|
Hello everyone,
For the interface of a coclass, we can use the interface pointer to point to not only the coclass instance itself, but also pointing to the proxy for the original coclass (during marshalling).
My question is, does it mean the proxy class has the same memory signature as the coclass itself? If not, what are the differences between them and why we can use the same pointer to point to different memory signature?
thanks in advance,
George
|
|
|
|
|
George_George wrote: does it mean the proxy class has the same memory signature as the coclass itself?
If by "memory signature" you mean the layout of the interfaces and the behaviour of QueryInterface, then the answer is yes.
Steve
|
|
|
|
|
Thanks Steve,
1.
If we call QueryInterface on proxy object, we just query the interface of the proxy, not the actual original object, correct?
2.
Stephen Hewitt wrote: you mean the layout of the interfaces and the behaviour
Sorry my bad English is confusing. My confusion is why the same type of interface variable could be pointed to different types -- original coclass type and proxy object type?
regards,
George
|
|
|
|
|
George_George wrote: If we call QueryInterface on proxy object, we just query the interface of the proxy, not the actual original object, correct?
Yes, but as I said, the proxy will implement the same set of interfaces as the real object and as long as you follow the COM rules you will not notice any difference.
George_George wrote: Sorry my bad English is confusing. My confusion is why the same type of interface variable could be pointed to different types -- original coclass type and proxy object type?
Because, from a C++ point of view, an interface is a abstract base class: different object can implement the same abstract base class but they all can be pointed to by it.
Steve
|
|
|
|
|
Thanks Steve,
Let me confirm with your comments. Since both proxy object implements the same set of interfaces as the original coclass object, we can use the same interface variable to point to both proxy object and original coclass object, correct?
regards,
George
|
|
|
|
|
Yes, that's what interfaces are for. In C++ an interface is a pure abstract base class.
Steve
|
|
|
|
|
Thanks Steve!
Question answered.
regards,
George
|
|
|
|
|
there is a bits field structure like this:
typedef struct _bit_struct{
unsigned int sync:16;
unsigned resv:3;
union{
unsigned network_id:13;
unsigned map_id:13;
};
}bit_struct;
Any problem? Maybe union couldn't be included in bits field structure? because when i access(write) the union field, i find it writes wrong address(according to its assembly code).
thanks
|
|
|
|
|
be sure you have structure alignment set to one with the "pack" #pragma.
#pragma pack(1)
typedef struct _bit_struct{
unsigned int sync:16;
unsigned resv:3;
union{
unsigned network_id:13;
unsigned map_id:13;
}bit_struct;
|
|
|
|
|
the problem remains.
but its strange that when i use named union line bellow:
typedef struct _bit_struct{
unsigned int sync:16;
unsigned resv:3;
union id{
unsigned network_id:13;
unsigned map_id:13;
}bit_struct;
then, i write the union value like this:
bit_struct st;
st.id::network_id=**;
all will be ok. I am puzzled.
|
|
|
|
|
Hi All,
I'm porting my neat little C++ application written in win32/minGW to MSVC9/MFC. My old WindowProcedure function for message handling compiles, but doesn't actually work anymore at runtime. So I am learning how to handle events the MFC way.
I've declared a function in my dialog application's class declaration like so:
afx_msg LRESULT OnMyUserMessage(WPARAM wParam, LPARAM lParam);
But as soon as I add
ON_MESSAGE( WM_USER+1, OnMyUserMessage)
to the message map in my cpp file, I get the following linker error:
error LNK2001: unresolved external symbol "protected: long __thiscall CMyAppDlg::OnMyUserMessage(unsigned int,long)" (?OnMyUserMessage@CMyAppDlg@@IAEJIJ@Z)
Been scouring the boards now and a lot of people have had problems with casting but I can't find any instances of this. MSDN page says for ON_MESSAGE you need to include the afxmsg_.h header: did this and no change.
The mingw linker and I had just become friends! Any suggestions as to how to resolve this?
|
|
|
|
|
I think you should define your specified MSG like:
in your UsrMsg.h or .h file anywhere
<br />
#define UM_MY_MSG WM_USER + 10
secondly, use ::SendMessage to consume the message:
::SendMessage(pWnd->GetSafeHwnd(), UM_MY_MSG, NULL, NULL); //Let's assume pWnd is a CMyDialog instance
thirdly in CMyDialog to map the UM_MY_MSG message
BEGIN_MESSAGE_MAP(CMyDialog , CDialog)
<font color="blue">ON_MESSAGE(UM_MY_MSG, OnDealMsg)</font>
END_MESSAGE_MAP
forthly implement the OnDealMsg method! Hope it helps!
modified on Tuesday, August 5, 2008 10:15 PM
|
|
|
|
|
The OnMyUserMessage() method has to exist for the link to succeed.
