Solved

convert .bmp to .jpeg and write to file

Posted on 2000-04-12
5
471 Views
Last Modified: 2013-11-20

I have the jpeglib that circulates in the shareware world, and I have been using it to "read a JPEG file and create a bitmap internally".  Now I want to be able to use the same library to "write a bitmap in JPEG format to a file".  I know the library has this output-JPEG function, but it seems non-trivial to call it.  For example, the code below is the constructor I use to create a bitmap from a JPEG file.  So I need another function perhaps similar to the one below, but that creates a JPEG file to disk from a bitmap.  I don't seem to have such a function nor is there any doc in what I have to explain what to call.

Can someone send me the code for this function??

Thanks...


EqBitmap::EqBitmap(CDC *cdc, const char *filename)
{
      struct jpeg_decompress_struct      cinfo;
      struct vw_error_mgr            jerr;
      JSAMPROW                  rowptr[1];
      FILE                        *fp;
      char                        *data      = (char *) 0,
                              *tmp,
                              *tmp2,
                              sv;
      int                        bperpix,
                              bperline,
                              wide,
                              high,
                              i;
      CDC                        *hdc1,
                              *hdc2;
      CBitmap                        *svb;
      BITMAPINFO                  bi;
      HBITMAP                        bm,
                              hsv;

      if(!filename || !strlen(filename))
            return;
      if(!(fp = fopen(filename, "rb")))                
            return;

      cinfo.err = jpeg_std_error(&jerr.pub);
      jerr.pub.error_exit = vw_error_handler;
      jerr.pub.output_message = vw_error_handler;
      if(setjmp(jerr.setjmp_buffer)) {
            jpeg_destroy_decompress(&cinfo);
            fclose(fp);
            if(data)
                  free(data);
            return;
      }

      jpeg_create_decompress(&cinfo);
      jpeg_stdio_src(&cinfo, fp);
      (void) jpeg_read_header(&cinfo, 1);
      jpeg_calc_output_dimensions(&cinfo);
      wide = cinfo.output_width;
      high = cinfo.output_height;

      if((bperpix = cinfo.output_components) != 1 && bperpix != 3) {
            jpeg_destroy_decompress(&cinfo);
            fclose(fp);
            return;
      }
      bperline = (((wide * 3) + 3) / 4) * 4;

      if(!(data = (char *) malloc(high * bperline))) {
            jpeg_destroy_decompress(&cinfo);
            fclose(fp);
            return;
      }

      jpeg_start_decompress(&cinfo);
      while(cinfo.output_scanline < cinfo.output_height) {
            tmp = &(data[cinfo.output_scanline * bperline]);
            rowptr[0] = (JSAMPROW) tmp;
            (void) jpeg_read_scanlines(&cinfo, rowptr, (JDIMENSION) 1);
            if(bperpix == 1) {
                  tmp2 = tmp + wide - 1;
                  tmp += wide * 3 - 1;
                  while(tmp != tmp2) {
                        *tmp-- = *tmp2;
                        *tmp-- = *tmp2;
                        *tmp-- = *tmp2--;
                  }
            } else {
                  for(i = 0; i < wide; i++, tmp += 3) {
                        sv = tmp[0];
                        tmp[0] = tmp[2];
                        tmp[2] = sv;
                  }
            }
      }
      jpeg_finish_decompress(&cinfo);
      jpeg_destroy_decompress(&cinfo);
      fclose(fp);

      bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
      bi.bmiHeader.biWidth = wide;
      bi.bmiHeader.biHeight = -high;
      bi.bmiHeader.biPlanes = 1;
      bi.bmiHeader.biBitCount = 24;
      bi.bmiHeader.biCompression = BI_RGB;
      bi.bmiHeader.biSizeImage = wide * high * 3;
      bi.bmiHeader.biXPelsPerMeter = 3273;
      bi.bmiHeader.biYPelsPerMeter = 3273;
      bi.bmiHeader.biClrUsed = 0;
      bi.bmiHeader.biClrImportant = 0;

      bm = ::CreateDIBitmap((HDC) cdc->m_hDC, &(bi.bmiHeader), CBM_INIT, (void *) data, &bi, 0);

      hdc1 = new CDC;
      hdc1->CreateCompatibleDC(cdc);
      CreateCompatibleBitmap(cdc, wide, high);
      svb = hdc1->SelectObject(this);

      hdc2 = new CDC;
      hdc2->CreateCompatibleDC(cdc);
      hsv = (HBITMAP) ::SelectObject((HDC) hdc2->m_hDC, (HGDIOBJ) bm);

      ::BitBlt((HDC) hdc1->m_hDC, 0, 0, wide, high, (HDC) hdc2->m_hDC, 0, 0, SRCCOPY);

      ::SelectObject((HDC) hdc2->m_hDC, (HGDIOBJ) hsv);
      hdc1->SelectObject(svb);
      delete hdc1;
      delete hdc2;
      ::DeleteObject((HGDIOBJ) bm);
      
      width = wide;
      height = high;

      free(data);

      return;
}

0
Comment
Question by:tullhead
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 
LVL 9

Expert Comment

by:ShaunWilde
ID: 2710932
maybe the following article will help http://www.codeguru.com/bitmap/dib_to_jpeg.shtml
0
 
LVL 3

Expert Comment

by:shaig
ID: 2711054
0
 
LVL 1

Expert Comment

by:Ik_Khan_Pk
ID: 2722990
0
 

Author Comment

by:tullhead
ID: 2724925
I ended up using the code that ShaunWilde pointed me to, so if you post to this again as an ANSWER (not a comment) I'll give you the points...
0
 
LVL 9

Accepted Solution

by:
ShaunWilde earned 100 total points
ID: 2725404
> so if you post to this again as an ANSWER

Okay :)

TIP: I think you can accept previous comments as an answer using the blue button in the comment header
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Exception Handling is in the core of any application that is able to dignify its name. In this article, I'll guide you through the process of writing a DRY (Don't Repeat Yourself) Exception Handling mechanism, using Aspect Oriented Programming.
Have you tried to learn about Unicode, UTF-8, and multibyte text encoding and all the articles are just too "academic" or too technical? This article aims to make the whole topic easy for just about anyone to understand.
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Monitoring a network: why having a policy is the best policy? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the enormous benefits of having a policy-based approach when monitoring medium and large networks. Software utilized in this v…

628 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question