工控编程吧

标题: DDB DIB MBP格式相互转换 [打印本页]

作者: qq263946146 时间: 2019-7-14 11:01
标题: DDB DIB MBP格式相互转换
把位图写入一个BMP文件
如果具有一个设备无关的位图句柄，把一个位图写入BMP文件非常简单：
在位图内容之后写入BITMAPINFOHEADER信息即可。
需要设置BITMAPINFOHEADER的三个成员是bfType，其值为"BM"，
bfSize，其值是位图的大小，
以及，bfOffBits，其值为文件开始到位图位的偏移量。
// WriteDIB - Writes a DIB to file
// Returns - TRUE on success
// szFile - Name of file to write to
// hDIB - Handle of the DIB
BOOL WriteDIB( LPTSTR szFile, HANDLE hDIB)
{
BITMAPFILEHEADER hdr;
LPBITMAPINFOHEADER lpbi;

if (!hDIB)
return FALSE;

CFile file;
if( !file.Open( szFile, CFile::modeWrite|CFile::modeCreate) )
return FALSE;

lpbi = (LPBITMAPINFOHEADER)hDIB;

int nColors = 1 << lpbi->biBitCount;

// Fill in the fields of the file header
hdr.bfType = ((WORD) ('M' << 8) | 'B'); // is always "BM" hdr.bfSize="GlobalSize" (hDIB) + sizeof( hdr ); hdr.bfReserved1="0;" hdr.bfReserved2="0;" hdr.bfOffBits="(DWORD)" (sizeof( hdr ) + lpbi->biSize +
nColors * sizeof(RGBQUAD));

// Write the file header
file.Write( &hdr, sizeof(hdr) );

// Write the DIB header and the bits
file.Write( lpbi, GlobalSize(hDIB) );

return TRUE;
}

把DDB转换成DIB
设备相关位图(DDB)显示方式是尽可能与显示设备驱动程序相匹配，
这样，DDB不可能与其他显示设备兼容；而设备无关位图（DIB）能与所有显示设备兼容，
但是，其缺点在于显示速度比较慢。
我们需要把DDB转换为DIB的一种情况是，需要将位图保存到一个文件中。
下面是其实现的代码。
// DDBToDIB - Creates a DIB from a DDB
// bitmap - Device dependent bitmap
// dwCompression - Type of compression - see BITMAPINFOHEADER
// pPal - Logical palette
HANDLE DDBToDIB( CBitmap& bitmap, DWORD dwCompression, CPalette* pPal )
{
BITMAP bm;
BITMAPINFOHEADER bi;
LPBITMAPINFOHEADER lpbi;
DWORD dwLen;
HANDLE hDIB;
HANDLE handle;
HDC hDC;
HPALETTE hPal;

ASSERT( bitmap.GetSafeHandle() );

// The function has no arg for bitfields
if( dwCompression == BI_BITFIELDS )
return NULL;

// If a palette has not been supplied use defaul palette
hPal = (HPALETTE) pPal->GetSafeHandle();
if (hPal==NULL)
hPal = (HPALETTE) GetStockObject(DEFAULT_PALETTE);

// Get bitmap information
bitmap.GetObject(sizeof(bm),(LPSTR)&bm);

// Initialize the bitmapinfoheader
bi.biSize = sizeof(BITMAPINFOHEADER);
bi.biWidth = bm.bmWidth;
bi.biHeight = bm.bmHeight;
bi.biPlanes = 1;
bi.biBitCount = bm.bmPlanes * bm.bmBitsPixel;
bi.biCompression = dwCompression;
bi.biSizeImage = 0;
bi.biXPelsPerMeter = 0;
bi.biYPelsPerMeter = 0;
bi.biClrUsed = 0;
bi.biClrImportant = 0;

// Compute the size of the infoheader and the color table
int nColors = (1 << bi.biBitCount); if( nColors> 256 )
nColors = 0;
dwLen = bi.biSize + nColors * sizeof(RGBQUAD);

// We need a device context to get the DIB from
hDC = GetDC(NULL);
hPal = SelectPalette(hDC,hPal,FALSE);
RealizePalette(hDC);

// Allocate enough memory to hold bitmapinfoheader and color table
hDIB = GlobalAlloc(GMEM_FIXED,dwLen);

if (!hDIB){
SelectPalette(hDC,hPal,FALSE);
ReleaseDC(NULL,hDC);
return NULL;
}

lpbi = (LPBITMAPINFOHEADER)hDIB;

*lpbi = bi;

