C / C++ / MFC Discussion Boards

Dave Kerr6-Jul-09 7:05

6-Jul-09 7:05

Hi All,

I have a very large application that creates many dialogs. I have a CDialog derived class that skins dialogs. I would like to automatically make EVERY dialog in my application use this class - even message boxes, TWAIN interfaces etc etc. I was hoping I could simply use SetWindowsHookEx to do this but the problem that I'm having is that my dialogs are already 'CWnd' objects - when I try to subclass them as another CWnd (i.e. my Skinned Dialog class) I get assertations.

Is there any way to safely subclass a CDialog object with another CDialog object?

Thanks in advance,

Dave

Re: Hooks

«_Superman_»6-Jul-09 17:13

«_Superman_»

6-Jul-09 17:13

You could use the CWnd::Detach method to detach the existing CWnd object and then use CWnd::Attach on the returned window handle to attach your CDialog derived class.

«_Superman_»
I love work. It gives me something to do between weekends.

How to convert an array of 32bit integers to image in C++

su_marvel6-Jul-09 4:14

su_marvel

6-Jul-09 4:14

Hi all,

I'm working on creating an application which will acquire image data from a camera and display it.

I have right now acquired image data from camera. The data is in the form of long integer array (32-bit signed integers). I would like to visualise this data. I am not sure how to display the data as an image. Could you please help me?

I am using Microsoft visual studio C++ 2008.

Thanks

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat6-Jul-09 5:08

Code-o-mat

6-Jul-09 5:08

What is the format of that image data? Compressed, uncompressed, RGB values, BGR values? 8 bits per color component, 16 bits per color components, using a palette? Generally i guess you could create a dib section using CreateDIBSection[^] and try to render that image into the dib and then you can do whatever you like with it like blitting it onto a window.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 1:06

su_marvel

7-Jul-09 1:06

Hi,

Each pixel value is in the form of 32 bit. I understand the last 24 bits represent RGB values(8bits each) and the rest 8 bits are unused (value=0).
I am not sure how I can create a proper pixel palette to convert this image to bitamp and display it.

Re: How to convert an array of 32bit integers to image in C++

chandu0047-Jul-09 1:16

chandu004

7-Jul-09 1:16

do you know the dimensions of the image?
i mean, pixels along x and pixels along y.

--------------------------------------------
Suggestion to the members:
Please prefix your main thread subject with [SOLVED] if it is solved.
thanks.
chandu.

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 1:54

su_marvel

7-Jul-09 1:54

Hi yes i know the dimensions of the image ..Its 1004*1002

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat7-Jul-09 1:34

Code-o-mat

7-Jul-09 1:34

I supose you do know the dimensions of your image (width and height) so when you create a DIB in memory of that size, as the documentation states, you get a pointer to the first pixel and can start copying your pixel data performing conversion if needed.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 3:56

su_marvel

7-Jul-09 3:56

Hi..
i know the dimensions of the image data. its 1004*1002. I created a DIB with CreateDIBSection. But the color information looks very different from the image which i obtained from the camera using its software. Right now my data is 32 bit (24bit RGB + 8bits unused). could u please advice me on how to convert the bit depth from 32bit to 8bit?

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat7-Jul-09 4:01

Code-o-mat

7-Jul-09 4:01

Why do you want to convert it to 8 bit? You can create 24 and 32 bit DIBs.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 4:21

su_marvel

7-Jul-09 4:21

The color imformation looks very different in the DIB which i have generated. I am not sure if i should use some color palette. Please find below the code which i used

        HDC dc= CreateCompatibleDC(NULL);
BITMAPINFO info;
ZeroMemory( &info.bmiHeader, sizeof (BITMAPINFOHEADER) );
info.bmiHeader.biHeight = 1002;
info.bmiHeader.biWidth = 1004;
info.bmiHeader.biPlanes = 1;
info.bmiHeader.biBitCount = 24;
info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
info.bmiHeader.biClrUsed= 0;
info.bmiHeader.biClrImportant= 0;
long* pixels;
int Buffersize = 1004*1002;

HBITMAP hbmp= CreateDIBSection( dc,
&info,
DIB_RGB_COLORS,
(void**)&pixels,
NULL,
0 );

pixels = (long*) malloc(Buffersize*sizeof(long));
        //arr contains pixels data (32bit unsigned integers)
for(int j=0; j < Buffersize; j++)
{
    pixels[j] = arr[j];
}

int nFile = _open ("c:\\Image.bmp", _O_CREAT | _O_TRUNC | _O_BINARY | _O_WRONLY, _S_IWRITE);

int nBitmapDataSize = (width * height * 3);
int nFileSize = sizeof (BITMAPFILEHEADER) + sizeof       (BITMAPINFOHEADER) + nBitmapDataSize;
int nOffset = sizeof (BITMAPFILEHEADER) + sizeof (BITMAPINFOHEADER);

