Re: BSTR to const char[] - ATL / WTL / STL Discussion Boards

User 21559730-Sep-04 0:35

30-Sep-04 0:35

Hi Nathan,
Thanks for the detailed explanation. I agree about the Binary Structure that must be standard for all interfaces and thats why COM avoids multiple inheritance among interfaces

Nathan Holt at CCEI wrote:
Multiple inheritence of interfaces would require the fourth slot to contain both the IBase1 member and the *Base2 member, which is not possible

Can you please explain me more on this. I am confused abt the above quote. What I know is there can be multiple inheritance possible among structures. COM interface is nothing but a Structure. So why would it be not possible to have multiple inhertance amongst interface ?

Thanks again

-------------------------
Have a great day ahead!
Regards,
Sohail Kadiwala

modified 21-Apr-21 21:01pm.

Re: COM and Multiple inheritance

Nathan Holt at EMOM30-Sep-04 4:49

Nathan Holt at EMOM

30-Sep-04 4:49

sohailkadiwala wrote:
Can you please explain me more on this. I am confused abt the above quote. What I know is there can be multiple inheritance possible among structures. COM interface is nothing but a Structure. So why would it be not possible to have multiple inhertance amongst interface ?

Sure. Multiple inheritance in C++ can rely on detailed information about the object. If both base classes have virtual functions, then the derived class will have two pointers to two different virtual function tables. (The virtual function tables are the tables I described in the previous message.) I don't know if C++ specifies the order the pointers occur in, and I'm pretty sure it doesn't specify how far apart the pointers are. This would make it difficult to specify a binary standard for multiple inheritance in interfaces.

In practice, I suspect that Microsoft could have defined their own standards for windows C++ compilers that would have made multiple inheritance of interfaces possible, but they didn't. In fact, there are a disturbing number of people who seem to think multiple inheritance was a mistake.

Nathan Holt

Re: COM and Multiple inheritance

User 2155971-Oct-04 4:00

User 215597

1-Oct-04 4:00

Thanks Nathan.
Very informative. Helped me understand the concept in a much better way.
Thanks Again Smile | :)

-------------------------
Have a great day ahead!
Regards,
Sohail Kadiwala

modified 21-Apr-21 21:01pm.

BSTR to const char[]

AssemblySoft20-Sep-04 7:10

AssemblySoft

20-Sep-04 7:10

I've created a get / put property inside an activeX control. I know the functionality is working ok because i've tested it with script <param =="" />

What i now need to do is copy the BSTR into a char* or c style array.
I've tried:

char str[MAX_PATH];
CComBSTR m_bstrString;

put:
ATLTRACE(_T("String assigned to: %ls\n"),newVal);
m_bstrFileString = newVal; //assign btr to CComBSTR

//do conversion
BSTR var = m_bstrString.Copy();
strcat(str,(LPCTSTR)var);

It only seems to be copying the first char?

Please help D'Oh! | :doh:

Re: BSTR to const char[]

Anonymous20-Sep-04 9:19

Anonymous

20-Sep-04 9:19

I'm sure this will help:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_atl_String_Conversion_Macros.asp[^]

Re: BSTR to const char[]

SandeepN20-Sep-04 10:21

SandeepN

20-Sep-04 10:21

The following line has undefined variable m_bstrFileString (could be typo)
m_bstrFileString = newVal; //assign btr to CComBSTR

Note : W2A macros has limitation, can not be used in loop. It can convert max 500KB of chars

One more soln would be using _bstr_t class..
For Ex:

char str[MAX_PATH];
_bstr_t str1(newVal);
strcpy(str,(char *)str1);

Sandeep Naik

Re: BSTR to const char[]

AssemblySoft20-Sep-04 12:56

AssemblySoft

20-Sep-04 12:56

thanks i will try that.

Could you please have a look at my thread 'ATL activeX control Initialize', directly below this one.

Re: BSTR to const char[]

AssemblySoft20-Sep-04 12:56

AssemblySoft

20-Sep-04 12:56

thanks i will try that.

Could you please have a look at my thread 'ATL activeX control Initialize', directly below this one.

Re: BSTR to const char[]

Michael Dunn20-Sep-04 10:56

Michael Dunn

20-Sep-04 10:56

See The Complete Guide to C++ Strings, Part II - String Wrapper Classes[^]

--Mike--
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Re: BSTR to const char[]

AssemblySoft20-Sep-04 12:57

AssemblySoft

20-Sep-04 12:57

thanks i will try that.

Could you please have a look at my thread 'ATL activeX control Initialize', directly below this one.

ATL activeX control Initialize

AssemblySoft20-Sep-04 7:02

AssemblySoft

20-Sep-04 7:02

Hi, i've just created an ATL dll which houses a full control for activeX support.

