Displaying Image from stream

This is a discussion on Displaying Image from stream within the C++ Programming forums, part of the General Programming Boards category; I'm trying to display an image from a stream data. But there is no image when getting image::from stream. It's ...

  1. #1
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    Displaying Image from stream

    I'm trying to display an image from a stream data.
    But there is no image when getting image::from stream.
    It's my source code:
    Code:
    IStream* pstream = NULL;   
      if(SUCCEEDED(CreateStreamOnHGlobal(NULL, TRUE, &pstream)))   
      {                  ULONG lreal = 0;         
      pstream->Write(chIncomingDataBuffer, iEnd, &lreal );     
        if(pstream!= NULL)     
        {                  MessageBox(hWnd,              
               " Stream is OK",               
              "Connection strt",              
               MB_ICONINFORMATION|MB_OK);                  }    
         Image* image =Image::FromStream(pstream);    
         if(image)      
       {                  RECT rect;            
       ::GetWindowRect(hWnd, &rect);     
            Graphics graphics(hWnd);         
        graphics.DrawImage(image, 0, 0, rect.right-rect.left, rect.bottom-rect.top);              }         else      
       {                  MessageBox(hWnd,                
             "No image is written",               
              "Connection strt",            
                 MB_ICONINFORMATION|MB_OK);                           }  
           if(image)       
          delete image;         
    image = NULL;      
       if(pstream)           
      pstream->Release();      
       pstream = NULL;          }
    There is no image from data.

  2. #2
    C++まいる!Cをこわせ! Elysia's Avatar
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    Please indent your code correctly and follow a well-accepted coding style such as Allman.
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    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

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  3. #3
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    Ok...

    Code:
    IStream* pstream = NULL;
        if(SUCCEEDED(CreateStreamOnHGlobal(NULL, TRUE, &pstream)))
        {
            
            ULONG lreal = 0;
            if(S_OK)
            {
            pstream->Write(chIncomingDataBuffer, iEnd, &lreal );
            
            }
            else
            {
            
                MessageBox(hWnd,
                            "No Stream is written",
                            "Connection strt",
                            MB_ICONINFORMATION|MB_OK);
            }
            
            if(pstream!= NULL)
            {
            
            MessageBox(hWnd,
                            " Stream is written",
                            "Connection strt",
                            MB_ICONINFORMATION|MB_OK);
            
            }
            Image* image =Image::FromStream(pstream);
            if(image)
            {
            
            RECT rect;
    
                ::GetWindowRect(hWnd, &rect);
                Graphics graphics(hWnd);
                graphics.DrawImage(image, 0, 0, rect.right-rect.left, rect.bottom-rect.top);
        
            }

  4. #4
    and the hat of wrongness Salem's Avatar
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    > pstream->Write(chIncomingDataBuffer, iEnd, &lreal );
    ...
    > Image* image =Image::FromStream(pstream);
    OK, what is the point of writing to a stream and immediately trying to read from it?
    Or even, what is the point of writing to a stream which is an Input stream to begin with?


    > if(image)
    Where is your error popup telling you what might be wrong, if this is false?


    > if(pstream!= NULL)
    It's too late for this, you already used pstream->Write
    Perhaps you're trying to check the status of the previous write, in which case, this isn't doing it for you.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  5. #5
    Algorithm Dissector iMalc's Avatar
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    if (S_OK) makes no sense.
    S_OK is defined as zero, so you're saying "if (0)", which is always false.
    I see no code to call Release on the IStream either.
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  6. #6
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    I took the reference from these two topics and started writing my own code-
    CreateStreamOnHGlobal function (Windows)
    Image.FromStream method (Windows)

    and on S_OK the value is zero on debugging, so it's been removed.
    on global allocating and on CreateStreamOnHGlobal-Istream is having some value.
    That value should be declared to an image.
    If I'm not drawing the image(Graphics only works on WM_PAINT), then it will load the image from stream.
    Code:
    Image*image = Image::FromStream(pstream);
                
            if(image)
            {
            MessageBox(hWnd,
                            " Image is there",
                            "Connection strt",
                            MB_ICONINFORMATION|MB_OK);
            
            
            }
            else
            {
            
            MessageBox(hWnd,
                            "no Image is there",
                            "Connection strt",
                            MB_ICONINFORMATION|MB_OK);
            
            
            }
            pstream->Release();
    it's always null value on image.

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