C / C++ / MFC

HBITMAP hBitmap = (HBITMAP)::LoadImage(NULL, _T("C:\\Some.bmp"), IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE);

if (hBitmap)
{
   // Get information about the loaded DIBSection

   DIBSECTION DibSection;
   ::GetObject(hBitmap, sizeof(DibSection), &DibSection);


   // Calculate a pointer to the pixel data for a given scanline

   LONG scanline = ...;
   BYTE *pScanlineBytes;

   if (DibSection.dsBmih.biHeight > 0)
      pScanlineBytes = (BYTE*)DibSection.dsBm.bmBits + (DibSection.dsBm.bmWidthBytes * ((DibSection.dsBm.bmHeight - 1) - scanline));
   else
      pScanlineBytes = (BYTE*)DibSection.dsBm.bmBits + (DibSection.dsBm.bmWidthBytes * scanline);


   // Clean up

   ::DeleteObject(hBitmap);
}

Mark Salsbery
Microsoft MVP - Visual C++

CPallini wrote:

I disagree. A window handle is unique on the system. You can post messages to the window whose that handle is assigned. At the end PostMessage is an IPC mechanism.

CPallini wrote:

BTW handles technically are not memory addresses.

typedef void* HANDLE;

Maxwell Chen wrote:

There is a translation mechanism.

Maxwell Chen wrote:

The type void* is memory address.

CPallini wrote:

The type void* is a number that may contain a memory address.

CPallini wrote:

Since the window handle of a particular window is the same on different process (this, for instance, allows you to use in your application the handle found with Spy++ tool) and the processes have different address spaces, then window handles cannot be valid memory pointers in the context of such processes (at least IMHO ).

// Process A.
struct MyBlock
{
  int a;
};
void main()
{
  MyBlock* p = new MyBlock; // p = 0x00A30210
  p->a = 3;
  // No delete to let it being kept.
}
// Process B.
struct MyBlock
{
  int a;
};
void main()
{
  void* p = reinterpret_cast<void*>(0x00A30210);
  cout << reinterpret_cast<myblock*>(p)->a;
}

Maxwell Chen wrote:

I am not sure, but if it is just a number, a ULONG is just fine. Since it is defined as a pointer type (void*), it must be some address pointing to something.

typedef  ULONG  HANDLE;

Maxwell Chen wrote:

I am not sure, but if it is just a number, a ULONG is just fine. Since it is defined as a pointer type (void*), it must be some address pointing to something.

Maxwell Chen wrote:

I guess that creating handle and free handle are something related with global allocating memory blocks in the heap

Hamid. wrote:

You can use of EnumWindows instead FindWindow

ashtwin. wrote:

Can anybody tell is that correct or any problem in using the handle of a window in one process from some other process.

ashtwin wrote:

Currently i am using FindWindow() to get the handle of a dialog and using that handle i am sending the message(using PostMessage api)to this dialog(which is part of seperate process). As of now it is working fine.