http://www.codeguru.com/bitmap/rotate_bitmap.shtml 旋转图像 如果你的应用程序仅工作在Windows NT下,那么你可以通过API函数旋转你的位图。 你或者使用world transformation和BitBlt()或者使用PlgBlt()旋转位图。一个 使用第一种方法的函数显示在下面。 如果你的目标是多平台的,那么你的任务变得非常困难。你只能通过旋转源位图中 每个象素或者直接操作DIB字节得到旋转位图。第一种方法通过每个点的处理是非 常慢的,第二种方法是很复杂的,但它有足够快的速度。注:下面的所有函数旋转 后产生新的位图,如果你需要直接绘制位图,请自已修改函数。 其中函数1仅工作 在NT环境下,它是最简单也是最快的,可惜它不支持Windows95。 所有的函数所接受的角度单位是弧度,如果是角度单位是度请用下面的公式转换。 radian = (2*pi *degree)/360 旋转步骤: 创建一对与设备兼容的显示设备。一个用于源位图,一个用于旋转后的目标位图。 预计算正弦和余弦函数值,这样可以避免重复计算。 用下面的公式计算旋转图像后的矩形 newx = x.cos(angle) + y.sin(angle) newy = y.cos(angle) - x.sin(angle) 旋转后的位图将不能占用整个新位图,我们将用背景色填充它。 点阵转换公式 newx = x * eM11 + y * eM21 + eDx newy = x * eM12 + y * eM22 + eDy 其中eM11和eM22是角度的余弦值,eM21是角度的正弦,eM12是eM21的负值。 eDx & eDy 目的是旋转后的位图在新的位图不被剪切。 函数一:适用于NT // GetRotatedBitmapNT Create a new bitmap with rotated image // Returns - Returns new bitmap with rotated image // hBitmap - Bitmap to rotate // radians - Angle of rotation in radians // clrBack - Color of pixels in the resulting bitmap that do // not get covered by source pixels HBITMAP GetRotatedBitmapNT( HBITMAP hBitmap, float radians, COLORREF clrBack ) / Create a memory DC compatible with the display DC sourceDC, destDC; ourceDC.CreateCompatibleDC( NULL ); estDC.CreateCompatibleDC( NULL ); / Get logical coordinates ITMAP bm; :GetObject( hBitmap, sizeof( bm ), &bm ); loat cosine = (float)cos(radians); loat sine = (float)sin(radians); / Compute dimensions of the resulting bitmap / First get the coordinates of the 3 corners other than origin nt x1 = (int)(bm.bmHeight * sine); nt y1 = (int)(bm.bmHeight * cosine); nt x2 = (int)(bm.bmWidth * cosine + bm.bmHeight * sine); nt y2 = (int)(bm.bmHeight * cosine - bm.bmWidth * sine); nt x3 = (int)(bm.bmWidth * cosine); nt y3 = (int)(-bm.bmWidth * sine); nt minx = min(0,min(x1, min(x2,x3))); nt miny = min(0,min(y1, min(y2,y3))); nt maxx = max(0,max(x1, max(x2,x3))); nt maxy = max(0,max(y1, max(y2,y3))); nt w = maxx - minx; nt h = maxy - miny; / Create a bitmap to hold the result BITMAP hbmResult = ::CreateCompatibleBitmap(CClientDC(NULL), w, h); BITMAP hbmOldSource = (HBITMAP)::SelectObject( sourceDC.m_hDC, hBitmap ); BITMAP hbmOldDest = (HBITMAP)::SelectObject( destDC.m_hDC, hbmResult ); / Draw the background color before we change mapping mode BRUSH hbrBack = CreateSolidBrush( clrBack ); BRUSH hbrOld = (HBRUSH)::SelectObject( destDC.m_hDC, hbrBack ); estDC.PatBlt( 0, 0, w, h, PATCOPY ); :DeleteObject( ::SelectObject( destDC.m_hDC, hbrOld ) ); / We will use world transform to rotate the bitmap etGraphicsMode(destDC.m_hDC, GM_ADVANCED); FORM xform; form.eM11 = cosine; form.eM12 = -sine; form.eM21 = sine; form.eM22 = cosine; form.eDx = (float)-minx; form.eDy = (float)-miny; etWorldTransform( destDC.m_hDC, &xform ); / Now do the actual rotating - a pixel at a time estDC.BitBlt(0,0,bm.bmWidth, bm.bmHeight, &sourceDC, 0, 0, SRCCOPY ); / Restore DCs :SelectObject( sourceDC.m_hDC, hbmOldSource ); :SelectObject( destDC.m_hDC, hbmOldDest ); eturn hbmResult; 函数二: GetRotatedBitmap()使用 GetPixel & SetPixel // GetRotatedBitmap Create a new bitmap with rotated image // Returns - Returns new bitmap with rotated image // hBitmap - Bitmap to rotate // radians - Angle of rotation in radians // clrBack - Color of pixels in the resulting bitmap that do // not get covered by source pixels // Note If the bitmap uses colors not in the system palette // then the result is unexpected. You can fix this by // adding an argument for the logical palette. HBITMAP GetRotatedBitmap( HBITMAP hBitmap, float radians, COLORREF clrBack ) / Create a memory DC compatible with the display DC sourceDC, destDC; ourceDC.CreateCompatibleDC( NULL ); estDC.CreateCompatibleDC( NULL ); / Get logical coordinates ITMAP bm; :GetObject( hBitmap, sizeof( bm ), &bm ); loat cosine = (float)cos(radians); loat sine = (float)sin(radians); / Compute dimensions of the resulting bitmap / First get the coordinates of the 3 corners other than origin nt x1 = (int)(-bm.bmHeight * sine); nt y1 = (int)(bm.bmHeight * cosine); nt x2 = (int)(bm.bmWidth * cosine - bm.bmHeight * sine); nt y2 = (int)(bm.bmHeight * cosine + bm.bmWidth * sine); nt x3 = (int)(bm.bmWidth * cosine); nt y3 = (int)(bm.bmWidth * sine); nt minx = min(0,min(x1, min(x2,x3))); nt miny = min(0,min(y1, min(y2,y3))); nt maxx = max(x1, max(x2,x3)); nt maxy = max(y1, max(y2,y3)); nt w = maxx - minx; nt h = maxy - miny; / Create a bitmap to hold the result BITMAP hbmResult = ::CreateCompatibleBitmap(CClientDC(NULL), w, h); BITMAP hbmOldSource = (HBITMAP)::SelectObject( sourceDC.m_hDC, hBitmap ); BITMAP hbmOldDest = (HBITMAP)::SelectObject( destDC.m_hDC, hbmResult ); / Draw the background color before we change mapping mode BRUSH hbrBack = CreateSolidBrush( clrBack ); BRUSH hbrOld = (HBRUSH)::SelectObject( destDC.m_hDC, hbrBack ); estDC.PatBlt( 0, 0, w, h, PATCOPY ); :DeleteObject( ::SelectObject( destDC.m_hDC, hbrOld ) ); / Set mapping mode so that +ve y axis is upwords ourceDC.SetMapMode(MM_ISOTROPIC); ourceDC.SetWindowExt(1,1); ourceDC.SetViewportExt(1,-1); ourceDC.SetViewportOrg(0, bm.bmHeight-1); estDC.SetMapMode(MM_ISOTROPIC); estDC.SetWindowExt(1,1); estDC.SetViewportExt(1,-1); estDC.SetWindowOrg(minx, maxy); / Now do the actual rotating - a pixel at a time / Computing the destination point for each source point / will leave a few pixels that do not get covered / So we use a reverse transform - e.i. compute the source point / for each destination point or( int y = miny; y < maxy; y++ ) for( int x = minx; x < maxx; x++ ) nt sourcex = (int)(x*cosine + y*sine); nt sourcey = (int)(y*cosine - x*sine); f( sourcex >= 0 && sourcex < bm.bmWidth && sourcey >= 0 & sourcey < bm.bmHeight ) destDC.SetPixel(x,y,sourceDC.GetPixel(sourcex,sourcey)); / Restore DCs :SelectObject( sourceDC.m_hDC, hbmOldSource ); :SelectObject( destDC.m_hDC, hbmOldDest ); eturn hbmResult; 函数三: GetRotatedBitmap()使用DIB // GetRotatedBitmap - Create a new bitmap with rotated image // Returns - Returns new bitmap with rotated image // hDIB - Device-independent bitmap to rotate // radians - Angle of rotation in radians // clrBack - Color of pixels in the resulting bitmap that do // not get covered by source pixels HANDLE GetRotatedBitmap( HANDLE hDIB, float radians, COLORREF clrBack) { // Get source bitmap info BITMAPINFO &bmInfo = *(LPBITMAPINFO)hDIB ; int bpp = bmInfo.bmiHeader.biBitCount; // Bits per pixel int nColors = bmInfo.bmiHeader.biClrUsed ? bmInfo.bmiHeader.biClrUsed : 1 << bpp; int nWidth = bmInfo.bmiHeader.biWidth; int nHeight = bmInfo.bmiHeader.biHeight; int nRowBytes = ((((nWidth * bpp) + 31) & ~31) / 8);
