WeSeeTips moving to new Home!

31 01 2010

Dears,

Its been a very long time, I know. But rejoice! WeSeeTips is moving to its new home. Due to several personal and technical reasons, the migration was a bit delayed. Anyway, We will be back soon in new style and new tips to rock you. Keep your fingers crossed!

For WeSeeTips,
Jijo.





How to get the CPU Name String?

21 06 2009


While taking the System properties, you have noticed the processor name string. For instance, in my laptop it is – “Intel(R) Core(TM)2 Duo CPU     T5250  @ 1.50GHz“. Ever though about how to get this processor name string?

cpuid
Image Courtesy – Wallpaper Mania.


You can use the function – __cpuid(), which generates the instruction – cpuid. Have a look at the code snippet. Code taken and modified from MSDN.

#include <iostream>
#include <intrin.h>

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    // Get extended ids.
    int CPUInfo[4] = {-1};
    __cpuid(CPUInfo, 0x80000000);
    unsigned int nExIds = CPUInfo[0];

    // Get the information associated with each extended ID.
    char CPUBrandString[0x40] = { 0 };
    for( unsigned int i=0x80000000; i<=nExIds; ++i)
    {
        __cpuid(CPUInfo, i);

        // Interpret CPU brand string and cache information.
        if  (i == 0x80000002)
        {
            memcpy( CPUBrandString,
            CPUInfo,
            sizeof(CPUInfo));
        }
        else if( i == 0x80000003 )
        {
            memcpy( CPUBrandString + 16,
            CPUInfo,
            sizeof(CPUInfo));
        }
        else if( i == 0x80000004 )
        {
            memcpy(CPUBrandString + 32, CPUInfo, sizeof(CPUInfo));
        }
}

    cout << "Cpu String: " << CPUBrandString;
}


You can get a lot of information about cpu by using __cpuid. Have a look at the MSDN Documentation.


Targeted Audiance – Intermeidate.





How to Change the Display Orientation?

10 05 2009


Are you using Windows XP? Press Ctrl+Atl+DownArrow, and then Ctrl+Atl+UpArrow. The screen changes its orientation upside down. isn’t it? But how to turn the screen, upside down programmatically?

ChangeDisplayOrientation
Image Courtesy – marieforleo.com


Get the current DEVMODE by calling –EnumDisplaySettings(). Then change orientation by setting DEVMODE.dmDisplayOrientation and calling ChangeDisplaySettings(). Have a look at the code snippet. Code taken from MSDN.

// Get current Device Mode.
DEVMODE DeviceMode = { 0 };
EnumDisplaySettings( NULL,
 ENUM_CURRENT_SETTINGS,
 &DeviceMode );

// Change display mode upside down.
DeviceMode.dmDisplayOrientation = DMDO_180;
ChangeDisplaySettings( &DeviceMode, 0 );

// Sleep for 10 seconds.
Sleep( 10000 );

// Change display mode back.
DeviceMode.dmDisplayOrientation = DMDO_DEFAULT;
ChangeDisplaySettings( &DeviceMode, 0 );


Be careful to restore the display orientation back. Or else 😉


Targeted Audiance – Intermeidate.





How to Parse Virtual Table?

7 05 2009

Virtual Table is one of the most fascinating stuff for C++ programmer. Well, did you ever  peek into virtual table, which is the real engine of virtual functions?

virtualfunction


The first 4 bytes of an objects points to another pointer which points to virtual table. Casting it to DWORD*, we can parse all virtual functions. Once you get function address, you can get the function name by calling – SymFromAddr(). Have a look at code snippet.

virtualfunction2

#include <ImageHlp.h>
...
// Get list of virtual functions.
void CRabbitDlg::ParseVtable()
{
    // Initialize symbols.
    InitializeSymbols();

    // We are going to parse vtable of CWinApp object.
    DWORD* pBase = (DWORD*)(AfxGetApp());
    DWORD* pVptr = (DWORD*)*pBase;

    // Iterate through VirtualTable.
    DWORD Index = 0;
    DWORD FnAddr = pVptr[Index];
    while( FnAddr )
    {
        // Translate FunctionAddress to FunctionName.
        CString FunctionName;
        GetSymbolNameFromAddr( FnAddr, FunctionName );

        // Format and add to list.
        CString Final;
        Final.Format( _T("%0x - %s"), FnAddr, FunctionName.operator LPCTSTR());
        m_List.AddString( Final );