Basically it's working ok.
However i need to run some code once the control has been installed successfully. (after Register server)
This control is windowless.
In an MFC based control i could use something like OnCreate() but i don't have a clue where to start here.

I basically need an event that gets called once the control is installed.

Please Help Eek! | :eek:

Thanks in advance!!!

Carl

Re: ATL activeX control Initialize

Michael Dunn20-Sep-04 13:27

Michael Dunn

20-Sep-04 13:27

You can add your code to the global function DllRegisterServer(), although maybe I'm misunderstanding because the type of control doesn't matter at registration time.

--Mike--
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RichEdit

_johan18-Sep-04 11:05

_johan

18-Sep-04 11:05

Hello
Every time I try to create a RichEdit (using CRichEditCtrl), Create fails and GetLastError returns either ERROR_CANNOT_FIND_WND_CLASS or ERROR_CLASS_DOES_NOT_EXIST. I looked in the CRichEditCtrl class and the window class seems to be "RICHEDIT". Has anyone else had this problem or am I just doing something wrong? (When I use MFC, it works fine.)

Re: RichEdit

Michael Dunn18-Sep-04 13:01

Michael Dunn

18-Sep-04 13:01

In your app's init code, call:
LoadLibrary ( CRichEditCtrl::GetLibraryName() );
This is the equivalent of AfxInitRichEdit() in MFC.

--Mike--
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Re: RichEdit

_johan19-Sep-04 17:47

_johan

19-Sep-04 17:47

Great! Thanks a lot.

why ATL based ACTIVEX control got flicker when Redraw

max_xiayi17-Sep-04 12:54

max_xiayi

17-Sep-04 12:54

Hi,All,I am developing an ACTIVEX control embedded in IE, which is used to display continuous jpegs captured from a server.Firstly I wrote my ACTIVEX control in MFC,and call InvalidateControl() to realize control window redraw.It is ok.Then I rewrote my ACTIVEX in ATL,most of the code regards to grapic are same,but this time since InvalidateControl() can not be called in ATL based control, I call FireViewChange() to realize control window redraw time by time.However,I found that the control window got flicker when it is redraw.What happened and how to deal with?

please contact:
max_xiayi@hotmail.com

Re: why ATL based ACTIVEX control got flicker when Redraw

Todd Smith17-Sep-04 14:12

Todd Smith

17-Sep-04 14:12

FireViewChange() calls InvalidateRect with bErase=TRUE. You'll need to write your own FireViewChange() and pass FALSE for bErase.

<br />
inline HRESULT CComControlBase::FireViewChange()<br />
{<br />
	if (m_bInPlaceActive)<br />
	{<br />
		// Active<br />
		if (m_hWndCD != NULL)<br />
			::InvalidateRect(m_hWndCD, NULL, TRUE); // Window based<br />
		else if (m_spInPlaceSite != NULL)<br />
			m_spInPlaceSite->InvalidateRect(NULL, TRUE); // Windowless<br />
	}<br />
	else // Inactive<br />
		SendOnViewChange(DVASPECT_CONTENT);<br />
	return S_OK;<br />
}<br />

Todd Smith

Re: why ATL based ACTIVEX control got flicker when Redraw

greekgoddj11-Jan-05 22:49

greekgoddj

11-Jan-05 22:49

Having the same problem here. I have tried the above suggestion but it has not worked. I still get flickering. I have also user temporary DC buffer to do all the drawing onto before copying the buffer to the final output in one step.

Anybody come up with another way arround this?

Thanks,

Aristotel Sniff | :^)

Re: why ATL based ACTIVEX control got flicker when Redraw

greekgoddj30-Jan-05 23:13

greekgoddj

30-Jan-05 23:13

Anyone?

Re: why ATL based ACTIVEX control got flicker when Redraw

greekgoddj31-Jan-05 3:14

greekgoddj

31-Jan-05 3:14

Ok...quite embarrasing but basically I had forgotten to add

MESSAGE_HANDLER(WM_ERASEBKGND, OnEraseBkgnd)

So onEraseBkgnd was not being called at all. Silly me... Unsure | :~

Can't make work FireOnChanged

Anonymous17-Sep-04 11:22

Anonymous

17-Sep-04 11:22

Hi
I create in VC.7 an control and when one of property change it affected other,
and container should change this second property also.But when i test
my control in VB.NET affected property not changed(in property window),althoughi invoke FireOnChange for one.

