Re: Detect USB drive writable - C / C++ / MFC Discussion Boards

The NULL Developer26-Oct-05 19:59

26-Oct-05 19:59

Hi,

This is what i'm doing, in VS .net 2003:

1. Create an SDI application.
2. Add a dialog to resource named IDD_DIALOG1 and make the Style as Child.
3. Add a Dialog class from that resource, say CDlgTest.
4. Add a member variable, say m_dlgTest to the View class of the application.
5. In the WM_CREATE message handler of the view class, I add the following two lines,

m_dlgTest.Create( IDD_DIALOG1, this );
m_dlgTest.ShowWindow( SW_SHOW );

The dialog window which shows up is never painted as activated. In my application, I'm having several such windows, so there is no way for the user to know which window is he working upon?

Please help.
Thanks in advance.

"Do first things first, and second things not at all."
— Peter Drucker.

IImageDecodeEventSink

Carsten Leue25-Oct-05 23:17

Carsten Leue

25-Oct-05 23:17

Does anybody know where I can find information on the
IImageDecodeEventSink and the IImageDecodeFilter interfaces that are declared in ocmm.h?

Best regards
Carsten

Calling from explicitly loaded .dll

DaveDrPop25-Oct-05 22:41

DaveDrPop

25-Oct-05 22:41

I am developing an application which explicitly loads a .dll (using LoadLibrary) and ideally I would like to access a static class member in the loading .exe from code in the dll.

The static member appears to be there, but is at a different address and is uninitialised.

Directly accessing the static data from within the .dll causes an exception.

It looks like the problem is the address space that the .exe and the .dll occupy - I'm presuming that it's the same if the .dll is implicitly load, but not if explicitly loaded

is there any way of calling from the .dll back into the .exe ?

any help appreciated

Re: Calling from explicitly loaded .dll

C^hris L^osinger26-Oct-05 1:39

C^hris L^osinger

26-Oct-05 1:39

DaveDrPop wrote:
is there any way of calling from the .dll back into the .exe ?

have the EXE give the DLL a pointer to a callback function in the EXE that the DLL can call whenever it wants. ex.

in the DLL:
 
// define the function type
typedef double      (CALLBACK* MyCALLBACKPTR)(int param1, int param2);
 
MyCALLBACKPTR globalCallback = NULL;
 
// export this function
void SetDLLCallback(MyCALLBACKPTR p)
{
  globalCallback = p;
}
 
// when the DLL wants something from the EXE
...
if (globalCallback!=NULL)
{
   // call the callback
   double v = *(globalCallback)(a,b);
}
 
 
in the EXE:
double CALLBACK foo(int a, int b)
{
  // the DLL has called this function, give it something in return..
  return 3.14156;
}
 
// tell the DLL where to call
SetDLLCallback(foo);

the parameters on the callback function are completely up to you, of course.

Cleek | Image Toolkits | Thumbnail maker

Detect USB drive writable

LiYS25-Oct-05 22:24

LiYS

25-Oct-05 22:24

How to detect wether USB drive is writable or not!I have tried CreatFile and GetLastError with the value of ERROR_ACCESS_DENIED.But creating a dummy file is not friendly gesture. Is there other ways around?

Re: Detect USB drive writable

kakan26-Oct-05 0:46

kakan

26-Oct-05 0:46

Create a HANDLE to the drive, then use this code:

BOOL IsDiskWriteProtected(HANDLE hDrive)
{
DWORD dwRet;

BOOL bWritable = DeviceIoControl(hDrive,
IOCTL_DISK_IS_WRITABLE,
NULL, 0, NULL, 0,
&dwRet,
NULL);

// If you don't have the SDK, IOCTL_DISK_IS_WRITABLE is a DWORD
// with the hex value 0x00070024

if(bWritable == TRUE) return FALSE;
return TRUE;
}

To get a HANDLE to the drive, do this:

BOOL OpenDrive(char drive)
{
char NtDriveName[10];
char m_drive = drive;

if(hDrive != (HANDLE) 0) CloseDrive();

// Open and Lock the drive
//

m_drive = (char) toupper((int) m_drive);
sprintf(NtDriveName, "\\\\.\\%c:", m_drive);

hDrive = CreateFile(
NtDriveName,
GENERIC_READ | GENERIC_WRITE, // Possibly just GENERIC_READ
0,
NULL,
OPEN_EXISTING,
FILE_FLAG_NO_BUFFERING,
NULL
);

if ( hDrive == INVALID_HANDLE_VALUE ) {
// Cannot open it, Error!
return FALSE;
}
// OK
return TRUE;
}

-- modified at 7:13 Wednesday 26th October, 2005

Re: Detect USB drive writable

LiYS26-Oct-05 5:32

LiYS

26-Oct-05 5:32

Thanks kakan!
The code finally turned into

CString strDrive;
strDrive.Format("\\\\.\\%c:", 'C');
HANDLE hDrive = CreateFile(strDrive,  GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE,
                            NULL, OPEN_EXISTING, FILE_FLAG_NO_BUFFERING, NULL);
DWORD dwRet;

BOOL bWritable = DeviceIoControl(hDrive, IOCTL_DISK_IS_WRITABLE, NULL, 0, NULL, 0,
                                    &dwRet, NULL);

But the question is I have "C;D;E;F;G(CDROM)" drives, if I don't specify dwDesiredAccess as GENERIC_READ | GENERIC_WRITE, the returned hDrive for "C;D;E" is INVALID_HANDLE_VALUE, and all the accessable drives' hDrive(valid) is the same(0x000006f8). Is this normal?

