Toddler Keys

December 28, 2008

Check out Toddler Keys, a nice little software that can protect your computer from young children.

Got some pictures to resize…Use ImageResizer power toy from Microsoft

December 28, 2008

Last week my wife uploaded some pictures taken from her camera to her online flickr account. Soon the account got filled up to its free 100 MB per month limit. She could have uploaded many more pictures if they had been re-sized before uploading. In my search for a simple and inexpensive tool, I found a Microsoft Power Toy called ImageResizer which can resize multiple files in one operation. You can download it from here.

Using ImageResizer

This tool is incredibly simple. Just explore to the folder on your desktop where the images are. Select all files that you want to resize, right-click and click Resize Pictures menu item. In the Resize Pictures screen, select the size to which you want to resize the pictures to. Thats it.

How it helped

In my tests an original 1.2 MB jpg file was resized into a 800×600 image of 60 kb. 20 times more pics can be uploaded with same 100 MB per month limit.

Thanks MS

Resize multiple pictures at one go...

Resize multiple pictures at one go...

ImageResizer PowerToy

Detecting Memory leaks with Application Verifier

December 25, 2008

Last week I spent some time understanding how Application Verifier works. For those who have never used Application Verifier, its a great free tool from Microsoft, that can detect memory leaks (heap/handle or resource leaks) in native Windows CE/Mobile applications. It not very hard to use, especially once you have the proper setup. You will need the following along with your regular application development environment:

1. Windows CE 5.0 Test Kit : Check this out here

2. Application Verifier Tool for Windows Mobile 5.0 : Check this out here

Although the Window CE 5.0 Test Kit contains the Application Verifier Tool, its binaries are not compatible with Windows Mobile 5.0 or later. For this reason you may need to replace the Application Verifier binaries in the Test Kit with the Application Verifier for WM 5.0 (in point 2 above).

And about the usage of this tool, there is a great Virtual Lab and an offline article.

MSDN Virtual Lab:

Offline Article:

5 reasons why softwares leak memory?

December 25, 2008

Memory leaks or corruption in programs occur mainly due to following reasons:

1. Inadequate knowledge about Memory Management:

This is true for most people when they start programming. With experience they learn how memory management works in general and overtime they become “responsible” developers who understand how precious memory is.

2. Inadequate knowledge of specific System APIs or tools

A Programmer starting to work with a new language or platform might not be aware of how stuff works inside that system. e.g. A newbie Windows programmer may not know that CreateCompatibleDC() call must have a corresponding DeleteDC() call and GetDC() call must have a corresponding ReleaseDC() call. Again experience helps here.

3. Unreviewed Code

Not spending enough time in reviewing code. We are always in a hurry and don’t bother to implement code to handle exceptions. Doing Self or Peer code review can eliminate most of these traps. Note that its very costly (in time and money) when problems surface later in the field. It easy to fix bugs when they are caught on the development machine.

4. Using Free Code

So much code is available on the web these days that software development has now become some sort of software integration activity. Well… reusing code is not bad, but not knowing how it works is. Quality of free code must be questioned at all times. Sample code is not always ready to be used for production purposes.

5. Not using memory detection tools

Your program might leak memory even if you take care of above five conditions. Its a good habit to use tools that can help in detecting memory leaks which would otherwise go undetected.

My next post will be about Application Verifier tool which is a great tool for detecting memory leaks in native embedded applications for Windows CE and Windows Mobile.

Programatically create icons from bmp, jpg, png, gif files in your native Windows Mobile applications

December 17, 2008

This post show how you can create and load icons (HICON) from bmp, png, jpg, gif files in your Windows  Mobile applications. Sample code here assumes that source files have 32×32 dimensions and generated icons will also be on same dimensions.


1. Load the source image file into memory and get HBITMAP handle. To accomplish this use GetBitmapHandle function below.

HBITMAP GetBitmapFromFile(TCHAR* pFileName)
OSVERSIONINFO osverinfo = {0};

// Get OS version

if (osverinfo.dwMajorVersion < 4)
hbm = SHLoadImageFile(pFileName);
if (hbm == NULL)
hbm = SHLoadDIBitmap(pFileName); // works only for bmp
// Use imaging library
IImagingFactory *pImgFactory = NULL;
IImage *pImage = NULL;

// Initialize COM

// Create the imaging factory.
if (SUCCEEDED(CoCreateInstance (CLSID_ImagingFactory, NULL, CLSCTX_INPROC_SERVER, IID_IImagingFactory,
(void **)&pImgFactory)))
//// Load the image from the JPG file.
if (SUCCEEDED(pImgFactory->CreateImageFromFile(pFileName, &pImage)))
// Draw the image.
RECT rc = { 0, 0, 32, 32};
// Get the Desktop HDC

// Create Compatible DC and Bitmap
HDC memDC = CreateCompatibleDC ( hDC );
hbm = CreateCompatibleBitmap ( hDC, 32, 32 );

// Select HBITMAP into memory DC
SelectObject ( memDC, hbm);

// Draw the image on the memDC
pImage->Draw(memDC, &rc, NULL);

// Release desktop DC
ReleaseDC(NULL, hDC);


// Ununitialize COM

// return the HBITMAP handle
return hbm;

2. Fillup ICONINFO strcuture and call CreateIconIndirect() API to retrieve HICON handle.

// Create an icon
ICONINFO iconinfo = {0};
iconinfo.fIcon = TRUE;
iconinfo.hbmMask  = hBitmap;
iconinfo.hbmColor = hBitmap;

HICON hCustomIcon = CreateIconIndirect(&iconinfo);

// Use hCustomIcon any way you want…..

Programmatically display system tray icon on Windows Mobile

December 13, 2008

As a Windows Mobile user you would see have some application specific icons near to the bottom right corner of the Today screen. It give users ability to directly launch the application or show an menu with more choices.