// Call GetDIBits with a NULL lpBits param, so the device driver
// will calculate the biSizeImage field
GetDIBits(hDC, (HBITMAP)bitmap.GetSafeHandle(), 0L, (DWORD)bi.biHeight,
(LPBYTE)NULL, (LPBITMAPINFO)lpbi, (DWORD)DIB_RGB_COLORS);

bi = *lpbi;

// If the driver did not fill in the biSizeImage field, then compute it
// Each scan line of the image is aligned on a DWORD (32bit) boundary
if (bi.biSizeImage == 0){
bi.biSizeImage = ((((bi.biWidth * bi.biBitCount) + 31) & ~31) / 8)
* bi.biHeight;

// If a compression scheme is used the result may infact be larger
// Increase the size to account for this.
if (dwCompression != BI_RGB)
bi.biSizeImage = (bi.biSizeImage * 3) / 2;
}

// Realloc the buffer so that it can hold all the bits
dwLen += bi.biSizeImage;
if (handle = GlobalReAlloc(hDIB, dwLen, GMEM_MOVEABLE))
hDIB = handle;
else{
GlobalFree(hDIB);

// Reselect the original palette
SelectPalette(hDC,hPal,FALSE);
ReleaseDC(NULL,hDC);
return NULL;
}

// Get the bitmap bits
lpbi = (LPBITMAPINFOHEADER)hDIB;

// FINALLY get the DIB
BOOL bGotBits = GetDIBits( hDC, (HBITMAP)bitmap.GetSafeHandle(),
0L, // Start scan line
(DWORD)bi.biHeight, // # of scan lines
(LPBYTE)lpbi // address for bitmap bits
+ (bi.biSize + nColors * sizeof(RGBQUAD)),
(LPBITMAPINFO)lpbi, // address of bitmapinfo
(DWORD)DIB_RGB_COLORS); // Use RGB for color table

if( !bGotBits )
{
GlobalFree(hDIB);

SelectPalette(hDC,hPal,FALSE);
ReleaseDC(NULL,hDC);
return NULL;
}

SelectPalette(hDC,hPal,FALSE);
ReleaseDC(NULL,hDC);
return hDIB;
}

把DIB转换成DDB
你可以把一个设备无关位图（DIB）在不转换成设备相关位图（DDB）的情况下显示到设备环境中，
但是，这样做显示速度将慢很多。如果进行转换，将提高显示速度。
下面是其实现代码。
HBITMAP DIBToDDB( HANDLE hDIB )
{
LPBITMAPINFOHEADER lpbi;
HBITMAP hbm;
CPalette pal;
CPalette* pOldPal;
CClientDC dc(NULL);

if (hDIB == NULL)
return NULL;

lpbi = (LPBITMAPINFOHEADER)hDIB;

int nColors = lpbi->biClrUsed ? lpbi->biClrUsed :
1 << lpbi->biBitCount;

BITMAPINFO &bmInfo = *(LPBITMAPINFO)hDIB ;
LPVOID lpDIBBits;
if( bmInfo.bmiHeader.biBitCount > 8 )
lpDIBBits = (LPVOID)((LPDWORD)(bmInfo.bmiColors +
bmInfo.bmiHeader.biClrUsed) +
((bmInfo.bmiHeader.biCompression == BI_BITFIELDS) ? 3 : 0));
else
lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);

// Create and select a logical palette if needed
if( nColors <= 256 && dc.GetDeviceCaps(RASTERCAPS) & RC_PALETTE) { UINT nSize="sizeof(LOGPALETTE)" + (sizeof(PALETTEENTRY) * nColors); LOGPALETTE *pLP="(LOGPALETTE" *) new BYTE[nSize]; pLP->palVersion = 0x300;
pLP->palNumEntries = nColors;

for( int i=0; i palPalEntry.peRed = bmInfo.bmiColors.rgbRed;
pLP->palPalEntry.peGreen = bmInfo.bmiColors.rgbGreen;
pLP->palPalEntry.peBlue = bmInfo.bmiColors.rgbBlue;
pLP->palPalEntry.peFlags = 0;
}

pal.CreatePalette( pLP );

delete[] pLP;

// Select and realize the palette
pOldPal = dc.SelectPalette( &pal, FALSE );
dc.RealizePalette();
}

hbm = CreateDIBitmap(dc.GetSafeHdc(), // handle to device context
(LPBITMAPINFOHEADER)lpbi, // pointer to bitmap info header
(LONG)CBM_INIT, // initialization flag
lpDIBBits, // pointer to initialization data
(LPBITMAPINFO)lpbi, // pointer to bitmap info
DIB_RGB_COLORS ); // color-data usage

if (pal.GetSafeHandle())
dc.SelectPalette(pOldPal,FALSE);

return hbm;
}

欢迎光临工控编程吧 (https://www.gkbc8.com/) Powered by Discuz! X3.4