Hi all, the function SetWindowExtEx() is returning false for me sometimes. I am using MM_ANISOTROPIC mapping mode. GetLastError() is returning error code 50(The request is not supported). This is happening very rarely and only during print operation. Can size may be a problem.

Thanks a lot, it worked after doing the changes suggested by you.

Hi, I am using default scrollbar for window. In OnSize i am calling SetScrollInfo() function whenever i am resizing the window. But in some situation the scrollbar is getting hidden, if i reduce or increase the size again scrollbar is becoming visible again. I checked the min and max position values but they are correct.

Hi, You are correct the x value is the root cause of the problem but i can't avoid this value. Is there any way to avoid overflow by doing some changes.

Thanks for replying. Actually this error occured only twice and i am not able to reproduce it. I have the following traces Conversion from LPtoDP failed.

>::LPtoDP(dc.GetSafeHdc(), points, noPoints);

noPoints = 2. ViewportExt.cx: 1000 ViewportExt.cy: 616 ViewportOrg.x: 0 ViewportOrg.y: 0 WindowExt.cx: 500 WindowExt.cy: 1000 WindowOrg.x: 68207250 WindowOrg.y: 0 points[0]: x = 68207250 y = 0 points[1]: x = 68207742 y = 1000. But i am not able to find out which parameter value is exceeding.

Hi, while using the function LPtoDP i am getting the error "Arithmetic result exceeded 32 bits". I am not able the find the root cause of the problem. I am using x = 1000 in SetViewportExt and x = 500 * (some dynamic value) in SetWindowExt. Is it Ok if i reduce x = 100 in SetViewportExt and x = 50 * (some dynamic value) in SetWindowExt.

I understood. Thanks you all for your replies.

But if we restore the temporary pointer returned from SelectObject in the DC immediately, the DC may be having some dangling references after the current call. Means if we store the current DC for some other call there are chances of using incorrect memory.

Thanks for the reply. But if i want to use the same DC after this call wiil it be ok.

Hi, I am using SelectObject() in my code but confused with the MSDN description.

CFont font;
font.CreateFont(-12, 0, 0, 0, 400, FALSE, TRUE, FALSE, ANSI_CHARSET, OUT_CHARACTER_PRECIS, CLIP_CHARACTER_PRECIS, DEFAULT_QUALITY, FIXED_PITCH | FF_MODERN, _T("Courier New"));
CFont* oldFont = pdc->SelectObject(font);
pdc->TextOut(0, 0, str);
pdc->SelectObject(oldFont);
font.DeleteObject();

As per MSDN we should not use the object return by SelectObject because it is a temporary one. But if we are restoring the old GDI object in the above way will it cause any problem because the same dc can be used in some other place.

Actually at one place i am using the follwing code and dcRef is NULL in my case so it is going to the else part.

mDC = new CMetaFileDC();
if (mDC != 0)
{
HDC myhdl;
if (dcRef != 0)
{
myhdl = dcRef->m_hAttribDC;
}
else
{
myhdl = getDC();
dcRef = CDC::FromHandle(myhdl);
}

	mDC->CreateEnhanced(dcRef, 0, bounds, description);
	mDC->SetAttribDC(myhdl);

	// Set default mapmode to MM\_HIMETRIC
	mDC->SetMapMode(MM\_HIMETRIC);
}

Is there any problem in passing a pointer acquired from CDC::FromHandle to CreateEnhanced.
At some other place i am using

mMetaFileHandle = mDC->CloseEnhanced();
delete mDC;
mDC = 0;
do something .....
if (mMetaFileHandle != 0)
{
// Release metafile handle if existing
::DeleteEnhMetaFile(mMetaFileHandle);
mMetaFileHandle = 0;
}
HDC myhdl = getDC();
CDC dc;
dc.Attach(myhdl);
dc.DeleteDC();

In the above code getDC is returning a handle to the device context.

Actually in my system it is not crashing. The logs i got from the client machine. I checked on the net and got the clue that it may the problem with installed drivers.

Hi, While performing the print operation my application is crashing(only some times). In logs i have found the following error: Violation address: 0x7c93426d Exception code: 3221225477 Description: EXCEPTION_ACCESS_VIOLATION: The thread tried to read from or write to a virtual address for which it does not have the appropriate access. Access violation error at READING from 0x0. Can somebody suggest me what may be the possible cause of error.

Ok, so the problem is with vc6. Thanks for the help.

Does it mean that whatever i was doing earlier was not correct.

The program is getting build properly if i use a function insted of make_pair in the last parameter of the function transform and return a pair from that function.

pair<PC::PC_type, PC> MyFunction(PC::PC_type pcType, PC pc)
{
return make_pair(pcType, pc);
}
transform( kind, kind+num_appliances, v.begin(),inserter( stock, stock.end() ),MyFunction);

Sorry, the declaration before main is

template std::pairPC::PC\_type,PC std::make_pairPC::PC\_type,PC(PC::PC_type,PC);

Hi, i tried the declaration before main

template std::pair<PC::PC_type,PC> std::make_pair<PC::PC_type,PC>(PC::PC_type,PC);
int main( ){

but still getting the same error. May be some problem in project settings.

Hi, Thanks for replying. I am using VS98(VC6.0) :) . The headers file and defination of PC is as follows

#include <algorithm>

#include <functional>

#include <iomanip>

#include <iostream>

#include <map>

#include <string>

#include <utility>

#include <vector>

using namespace std;

class PC

{

public:

        enum PC\_type { Dell, HP, IBM, Compaq };

        

        PC( PC\_type appliance = Dell, int model = 220,

                    int serial = 0 );

        

        bool operator<( const PC& rhs ) const;

        

        PC\_type appliance() const;

        int model() const;

        string name() const;

        

        void print() const;

        

        int serial() const;

private:

        PC\_type appliance\_;

        int model\_;

        int serial\_;

};

Hi, i am using transform function to transform a vector to a map but getting the following error. multiMapType.obj : error LNK2001: unresolved external symbol "struct std::pair<enum PC::PC_type,class PC> __cdecl std::make_pair(enum PC::PC_type const &,class PC const &)" (?make_pair@std@@YA?AU?$pair@W4PC_type@PC@@V2@@1@ABW4PC_type@PC@@ABV4@@Z) Debug/MultiMapType.exe : fatal error LNK1120: 1 unresolved externals The code snippet is as follows

int main( )
{
const PC::PC_type kind[] = { PC::IBM,PC::IBM, PC::Dell, PC::HP,PC::HP, PC::HP };

const int num\_appliances = 3;

vector<PC> v;
for( int i = 0; i < num\_appliances; ++i )
	v.push\_back( PC( kind\[i\], i, i ) );


// work with a multimap. key is appliance type, value is PC
typedef multimap<PC::PC\_type,PC> PC\_multimap\_type;

PC\_multimap\_type stock;
const PC desired( PC::HP );

// load the appliances into the multimap
**transform( kind, kind+num\_appliances, v.begin(),inserter( stock, stock.end() ),make\_pair<PC::PC\_type,PC> );**	
    PC\_multimap\_type::const\_iterator stock\_end = stock.end();

// search for first occurrence of key
PC\_multimap\_type::const\_iterator spot = stock.find( desired.appliance() );

if( spot != stock\_end )
	spot->second.print();
else
	cout << "Don't have a " << desired.name() << " in stock\\n";
return 0;

}

Please help. Thanks