Tray icons on Today screen (Dell Axim)

Tray icons on Today screen (Dell Axim)

This post discusses the steps and code to put your own icon in the system tray.  I will also provide a solution to a common issue with Windows Mobile whereby its not easy to know the coordinates of the icon or the coordinates where the user might have tapped within the tray area.

okay…I will take an example of a Win32 native application. The concepts will hold good even if you are programming with some other framework.

1. Declare some variables and function prototypes

// some required defines
#define ID_TRAY            1

// some variables
static NOTIFYICONDATA    g_structNotifyIconData = {0};
static HWND                g_hWndMain = NULL;
static HWND                g_hWnd = NULL;
static WNDPROC            g_fnProc = NULL;
static DWORD            g_dwTapPos = 0;

LRESULT DesktopExplorerWindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

2. Implement a wrapper function to show and hide tray icon.

BOOL ShowTrayIcon(HWND hWnd, BOOL bShowIcon)

g_structNotifyIconData.cbSize = sizeof(NOTIFYICONDATA);
g_structNotifyIconData.hIcon = LoadIcon(g_hInst, MAKEINTRESOURCE(IDI_SHOWTRAYICON));
g_structNotifyIconData.hWnd = hWnd;
g_structNotifyIconData.uCallbackMessage = WM_SYSTRAY_MSG;
g_structNotifyIconData.uFlags = NIF_MESSAGE | NIF_ICON;
g_structNotifyIconData.szTip[0] = ”;
g_structNotifyIconData.uID = ID_TRAY;

if (bShowIcon)
bRet = Shell_NotifyIcon(NIM_ADD, &g_structNotifyIconData);
bRet = Shell_NotifyIcon(NIM_DELETE, &g_structNotifyIconData);

return bRet;

Above function fills up fields in NOTIFYICONDATA structure, setting the icon resource handle, parent window handle, callback message identifier, flags specifying that uCallbackMessage and icon information is being set and an user defined ID value.

3. Call ShowTrayIcon function in WM_CREATE handler

In the WM_CREATE  handler portion of the main WndProc function, call ShowTrayIcon(hWnd, TRUE).


ShowTrayIcon(hWnd, TRUE);

4. Add handler for WM_SYSTRAY_MSG

WM_SYSTRAY_MSG will be sent to the main window procedure (WndProc) when the user taps or clicks on the icon. We must add the following code to make some good use of the icon.

switch (message)
switch (lParam)
if (ID_TRAY == wParam)
POINT pt = {0};
if (hTrayMenu)
HMENU hSubMenu = GetSubMenu(hTrayMenu, 0);
pt.x = LOWORD(g_dwTapPos);
pt.y = HIWORD(g_dwTapPos);
bRet = TrackPopupMenu(hSubMenu, TPM_CENTERALIGN | TPM_BOTTOMALIGN, pt.x, pt.y, 0, hWnd, NULL);
dwError = GetLastError();

Here we know that user has tapped on the icon area. As a result we can do anything that we might want. Here I an showing up a popup menu using TrackPopupMenu API. g_dwTapPos variable contains the x & y position where the user tapped on the system tray area. We will see later how we get the information in g_dwTapPos. Note that GetCursorPos() does not get us this position value on Windows Mobile whereas it works on Windows desktop.

5. Getting the tap coordinates on system tray icon

One way I found to know the coordinates where the user tapped or clicked on the taskbar is to subclass the DesktopExplorerWindow and trap WM_CANCELMODE message. In the handler for WM_CANCELMODE, calling GetMessagePos() will return the position into a g_dwTapPos variable.

// DesktopExplorerWindow
LRESULT DesktopExplorerWindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
switch (msg)
// Trap WM_CANCELMODE message
// This will get us the point at which tap occurred
g_dwTapPos = GetMessagePos();

return ::CallWindowProc(g_fnProc, hWnd, msg, wParam, lParam);

BOOL HookDesktopExplorerWindow()
return FALSE;

g_hWnd = ::FindWindow(_T(“DesktopExplorerWindow”), NULL);
g_fnProc = (WNDPROC)::SetWindowLong(g_hWnd, GWL_WNDPROC, (LONG)DesktopExplorerWindowProc);

return g_hWnd != NULL;

BOOL FreeDesktopExplorerWindow()
return FALSE;

::SetWindowLong(g_hWnd, GWL_WNDPROC, (LONG)g_fnProc);
g_fnProc = NULL;

return TRUE;

HookDesktopExplorerWindow can be called from WM_CREATE handler in main Window procedure before calling ShowTrayIcon. FreeDesktopExplorerWindow can be called from WM_DESTROY handler in main Window procedure.

See below how the icon and popup menu shows up in my sample application.

Sample application showing System Tray Icon

Sample application showing System Tray Icon

Setting ES_MULTILINE of a CEditView derived class

December 5, 2008

CEditView class provides functionality of a Windows edit control to MFC applications. If ES_MULTILINE style is set, the edit control shows as many lines as possible to display the embedded text. Otherwise the whole text string is shown on the first line and if required, horizontal scrollbar is also shown.

ES_MULTILINE is one of those edit control styles which can not be changed if an instance of the class is already created. Basically there is no easy way to turn this style on and off once the object has been created. If your class is derived from CEditView and you want to turn on this style, override the PreCreateWindow method of the base class and modify the style field to set ES_MULTILINE.

BOOL CPreView::PreCreateWindow(CREATESTRUCT& cs)
// TODO: Add your specialized code here and/or call the base class |= ES_MULTILINE | ES_AUTOVSCROLL;
return CEditView::PreCreateWindow(cs);

Since derived class implementation is called before the base class implementation, the style is set before the object is created. This method can be used to set other styles also.