C / C++ / MFC

MAAK14-Feb-03 2:41

14-Feb-03 2:41

Just to ensure there is no confusion. The bits I mean are the values of pixels, sorry for that term, but it's used in the BITMAP structure.

What I do mean, that if you are comparing images with true colors (24-bit color depth or more) there will be no problem, but for indexed images(16-bit, 8-bit etc) the problem of color table arise.

If all pixel values match in an indexed bitmaps that does not mean their color tables match.

I just wanted to be clearer.

jeremysay14-Feb-03 3:18

14-Feb-03 3:18

AH ok ok, sorry I had not understood !
so i shouldn't have probleme with that.

thank you to take your time to explain me.

jeremysay14-Feb-03 4:27

14-Feb-03 4:27

ok, i try your example, but i have a problem with :
if(memcmp(data1, data2, bytesize) == 0)
i have always windows error, i think it's because bytesize
you know how can i find the problem?
thx in advance

MAAK14-Feb-03 6:14

14-Feb-03 6:14

I assume that the error is a crash due to access viloation, so firstly check if either pointers are not null, this method works only with DIB bitmaps (i.e. you can't try it with bitmaps of a Client area DC or a Window DC) otherwise the pixels array is null.

If they are not null then I need to know the winodws version you use and the bitmaps dimensions and color depth to identiy the problem.

You my also try to replace the 4 with 2 in this line
DWORD bmWidthBytes = bmWidth + (4 - bmWidth % 4) * bool(bmWidth % 4);

jeremysay14-Feb-03 10:23

14-Feb-03 10:23

Thx to help me !

MAAK wrote:
I assume that the error is a crash due to access viloation
completely !

this is what i do :

1 - I do a snapshot and save the bitmap in Clipboard

  CMainFrame *pFrame = (CMainFrame*)AfxGetMainWnd();
  CChildFrame *pChild = (CChildFrame *) pFrame->GetActiveFrame();

  CRect WndRect;

      //:-D thx Schlaubi
  CWnd* pMDIClientWnd = CWnd::FromHandle(pFrame->m_hWndMDIClient);


  GetClientRect(WndRect);

  CBitmap     bitmap;
  CDC         *dcP;
  CDC         memDC;
  CRect       rect;

  dcP = GetWindowDC();
  memDC.CreateCompatibleDC(dcP);

 bitmap.CreateCompatibleBitmap(dcP,WndRect.right, WndRect.bottom);


 CBitmap *pOldBitmap = memDC.SelectObject(&bitmap);
 memDC.BitBlt(0, 0, WndRect.right,WndRect.bottom, dcP,2 , 2, SRCCOPY);

OpenClipboard();
 EmptyClipboard();

 SetClipboardData(CF_BITMAP, bitmap.GetSafeHandle());

 CloseClipboard();
 memDC.SelectObject(pOldBitmap);

2 - i want to compare tw bitmap

    HBITMAP hbmp1 = (HBITMAP) SignatureBitmap;
    HBITMAP hbmp2 = (HBITMAP) bitmap;
    BITMAP bmp1, bmp2;
  //load the bitmaps in hbmp1 and hbmp2
    GetObject(hbmp1, sizeof(BITMAP), &bmp1);
  //get the first bitmap's data
    GetObject(hbmp2, sizeof(BITMAP), &bmp2);
  //get the first bitmap's data
  //if they differ in color depth or dimenstions they mismatch
    if(bmp1.bmBitsPixel != bmp2.bmBitsPixel ||	bmp1.bmHeight != bmp2.bmHeight || bmp1.bmWidth !=  bmp2.bmWidth)
	AfxMessageBox("prob");
else
{
	//get the bits of both bitmaps	
	LPBYTE data1 = (LPBYTE)bmp1.bmBits,		
		data2 = (LPBYTE)bmp2.bmBits;
	//the number of bytes per width	
	DWORD bmWidth = bmp1.bmWidth * (bmp1.bmBitsPixel / 8);
	//somthing is wrong with bmWidthBytes member in Win9x and Win2k
	//so it's better to calculate the offset yourself
       DWORD bmWidthBytes = bmWidth + (2 - bmWidth % 2) * bool(bmWidth % 2);
	//number of bytes in data1 and data2
	DWORD bytesize = bmp1.bmHeight * bmWidthBytes;
	//compare the two bitmap's bits	
	if(memcmp(data1, data2, bytesize) == 0)
		AfxMessageBox("goooooood");

	bitmap.Detach();
}

P.S : Two Bitmaps are two snapshot with few second interval (they have same confoguration).
i'm work with VC7, Windows XP with color definition 32bits.

