Re: bitmap file format - C / C++ / MFC Discussion Boards

Rüpel18-Aug-04 3:42

18-Aug-04 3:42

hi,

i'm writing a (legacy, non-MFC) dll and there might get an exception thrown in there. it is caught in the exe-file that uses that dll.

dll:

//some error<br />
throw new CSomeException();

exe:

catch (CSomeException *e)<br />
{<br />
  e->SomeFunction(); // works fine<br />
  delete e; // crash<br />
}

the delete-call crashes because the object is not a valid *local* heap-pointer.

stepping in dbgheap.c reveales the following passage

/*<br />
 * If this ASSERT fails, a bad pointer has been passed in. It may be<br />
 * totally bogus, or it may have been allocated from another heap.<br />
 * The pointer MUST come from the 'local' heap.<br />
 */<br />
_ASSERTE(_CrtIsValidHeapPointer(pUserData)); // fails

so, finally. how am i supposed to handle this? i mean throwing an exception in a library isn't that uncommon, is it? Confused | :confused:

:wq

Re: new in dll, delete in exe, bang :(

Nemanja Trifunovic18-Aug-04 3:58

Nemanja Trifunovic

18-Aug-04 3:58

I bet at least one of your modules (exe or dll) has CRT statically linked. That means that one instance of CRT is allocating the memory and another one tries to release it ... BANG!

A solution is to link all your modules dinamically (option /MD) against CRT. This way they will share the same CRT instance, and you should be able to allocate memory in one module and release it in another.

Either that, or make sure that each module cleans its own memory.

My programming blahblahblah blog. If you ever find anything useful here, please let me know to remove it.

Re: new in dll, delete in exe, bang :(

Rüpel18-Aug-04 4:22

Rüpel

18-Aug-04 4:22

bingo! the DLL was set to /MT[d] - I changed that to /MD[d] and it seems to work (just gave it a quick shot)

thx, man! Rose | [Rose]

:wq

Re: new in dll, delete in exe, bang :(

Ravi Bhavnani18-Aug-04 4:13

Ravi Bhavnani

18-Aug-04 4:13

If my memory serves me right, an object new'd by a regular MFC DLL must be destructed by that DLL. An object new'd by an extension MFC DLL can be destructed by the client. See this[^] article.

/ravi

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bitmap file format

peterworth18-Aug-04 3:21

peterworth

18-Aug-04 3:21

i am reading the first 14 bytes of a bitmap into a struct like this:

struct bmfh
{
unsigned short int bfType;
unsigned long int bfSize;
unsigned short int bfReserved1, bfReserved2;
unsigned long int bfOffBits;
};

and the results come out like this:

type: BM
size: 5
reserved1: 0
reserved2: 1078
bit offset: 3452764160

surely the size and offset cant be correct, does anyone know what i'm doing wrong? other bitmaps give similar values.

Re: bitmap file format

C^hris L^osinger18-Aug-04 4:27

C^hris L^osinger

18-Aug-04 4:27

what are the first 14 bytes of the file? (you look at it in VC, if you open it as a "binary" file)

Software | Cleek

Re: bitmap file format

Anonymous18-Aug-04 4:46

Anonymous

18-Aug-04 4:46

aha, i didnt know you could do that in vc++..

42 4D 9A 31 08 00 00 00 00 00 36 04 00 00

Re: bitmap file format

C^hris L^osinger18-Aug-04 4:54

C^hris L^osinger

18-Aug-04 4:54

any reason you're not using MS's BITMAPFILEHEADER struct?

when i do this:

<br />
BYTE buf[14] = {0x42 ,0x4D ,0x9A ,0x31 ,0x08 ,0x00 ,0x00 ,0x00  ,0x00 ,0x00 ,0x36 ,0x04 ,0x00 ,0x00 };<br />
BITMAPFILEHEADER *b = (BITMAPFILEHEADER *)buf;<br />

the values look fine:

bfType: 19778 ('BM')
bfSize: 536986
bfReserved1: 0
bfReserved2: 0
bfOffBits: 1078

-c

Software | Cleek

Re: bitmap file format

Anonymous18-Aug-04 4:57

Anonymous

18-Aug-04 4:57

hmm, thats what should happen with mine. i'm just using my own struct to better understand the file format and stuff. as far as i can see, mine is identical to the microsoft one..