BITMAPFILEHEADER bmfh;
bmfh.bfType = ((WORD) ('M' << 8) | 'B');
bmfh.bfSize = nFileSize;
bmfh.bfReserved1 = 0;
bmfh.bfReserved2 = 0;
bmfh.bfOffBits = nOffset;

BITMAPINFOHEADER bmih;
memset (&bmih, 0, sizeof (BITMAPINFOHEADER));
bmih.biSize = sizeof (BITMAPINFOHEADER);
bmih.biPlanes = 1;
bmih.biBitCount = 24;
bmih.biCompression = BI_RGB;
bmih.biWidth = width;
bmih.biHeight = height;

_write (nFile, &bmfh, sizeof (BITMAPFILEHEADER));
_write (nFile, &bmih, sizeof (BITMAPINFOHEADER));
_write (nFile, pixels, nBitmapDataSize);
_close (nFile);

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat7-Jul-09 4:54

Code-o-mat

7-Jul-09 4:54

What are you trying to achieve here? If you wish to save your image you don't need a DIB section, i thought you wanted to display the image on some window for example, for that you could use the DIB, to save a bitmap to a file you can simply write the headers and the pixel data as you did without any device contexts or HBITMAPs. So let's forget the DIB and consider you just want to save the data to a bmp file. Explain what you mean by "looks very different". You should know that in a bitmap each scanline's bytecount has to be dividable by 4 otherwise your image will look disorted. To explain what i mean: you say your image's width is 1002 pixels. If you want a 24 bits per pixel bitmap, then every pixel is 3 bytes, right? So 1002 pixels is 1002 * 3 = 3006 bytes. 3006 / 4 = 751.5, so your scanlines do not occupy a multitple of 4 bytes. You need padding to overcome this, you have to add zeros to the end of each scanline till your scanline's bytecount can be divided by 4. So after you write 3006 bytes into the file for the RGB data you also need to write 2 additional bytes of 0, this way your scanlines will have 3008 bytes, which can be divided by 4 (752). You have to do this for each scanline. You should read about the bitmap file format here[^] or just google[^] a bit around.
Imho, you are better of trying to save a 32 bpp bitmap, since 32 bits are 4 bytes, your 1002 pixels on a scanline will occuppy 4008 bytes which is -obviously- dividable by 4.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 5:06

su_marvel

7-Jul-09 5:06

hii.

I am trying to display the image onto a window. But i'm not sure how to do it with DIB. So i just thought of saving it onto disk. Can u advice me on how to use DIB for displaying?

Actually the width of my image is 1004 and the height is 1002. So the width will be divisible by 4.

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat7-Jul-09 5:33

Code-o-mat

7-Jul-09 5:33

Well, you were on the right track there with creating the DIB section as you have shwon in your code but you don't need a DC, just feed it NULL there. Once you copied the pixel data into your DIB you can blit it onto a window like any other bitmap. So something like this for example:

void CMyWindow::OnPaint()
{
  CPaintDC dc(this);
  CDC MemDC;
  MemDC.CreateCompatibleDC(dc);
  HBITMAP original_bitmap = (HBITMAP)::SelectObject(MemDC, my_dib_handle);
  dc.BitBlt(0, 0, 1004, 1002, &MemDC, 0, 0, SRCCOPY);
  ::SelectObject(MemDC, original_bitmap);
}

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 22:11

su_marvel

7-Jul-09 22:11

hi there.

I tried using the onpaint function in my program. But it does not seem to recognise the function. It throws error like
1. CMywindow: is not a class or namespace name
2. CPaintDC : undeclared identifier
I think i'm making a big mistake somewhere.
Could you please help me on where i should use this function in my above code? Or is it to be done in MFC's?

Thanks very much

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat7-Jul-09 23:31

Code-o-mat

7-Jul-09 23:31

I believe your biggest mistake is that you are trying to literally integrate the example i gave you into your program word by word... that code snipplet was just an example. Do you have a window in your application you wish to show the image on? You should do that when that window gets the WM_PAINT message. If you don't know what i am talking about then you should read some windows programming books or google around for tutorials and such. Good luck. Smile | :)

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel8-Jul-09 3:36

su_marvel

8-Jul-09 3:36

Ya. I have been doing some learning to get this working. Can u pls let me know how to use OnPaint function? Does it work with MFC's?
I am getting confused with them.

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat8-Jul-09 5:11

Code-o-mat

8-Jul-09 5:11

Well, as said, google is your friend, you can find all that info, however, add this to the message map of your window: ON_WM_PAINT()
It would look something like this, please don't copy paste this into your code and try to compile, it is just an example so you know how it should look...so about...

BEGIN_MESSAGE_MAP(CMyWindow, CMyWindowsSuperClass)
  ...
  ON_WM_PAINT()
  ...
END_MESSAGE_MAP()

Let's assume you named the class for your window CMyWindow, so in the header file, declare the OnPaint method similarry to this:

class CMyWindow: public CMyWindowsSuperClass
{
  ...
  void OnPaint();
  ...
};

and then implement this method in the cpp file that contains your window class' implementation, similar to this:

void CMyWindow::OnPaint()
{
  CPaintDC dc(this);
  //Perform drawing here using the dc as shown to you in earlier posts...
}

I hope this helps...