MAAK14-Feb-03 15:13

14-Feb-03 15:13

The problem is as I expected in the previous reply. You are working with DDBs (Decive Dependent Bitmaps) and not DIB (Decive Independent Bitmaps). As far as I know there is no easy way (if exist) to get the bits of DDBs, and the BITMAP structure returned from them points to NULL memory address.

To be more clear any bitmaps got from windows DC , clients DC or any bitmaps created compatible with them are DDBs, and I think, but not sure, that they have variable size.

DIBs are the bitmaps that are normally used in file saving and it has a definit size.
More information about DDBs and DIBs

Hope you are not disappointed, but there is an easy solution, especially since you use VC++7 and have the CImage class.

All you have to do is, instead of bliting into a memory DC compatible with the window DC, you should create a CImage object and blit int it the window DC;

this is how to be get a DIB from DDB using CImage.

CDC         *dcP;
CDC         memDC;
CRect       WndRect;

dcP = GetWindowDC();
GetWindowRect(WndRect); //the window rect is the rect of the whole window
                            //while the client rect is of the client area only

CImage im; //CImage object
    //this is to create a DIB using CImage, the parameters are width, height,
    //color depth
im.Create(WndRect.Width(), WndRect.Height(), 24);
    //CImage::GetDC() return an HDC to the bitmap so you can use it
    //as any other dc
memDC.Attach(im.GetDC()); //attach the HDC into the memDC object
    //blit the window DC
memDC.BitBlt(0, 0, WndRect.right,WndRect.bottom, dcP,2 , 2, SRCCOPY);
memDC.Detach(); //detach the image HDC to prevent its destruction
im.ReleaseDC(); //this is needed for every call to GetDC()
    HBITMAP hbmp = im.Detach(); //you now have handle to DIB ready for use

The CImage is included in <atlimage.h> and please note that it needs the GDI+ runtimes. The GDI+ is inlcude in a file named gdiplus.dll, it comes already with WinXP and VS.Net, but if you are going to use it at any system other than WinXP then the DLL should be put with the application file.

For the clipboard part, copying DIBs to clipboard is more complicated than copying DDBs, you may refer to this page in the msdn, SetClipboardData Function .

However if think that you can just copy DDBs to clipboard then convert them to DIB when pasting.

I hope you are not bored from that lecture;)

jeremysay14-Feb-03 21:48

14-Feb-03 21:48

MAAK wrote:
Hope you are not disappointed

arf... a litlle bit

MAAK wrote:
HBITMAP hbmp = im.Detach(); //you now have handle to DIB ready for use
ok now i can work with hbmp and it will work fine?

i try to compare the same bitmap :

BITMAP bmp1, bmp2;

GetObject(hbmp, sizeof(hbmp), &bmp1); //get the first bitmap's data
GetObject(hbmp, sizeof(hbmp), &bmp2); //get the first bitmap's data

if(memcmp(&bmp1, &bmp2, sizeof(bmp1) - sizeof(bmp1.bmBits)))
{
    AfxMessageBox("Prob");
}
else
{
    //get the bits of both bitmaps
    LPBYTE data1 = (LPBYTE)bmp1.bmBits,     data2 = (LPBYTE)bmp2.bmBits;
    //the number of bytes per width
    DWORD bmWidth = bmp1.bmWidth * (bmp1.bmBitsPixel / 8);
    //somthing is wrong with bmWidthBytes member in Win9x and Win2k
    //so it's better to calculate the offset yourself
    DWORD bmWidthBytes = bmWidth + (2 - bmWidth % 2) * bool(bmWidth % 2);
    //number of bytes in data1 and data2
    DWORD bytesize = bmp1.bmHeight * bmWidthBytes;
    //compare the two bitmap's bits
    if(memcmp(data1, data2, bytesize) == 0)
        AfxMessageBox("gooooooooooooooood");
}

but i have the same error Confused | :confused:

there is something which I did not understand?