Re: bitmap file format

C^hris L^osinger18-Aug-04 5:03

C^hris L^osinger

18-Aug-04 5:03

are you using the 'pack' pragmas to ensure the members of your struct are aligned correctly?

ie.:

<br />
#pragma pack(2)<br />
typedef struct tagBITMAPFILEHEADER {<br />
        WORD    bfType;<br />
        DWORD   bfSize;<br />
        WORD    bfReserved1;<br />
        WORD    bfReserved2;<br />
        DWORD   bfOffBits;<br />
} BITMAPFILEHEADER, FAR *LPBITMAPFILEHEADER, *PBITMAPFILEHEADER;<br />
#pragma pack()<br />

-c

Software | Cleek

Re: bitmap file format

Anonymous18-Aug-04 5:08

Anonymous

18-Aug-04 5:08

that works perfectly now, could you explain what this pragma pack nonsense is all about and what it does?

thanks very much for your help.

Re: bitmap file format

C^hris L^osinger18-Aug-04 5:14

C^hris L^osinger

18-Aug-04 5:14

#pragma pack(n) tells the compiler to arrange your structs so that the struct members each start on addresses that are multiples of 'n'. your problem was that the members of the struct weren't in the right places to be filled by your file read function, because they weren't aligned the way you assumed they were.

the default packing size is 8; so, in effect, each member of a struct takes a minimum of 8 bytes. you can change this on a project-wide level in Project / Settings / C/C++ / Code Generation, or on specific structs using the #pragma pack constructs.

this is one of those things we all have to learn the hard way, since it's not exactly well-advertized Smile | :)

Software | Cleek

Re: bitmap file format

Rick York18-Aug-04 10:22

Rick York

18-Aug-04 10:22

This is what the documentation says but in practice it doesn't seem to work that way. Data structure members get packed to offset that corresponds to the size of their type ie., shorts to a two-byte boundary, ints to a four-byte boundary.

Here is a sample program and its output :

<br />
#include "stdafx.h"<br />
<br />
typedef struct<br />
{<br />
	unsigned short int	bfType; <br />
	unsigned long int	bfSize; <br />
	unsigned short int	bfReserved1;<br />
	unsigned short int	bfReserved2;<br />
	unsigned long int	bfOffBits; <br />
} BMFH;<br />
<br />
<br />
int main( int argc, char* argv[] )<br />
{<br />
	printf( "sizeof BMFH is %d bytes\n", sizeof( BMFH ) );<br />
	printf( "offset of bfSize      is %2d\n", offsetof( BMFH, bfSize ) );<br />
	printf( "offset of bfReserved1 is %2d\n", offsetof( BMFH, bfReserved1 ) );<br />
	printf( "offset of bfReserved2 is %2d\n", offsetof( BMFH, bfReserved2 ) );<br />
	printf( "offset of bfOffBits   is %2d\n", offsetof( BMFH, bfOffBits ) );<br />
	return 0;<br />
}<br />

sizeof BMFH is 16 bytes
offset of bfSize      is  4
offset of bfReserved1 is  8
offset of bfReserved2 is 10
offset of bfOffBits   is 12

__________________________________________
a two cent stamp short of going postal.

HELP NEEDED, With Windows Default Settings.

Yaxcidia18-Aug-04 2:52

Yaxcidia

18-Aug-04 2:52

I want to change the default settings, to be precise the color of the buttons and the message background that they appear. I want the background and the button to have to different colors. I have research the Internet and have found no answer. I’m programming in Microsoft Visual C++ 6.0. Thank you in advance. Rose | [Rose]

YaX

Re: HELP NEEDED, With Windows Default Settings.