        // Next function pointer.
        FnAddr = pVptr[++Index];
    }
}

// Initialize Symbol engine.
void CRabbitDlg::InitializeSymbols()
{
    DWORD Options = SymGetOptions();
    Options |= SYMOPT_DEBUG;
    Options |= SYMOPT_UNDNAME; 

    ::SymSetOptions( Options ); 

    // Initialize symbols.
    ::SymInitialize ( GetCurrentProcess(),
                      NULL,
                      TRUE );
}

// Get symbol name from address.
void CRabbitDlg::GetSymbolNameFromAddr( DWORD SymbolAddress, CString& csSymbolName )
{
    DWORD64 Displacement = 0;
    SYMBOL_INFO_PACKAGE SymbolInfo = {0};
    SymbolInfo.si.SizeOfStruct  = sizeof( SYMBOL_INFO );
    SymbolInfo.si.MaxNameLen = sizeof(SymbolInfo.name);

    // Get symbol from address.
    ::SymFromAddr( GetCurrentProcess(),
                   SymbolAddress,
                   &Displacement,
                   &SymbolInfo.si );

    csSymbolName = SymbolInfo.si.Name;
}


Don’t forget to include ImageHlp.lib to project settings.


Targeted Audiance – Intermediate.





How to set Font for Static Text Controls?

4 03 2009


By default, static text is displayed in normal fonts. And you don’t have any option to make it bold or italic or underline. Is there any way to enable these styles and change the font of the static text control?

staticfont


Yes! you can do it. First you’ve to get the current font of the text control and then enable the styles you need then set it back. Setting font is done in OnInitDialog() and new font is kept as member variable. See the code snippet below.

BOOL CStaticFontDlg::OnInitDialog()
{
	...

    // Get current font.
    CFont* pFont = GetDlgItem( IDC_STATIC_ITALIC )->GetFont();
    LOGFONT LogFont = { 0 };
    pFont->GetLogFont( &LogFont );

    // Create new font with underline style.
    LogFont.lfUnderline = TRUE;
    m_StaticFont.CreateFontIndirect( &LogFont );

	// Sets the new font back to static text.
    GetDlgItem( IDC_STATIC_ITALIC )->SetFont( &m_StaticFont );

	return TRUE;
}

Now the static text will look like this.

staticfont3


Don’t forget to change the Id of static text control from IDC_STATIC to something else. Or else GetDlgItem() will return invalid handle.


Targeted Audiance – Intermediate.





How to restrict the tree control labels to be integer?

18 01 2009


Tree Controls supports label editing and by default it accepts all kind of chars for label. But is there any trick to restrict the input label to be an integer?

limittreeinputasint


Yes. You can. When user starts editing tree control will send a notification message – TVN_BEGINLABELEDIT. At first you have to handle the message and in the message handler, you can get the label edit control by calling GetEditControl(). Then set the edit control style to ES_NUMBER. Then the label edit control of tree, will allow only integers as input. Have a look at the code snippet.

// Message Map.
BEGIN_MESSAGE_MAP(CRabbitDlg, CDialog)
	...
	ON_NOTIFY(TVN_BEGINLABELEDIT, IDC_TREECTRL, OnBeginlabeleditTreectrl)
END_MESSAGE_MAP()

// Begin Label edit - Message Handler.
void CRabbitDlg::OnBeginlabeleditTreectrl(NMHDR* pNMHDR,
					  LRESULT* pResult)
{
    // Get the edit control which of tree control and set
    // its style to number only.
    CEdit* pEdit = m_TreeCtrl.GetEditControl();
    if( pEdit )
    {
        // Allow only numbers
        pEdit->ModifyStyle( 0, ES_NUMBER );
    }

    *pResult = 0;
}


Feel the power!


Targeted Audience – Intermediate.





How to check whether the Pointer is allocated in Stack or Heap in Debug?

14 12 2008


What if you call delete operator by using a stack pointer? Like that, while writing frameworks sometimes we expects the pointer that gets passed to the function should point a valid memory block which is allocated on heap itself. So how can we check whether the pointer points to stack or heap in debug version?

stackorheap


You can use the function – _CrtIsValidHeapPointer(). Its an undocumented CRT function. But it works only in debug version. Well, please check the code snippet below,

#include "malloc.h"
...

// Check heap pointer.
int* pInteger = new int;
BOOL bHeap = _CrtIsValidHeapPointer( pInteger );

// Check stack pointer and you'll get an assertion.
char CharArray[100];
bHeap = _CrtIsValidHeapPointer( CharArray );


Its annoying that its not available in release version. Well, atleast we could make our framework to notify the user while debugging in the debug build. isn’t it?


Targeted Audience – Beginners.