// Make sure height is positive and biCompression is BI_RGB or BI_BITFIELDS DWORD &compression = bmInfo.bmiHeader.biCompression; if( nHeight < 0 || (compression!=BI_RGB && compression!=BI_BITFIELDS)) return NULL; LPVOID lpDIBBits; if( bmInfo.bmiHeader.biBitCount > 8 ) lpDIBBits = (LPVOID)((LPDWORD)(bmInfo.bmiColors + bmInfo.bmiHeader.biClrUsed) + ((compression == BI_BITFIELDS) ? 3 : 0)); else lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors); // Compute the cosine and sine only once float cosine = (float)cos(radians); float sine = (float)sin(radians); // Compute dimensions of the resulting bitmap // First get the coordinates of the 3 corners other than origin int x1 = (int)(-nHeight * sine); int y1 = (int)(nHeight * cosine); int x2 = (int)(nWidth * cosine - nHeight * sine); int y2 = (int)(nHeight * cosine + nWidth * sine); int x3 = (int)(nWidth * cosine); int y3 = (int)(nWidth * sine); int minx = min(0,min(x1, min(x2,x3))); int miny = min(0,min(y1, min(y2,y3))); int maxx = max(x1, max(x2,x3)); int maxy = max(y1, max(y2,y3)); int w = maxx - minx; int h = maxy - miny; // Create a DIB to hold the result int nResultRowBytes = ((((w * bpp) + 31) & ~31) / 8); long len = nResultRowBytes * h; int nHeaderSize = ((LPBYTE)lpDIBBits-(LPBYTE)hDIB) ; HANDLE hDIBResult = GlobalAlloc(GMEM_FIXED,len+nHeaderSize); // Initialize the header information memcpy( (void*)hDIBResult, (void*)hDIB, nHeaderSize); BITMAPINFO &bmInfoResult = *(LPBITMAPINFO)hDIBResult ; bmInfoResult.bmiHeader.biWidth = w; bmInfoResult.bmiHeader.biHeight = h; bmInfoResult.bmiHeader.biSizeImage = len; LPVOID lpDIBBitsResult = (LPVOID)((LPBYTE)hDIBResult + nHeaderSize); // Get the back color value (index) ZeroMemory( lpDIBBitsResult, len ); DWORD dwBackColor; switch(bpp) { case 1: //Monochrome if( clrBack == RGB(255,255,255) ) memset( lpDIBBitsResult, 0xff, len ); break; case 4: case 8: //Search the color table int i; for(i = 0; i < nColors; i++ ) { if( bmInfo.bmiColors[i].rgbBlue == GetBValue(clrBack) && bmInfo.bmiColors[i].rgbGreen == GetGValue(clrBack) && bmInfo.bmiColors[i].rgbRed == GetRValue(clrBack) ) { if(bpp==4) i = i | i<<4; memset( lpDIBBitsResult, i, len ); break; } } // If not match found the color remains black break; case 16: // Windows95 supports 5 bits each for all colors or 5 bits for red & blue // and 6 bits for green - Check the color mask for RGB555 or RGB565 if( *((DWORD*)bmInfo.bmiColors) == 0x7c00 ) { // Bitmap is RGB555 dwBackColor = ((GetRValue(clrBack)>>3) << 10) + ((GetRValue(clrBack)>>3) << 5) + (GetBValue(clrBack)>>3) ; } else { // Bitmap is RGB565 dwBackColor = ((GetRValue(clrBack)>>3) << 11) + ((GetRValue(clrBack)>>2) << 5) + (GetBValue(clrBack)>>3) ; } break; case 24: case 32: dwBackColor = (((DWORD)GetRValue(clrBack)) << 16) | (((DWORD)GetGValue(clrBack)) << 8) | (((DWORD)GetBValue(clrBack))); break; } // Now do