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

su_marvel8-Jul-09 22:21

su_marvel

8-Jul-09 22:21

Hi there,

The image data that i have got represent intensity of light falling on the sensor(whcih is 32 bits per pixel) . Can u pls suggest me how i can use palette files when displaying images to visualise contrast in intensities?

Many Thanks

Re: How to convert an array of 32bit integers to image in C++

Code-o-mat8-Jul-09 22:28

Code-o-mat

8-Jul-09 22:28

Never worked with palettes so i can't, sorry...

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

Re: How to convert an array of 32bit integers to image in C++

Adam Roderick J6-Jul-09 5:27

Adam Roderick J

6-Jul-09 5:27

Currently your data is in long integer right.
So now just ur data is actualy a pixel data. which contains the pixel intensity for Monochrome and RGB for color.
So use GDI+ Smile | :)

You want pixel data as long pointer array to bitmap from which it will be easy to create a image. Smile | :)

Bitmap * BitMapHandler::PixelInfo2BitMap(int width, int height,
int *pixData )
{

// Fistly create a temp Bmp with the height and width of the image.
Bitmap bit(width, height, PixelFormat32bppARGB );

// Create clone as as to return as output.
Bitmap *bmp = bit.Clone(0, 0, bit.GetWidth(), bit.GetHeight(),
PixelFormat32bppARGB);

BitmapData bmData;
Rect rect(0, 0, bmp->GetWidth(), bmp->GetHeight());
bmp->LockBits(rect,
ImageLockModeRead | ImageLockModeWrite,
PixelFormat32bppARGB,
&bmData);

int stride = bmData.Stride;
BYTE *pArr = (BYTE *)((void *)bmData.Scan0);
int nOffset = stride - width*4;

int pixel;

for(int y=0; y < height;y++) {
for(int x=0; x < width; ++x ) {
// GDI lies about RGB - internally it's BGR
pixel = pixData[y*width+x];
pArr[3] = (BYTE) ((pixel >> 24) & 0xff); // alpha
pArr[2] = (BYTE) ((pixel >> 16) & 0xff); // pixel red
pArr[1] = (BYTE) ((pixel >> 8 ) & 0xff); // pixel green
pArr[0] = (BYTE) ((pixel ) & 0xff); // pixel blue
pArr += 4;
}
pArr += nOffset;
}
bmp->UnlockBits(&bmData);

return (bmp);
}
Hope it is enough Smile | :)

Re: How to convert an array of 32bit integers to image in C++

su_marvel7-Jul-09 1:01

su_marvel

7-Jul-09 1:01

Hi ARJ,

Thnaks for your code.Actually,the code throws an exception at

Bitmap *bmp = bit.Clone(0, 0, bit.GetWidth(), bit.GetHeight(),PixelFormat32bppARGB);

in getting the values of widht and height in GdiPlusBitmap.h

The exception is
Unhandled exception at 0x00411bc1 in test.exe: 0xC0000005: Access violation reading location 0x00000004.

I am not sure why it occurs. Could you please advice me on this?

How to differenciate?

FISH7866-Jul-09 3:20

FISH786

6-Jul-09 3:20

Hello,

I am trying to capture a window from an external App Example Calculator.
I am able to get the handle of the window. If the user opens a second instance, I am able to get that handle too using EnumWindows.
Which means I have 2 handles for the 2 calculators. Short of using the Handle is there anything else that I could use to differenciate the 2 windows. I can't use the window title since they are both the same.

Reason for asking:
I know the handle gets reused, but is it possible for the handle to change after the window has been created or does it stay the same after creation? Yes, if I close the window, I know I will not get the same handle.
Is it possible that If the user minimizes the window and activates it again, we get a new handle?
If the handle changes during the lifetime of the window whats the best way of keeping track of that window?

I have created a thread and am using the same function to handle capturing data from the 2 windows by passing the handle as a parameter. However, I can only get the data from one of the windows, or am I better off creating multiple threads which is what I was avoiding?

Could someone please help.

Re: How to differenciate?

Stuart Dootson6-Jul-09 4:04

Stuart Dootson

6-Jul-09 4:04

FISH786 wrote:
but is it possible for the handle to change after the window has been created or does it stay the same after creation

AFAIK, a window handle doesn't change over the lifetime of a window.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: How to differenciate?

FISH7866-Jul-09 4:11

FISH786

6-Jul-09 4:11

Thanks again.

which is what I thought but wanted to be sure.

I guess back to debugging and find out why I can't get the data from the second window.
However, I should be able to use the same thread and pass the handle as a parameter? or am I better off creating multiple threads and dedicate each thread to a window for the lifetime of that particular window?

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