo.y = point.y;
m_pDC->Ellipse(Anchor.x, Anchor.y, DrawTo.x, DrawTo.y);
m_CompatibleDC.DeleteDC (); // remove helper DC
m_pBitmap->DeleteObject (); // and bitmap
}
//======================================================
|
|
|
|
|
Hi edenburg,
very very thanks to you, you have solved my problem.
i am really thankful to you.
uday
|
|
|
|
|
Hai all,
I am working with MFC Vc++ 6.0.I wanted to add some external header files in to extenal dependencies fileview.How is it possible.Please help me
Thanks in advance
vinod
|
|
|
|
|
open your project properties
in the C/C++ section, there might be a "Additional Include Directories" section. then add the folder which contains the headers you need. be sure to add it on both debug and release configurations
|
|
|
|
|
if u include a file say #include"Iostream.h" in any of ur project files, it will automatically get added in the external dependencies fileview.
nave
|
|
|
|
|
|
But why u want to add that files in the external dependencies?
nave
|
|
|
|
|
Hi All,
I was trying with Michael Dunn's article on Introduction to COM
I had a try with my own console application. But in the beginning itself, it said that IActiveDesktop is undeclared. I included shlobj.h but no use at all.
But the sample he provided working fine in VC++ 7.0 but mine is not working well
could you please help me in this regard?
|
|
|
|
|
Did you see StdAfx.h in example form Mr Michael Dunn's if you see you can solve your problem
|
|
|
|
|
I created an application which is using precompiled header.
Even I copied his code to a new project file with same name, it's not working.
I think i have to do something wtih project settings.. can't find what it is
|
|
|
|
|
I dont understand why you cant find your problem its not hard I see this article and see stdafx.h I suggest you check all include files in this article I hope you find your problem
|
|
|
|
|
Look in the header files. I've had a look and it seems that:
- WIN32_IE needs to be defined >= 0x400.
- _WININET_ needs to be defined.
You get _WININET_ defined by #include ing <WinInet.h> before you #include <ShlObj.h> . You typically define WIN32_IE in your "stdafx.h" with code something like the following:
#define _WIN32_IE 0x0400
Do this before you include any files.
Steve
|
|
|
|
|
Can I pass a parameter to the function if I have a worker thread and use AfxBeginThread?
|
|
|
|
|
From MSDN[^]:
CWinThread* AfxBeginThread(
AFX_THREADPROC pfnThreadProc,
LPVOID pParam,
int nPriority = THREAD_PRIORITY_NORMAL,
UINT nStackSize = 0,
DWORD dwCreateFlags = 0,
LPSECURITY_ATTRIBUTES lpSecurityAttrs = NULL
);
pParam<br />
Parameter to be passed to the controlling function as shown in the parameter to the function declaration in pfnThreadProc.
|
|
|
|
|
I've also read that but I still don't understand??!!?
|
|
|
|
|
Then ask a clear question. What is your problem ?? We cannot guess it.
Why don't you just pass your data (as a pointer for example) using this parameter ?
|
|
|
|
|
This is my controling function
UINT CMina_sView::run(LPVOID p)<br />
{<br />
<br />
CMina_sView * me = (CMina_sView *)p;<br />
me->ascultarea();<br />
return 0;<br />
<br />
}
And this is how I start the thread
void CMina_sView::OnList() <br />
{ <br />
running = TRUE;<br />
AfxBeginThread(run, this);<br />
}
I want to pass a paramater to ascultarea. How do i do it?
|
|
|
|
|
You already passed a parameter to your thread: it's the address of the class (the this parameter). So, you cannot pass two parameters.
But, why do you want to pass a parameter to this function ? Why don't you just have a member variable that hold this variable so that the function ascultarea can use it ?
|
|
|
|
|
The OnList is a menu item that opens a dialog in which I can select smth a i hold that in dlg.m_sel. I want to be able to pass dlg.m_sel to ascultarea.
|
|
|
|
|
tanarnelinistit wrote: I can select smth a i hold that in dlg.m_sel
Please make a little effort on the spelling because I cannot understand (english is not my mother tongue).
When are you opening the dialog ? Before or after spawning the thread ? If it is after, then why don't you simply take this value (dlg.m_sel) and store it into a member variable of CMina_sView ? Then in your thread, as you call the function ascultarea, as it is inside the SAME class, you don't need to pass it to the function. The function can simply get it from the member variable.
I think the problem is that you don't know what you are doing. You probably found some snippet of code to start the thread but you don't understand the mechanics beyond that. Am I right ? Then, I cannot explain you in details because the subject is fairly too large. (And I already provided you with the solution).
|
|
|
|
|
1)I knew I should've studied french a little more in highschool.
2)I started programing in VC++ just one month ago but I've read and understood anything I could in one month.
3) I open the dialog and then I spawn the thread.
|
|
|
|
|
I already explained you the solution 2 times. Once more won't help you to understand it better. After one month of studying C++, it is not a good idea to jump directly to thread manipulation (even more if you didn't know a programming language before).
The only advice I can give you is: start slowly. Try to find a good book or course and start to learn the basics first. Otherwise, you'll screw up everything and you'll be really disgusted for life.
|
|
|
|
|
Ok. Thanks a lot. Although I feel a little bit disapointed now, I got your point.
|
|
|
|
|