the actual rotating - a pixel at a time // Computing the destination point for each source point // will leave a few pixels that do not get covered // So we use a reverse transform - e.i. compute the source point // for each destination point for( int y = 0; y < h; y++ ) { for( int x = 0; x < w; x++ ) { int sourcex = (int)((x+minx)*cosine + (y+miny)*sine); int sourcey = (int)((y+miny)*cosine - (x+minx)*sine); if( sourcex >= 0 && sourcex < nWidth && sourcey >= 0 && sourcey < nHeight ) { // Set the destination pixel switch(bpp) { BYTE mask; case 1: //Monochrome mask = *((LPBYTE)lpDIBBits + nRowBytes*sourcey + sourcex/8) & (0x80 >> sourcex%8); //Adjust mask for destination bitmap mask = mask ? (0x80 >> x%8) : 0; *((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) + (x/8)) &= ~(0x80 >> x%8); *((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) + (x/8)) |= mask; break; case 4: mask = *((LPBYTE)lpDIBBits + nRowBytes*sourcey + sourcex/2) & ((sourcex&1) ? 0x0f : 0xf0); //Adjust mask for destination bitmap if( (sourcex&1) != (x&1) ) mask = (mask&0xf0) ? (mask>>4) : (mask<<4); *((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) + (x/2)) &= ~((x&1) ? 0x0f : 0xf0); *((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) + (x/2)) |= mask; break; case 8: BYTE pixel ; pixel = *((LPBYTE)lpDIBBits + nRowBytes*sourcey + sourcex); *((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) + (x)) = pixel; break; case 16: DWORD dwPixel; dwPixel = *((LPWORD)((LPBYTE)lpDIBBits + nRowBytes*sourcey + sourcex*2)); *((LPWORD)((LPBYTE)lpDIBBitsResult + nResultRowBytes*y + x*2)) = (WORD)dwPixel; break; case 24: dwPixel = *((LPDWORD)((LPBYTE)lpDIBBits + nRowBytes*sourcey + sourcex*3)) & 0xffffff; *((LPDWORD)((LPBYTE)lpDIBBitsResult + nResultRowBytes*y + x*3)) |= dwPixel; break; case 32: dwPixel = *((LPDWORD)((LPBYTE)lpDIBBits + nRowBytes*sourcey + sourcex*4)); *((LPDWORD)((LPBYTE)lpDIBBitsResult + nResultRowBytes*y + x*4)) = dwPixel; } } else { // Draw the background "color." tppabs="http://www.codeguru.com/bitmap/color." The background color // has already been drawn for 8 bits per pixel and less switch(bpp) { case 16: *((LPWORD)((LPBYTE)lpDIBBitsResult + nResultRowBytes*y + x*2)) = (WORD)dwBackColor; break; case 24: *((LPDWORD)((LPBYTE)lpDIBBitsResult + nResultRowBytes*y + x*3)) |= dwBackColor; break; case 32: *((LPDWORD)((LPBYTE)lpDIBBitsResult + nResultRowBytes*y + x*4)) = dwBackColor; break; } } } } return hDIBResult; } http://www.ittide.com/document/article/graphic/13.html
BITMAPINFOHEADER ih;
BYTE *lpBitBuff//转换后的图像//
//图像数据初始化
//
//int iBytesInRow=((ih.biBitCount) + 31) / 32 * 4//每行图像的字节数lpBitBuff=new BYTE(ih.biSizeImage)
for(int i=0;i<ih.biHeight;i++)
{
for(int j=0;j<ih.biWidth;j++)
memset(lpBitBuff[i*iBytesInRow+j],
lpBitBuff[(ih.biHeight-i)*iBytesInRow+(ih.biWidth-j)],
ih.biBitCount/8);}
//此时,lpBitBuff包含的图像即为旋转180度的图像
旋转图像
如果你的应用程序仅工作在Windows NT下,那么你可以通过API函数旋转你的位图。
你或者使用world transformation和BitBlt()或者使用PlgBlt()旋转位图。一个
使用第一种方法的函数显示在下面。
如果你的目标是多平台的,那么你的任务变得非常困难。你只能通过旋转源位图中
每个象素或者直接操作DIB字节得到旋转位图。第一种方法通过每个点的处理是非
常慢的,第二种方法是很复杂的,但它有足够快的速度。注:下面的所有函数旋转
后产生新的位图,如果你需要直接绘制位图,请自已修改函数。 其中函数1仅工作
