loading jpg/gif/bmp without VCL

**virtual** · 27-04-2009, 08:01 PM

hi

i've tryed translating cpp function to pascal , but it dosen't work
the function is simply convert jpeg file to HBITMAP Object , using IPicture interface

the cpp code work fine , could any one correct my pascal translation !!

// CPP CODE

Code:

 HBITMAP Ole2BITMAP(char *szFile)
{

HBITMAP hBitmap;
HBITMAP bmp;
DWORD dwFileSize;
DWORD dwBytesRead;
HANDLE hFile;
LPPICTURE gpPicture;
LPVOID lpPicData;
LPVOID pvData;
LPSTREAM pstm;
LPVOID hrlp;
HGLOBAL hGlobal;
BITMAP bm ;

 

hFile=CreateFile(szFile,GENERIC_READ,0,NULL,OPEN_EXISTING,0,NULL);
dwFileSize=GetFileSize(hFile,NULL);


pvData=NULL;
hGlobal=GlobalAlloc(GMEM_MOVEABLE,dwFileSize);
pvData=GlobalLock(hGlobal);
ReadFile(hFile,pvData,dwFileSize,&dwBytesRead,NULL);
GlobalUnlock(hGlobal);
CloseHandle(hFile);


CreateStreamOnHGlobal(hGlobal,TRUE,&pstm);
OleLoadPicture(pstm,0,FALSE,IID_IPicture,(void**)&gpPicture);
pstm->Release();
gpPicture->get_Handle((OLE_HANDLE*)&hBitmap);

GetObject (hBitmap, sizeof (BITMAP), (PSTR) &bm) ;



bmp = (HBITMAP)CopyImage(hBitmap,IMAGE_BITMAP,bm.bmWidth, bm.bmHeight,LR_COPYRETURNORG);
return bmp;

}

// PASCAL TRANSLATION

Code:

uses activex
function ole2bitmap(name : string): HBITMAP;
var hBmp ,bmp : HBITMAP;
  dwFileSize,dwBytesRead : DWORD;
  hFile : integer;
  gpPicture : IPicture;
  pvData  : pointer;
  pstm   : ISTREAM;
  hGlob   : hGlobal;
  bm    : BITMAP;
begin

  hFile := CreateFile(Pchar(name),GENERIC_READ,0,NIL,OPEN_EXISTING,0,0);
  dwFileSize :=GetFileSize(hFile,NIL);

  pvData := NIL;
  hGlob := GlobalAlloc(GMEM_MOVEABLE,dwFileSize);
  pvData:=GlobalLock(hGlob);
  ReadFile(hFile,pvData,dwFileSize,dwBytesRead,NIL);
  GlobalUnlock(hGlob);
  CloseHandle(hFile);

  CreateStreamOnHGlobal(hGlob,TRUE,pstm);
  OleLoadPicture(pstm,0,FALSE,IPICTURE,gpPicture);
  pstm._Release();
  gpPicture.get_Handle(LongWord(hBmp));

  GetObject (hBmp, sizeof (BITMAP), @bm) ;

  bmp := CopyImage(hBmp,IMAGE_BITMAP,bm.bmWidth, bm.bmHeight,LR_COPYRETURNORG);

 Result := bmp;

end;

thanks

**noeska** · 27-04-2009, 08:33 PM

Try this one:

[pascal]
{------------------------------------------------------------------}
{ Load BMP Texture }
{------------------------------------------------------------------}
function LoadBMPTexture(Filename: Tstream; var Texture: GLuint): Boolean;
var
FileHeader: TBITMAPFILEHEADER;
InfoHeader: TBITMAPINFOHEADER;
Palette: array of RGBQUAD;
BitmapLength: LongWord;
PaletteLength: LongWord;
ReadBytes: LongWord;
TextureImage: TTextureImage;
begin
LoadBMPTexture:=False;
// Get header information
Filename.Read(FileHeader, SizeOf(FileHeader));
Filename.Read(InfoHeader, SizeOf(InfoHeader));
// Get palette
PaletteLength := InfoHeader.biClrUsed;
SetLength(Palette, PaletteLength);
ReadBytes:=Filename.Read(Palette,PaletteLength);
if (ReadBytes <> PaletteLength) then
begin
MessageBox(0, PChar('Error reading palette'), PChar('BMP Loader'), MB_OK);
Exit;
end;
textureimage.Width := InfoHeader.biWidth;
textureimage.Height := InfoHeader.biHeight;
BitmapLength := InfoHeader.biSizeImage;
if BitmapLength = 0 then
BitmapLength := Textureimage.Width * Textureimage.Height * InfoHeader.biBitCount Div 8;
// Get the actual pixel data
GetMem(textureimage.imageData, BitmapLength);
ReadBytes:=Filename.Read(textureimage.imagedata^, BitmapLength);
if (ReadBytes <> BitmapLength) then
begin
MessageBox(0, PChar('Error reading bitmap data'), PChar('BMP Unit'), MB_OK);
Exit;
end;
//BMP files are stored BGR so use GL_BGR
Texture:=CreateTexture(textureimage.width, textureimage.height, GL_BGR, textureimage.imagedata);
//clean up
FreeMem(textureimage.imageData)
end;
[/pascal]

You may want to remove opengl specifcs like the call to CreateTexture.

**virtual** · 28-04-2009, 10:32 AM

thanks noeska

but i am looking for JPG
because i belive that this is the easy way to load jpg using pure API
and this function keep my exe small ~ 20kb .

so any one have an idea how to fix this function ?!