David Crow18-Aug-04 6:19

David Crow

18-Aug-04 6:19

Are you talking about the Appearance tab of the Display Properties dialog?

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: HELP NEEDED, With Windows Default Settings.

Yaxcidia18-Aug-04 8:19

Yaxcidia

18-Aug-04 8:19

Thanks Dave... I was thinking more of hard coding the color... but yes i'm talking about the appearance tab... if i change the colors of the 3-d object it changes both the button and the window color. I only want to change the color of the button. Do you have any Suggestions on how i could possible hard coded.

YaX

Re: HELP NEEDED, With Windows Default Settings.

David Crow18-Aug-04 8:38

David Crow

18-Aug-04 8:38

To change the color of a button, I believe you need to override the OnCtlColor() method of the dialog class.

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Dialogs Skins ???

zahid_ash18-Aug-04 2:04

zahid_ash

18-Aug-04 2:04

HI,

There r examples on CP. abut Skin thay use BMPs for skin

I want to use GIF or PNG (fire works) files

Like animated Skins on dialogs.
How can i do this.

any link , example etc

thanx

Regards.

Re: Dialogs Skins ???

RChin18-Aug-04 3:35

RChin

18-Aug-04 3:35

have a browse through the dialog[^] section of CP. There are a few articles there dealing with skinable dialogs.

I Dream of Absolute Zero

Re: Dialogs Skins ???

zahid_ash18-Aug-04 18:32

zahid_ash

18-Aug-04 18:32

There r many but use BMP Images/files.

I want to Use GIF and PNG images.

any help in this regard.

thanx

Regards.

Problem:big dll size

happycpp18-Aug-04 1:50

happycpp

18-Aug-04 1:50

hello everyone..
this is my first post in this forum and actually it's a question about DLL's:
I made a *.cpp file with the following

#include <afx.h><br />
#include <Mmsystem.h><br />
<br />
LPCSTR _stdcall OpenSound (LPCSTR lpfile){<br />
	CString str = lpfile;<br />
	MCIERROR dwRet;<br />
<br />
	str = "open \"" + str + "\" alias jack";<br />
	<br />
	dwRet = mciSendString(str,NULL,0,NULL);<br />
	if (dwRet)<br />
		MessageBox(NULL,"Fail to open","Hello!",0);<br />
	else<br />
		if (mciSendString("close all",NULL,0,NULL))<br />
			MessageBox(NULL,"Fail to close","Hello!",0);<br />
			<br />
<br />
	//MessageBox(NULL,(LPCSTR)str,"Hello!",0);<br />
	return lpfile;<br />
}

and ofcourse I made a *.def file for it..
the problem is that the final DLL is TOO big ((80.0 kb in Release and 1.23 mb in Debug))
I made a dll in vb which contains a lot of functions and the size of it was about 60.0 kb..
so is there a way to minimize the DLL made by c++..

Re: Problem:big dll size

Michael P Butler18-Aug-04 1:56

Michael P Butler

18-Aug-04 1:56

80kb doesn't sound too large to me.

What version of CString are you using?

Is it the MFC or ATL version? Are you statically linking or dynaminc link ATL/MFC

What kind of compiler optimisation settings are you using?

Michael

CP Blog [^]

Re: Problem:big dll size

happycpp18-Aug-04 4:16

happycpp

18-Aug-04 4:16

I'm using the MFC and I don't know how to know if it's statically or dynamically!!
also I don't know about the optimisation thing..
actually I'm a very newb to these stuff..

Re: Problem:big dll size

David Crow18-Aug-04 6:22

David Crow

18-Aug-04 6:22

This is a very common misconception among new Windows programmers. I suggest you read these three articles:

http://www.flounder.com/howbig.htm
http://msdn.microsoft.com/msdnmag/issues/01/01/hood/
http://www.microsoft.com/msj/archive/S569.aspx

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

Re: Problem:big dll size

gamitech19-Aug-04 12:42

gamitech

19-Aug-04 12:42

too big for what man
?

gabby

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