<br />
//In header <br />
class ATL_NO_VTABLE CMyControl : <br />
	public CComObjectRootEx<CComSingleThreadModel>,<br />
	public CStockPropImpl<CMyControl, IDigDisplay><br />
	public IPersistStreamInitImpl<CMyControl>,<br />
	public IOleControlImpl<CMyControl>,<br />
	public IOleObjectImpl<CMyControl>,<br />
	public IOleInPlaceActiveObjectImpl<CMyControl>,<br />
	public IViewObjectExImpl<CMyControl>,<br />
	public IOleInPlaceObjectWindowlessImpl<CMyControl>,<br />
	public IConnectionPointContainerImpl<CMyControl>,<br />
	public IPropertyNotifySinkCP<CMyControl>,<br />
	public CProxy_IDigDisplayEvents<CMyControl>, <br />
	public IPersistStorageImpl<CMyControl>,<br />
	public ISpecifyPropertyPagesImpl<CMyControl>,<br />
	public IQuickActivateImpl<CMyControl>,<br />
	public IDataObjectImpl<CMyControl>,<br />
	public IProvideClassInfo2Impl<&CLSID_CMyControl, &__uuidof(_IMyControlEvents), &LIBID_MyControlLib>,<br />
	public CComCoClass<CDigDisplay, &CLSID_CMyControl>,<br />
	public CComControl<CMyControl><br />
{<br />
..<br />
}<br />
//All aboved interfaces include in com_map<br />
//and IPropertyNotifySinkCP inclued in connection_point_map <br />
<br />
//cpp<br />
<br />
// [id(1),firerequestedit,bindable]<br />
CMyControl()::put_FirstProperty(short newVal)<br />
{<br />
 m_firstValue = newVal;<br />
 m_secondValue = newVal + 1;<br />
<br />
FireOnChanged(1);<br />
FireOnChanged(2);<br />
}<br />
<br />
...<br />
<br />
//[id(2),firerequestedit,bindable]<br />
CMyControl()::put_SecondProperty(short newVal)<br />
{<br />
m_secondValue = newVal;<br />
FireOnChanged(2);<br />
}<br />
<br />
//[id(2),firerequestedit,bindable]<br />
CMyControl()::get_SecondProperty(short* pVal)<br />
{<br />
*pVal = m_secondValue;<br />
}<br />
<br />

Thats i miss here???
Thank

Flickering problem

qur17-Sep-04 0:42

qur

17-Sep-04 0:42

I am trying to develop the gird control in which Comboboxes are displayed over each subitem.
In DrawItem event i am displaying the combobox for each subitem, which is i think cause the flickering problem. Anyone knows the solution to remove the flickering in this scenario.

<br />
for(int nRow = 0; nRow < rows; ++ nRow)<br />
{<br />
	<br />
        for(int nCol = 0; cols; nCol++ )<br />
	{<br />
              //Drawing combos by ShowWindow(SW_SHOW) call<br />
	}<br />
}<br />

Re: Flickering problem

Jason De Arte20-Sep-04 12:56

Jason De Arte

20-Sep-04 12:56

While I've never had to do what you're doing, two things come to mind
1. Queue up the display of multiple windows with DeferWindowPos()
2. In the parent, change the erase background code to create a region that exclude the area of the child windows - I neat trick for dealing with excessive flickering when resizing a dialog.
I hope this helps

[ Jason De Arte | Toy Maker | 1001010.com ]

Re: Flickering problem

Jörgen Sigvardsson20-Sep-04 13:47

Jörgen Sigvardsson

20-Sep-04 13:47

Jason De Arte wrote:
2. In the parent, change the erase background code to create a region that exclude the area of the child windows - I neat trick for dealing with excessive flickering when resizing a dialog.

Isn't WS_CLIPCHILDREN supposed to do this... Confused | :confused:

I've a couple of dialogs which I want flicker free. WS_CLIPCHILDREN doesn't always help me. Hmmm | :|

Say, you don't have a small dialog sample anywhere you'd like to show me, or better yet, write an article about it? Smile | :)

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Re: Flickering problem

Jason De Arte21-Sep-04 12:57

Jason De Arte

21-Sep-04 12:57

Jörgen Sigvardsson wrote:
Say, you don't have a small dialog sample anywhere you'd like to show me, or better yet, write an article about it?

When I have some time, I might write a small article - but it's realy easy to do for most controls (except group boxes) on your resizing dialog.
1. In your WM_ERASEBKGND handler...
2. Create a region of the client area
3. For each valid & visible child window you want to exclude,
3.a. create a region of that window (try GetWindowRgn, XP Themes tends to make buttons round)
3.b. remove the child region - CombineRgn(rgnChild,rgnDlg,RGN_XOR)
4. Paint your background, I use FillRgn
5. return TRUE from WM_ERASEBKGRND, or all your work will be undone.

Minor details were left out, but you'll get the idea.

[ Jason De Arte | Toy Maker | 1001010.com ]

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