Re: Detect USB drive writable

Blake Miller26-Oct-05 6:59

Blake Miller

26-Oct-05 6:59

and all the accessable drives' hDrive(valid) is the same(0x000006f8). Is this normal?

A handle's value is an opaque value to your program. It would only be ABNORMAL if you have OPENED more than a single drive simultaneously. If you are opening one drive at a time and then closing the handle, it would not be uncharacteristic for windows to recycle the handle value to you for each drive. If you opened two separate files or drives and got the same handle value back for both while they were BOTH opened, I would be concerned.

Re: Detect USB drive writable

kakan26-Oct-05 19:35

kakan

26-Oct-05 19:35

Hello LiYS.

Your second question is already answered, so I will try to answer yor first question.

To be honest, I'm not 100% sure, but my guess is that it isn't possible to open a CDROM-drive in GENEREIC_WRITE-mode.

In my own code, I first try to open the drive in GENERIC_READ | GENERIC_WRITE-mode. If it doesnt work, I try again, in GENERIC_READ-mode.
It seems to work at all times. But of course, if it's possible only to open the drive in GENERIC_READ-mode, then it's obviously read-only. Smile | :)

A comment: You should check your handle for INVALID_HANDLE_VALUE before calling DeviceIoControl.

kakan

Re: Detect USB drive writable

LiYS27-Oct-05 19:19

LiYS

27-Oct-05 19:19

Hi Kakan do you know how to make this code works under Win98?

How to set a Textcolor in a CListCtrl

bosfan25-Oct-05 22:23

bosfan

25-Oct-05 22:23

Hi community,
how can i set a Textcolor in a CListCtrl for each Item?
In addiction from an Itemvalue i want to set a different Item's Textcolor! Confused | :confused:

Any Idea?
thanx
break;

Re: How to set a Textcolor in a CListCtrl

prasad_som25-Oct-05 23:34

prasad_som

25-Oct-05 23:34

Use NM_CUSTOMDRAW. Sample for this code will be like this

void MyDlg::OnCustomdrawList ( NMHDR* pNMHDR, LRESULT* pResult )
{
NMLVCUSTOMDRAW* pLVCD = reinterpret_cast<NMLVCUSTOMDRAW*>( pNMHDR );


    *pResult = 0;

    if ( CDDS_PREPAINT == pLVCD->nmcd.dwDrawStage )
        {
        *pResult = CDRF_NOTIFYITEMDRAW;
        }
    else if ( CDDS_ITEMPREPAINT == pLVCD->nmcd.dwDrawStage )
        {
        *pResult = CDRF_NOTIFYSUBITEMDRAW;
        }
    else if ( (CDDS_ITEMPREPAINT | CDDS_SUBITEM) == pLVCD->nmcd.dwDrawStage )
        {
                 //this will get called for each column in list box
                 //you can deter mine column number by pLVCD->iSubItem
                 COLORREF crText, crBkgnd;
                 crText = RGB(0,255,100);
                 crBkgnd = RGB(255,32,11);
                 pLVCD->clrText = crText;
                 pLVCD->clrTextBk = crBkgnd;
                *pResult = CDRF_DODEFAULT;
        }
}

Re: How to set a Textcolor in a CListCtrl

Anonymous26-Oct-05 1:02

Anonymous

26-Oct-05 1:02

Hi,
thanx, i it helps! Smile | :)

regards
break;

How can I get a copy of wav file with other format

extraf25-Oct-05 21:38

extraf

25-Oct-05 21:38

every wav file have it's own format described by the WAVEFORMATEX struct,I want to get a copy of a wav file with changing it's WAVEFORMATEX .So what can I do? Confused | :confused:

Re: How can I get a copy of wav file with other format

Blake Miller26-Oct-05 7:00

Blake Miller

26-Oct-05 7:00

Pass the data through the audio compression manager to change its format for you.

Hide the blue task pane in a CHtmlView

gleditzsch25-Oct-05 21:26

gleditzsch

25-Oct-05 21:26

I'm using a class derived from CHtmlView as listview in an internal Folder
Browser of my application.

Exist a facility to hide the left blue task pane (if user have activate this
feature in Folder Options)?

Another fine feature will be, to set the "list" as active default view in my
application (may be the user has set "icon" as default). Any idea?

Thx for help

Density sampling

Arrun25-Oct-05 20:50

Arrun

25-Oct-05 20:50

What is density sampling?

How can it be used in image resizing?

Pls help

prime number with recursion

Rajesh_K_Sharma25-Oct-05 20:07

Rajesh_K_Sharma

25-Oct-05 20:07

Write a program in c language to print prime number using recursion

rajesh

Re: prime number with recursion

sunit525-Oct-05 22:11

sunit5

25-Oct-05 22:11

//it will print the no which r prime no and greater than 9
void divisiblity(int divident,int divisor);
main()
{

const int divisor=9;//keep it const
int divident=10;

while(1)
{
divisibility(divident,divisor);
divident++;
}
}

void divisibility(int divident,int divisor)
{
if(divisor==1)
{
printf("the no is a prime no\t%d",divident)
return ;
}
int remainder=divident%divisor;
if(remainder==0)
return;

divisibility(divident,divisor-1);
return;
}

Laugh | :laugh:

hope this may help u

-- modified at 6:43 Wednesday 26th October, 2005

Re: prime number with recursion

toxcct25-Oct-05 22:25

toxcct

25-Oct-05 22:25

you suck !!

do your homework by yourself.

assignments are made to make you progress ; asking someone to do it for you will never deserves you.

D'Oh! | :doh: