C / C++ / MFC

CListCtrl (not visible), no header?

21-Jan-07 6:58

gigo2k6 wrote:
ahh ok / is there a good manual for creating a dll for com on c++ ?

Of course there are a lot (but I don't know them...)
When building a COM DLL, basically you have three ways:

(1) Using MFC COM support. This maybe the 'easyest way' (AFAIK Jeff Prosise's "Programming Windows With MFC" contains an introduction about, maybe enough...)

(2) Using ATL. This is a bit lower level, but it is also lighter and gives you (at least in my opinion) more power. About the argument I remember only Shepherd G., King B., "Inside ATL" a quite advanced book (Anyway using the ATL COM Wizard of Visual Studio it's strighforward).

(3) Handcrafting your COM component: there is a beatyful article series, written by Jeff Glatt, here at CodeProject, starting with [^].

hope that helps
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Cpt Rick21-Jan-07 4:53

Cpt Rick

21-Jan-07 4:53

If I programmatically create a CListCtrl in report mode (or derived class) without the WS_VISIBLE attribute, it blows chunks trying to init a header for it.

It blows when, during my header init, I try to delete any old header columns that might be there already. The header init is in a separate DLL, if that matters. Here's the line of code that blows:

int nColumnCount = pList->GetHeaderCtrl()->GetItemCount();

Any clues as to why this happens, or a workaround?

Thanx.

Mark Salsbery21-Jan-07 7:31

21-Jan-07 7:31

Exactly how does it blow chunks? Assertion error? BSOD?

Cpt Rick21-Jan-07 23:20

Cpt Rick

21-Jan-07 23:20

First chance exception: Access violation trying to get the header.

Everything looks fairly normal, window handles ok, etc.

The only thing different between working and not, is the visible flag is removed when creating the control.

I'm presuming that the header control is not actually created until the list control is made visible. I can create the list control visible, and then hide it, but that's kind of hokey I think...

Hamid_RT22-Jan-07 5:57

Hamid_RT

22-Jan-07 5:57

When you remove WS_VISIBLE you have this problem?and do you need to remove this style

WhiteSky

Mark Salsbery22-Jan-07 6:51

Re: CListCtrl (not visible), no header? [modified]

22-Jan-07 6:51

I don't tthink it's a visibility problem.

Are you creating the control with the LVS_REPORT style?

Something is failing across this call "pList->GetHeaderCtrl()->GetItemCount();".
You can break it down...

1) If the listview control is created then pList should be non-zero and should have a valid HWND.

2) HWND hwndHeader ListView_GetHeader(*pList); should give you a valid HWND in hwndHeader.

3) int nItemCount = Header_GetItemCount(hwndHeader); should give a valid count.

If you're initializing a new control how can there be any columns in it?

Cpt Rick23-Jan-07 2:40

Cpt Rick

23-Jan-07 2:40

Ok, I tried doing it this way, and not even using my DLL for initing the header, and it fails. m_SearchList has a valid hwnd after being created, but the header does not (all zeros). If I put WS_VISIBLE in the create flags, it works fine, and gets a valid header...

m_SearchList.Create(WS_CHILD | WS_BORDER | LVS_REPORT, ctrl.cr, this, ctrl.nID);

CHeaderCtrl *hdr;
hdr = m_SearchList.GetHeaderCtrl();

BTW: This is a skinned based app, so the skin designer controls the visibility of the individual controls, although they still have to exist. That is the reason for creating them without visibility.

-- modified at 9:16 Tuesday 23rd January, 2007

Mark Salsbery23-Jan-07 8:01

Monitoring file IO like Filemon

23-Jan-07 8:01

Cpt Rick wrote:
BTW: This is a skinned based app, so the skin designer controls the visibility of the individual controls, although they still have to exist. That is the reason for creating them without visibility.

I'm with ya there. Creating/initializing controls before displaying them is common.
I'm going to investigate this further. That kinda sucks if the list control doesn't create
it's header until it becomes visible (as you know Smile | :)

)

I'll get back to you.
Mark

Toubou21-Jan-07 4:25

Toubou

21-Jan-07 4:25

how do I monitor file/directory operations like Filemon (http://www.microsoft.com/technet/sysinternals/utilities/filemon.mspx) do?

