C / C++ / MFC

7-Mar-06 3:52

Does anyone know an easy way to overcome the problem with the SRT_MAX limit of scrollbars? Confused | :confused:

-- modified at 12:08 Tuesday 7th March, 2006

Gary R. Wheeler7-Mar-06 4:39

7-Mar-06 4:39

Use SetScrollInfo()[^].

Software Zen: delete this;

pgrohs7-Mar-06 6:16

7-Mar-06 6:16

This is my code:

void CEditor::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)<br />
	{<br />
		SCROLLINFO ScrollInfo;<br />
<br />
		ScrollInfo.cbSize	= sizeof(SCROLLINFO);<br />
		ScrollInfo.fMask	= SIF_POS | SIF_RANGE;<br />
<br />
		GetScrollInfo(SB_VERT, &ScrollInfo);<br />
<br />
		switch(nSBCode){<br />
<br />
	...<br />
<br />
		case SB_THUMBPOSITION:<br />
			ScrollInfo.nPos = nPos;<br />
			break;<br />
<br />
		case SB_THUMBTRACK:<br />
			ScrollInfo.nPos = nPos;<br />
			break;<br />
		}<br />
<br />
		SetVScroll(ScrollInfo.nPos);<br />
<br />
		CWnd::OnVScroll(nSBCode, nPos, pScrollBar);<br />
	}

The problem is that nPos does not become bigger than SRT_MAX. This is because nPos comes from the high-order word of the wParam of the message WM_VSCROLL. So it is just a short value that is casted to an integer. Is there another way to get the current position of the scroll box?

Thanks

Gary R. Wheeler7-Mar-06 6:39

7-Mar-06 6:39

You have to initialize the scroll bar at some point with a call to SetScrollInfo. My guess would be you want to do this in your CEditor::OnCreate handler.

The nPos value you are seeing in your OnVScroll handler varies between the values of nMin and nMax in the SCROLLINFO structure.

Software Zen: delete this;

pgrohs7-Mar-06 7:10

7-Mar-06 7:10

Thank you for your help, but I think I have to describe the problem more detailed.

The scrollbar works fine when I move the scroll box with SB_PAGEDOWN or SB_LINEDOWN because in this case I do not need nPos. But when I react on SB_THUMBTRACK or SB_THUMBPOSITION I need nPos. So when I move the scroll box with the mouse to a position that is bigger than SRT_MAX nPos becomes zero and the scroll box jumps back to the top. Again: this is only the case if the scroll box is directly moved with the mouse. When I click on the scroll arrows everything works fine.

So what I need is a way to find out where the user has moved the scroll box when it is above SRT_MAX.

Thanks

Gary R. Wheeler7-Mar-06 12:23

7-Mar-06 12:23

When handling SB_THUMBTRACK, you need to look at the nTrackPos member of the SCROLLINFO structure, not nPos.

Software Zen: delete this;

pgrohs7-Mar-06 22:34

Ok to use unsigned __int64 for an API expecting ULARGE_INTEGER?

7-Mar-06 22:34

Thank you very much. It works.
MSDN is such a great thing, but it happens the you do not to see the wood for the trees. Roll eyes | :rolleyes:

dandy727-Mar-06 3:42

dandy72

7-Mar-06 3:42

I need a refresher...

Are there any circumstances where using a pointer to an unsigned __int64 value could cause problems for an API expecting a PULARGE_INTEGER? For example, GetDiskFreeSpaceEx()...

If it matters...I'm using VC6 to compile an x86 EXE.

Re: Ok to use unsigned __int64 for an API expecting ULARGE_INTEGER?

Jack Puppy7-Mar-06 4:18

Jack Puppy

7-Mar-06 4:18

I had the same problem recently using GetFileSizeEx. Turns out LARGE_INTEGER is a struct.

MSDN says...

The ULARGE_INTEGER structure is actually a union. If your compiler has built-in support for 64-bit integers, use the QuadPart member to store the 64-bit integer. Otherwise, use the LowPart and HighPart members to store the 64-bit integer.

<br />
LARGE_INTEGER nTemp;<br />
::GetFileSizeEx(hFile, &nTemp);<br />
<br />
unsigned __int64 nFileSize = nTemp.QuadPart;<br />

"My dog worries about the economy. Alpo is up to 99 cents a can. That's almost seven dollars in dog money" - Wacky humour found in a business magazine

Re: Ok to use unsigned __int64 for an API expecting ULARGE_INTEGER?