在NT环境下,它是最简单也是最快的,可惜它不支持Windows95。
所有的函数所接受的角度单位是弧度,如果是角度单位是度请用下面的公式转换。
radian = (2*pi *degree)/360
旋转步骤:
创建一对与设备兼容的显示设备。一个用于源位图,一个用于旋转后的目标位图。
预计算正弦和余弦函数值,这样可以避免重复计算。
用下面的公式计算旋转图像后的矩形
newx = x.cos(angle) + y.sin(angle)
newy = y.cos(angle) - x.sin(angle)
旋转后的位图将不能占用整个新位图,我们将用背景色填充它。
点阵转换公式
newx = x * eM11 + y * eM21 + eDx
newy = x * eM12 + y * eM22 + eDy
其中eM11和eM22是角度的余弦值,eM21是角度的正弦,eM12是eM21的负值。 eDx & eDy
目的是旋转后的位图在新的位图不被剪切。
函数一:适用于NT
// GetRotatedBitmapNT
Create a new bitmap with rotated image
// Returns
- Returns new bitmap with rotated image
// hBitmap
- Bitmap to rotate
// radians
- Angle of rotation in radians
// clrBack
- Color of pixels in the resulting bitmap that do
//
not get covered by source pixels
HBITMAP GetRotatedBitmapNT( HBITMAP hBitmap, float radians, COLORREF clrBack )
/ Create a memory DC compatible with the display
DC sourceDC, destDC;
ourceDC.CreateCompatibleDC( NULL );
estDC.CreateCompatibleDC( NULL );
/ Get logical coordinates
ITMAP bm;
:GetObject( hBitmap, sizeof( bm ), &bm );
loat cosine = (float)cos(radians);
loat sine = (float)sin(radians);
/ Compute dimensions of the resulting bitmap
/ First get the coordinates of the 3 corners other than origin
nt x1 = (int)(bm.bmHeight * sine);
nt y1 = (int)(bm.bmHeight * cosine);
nt x2 = (int)(bm.bmWidth * cosine + bm.bmHeight * sine);
nt y2 = (int)(bm.bmHeight * cosine - bm.bmWidth * sine);
nt x3 = (int)(bm.bmWidth * cosine);
nt y3 = (int)(-bm.bmWidth * sine);
nt minx = min(0,min(x1, min(x2,x3)));
nt miny = min(0,min(y1, min(y2,y3)));
nt maxx = max(0,max(x1, max(x2,x3)));
nt maxy = max(0,max(y1, max(y2,y3)));
nt w = maxx - minx;
nt h = maxy - miny;
/ Create a bitmap to hold the result
BITMAP hbmResult = ::CreateCompatibleBitmap(CClientDC(NULL), w, h);
BITMAP hbmOldSource = (HBITMAP)::SelectObject( sourceDC.m_hDC, hBitmap );
BITMAP hbmOldDest = (HBITMAP)::SelectObject( destDC.m_hDC, hbmResult );
/ Draw the background color before we change mapping mode
BRUSH hbrBack = CreateSolidBrush( clrBack );
BRUSH hbrOld = (HBRUSH)::SelectObject( destDC.m_hDC, hbrBack );
estDC.PatBlt( 0, 0, w, h, PATCOPY );
:DeleteObject( ::SelectObject( destDC.m_hDC, hbrOld ) );
/ We will use world transform to rotate the bitmap
etGraphicsMode(destDC.m_hDC, GM_ADVANCED);
FORM xform;
form.eM11 = cosine;
form.eM12 = -sine;
form.eM21 = sine;
form.eM22 = cosine;
form.eDx = (float)-minx;
form.eDy = (float)-miny;
etWorldTransform( destDC.m_hDC, &xform );
/ Now do the actual rotating - a pixel at a time
estDC.BitBlt(0,0,bm.bmWidth, bm.bmHeight, &sourceDC, 0, 0, SRCCOPY );
/ Restore DCs
:SelectObject( sourceDC.m_hDC, hbmOldSource );
:SelectObject( destDC.m_hDC, hbmOldDest );
eturn hbmResult;
函数二: GetRotatedBitmap()使用 GetPixel & SetPixel
// GetRotatedBitmap
Create a new bitmap with rotated image
// Returns
- Returns new bitmap with rotated image
// hBitmap
- Bitmap to rotate
// radians
- Angle of rotation in radians
// clrBack
- Color of pixels in the resulting bitmap that do
//
not get covered by source pixels
// Note
If the bitmap uses colors not in the system palette
//
then the result is unexpected. You can fix this by
//
adding an argument for the logical palette.
