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Library to display an image (JPG/GIF/BMP) in 300 lines/8K of code

, 1 Dec 2002
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A simple yet powerful library to display an image in a window.

Introduction

Here is a sample of what is possible to do with just plain C. This code will display in a window an image that can be in JPG, GIF, BMP, or Windows metafile format.

Compiled with the lcc-Win32 compiler, the code is just 8K. No other language gives you this kind of efficiency. A similar piece of code in C++ weights more than 170K!

The interface is like this:

  1. You tell it the name of the graphic file
    HANDLE h = OpenGraphic(char *filename);

    That handle is used for closing the image.

  2. When painting your window, you pass it the hwnd and the hDC you get from BeginPaint.
    DisplayGraphic(HWND hwnd,HDC hdc);
  3. When finished, you close it with.
    void CloseGraphic(HANDLE h);

Note that CoInitialize() must be called before using these functions.

I did not add "bells and whistles" to keep the code simple to understand. You may add scrollbars, redimensioning whatever.

This code was developed with the lcc-win32 C compiler. You can download it at no charge from here.

P.S.: This contribution was critized because I did not use Microsoft tools. I know I am biased, but I tried to correct my evil ways. I took the dust out of MSVC 6.0 and OK, here is it, complete with .dsw file in a standard Microsoft Project.

Other critics pointed out to a bug in the transcription, where I added a "*" too much. I fixed that, and I thank the people who pointed me that bug.

It is interesting to note that the code size of the program as compiled with MSVC is 32K, with lcc-win32 is just 8K.

Nobody is perfect...

#include "windows.h"
#include "ocidl.h"
#include "olectl.h"

typedef struct tagImgInfo {
  IPicture *Ipic;
  SIZE sizeInHiMetric;
  SIZE sizeInPix;
  char *Path;
} IMG_INFO;

static IMG_INFO ImageInfo;

void *OpenGraphic(char *name)
{
  IPicture *Ipic = NULL;
  SIZE sizeInHiMetric,sizeInPix;
  const int HIMETRIC_PER_INCH = 2540;
  HDC hDCScreen = GetDC(NULL);
  HRESULT hr;
  int nPixelsPerInchX = GetDeviceCaps(hDCScreen, LOGPIXELSX);
  int nPixelsPerInchY = GetDeviceCaps(hDCScreen, LOGPIXELSY);
  unsigned short OlePathName[512];

  ReleaseDC(NULL,hDCScreen);
  mbstowcs(OlePathName,name,strlen(name)+1);
  hr = OleLoadPicturePath(OlePathName,
        NULL,
        0,
        0,
        &IID_IPicture,
        (void *)(&Ipic));
  if (hr)
    return 0;
  if (Ipic) {
    // get width and height of picture
    hr = Ipic->lpVtbl->get_Width(Ipic,&sizeInHiMetric.cx);
    if (!SUCCEEDED(hr))
      goto err;
    Ipic->lpVtbl->get_Height(Ipic,&sizeInHiMetric.cy);
    if (!SUCCEEDED(hr))
      goto err;

    // convert himetric to pixels
    sizeInPix.cx = (nPixelsPerInchX * sizeInHiMetric.cx +
              HIMETRIC_PER_INCH / 2) / HIMETRIC_PER_INCH;
    sizeInPix.cy = (nPixelsPerInchY * sizeInHiMetric.cy +
              HIMETRIC_PER_INCH / 2) / HIMETRIC_PER_INCH;
    ImageInfo.sizeInPix = sizeInPix;
    ImageInfo.sizeInHiMetric = sizeInHiMetric;
    ImageInfo.Ipic = Ipic;
    ImageInfo.Path = name;
    return Ipic;

  }
err:
  return 0;
}
void DisplayGraphic(HWND hwnd,HDC pDC)
{
  IPicture *Ipic = ImageInfo.Ipic;
  DWORD dwAttr = 0;
  HBITMAP Bmp,BmpOld;
  RECT rc;
  HRESULT hr;
  HPALETTE pPalMemOld;

  if (Ipic != NULL)
  {
    // get palette
    OLE_HANDLE hPal = 0;
    HPALETTE hPalOld=NULL,hPalMemOld=NULL;
    hr = Ipic->lpVtbl->get_hPal(Ipic,&hPal);

    if (!SUCCEEDED(hr))
      return;
    if (hPal != 0)
    {
      hPalOld = SelectPalette(pDC,(HPALETTE)hPal,FALSE);
      RealizePalette(pDC);
    }

