FILE.C
//*******************************************************************
//
// file.c
//
// Source file for Device-Independent Bitmap (DIB) API. Provides
// the following functions:
//
// SaveDIB() - Saves the specified dib in a file
// LoadDIB() - Loads a DIB from a file
// DestroyDIB() - Deletes DIB when finished using it
//
// Written by Microsoft Product Support Services, Developer Support.
// Copyright 1991-1998 Microsoft Corporation. All rights reserved.
//*******************************************************************
#define STRICT // enable strict type checking
#include <windows.h>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <io.h>
#include <direct.h>
#include <stdlib.h>
#include "dibutil.h"
#include "dibapi.h"
// Dib Header Marker - used in writing DIBs to files
#define DIB_HEADER_MARKER ((WORD) ('M' << 8) | 'B')
/*********************************************************************
*
* Local Function Prototypes
*
*********************************************************************/
HANDLE ReadDIBFile(HANDLE);
BOOL SaveDIBFile(void);
BOOL WriteDIB(LPSTR, HANDLE);
/*************************************************************************
*
* LoadDIB()
*
* Loads the specified DIB from a file, allocates memory for it,
* and reads the disk file into the memory.
*
*
* Parameters:
*
* LPSTR lpFileName - specifies the file to load a DIB from
*
* Returns: A handle to a DIB, or NULL if unsuccessful.
*
* NOTE: The DIB API were not written to handle OS/2 DIBs; This
* function will reject any file that is not a Windows DIB.
*
*************************************************************************/
HDIB LoadDIB(LPSTR lpFileName)
{
HDIB hDIB;
HANDLE hFile;
// Set the cursor to a hourglass, in case the loading operation
// takes more than a sec, the user will know what's going on.
SetCursor(LoadCursor(NULL, IDC_WAIT));
if ((hFile = CreateFile(lpFileName, GENERIC_READ, FILE_SHARE_READ, NULL,
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,
NULL)) != INVALID_HANDLE_VALUE)
{
hDIB = ReadDIBFile(hFile);
CloseHandle(hFile);
SetCursor(LoadCursor(NULL, IDC_ARROW));
return hDIB;
}
else
{
DIBError(ERR_FILENOTFOUND);
SetCursor(LoadCursor(NULL, IDC_ARROW));
return NULL;
}
}
/*************************************************************************
*
* SaveDIB()
*
* Saves the specified DIB into the specified file name on disk. No
* error checking is done, so if the file already exists, it will be
* written over.
*
* Parameters:
*
* HDIB hDib - Handle to the dib to save
*
* LPSTR lpFileName - pointer to full pathname to save DIB under
*
* Return value: 0 if successful, or one of:
* ERR_INVALIDHANDLE
* ERR_OPEN
* ERR_LOCK
*
*************************************************************************/
WORD SaveDIB(HDIB hDib, LPSTR lpFileName)
{
BITMAPFILEHEADER bmfHdr; // Header for Bitmap file
LPBITMAPINFOHEADER lpBI; // Pointer to DIB info structure
HANDLE fh; // file handle for opened file
DWORD dwDIBSize;
DWORD dwWritten;
if (!hDib)
return ERR_INVALIDHANDLE;
fh = CreateFile(lpFileName, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);
if (fh == INVALID_HANDLE_VALUE)
return ERR_OPEN;
// Get a pointer to the DIB memory, the first of which contains
// a BITMAPINFO structure
lpBI = (LPBITMAPINFOHEADER)GlobalLock(hDib);
if (!lpBI)
{
CloseHandle(fh);
return ERR_LOCK;
}
// Check to see if we're dealing with an OS/2 DIB. If so, don't
// save it because our functions aren't written to deal with these
// DIBs.
if (lpBI->biSize != sizeof(BITMAPINFOHEADER))
{
GlobalUnlock(hDib);
CloseHandle(fh);
return ERR_NOT_DIB;
}
// Fill in the fields of the file header
// Fill in file type (first 2 bytes must be "BM" for a bitmap)
bmfHdr.bfType = DIB_HEADER_MARKER; // "BM"
// Calculating the size of the DIB is a bit tricky (if we want to
// do it right). The easiest way to do this is to call GlobalSize()
// on our global handle, but since the size of our global memory may have
// been padded a few bytes, we may end up writing out a few too
// many bytes to the file (which may cause problems with some apps,
// like HC 3.0).
//
// So, instead let's calculate the size manually.
//
// To do this, find size of header plus size of color table. Since the
// first DWORD in both BITMAPINFOHEADER and BITMAPCOREHEADER conains
// the size of the structure, let's use this.
// Partial Calculation
dwDIBSize = *(LPDWORD)lpBI + PaletteSize((LPSTR)lpBI);
// Now calculate the size of the image
// It's an RLE bitmap, we can't calculate size, so trust the biSizeImage
// field
if ((lpBI->biCompression == BI_RLE8) || (lpBI->biCompression == BI_RLE4))
dwDIBSize += lpBI->biSizeImage;
else
{
DWORD dwBmBitsSize; // Size of Bitmap Bits only
// It's not RLE, so size is Width (DWORD aligned) * Height
dwBmBitsSize = WIDTHBYTES((lpBI->biWidth)*((DWORD)lpBI->biBitCount)) *
lpBI->biHeight;
dwDIBSize += dwBmBitsSize;
// Now, since we have calculated the correct size, why don't we
// fill in the biSizeImage field (this will fix any .BMP files which
// have this field incorrect).
lpBI->biSizeImage = dwBmBitsSize;
}
// Calculate the file size by adding the DIB size to sizeof(BITMAPFILEHEADER)
bmfHdr.bfSize = dwDIBSize + sizeof(BITMAPFILEHEADER);
bmfHdr.bfReserved1 = 0;
bmfHdr.bfReserved2 = 0;
// Now, calculate the offset the actual bitmap bits will be in
// the file -- It's the Bitmap file header plus the DIB header,
// plus the size of the color table.
bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + lpBI->biSize +
PaletteSize((LPSTR)lpBI);
// Write the file header
WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
// Write the DIB header and the bits -- use local version of
// MyWrite, so we can write more than 32767 bytes of data
WriteFile(fh, (LPSTR)lpBI, dwDIBSize, &dwWritten, NULL);
GlobalUnlock(hDib);
CloseHandle(fh);
if (dwWritten == 0)
return ERR_OPEN; // oops, something happened in the write
else
return 0; // Success code
}
/*************************************************************************
*
* DestroyDIB ()
*
* Purpose: Frees memory associated with a DIB
*
* Returns: Nothing
*
*************************************************************************/
WORD DestroyDIB(HDIB hDib)
{
GlobalFree(hDib);
return 0;
}
//************************************************************************
//
// Auxiliary Functions which the above procedures use
//
//************************************************************************
/*************************************************************************
*
* Function: ReadDIBFile (int)
*
* Purpose: Reads in the specified DIB file into a global chunk of
* memory.
*
* Returns: A handle to a dib (hDIB) if successful.
* NULL if an error occurs.
*
* Comments: BITMAPFILEHEADER is stripped off of the DIB. Everything
* from the end of the BITMAPFILEHEADER structure on is
* returned in the global memory handle.
*
*
* NOTE: The DIB API were not written to handle OS/2 DIBs, so this
* function will reject any file that is not a Windows DIB.
*
*************************************************************************/
HANDLE ReadDIBFile(HANDLE hFile)
{
BITMAPFILEHEADER bmfHeader;
DWORD dwBitsSize;
UINT nNumColors; // Number of colors in table
HANDLE hDIB;
HANDLE hDIBtmp; // Used for GlobalRealloc() //MPB
LPBITMAPINFOHEADER lpbi;
DWORD offBits;
DWORD dwRead;
// get length of DIB in bytes for use when reading
dwBitsSize = GetFileSize(hFile, NULL);
// Allocate memory for header & color table. We'll enlarge this
// memory as needed.
hDIB = GlobalAlloc(GMEM_MOVEABLE, (DWORD)(sizeof(BITMAPINFOHEADER) +
256 * sizeof(RGBQUAD)));
if (!hDIB)
return NULL;
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDIB);
if (!lpbi)
{
GlobalFree(hDIB);
return NULL;
}
// read the BITMAPFILEHEADER from our file
if (!ReadFile(hFile, (LPSTR)&bmfHeader, sizeof (BITMAPFILEHEADER),
&dwRead, NULL))
goto ErrExit;
if (sizeof (BITMAPFILEHEADER) != dwRead)
goto ErrExit;
if (bmfHeader.bfType != 0x4d42) // 'BM'
goto ErrExit;
// read the BITMAPINFOHEADER
if (!ReadFile(hFile, (LPSTR)lpbi, sizeof(BITMAPINFOHEADER), &dwRead,
NULL))
goto ErrExit;
if (sizeof(BITMAPINFOHEADER) != dwRead)
goto ErrExit;
// Check to see that it's a Windows DIB -- an OS/2 DIB would cause
// strange problems with the rest of the DIB API since the fields
// in the header are different and the color table entries are
// smaller.
//
// If it's not a Windows DIB (e.g. if biSize is wrong), return NULL.
if (lpbi->biSize == sizeof(BITMAPCOREHEADER))
goto ErrExit;
// Now determine the size of the color table and read it. Since the
// bitmap bits are offset in the file by bfOffBits, we need to do some
// special processing here to make sure the bits directly follow
// the color table (because that's the format we are susposed to pass
// back)
if (!(nNumColors = (UINT)lpbi->biClrUsed))
{
// no color table for 24-bit, default size otherwise
if (lpbi->biBitCount != 24)
nNumColors = 1 << lpbi->biBitCount; // standard size table
}
// fill in some default values if they are zero
if (lpbi->biClrUsed == 0)
lpbi->biClrUsed = nNumColors;
if (lpbi->biSizeImage == 0)
{
lpbi->biSizeImage = ((((lpbi->biWidth * (DWORD)lpbi->biBitCount) +
31) & ~31) >> 3) * lpbi->biHeight;
}
// get a proper-sized buffer for header, color table and bits
GlobalUnlock(hDIB);
hDIBtmp = GlobalReAlloc(hDIB, lpbi->biSize + nNumColors *
sizeof(RGBQUAD) + lpbi->biSizeImage, 0);
if (!hDIBtmp) // can't resize buffer for loading
goto ErrExitNoUnlock; //MPB
else
hDIB = hDIBtmp;
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDIB);
// read the color table
ReadFile (hFile, (LPSTR)(lpbi) + lpbi->biSize,
nNumColors * sizeof(RGBQUAD), &dwRead, NULL);
// offset to the bits from start of DIB header
offBits = lpbi->biSize + nNumColors * sizeof(RGBQUAD);
// If the bfOffBits field is non-zero, then the bits might *not* be
// directly following the color table in the file. Use the value in
// bfOffBits to seek the bits.
if (bmfHeader.bfOffBits != 0L)
SetFilePointer(hFile, bmfHeader.bfOffBits, NULL, FILE_BEGIN);
if (ReadFile(hFile, (LPSTR)lpbi + offBits, lpbi->biSizeImage, &dwRead,
NULL))
goto OKExit;
ErrExit:
GlobalUnlock(hDIB);
ErrExitNoUnlock:
GlobalFree(hDIB);
return NULL;
OKExit:
GlobalUnlock(hDIB);
return hDIB;
}