MAAK14-Feb-03 23:14

14-Feb-03 23:14

You wrote in the last reply the code for obtaining one of the bitmaps, but you did not wrote how the other is obtained (and did not say if it was the same way or not).

Any way put this diagnositc lines of code before the if(memcmp(...

if(data1 == 0)
   AfxMessageBox("Error in bitmap 1");
if(data2 == 0)
   AfxMessageBox("Error in bitmap 2");

if the data of an HBITMAP is NULL then it should be either a DDB or and invalid handle, however if it's invalid handle the BITMAP structure won't be obtain in the first place. So, if the BITMAP structure is obtained successfully and the data is NULL then it's probably a DDB. If you debugged the program and stepped after the two calls to GetObject() you may check the values of the bmp1 and bmp2, if the HBITMAP is for a DDB you'll see all the members have normal values except the bmBits, which will contain 0.

By the way, do not compare the BITMAP structure using memcmp() because if both are inavalid you may obtain unexpected reults

jeremysay17-Feb-03 3:10

17-Feb-03 3:10

hi,
in degug i see data1 & data2 are not good :
data1 = 0xcccccccc <Ptr> incorrect
data2 = 0xcccccccc <Ptr> incorrect
now i try to convert DDB to DIB....
but it is very confused for me. Confused | :confused:

jeremysay14-Feb-03 5:01

14-Feb-03 5:01

You know how get pointer on the bitmap which is in clipboard ??
THX

MFC accelerators & activeX

includeh1014-Feb-03 23:57

includeh10

14-Feb-03 23:57

very confused: u want to compare a lots bitmaps, but last request sounds that there are lots of bitmaps on clipboard.

the key for fast comparing is if u can get bitmap buffer properly (BITMAP structure does not work always), where are those bitmaps? in files? VC resource?

includeh10

peterchen13-Feb-03 22:47

peterchen

13-Feb-03 22:47

Hi,
I have an MFC app with ActiveX controls as child views.
The frame's accelerator handling seems to catch hotkeys and translate them into menu commands (e.g. Ctrl-C --> ID_EDIT_COPY), even though the ActiveX has the focus.

One of the controls needs a fairly extensive keyboard handling, that might in certain cases even interfere with the "application" hotkeys.

Now I see three solutions, and am looking for recommendations which route to take:

a) adding all accelerators to the MFC application, and handling the WM_COMMAND's. Doesn't sound like a good design though (as the ActiveX'es should be allowed to define their own hotkeys)

b) "somehow" separate the accelerator tables - the nicest would be one for the applicaiton, and one provided by the ActiveX - is this possible?

c) Usign a keyboard hook as long as one of activeX has focus.

d) Other ideas?

TIA
Peter

So many people long for eternity that don't know what to do on a rainy sunday afternoon.
[sighist] | [Agile Programming] [doxygen]
If you look for evil in me you will find it whether it's there or not.

Get the HWND value of a Dialog

Willem B13-Feb-03 22:41

Willem B

13-Feb-03 22:41

hi,

i want to send a message from a thread to my Dialog, but how do i get the HWND value from my dialog? I created the dialog by doing DoModal()

thanks in advance,

[]D [] []D []

bryce13-Feb-03 22:50

bryce

13-Feb-03 22:50

does GetSafeHwnd() not work?
Bryce

Willem B13-Feb-03 23:03

Willem B

13-Feb-03 23:03

nope, it gives back a NULL value... so i need to get it in another way...

i don't even know if the dialog has its own HWND, maybe i need to get it in a different way.

[]D [] []D []

bryce13-Feb-03 23:08

bryce

13-Feb-03 23:08

lets see...fromthe help files

CWnd::GetSafeHwnd
HWND GetSafeHwnd( ) const;
Return Value
Returns the window handle for a window. Returns NULL if the CWnd is not attached to a window or if it is used with a NULL CWnd pointer.

are you getting the hwnd before you start the thread?
Bryce