    // Fit the image to the size of the client area. Change this
    // For more sophisticated scaling
    GetClientRect(hwnd,&rc);
    // transparent?
    if (SUCCEEDED(Ipic->lpVtbl->get_Attributes(Ipic,&dwAttr)) ||
      (dwAttr & PICTURE_TRANSPARENT))
    {
      // use an off-screen DC to prevent flickering
      HDC MemDC = CreateCompatibleDC(pDC);
      Bmp = 
       CreateCompatibleBitmap(pDC,ImageInfo.sizeInPix.cx,ImageInfo.sizeInPix.cy);

      BmpOld = SelectObject(MemDC,Bmp);
      pPalMemOld = NULL;
      if (hPal != 0)
      {
        hPalMemOld = SelectPalette(MemDC,(HPALETTE)hPal, FALSE);
        RealizePalette(MemDC);
      }
/* Use this to show the left corner
      rc.left = rc.top = 0;
      rc.right = ImageInfo.sizeInPix.cx;
        rc.bottom = ImageInfo.sizeInPix.cy;
*/
      // display picture using IPicture::Render
      hr = Ipic->lpVtbl->Render(Ipic,MemDC,
      0,
      0,
      rc.right,
      rc.bottom,
      0,
      ImageInfo.sizeInHiMetric.cy,
      ImageInfo.sizeInHiMetric.cx,
      -ImageInfo.sizeInHiMetric.cy,
      &rc);

      BitBlt(pDC,0, 0, ImageInfo.sizeInPix.cx, 
                               ImageInfo.sizeInPix.cy,
        MemDC, 0, 0, SRCCOPY);

      SelectObject(MemDC,BmpOld);

      if (pPalMemOld)  SelectPalette(MemDC,pPalMemOld, FALSE);
      DeleteObject(Bmp);
      DeleteDC(MemDC);

    }
    else
    {
      // display picture using IPicture::Render
      Ipic->lpVtbl->Render(Ipic,pDC,
       0,
       0,
       rc.right,
       rc.bottom,
       0,
       ImageInfo.sizeInHiMetric.cy,
       ImageInfo.sizeInHiMetric.cx,
       -ImageInfo.sizeInHiMetric.cy,
       &rc);
    }

    if (hPalOld != NULL) SelectPalette(pDC,hPalOld, FALSE);
    if (hPal)  DeleteObject((HPALETTE)hPal);
  }
}

void CloseImage(void *Ipict)
{
  IPicture *ip = (IPicture *)Ipict;

  if (ip == NULL)
    ip = ImageInfo.Ipic;
  if (ip == NULL)
    return;
  ip->lpVtbl->Release(ip);
  memset(&ImageInfo,0,sizeof(ImageInfo));
}

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Jacob Navia
Web Developer
France France
I am the author of the lcc-win32 C compiler system. http://www.cs.virginia.edu/~lcc-win32

Comments and Discussions

 
GeneralMy vote of 5 - demonstrates use of non-Microsoft tools PinmemberEdCaputo20-Jun-14 0:10 
GeneralMy vote of 5 Pinmembermanoj kumar choubey26-Feb-12 21:56 
GeneralMy vote of 5 PinmemberRaghavan145-Jan-12 7:27 
GeneralMy vote of 3 PinmemberMarcus Elliott13-Oct-10 1:45 
GeneralI need help PinmemberGbenbam6-Aug-10 3:43 
GeneralLooks like a little bug Pinmembermouseparty17-Feb-06 2:24 
GeneralRe: Looks like a little bug Pinmembervictoryli14-Apr-08 11:12 
GeneralRelease VS PinsussAnonymous6-Feb-05 18:20 
GeneralRotating the image PinmemberAlex Evans4-Jan-05 10:24 
GeneralBinary size PinmemberMr.Prakash2-Mar-04 5:37 
General28 Kb Pinmemberessersr11-Feb-04 10:31 
GeneralRe: 28 Kb Pinmembervictoryli14-Apr-08 9:25 
GeneralPlease help me ! PinsussAnonymous18-Oct-03 2:39 
QuestionRender ? Pinmemberlibrazone20-Jun-03 17:29 
AnswerRe: Render ? PinsussAnonymous24-Jun-03 22:55 
GeneralRe: Render ? Pinmemberkubicle7-Jan-05 21:21 
GeneralCode Size PinsussAnonymous9-Mar-03 0:39 
GeneralRe: Code Size PinmemberKvasi30-Mar-03 6:37 
GeneralRe: Code Size PinsussAnonymous5-May-03 21:16 
GeneralRe: Code Size PinsussAnonymous19-Mar-05 5:35 
Generalneither simple nor powerful PinsussAnonymous3-Dec-02 14:16 
GeneralRe: neither simple nor powerful PinmemberJacob Navia5-Dec-02 4:11 
GeneralRe: neither simple nor powerful PinmemberRufus V. Smith5-Aug-03 7:45 
General170K? no way PinsussAnonymous2-Dec-02 21:55 
GeneralBad news PinsussAnonymous2-Dec-02 20:09 

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