Gary R. Wheeler7-Mar-06 4:42

7-Mar-06 4:42

Yes, it's OK.

As it turns out, the LARGE_INTEGER struct is identical to unsigned __in64 as far as memory layout goes. The struct was added back in the days when 64 bit integer arithmetic wasn't readily available in the processors, and they provided the arithmetic via library functions.

Software Zen: delete this;

Re: Ok to use unsigned __int64 for an API expecting ULARGE_INTEGER?

dandy727-Mar-06 7:27

dandy72

7-Mar-06 7:27

Thanks Gary.

I should've dug one extra level deeper in the definitions--the struct's QuadPart member is a ULONGLONG, which in turn is an unsigned __int64.

And since the LARGE_INTEGER is a union, then you're right, the memory layout is identical...

comparing two void* values

Amr Shahin7-Mar-06 3:42

Amr Shahin

7-Mar-06 3:42

hi every1

im writing a code that needs to compare two poitner of type (void *)
i dont know how to do that; i tries to use the memcmp function but it requires a length parameter !

thanks already

Re: comparing two void* values

toxcct7-Mar-06 3:46

toxcct

7-Mar-06 3:46

same question[^], same answers... templates are what you need.

you cannot know what kind of object is pointed to by a void* address...

Re: comparing two void* values

James R. Twine7-Mar-06 4:12

James R. Twine

7-Mar-06 4:12

If you need to compare the pointer values, just compare them using normal operators. If you need to compare the things that the pointers point to you need more information about them:

int	iValueA = 1;
int	iValueB = 1;
 
void *vp1 = &iValueA;
void *vp2 = &iValueB;
void *vp3 = &iValueA; 
 
if( vp1 == vp3 )                              
{                                             
    OutputDebugString( _T( "vp1 == vp3\n" ) );
}                                             
if( vp1 == vp2 )                              
{                                             
    OutputDebugString( _T( "vp1 == vp2\n" ) );
}
if( *(int*)vp1 == *(int*)vp2 )                              
{                                             
    OutputDebugString( _T( "*vp1 == *vp2\n" ) );
}

Peace!

[edit] Alright - who is the buttmonkey that voted this a 2 with no reason given? Poke tongue | ;-P

[/edit]
-=- James

If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
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IE Active X Control

folkenmax7-Mar-06 2:46

folkenmax

7-Mar-06 2:46

Hello folks,

I trying to instatiate a activex control, print template from Internet Explorer. The argv[1] parameter it's a path string to a HTML file(like these: c:\MyTemplate.htm). But it seems the type of vTemplatePath don't match and an exception is launched:

Error on line 474 atlbase.h
Expression: p!=0

I'm sorry to post this question here, but I'm a noob in C++. I'm a web programer(PHP, javascript, action script II), and I need very much of this.
Someone can help me to solve this?

Thanks a lot!

//Microsoft reference
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnie55/html/beyondprintpreview.asp

//code
int main(int argc, char * argv[])
{
int i;
IOleCommandTarget* pCmdTarg;
CComPtr<iwebbrowser2> pWB;

pWB->QueryInterface(IID_IOleCommandTarget, (void**)&pCmdTarg);
VARIANT vTemplatePath;
V_VT(&vTemplatePath) = VT_BSTR;
CComVariant vPTPath = argv[1];
pCmdTarg->Exec(&CGID_MSHTML, IDM_PRINTPREVIEW, NULL, &vPTPath, NULL);
return 0;
}

Stephen Hewitt7-Mar-06 3:17

Stephen Hewitt

7-Mar-06 3:17

pWB is NULL.
No Webbrowser conrol bas been created.
COM hasn't been initialized (by calling CoInitialize or friends).

Steve

folkenmax7-Mar-06 3:29

folkenmax

7-Mar-06 3:29

Use:
CoCreateInstance(CLSID_WebBrowser, NULL, CLSCTX_INPROC, IID_IWebBrowser2, (void**)&pWB);

received same error.

Stephen Hewitt7-Mar-06 12:04

Stephen Hewitt

7-Mar-06 12:04

Call CoInitialize - It should be the first (or close to) thing your program does. The WebBrowser in an ActiveX control - Do you plan in implementing ActiveX control containment youself? I suggest looking up ActiveX controls and how to host them.

Steve