dibfile.cpp
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上传日期:2010-02-01
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Visual C++
- // myfile.cpp
- //
- // Source file for Device-Independent Bitmap (DIB) API. Provides
- // the following functions:
- //
- // SaveDIB() - Saves the specified dib in a file
- // ReadDIBFile() - Loads a DIB from a file
- //
- //
- // This is a part of the Microsoft Foundation Classes C++ library.
- // Copyright (C) 1992-1998 Microsoft Corporation
- // All rights reserved.
- //
- // This source code is only intended as a supplement to the
- // Microsoft Foundation Classes Reference and related
- // electronic documentation provided with the library.
- // See these sources for detailed information regarding the
- // Microsoft Foundation Classes product.
- #include "stdafx.h"
- #include <math.h>
- #include <io.h>
- #include <direct.h>
- #include "dibapi.h"
- /*
- * Dib Header Marker - used in writing DIBs to files
- */
- #define DIB_HEADER_MARKER ((WORD) ('M' << 8) | 'B')
- /*************************************************************************
- *
- * SaveDIB()
- *
- * Saves the specified DIB into the specified CFile. The CFile
- * is opened and closed by the caller.
- *
- * Parameters:
- *
- * HDIB hDib - Handle to the dib to save
- *
- * CFile& file - open CFile used to save DIB
- *
- * Return value: TRUE if successful, else FALSE or CFileException
- *
- *************************************************************************/
- BOOL WINAPI SaveDIB(HDIB hDib, CFile& file)
- {
- BITMAPFILEHEADER bmfHdr; // Header for Bitmap file
- LPBITMAPINFOHEADER lpBI; // Pointer to DIB info structure
- DWORD dwDIBSize;
- if (hDib == NULL)
- return FALSE;
- /*
- * Get a pointer to the DIB memory, the first of which contains
- * a BITMAPINFO structure
- */
- lpBI = (LPBITMAPINFOHEADER) ::GlobalLock((HGLOBAL) hDib);
- if (lpBI == NULL)
- return FALSE;
- if (!IS_WIN30_DIB(lpBI))
- {
- ::GlobalUnlock((HGLOBAL) hDib);
- return FALSE; // It's an other-style DIB (save not supported)
- }
- /*
- * 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).
- //
- // So, instead let's calculate the size manually (if we can)
- //
- // First, 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.
- dwDIBSize = *(LPDWORD)lpBI + ::PaletteSize((LPSTR)lpBI); // Partial Calculation
- // Now calculate the size of the image
- if ((lpBI->biCompression == BI_RLE8) || (lpBI->biCompression == BI_RLE4))
- {
- // It's an RLE bitmap, we can't calculate size, so trust the
- // biSizeImage field
- 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);
- TRY
- {
- // Write the file header
- file.Write((LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER));
- //
- // Write the DIB header and the bits
- //
- file.WriteHuge(lpBI, dwDIBSize);
- }
- CATCH (CFileException, e)
- {
- ::GlobalUnlock((HGLOBAL) hDib);
- THROW_LAST();
- }
- END_CATCH
- ::GlobalUnlock((HGLOBAL) hDib);
- return TRUE;
- }
- /*************************************************************************
- Function: ReadDIBFile (CFile&)
- 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.
- *************************************************************************/
- HDIB WINAPI ReadDIBFile(CFile& file)
- {
- BITMAPFILEHEADER bmfHeader;
- DWORD dwBitsSize;
- HDIB hDIB;
- LPSTR pDIB;
- /*
- * get length of DIB in bytes for use when reading
- */
- dwBitsSize = file.GetLength();
- /*
- * Go read the DIB file header and check if it's valid.
- */
- if (file.Read((LPSTR)&bmfHeader, sizeof(bmfHeader)) != sizeof(bmfHeader))
- return NULL;
- if (bmfHeader.bfType != DIB_HEADER_MARKER)
- return NULL;
- /*
- * Allocate memory for DIB
- */
- hDIB = (HDIB) ::GlobalAlloc(GMEM_MOVEABLE | GMEM_ZEROINIT, dwBitsSize);
- if (hDIB == 0)
- {
- return NULL;
- }
- pDIB = (LPSTR) ::GlobalLock((HGLOBAL) hDIB);
- /*
- * Go read the bits.
- */
- if (file.ReadHuge(pDIB, dwBitsSize - sizeof(BITMAPFILEHEADER)) !=
- dwBitsSize - sizeof(BITMAPFILEHEADER) )
- {
- ::GlobalUnlock((HGLOBAL) hDIB);
- ::GlobalFree((HGLOBAL) hDIB);
- return NULL;
- }
- ::GlobalUnlock((HGLOBAL) hDIB);
- return hDIB;
- }