Controlling Progressive Loads and Saves

/******************************************************************************************* 
This example uses L_LoadFile with a callback function to implement a progressive 
paint-while-load feature. Refer to the FILEREADCALLBACK 
function to see how the callback function paints the image data. 
The sample code uses the following global declarations: */ 
HINSTANCE hInst;   /* Current instance of the application, set by the InitInstance function */ 
RECT rClientSize;          /* RECT for the client area */ 
RECT rLeadDest;            /* Destination rectangle for painting */ 
RECT rLeadSource;          /* Source rectangle for painting */ 
BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image */ 
FILEINFO FileInfo;         /* LEAD File Information structure. */ 
/* Structure used for the callback function's user data */ 
typedef struct tagIMAGECBPARM 
{ 
   HWND hwnd;     /* Current window */ 
   HDC hdc;       /* Device context for the current window */ 
} IMAGECBPARM; 
/* Prototype for the FILEREADCALLBACK function */ 
L_INT L_EXPORT EXT_CALLBACK LoadImageCB(pFILEINFO pFileInfo, pBITMAPHANDLE pBitmap, 
L_UCHAR  *pBuffer, 
L_UINT uFlags, L_INT nRow, L_INT nLines, IMAGECBPARM * pUserData ); 
/*********************************************************************************************/ 
void TestLoad(L_TCHAR  * pszFilename, HWND hWnd) 
{ 
   static IMAGECBPARM UserData; /* Structure used for the callback function's user data */ 
   LOADFILEOPTION LoadFileOption;  /* Structure for progressive options */ 
   SAVEFILEOPTION SaveFileOption;  /* Structure for progressive options */ 
   FILEREADCALLBACK lpfnCallBack; 
   /* Load a bitmap */ 
   L_LoadBitmap(pszFilename, &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL); 
   /* Get the current EXTFILEOPTION values and save the current Passes value */ 
   L_GetDefaultLoadFileOption(&LoadFileOption, sizeof(LOADFILEOPTION)); 
   L_GetDefaultSaveFileOption(&SaveFileOption, sizeof(SAVEFILEOPTION)); 
   /* Set the number of passes for a progressive LEAD file */ 
   SaveFileOption.Passes = 8; 
   /* Save the file */ 
   L_SaveBitmap(TEXT("C:\\LEADTOOLS21\\images\\TEST.CMP"), &LeadBitmap, FILE_CMP, 24, PQ2, &SaveFileOption); 
   /* Set the number of callback passes for loading a progressive LEAD file */ 
   LoadFileOption.Passes = CALLBACK_WHEN_MEANINGFUL; 
   /* Get the client area of the window. We assume that elsewhere in the program, the 
   L_FileInfo function has been used to update the FileInfo structure and that the 
   window dimensions have been adjusted to the bitmap's aspect ratio. */ 
   GetClientRect(hWnd,&rClientSize); 
   /* Make the destination rectangle for painting the same as the client area */ 
   rLeadDest = rClientSize; 
   /* Initialize the bitmap handle */ 
   L_InitBitmap( &LeadBitmap, sizeof(BITMAPHANDLE), FileInfo.Width, FileInfo.Height, FileInfo.BitsPerPixel ); 
   LeadBitmap.ViewPerspective = FileInfo.ViewPerspective; 
   /* Set the user data used for the callback in the L_LoadFile function */ 
   UserData.hwnd = hWnd;         /* Current window */ 
   UserData.hdc = GetDC( hWnd ); /* Device context for the current window */ 
   /* Set the callback function for the L_LoadFile function.*/ 
   lpfnCallBack = (FILEREADCALLBACK) MakeProcInstance( 
   (FARPROC) LoadImageCB, hInst ); 
   /* Load the file, calling lpfnCallBack to paint the bitmap. */ 
   L_LoadFile(TEXT("C:\\LEADTOOLS21\\TEST.CMP"), 
   &LeadBitmap, sizeof(BITMAPHANDLE), 
   0, 
   ORDER_BGR, 
   LOADFILE_ALLOCATE |  LOADFILE_STORE, 
   lpfnCallBack, 
   &UserData, 
   &LoadFileOption); 
   FreeProcInstance ((FARPROC) lpfnCallBack); 
   /* Avoid an unnecessary repaint */ 
   ValidateRect(hWnd, &rLeadDest); 
   return; 
}