Thanks in advance

Re: Monitoring file IO like Filemon

CPallini21-Jan-07 6:27

Re: gdi+ example ? [modified]

21-Jan-07 6:27

It's a rather advanced topic. Maybe the authors of Filemon are you best friends, see here [^].

Cheers
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

gdi+ example ?

s98769021-Jan-07 4:08

s987690

21-Jan-07 4:08

how does one do this in gdi+, mfc

- load png image into memory
- access array of values, eg as int or rgb bytes
and apply any changes to image, if this step is needed
- rotate image
- crop image
- save as bmp

i currently used CxImage, but it seems buggy - totally weird things happen after i use ::Rotate Cry | :((

Thank You

Mark Salsbery21-Jan-07 7:53

21-Jan-07 7:53

Bitmap class constructors will load a png image (as well as Bitmap::FromFile())
Image::RotateFlip() will rotate and/or flip
To crop, extract the desired portion from the source image into a second image (see below).
There's a Graphics::DrawImage() overload that will do just that.
Bitmap::Save() will save as any of the supported types (see below).

This sample code should be enough to get you started...

// Resize png to 320x240 bmp
// The GDI+ Bitmap class is derived from the GDI+ Image class
// I've made no assumptions on the src image dimensions
//   You should use Image::GetHeight()/Image::GetWidth() in real life :)
 
   Gdiplus::Bitmap SrcBitmap(L"C:\\test.png", FALSE);
 
   Gdiplus::Bitmap DstBitmap(320, 240, SrcBitmap.GetPixelFormat()); 
 
   Graphics DstGraphics(&DstBitmap);
   DstGraphics.DrawImage(&SrcBitmap, 0, 0, 320, 240);
 
   CLSID bmpClsid;
   GetEncoderClsid(L"image/bmp", &bmpClsid);
 
   DstBitmap.Save(L"C:\\test.bmp", &bmpClsid, NULL);

// This utility ripped right from the SDK
 
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
   UINT  num = 0;          // number of image encoders
   UINT  size = 0;         // size of the image encoder array in bytes
 
   ImageCodecInfo* pImageCodecInfo = NULL;
 
   GetImageEncodersSize(&num, &size);
   if(size == 0)
      return -1;  // Failure
  
   pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
   if(pImageCodecInfo == NULL)
      return -1;  // Failure
 
   GetImageEncoders(num, size, pImageCodecInfo);
 
   for(UINT j = 0; j < num; ++j)
   {
      if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
      {
         *pClsid = pImageCodecInfo[j].Clsid;
         free(pImageCodecInfo);
         return j;  // Success
      }    
   }
 
   free(pImageCodecInfo);
   return -1;  // Failure
}

-- modified at 14:14 Sunday 21st January, 2007
edited for splelling

Re: gdi+ example ?

Mark Salsbery21-Jan-07 8:13

21-Jan-07 8:13

Forgot one...

You can use Bitmap::LockBits()/Bitmap::UnlockBits() to access the image bits.

Mark

Re: gdi+ example ?

Hamid_RT22-Jan-07 5:46

Hamid_RT

22-Jan-07 5:46

You can use of GDI+ about this subjects but if you want to load and change some things on the image and save it you can use also of CImage class but for rotate GDI+ is better however its possible with CImage but GDI+ is easy.

WhiteSky

about a = b | c | ...

HOW WHAT21-Jan-07 2:50

HOW WHAT

21-Jan-07 2:50

a = b | c | ...

(1)
if (a & b)
{
....
}

(2)
if ((a & b) == b)
{
....
}

(1) and (2), use which is better? why?

thanks.

Gary R. Wheeler21-Jan-07 3:02

Gary R. Wheeler

21-Jan-07 3:02

If the value 'b' is a single bit, then the two approaches are equivalent.

If there are multiple bits set in 'b', then they are not. (1) will be true if any of the bits in b are also set in a. (2) will be true if and only if the same bits that are set in b are also set in a.

