asked on

CImage Load problem.

Hello experts,

I have a program that allows people to load in picture files and then display them. They can then save the document or file for my app and send it to someone else who opens and views the file for this reason i have chosen to implement CImage and the loading function is

HRESULT CImage::Load(IStream* pStream).

I have implemented it this way.
This works because the file is read into a buffer which we save. This buffer is where the data is kept.

CFile file;
if( !file.Open( file_name, CFile::modeRead) )
      return FALSE;
m_buffer_size = (long)file.GetLength();
if ( alocate_buffer(m_buffer_size) == NULL )
      return FALSE;
if ( file.Read(m_buffer, m_buffer_size) != m_buffer_size )
      return FALSE;
file.Close();

CImage image;
image.Destroy();
if ( m_buffer == NULL )
return;
CMemFile mem_file(m_buffer,m_buffer_size);
CArchiveStream stm (&ar);
image.Load(&stm);
ar.Close();
mem_file.Detach ();
mem_file.Close();

The wierd part about this is it will work with some BMP's and not with others. sometimes it will crash and at other times it will simply not display. For example.

for example the following bit map will work.

width: 350 pixels
height: 327 pixels
horizontal resolution: 95 dpi
vertical resolution: 95 dpi
bit depth: 24
frame count: 1

but this one will fail on the above call
"image.Load(&stm);"
producing the error message
"Unhandled exception at 0x006609f3 in myApp.exe: 0xC0000005: Access violation reading location 0x0000000c."

its properties are

width: 919 pixels
height: 690pixels
horizontal resolution: 96 dpi
vertical resolution: 96 dpi
bit depth: 32
frame count: 1

Please help!!!

AndyAinscow

Possibly bad news for you. Have a look at, specifically the final question
MSDN magazine, 2002, March, C++ Q & A, Paul DiLascia

CArchiveStream isn't an officially supported MFC class and may be buggy.

wdhough

ASKER

Hi,

Thanks for your post i read the comment and yes your right it doesnt seem like good news does it! Can u think of another way to achieve what i have mentioned above then?

Thanks.

AndyAinscow

There is an MFC sample <SimpleImage Sample: Loads, Resizes, Converts, and Saves Images > but I haven't looked at it.

mahesh1402

Using OleLoadPicture.

Rendering GIF, JPEG, Icon, or Bitmap Files with OleLoadPicture:http://www.codeproject.com/bitmap/render.asp

Displaying a JPG in your MFC Application :http://msdn.microsoft.com/msdnmag/issues/01/10/c/

-MAHESH

ASKER CERTIFIED SOLUTION

Mazen

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AndyAinscow

I've just tried loading/saving bitmaps with CImage using the file path. Works fine here.

CImage img;
img.Load("C:\\x.bmp");
img.Save("C:\\y.bmp"); //now have a copy of x.bmp called y.bmp

wdhough

ASKER

Hi Experts again.

Actually I have just loaded in a picture that is
175 by 246 pixels
and 96dpi
bit depth 8
and frame count 1.

The image just turns up black. It doesnt crash which my original post was about, but does anyone know why I get black or rather how i can get the picture instead. When i used the load function with the filename instead it worked! Oh dear!

thanks

AndyAinscow

You can make a comment in community support with a link to this question asking for it to be reopened (or any other change you wish).

Mazen

Can you post the new code you are using starting from the line where you buffer the image till you load it?

Mazen

wdhough

ASKER

Sure no worries.

CFile file;
if( !file.Open( file_name, CFile::modeRead) )
      return FALSE;

m_buffer_size = (long)file.GetLength();
if ( alocate_buffer(m_buffer_size) == NULL )
      return FALSE;

if ( file.Read(m_buffer, m_buffer_size) != m_buffer_size )
      return FALSE;
file.Close();


IStream *pIstream;
CreateStreamOnHGlobal(NULL, TRUE, (LPSTREAM*)&pIstream);
ULARGE_INTEGER ulnSize;
ulnSize.QuadPart = m_buffer_size;
pIstream->SetSize(ulnSize);
LARGE_INTEGER lnOffset;
lnOffset.QuadPart = 0; //starting location is 0
pIstream->Seek(lnOffset, STREAM_SEEK_SET, NULL);
ULONG mysize;
pIstream->Write(m_buffer,m_buffer_size,&mysize);

image.Load(pIstream);

thats the code. Try using it with a file thats 8 bits depth i think that may be the problem. if its turning up black its just not loading properly i would imagine

thanks for your help with this.

wdhough

ASKER

Hi, just some more infor for the problem. If you go to MSPaint and create a picture, something with some coloured shapes on is what i am using. And save 3 versions of the file. These are the results.

1. 24-bit Bitmap - This works fine
2. 16 color Bitmap - this turns up black
3. 256 color Bitmap - this turns up black

Thanks

Mazen

Hi,
I did a test on all types of BMPs (even monochrome) and I didn't face a problem.

- Is the image you are trying to load created with MSPaint or by your application, maybe something went wrong with the way you saved the image (incase it was created by your application)
- Try checking if "mysize" is equal to "m_buffer_size" to see if the whole file has been loaded into the IStream.

- How can I get the images you are perfroming your tests on? Can you email them to mazen@realtechdesign.com ?

Here's the code that I have tried:

CImage image;
HDC dc = GetWindowDC()->GetSafeHdc();
BYTE *m_buffer;
CFile file;
if( !file.Open( "c:/image1.bmp", CFile::modeRead) )
return ;
long m_buffer_size = (long)file.GetLength();
m_buffer = new BYTE[m_buffer_size];
if ( file.Read(m_buffer, m_buffer_size) != m_buffer_size )
return ;
file.Close();
IStream *pIstream;
CreateStreamOnHGlobal(NULL, TRUE, (LPSTREAM*)&pIstream);
ULARGE_INTEGER ulnSize;
ulnSize.QuadPart = m_buffer_size;
pIstream->SetSize(ulnSize);
LARGE_INTEGER lnOffset;
lnOffset.QuadPart = 0; //starting location is 0
pIstream->Seek(lnOffset, STREAM_SEEK_SET, NULL);
ULONG mysize;
pIstream->Write(m_buffer,m_buffer_size,&mysize);
image.Load(pIstream);
image.Draw(dc,0,0);

Mazen

wdhough

ASKER

Hi,

Thanks after trying your code and getting it working, i realise the problem must be in my own code and found the problem. Thank you very much for your help the original accepted answer is the correct one.

Thank you