You should also base your messages on WM_APP (or a registered window message)
instead of WM_USER to prevent conflicts with window messages used by MFC.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://www.codeproject.com/script/Forums/Images/coffee.gif)
|
|
|
|
|
Thanks guys, I'm back up and running now thanks to your suggestions. Mark's hint to change the message to WM_APP seemed to do the trick!
|
|
|
|
|
How do I alter the mfc image icon - (on the top left corner of all programs)
I have tried to do this in the resource - icon - idr_mainframe section
but nothing is implemented when I modify the image
Thanks
Simon
|
|
|
|
|
After the window is created, you can use something like
hIcon = AfxGetApp()->LoadIcon(IDI_ICON1);
SetIcon(m_hIcon, TRUE);
SetIcon(m_hIcon, FALSE);
hIcon = ::LoadIcon(hInstance, MAKEINTRESOURCE(IDI_ICON1));
::SendMessage(hwnd, WM_SETICON, ICON_BIG, (LPARAM)hIcon);
::SendMessage(hwnd, WM_SETICON, ICON_SMALL, (LPARAM)hIcon);
Mark Salsbery
Microsoft MVP - Visual C++
|
|
|
|
|
Keep in mind that an Icon resource can contain multiple images in many sizes and color depths. The operating system attempts to load the best icon for the situation. In your case, you may have edited the 32x32 icon but not the 16x16 icon used for the upper left corner.
|
|
|
|
|
Hello,
I am writing a program about using the CSliderCtrl (vc provided) to control the ruler.
There is also a scroll bar for the ruler. (Sometimes the ruler length may be too long)
All I want is when I dragging the slider, the interval between two meter unit of the ruler will be changed automatically.
The ruler I used is this : http://www.codeproject.com/KB/miscctrl/uhrulerctrl.aspx
Now the interval between two meter unit would be changed when I dragged the slider.
But there's another problem. The problem is the ruler will jump to the start meter of the ruler automatically. (The scrollbar is activated)
I want the ruler can keep the original position when I dragged the slider.
(The ruler can keep the original position by a scrollbar in the demo project)
I tried some methods but the ruler always jump to the start meter...
Can someone help me to solve this question ?
Below is my part code :
void CtrlRulerDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)<br />
{ <br />
SCROLLINFO si;<br />
m_ScrollBar.GetScrollInfo( &si , SIF_ALL );<br />
INT iScrollPos = si.nPos;<br />
int i = 0;<br />
<br />
switch( nSBCode ) {<br />
case TB_PAGEDOWN:<br />
si.nPos += 5;<br />
i = m_Slider.GetPos();<br />
break;<br />
case TB_PAGEUP:<br />
si.nPos -= 5;<br />
i = m_Slider.GetPos();<br />
break;<br />
case TB_THUMBTRACK:<br />
i = m_Slider.GetPos();<br />
si.nPos = i*10;<br />
break;<br />
};<br />
<br />
si.fMask = SIF_POS;<br />
<br />
if( iScrollPos != si.nPos )<br />
{<br />
m_ScrollBar.SetScrollInfo( &si );<br />
UpdateData();<br />
m_HRuler.SetMilimeterPixel(i); <br />
m_HRuler.SetScrollPos( m_nScrolPos ); <br />
m_HRuler.Invalidate(); <br />
}<br />
<br />
CDialog::OnHScroll(nSBCode, nPos, pScrollBar);<br />
}<br />
My Environment is : Windows Vista SP1, VS 2005 SP1, MS Platform SDK 2003 SP1
Thank you very much!
|
|
|
|
|
Hi all,
I have a static control which i converted into a hyperlink control. Whenever i needs to set focus to this control, i done it using "DrawFocusRect()". Now what should be done in order to remove that focus rectangle.
Please suggest.
By default, the color of the hyperlink is appearing black. I need to change it to blue(default) and violet (when visited).
Please suggest.
|
|
|
|
|
Typically, calling DrawFocusRect a second time with the same coordinates erases the rectangle.
What version of Visual C++ are you using? 2003 and later have a hyperlink control (CLinkCtrl) that is not very well documented until VS2008, but still usable. If you want to use it, it is a little tricky to set up since there is no item in the toolbox for it, but if you drop a custom control on the dialog and set the window class to "SysLink" and give it a non IDC_STATIC ID, all the goodies for it come alive and you can add event handlers, etc. It will do all the visited, focused, etc. on its own.
|
|
|
|
|
I am using VS2003 but i did'nt use CLinkCtrl. I created a seperate class which converts the static text to hyperlink control.
|
|
|
|
|
I use ado _RecordsetPtr to get an item from oracle database using GetValue()to read a field named Source which is of varchar2(10) datatype.
variant_t vtSource = rst->Fields->GetItem("SOURCE")->GetValue();
Can anyone show me sample code on how to convert vtSource which is of variant_t data type to char* or char array or const char* or CString data type?
|
|
|
|
|
yklim wrote: variant_t vtSource = rst->Fields->GetItem("SOURCE")->GetValue();
if you meant _variant_t then take a look at _bstr_t
led mike
|
|
|
|
|
CString has an overloaded = operator for VARIANT type so long as the variant is filled with BSTR data (ie what you would get from ADO) so you could do this:
VARIANT vt;<br />
CString str; <br />
<br />
<br />
str=vt;<br />
|
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