Software Zen: delete this;

Fold With Us![^]

HOW WHAT21-Jan-07 3:19

HOW WHAT

21-Jan-07 3:19

umm... Can you example some?

Gary R. Wheeler21-Jan-07 4:28

Gary R. Wheeler

21-Jan-07 4:28

Example 1: Suppose a=0x1A (00011010 binary), and b=0x08 (00001000). In that case, 'if (a & b)' and 'if ((a & b) == b)' are both satisfied, since 'a & b' evaluates to 0x08.

Example 2: Suppose a=0x1A (00011010 binary) again, but this time b=0x09 (00001001 binary). In that case, 'if (a & b)' is satisfied, yet 'if ((a & b) == b)' is not.

Remember that the first if is satisfied by any non-zero value, while the second one requires that the result of the '(a & b)' expression equal the value of b.

Software Zen: delete this;

Fold With Us![^]

CPallini21-Jan-07 3:37

21-Jan-07 3:37

It depends.

If each of b,c,... corrensponds to just one bit set (e.g. <ode>b=1; c=2;...), then the expressions are equivalent (maybe (1) is faster).

On the other hand, if b,c,... holds composite bit values (e.g. <ode>b=3; c=5;...) then you have to carefully choose the expression you need, since (1) meets the requisite of an OR condition, while (2) corrensponds to an AND one). For instance, conside the following code snippet:

enum
{
  FEMALE = 1, //MALE: bit unset
  YOUNG  = 2, //OLD: bit unset
  ...
};

if b=FEMALE; then both the (1) and (2) meet the condition, but if you are searching for a young female (b=YOUNG|FEMALE;), the you have to be careful, because (1) holds true also when a represents a young guy or an old lady!
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

HOW WHAT21-Jan-07 3:57

HOW WHAT

21-Jan-07 3:57

a = 1 | 0x10000000

a & 3 = 1 -> if (a & 3) { ...} error
a & 4 = 0

not understand about bit

a = b | c | d

how to define value of b,c, d

CPallini21-Jan-07 4:55

Some basic Qs abt MFC,VC++,SDK....

21-Jan-07 4:55

What I mean is that if you have b,c,d,e,f,... each corrensponding to only one bit set, for instance:

b=0x00000001;// bit 0 set
c=0x00000002;// bit 1 set
d=0x00000004;// bit 2 set
e=0x00000008;// bit 3 set
f=0x00000010;// bit 4 set

then a condition using (a & b) evaluates to true (non-zero) only if a has the bit 0 set and the same holds for a condition using ((a & b) == b). In the same way, a condition using (a & c) evaluates to non-zero only if a has the bit 1 set, the same holding for a condition using ((a & c)==c), and so on...

On the other hand, suppose that x is a combination (sum using OR) of the above indipendent values, for instance x= b | e;, so that x=0x00000009, i.e. x has both the bits 0 and 3 set.
In this case, a condition using (a & x) evaluates to non-zero either if a has:
<list>

only bit 0 set

only bit 3 set

both bit 0 and 3

while a condition using ((a & x) == x) holds true only if both bit 0 and 3 are set.

In other words, if x = 0x00000009; then

(a & x) holds true if a = 0x00000001;, or a = 0x00000008;, or a = 0x00000009;

while ((a & x) == x) holds true if a = 0x00000009.

hope that helps
Smile | :)

BTW both conditions are also true if a = 0x00000019 and so on...

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Sameer_Thakur21-Jan-07 1:01

Sameer_Thakur

21-Jan-07 1:01

Hi all.

I am a new comer to the MFC and VC++ fields.

There are some questions those sounds bit confusing to me, like....

1. What is MFC? Offcource I know that is a collection of classes, structures etc, etc predefined by Microsoft Smile | :)

2. What is VC++? a language or a platforma or something else?
3. VC++ 6.0 or 5.0 (or whatever) is the IDE. Is that right?

Sameer Thakur

Re: Some basic Qs abt MFC,VC++,SDK....

CPallini21-Jan-07 2:02