HBITMAP GetRotatedBitmap( HBITMAP hBitmap, float radians, COLORREF clrBack )
/ Create a memory DC compatible with the display
DC sourceDC, destDC;
ourceDC.CreateCompatibleDC( NULL );
estDC.CreateCompatibleDC( NULL );
/ Get logical coordinates
ITMAP bm;
:GetObject( hBitmap, sizeof( bm ), &bm );
loat cosine = (float)cos(radians);
loat sine = (float)sin(radians);
/ Compute dimensions of the resulting bitmap
/ First get the coordinates of the 3 corners other than origin
nt x1 = (int)(-bm.bmHeight * sine);
nt y1 = (int)(bm.bmHeight * cosine);
nt x2 = (int)(bm.bmWidth * cosine - bm.bmHeight * sine);
nt y2 = (int)(bm.bmHeight * cosine + bm.bmWidth * sine);
nt x3 = (int)(bm.bmWidth * cosine);
nt y3 = (int)(bm.bmWidth * sine);
nt minx = min(0,min(x1, min(x2,x3)));
nt miny = min(0,min(y1, min(y2,y3)));
nt maxx = max(x1, max(x2,x3));
nt maxy = max(y1, max(y2,y3));
nt w = maxx - minx;
nt h = maxy - miny;
/ Create a bitmap to hold the result
BITMAP hbmResult = ::CreateCompatibleBitmap(CClientDC(NULL), w, h);
BITMAP hbmOldSource = (HBITMAP)::SelectObject( sourceDC.m_hDC, hBitmap );
BITMAP hbmOldDest = (HBITMAP)::SelectObject( destDC.m_hDC, hbmResult );
/ Draw the background color before we change mapping mode
BRUSH hbrBack = CreateSolidBrush( clrBack );
BRUSH hbrOld = (HBRUSH)::SelectObject( destDC.m_hDC, hbrBack );
estDC.PatBlt( 0, 0, w, h, PATCOPY );
:DeleteObject( ::SelectObject( destDC.m_hDC, hbrOld ) );
/ Set mapping mode so that +ve y axis is upwords
ourceDC.SetMapMode(MM_ISOTROPIC);
ourceDC.SetWindowExt(1,1);
ourceDC.SetViewportExt(1,-1);
ourceDC.SetViewportOrg(0, bm.bmHeight-1);
estDC.SetMapMode(MM_ISOTROPIC);
estDC.SetWindowExt(1,1);
estDC.SetViewportExt(1,-1);
estDC.SetWindowOrg(minx, maxy);
/ Now do the actual rotating - a pixel at a time
/ Computing the destination point for each source point
/ will leave a few pixels that do not get covered
/ So we use a reverse transform - e.i. compute the source point
/ for each destination point
or( int y = miny; y < maxy; y++ )
for( int x = minx; x < maxx; x++ )
nt sourcex = (int)(x*cosine + y*sine);
nt sourcey = (int)(y*cosine - x*sine);
f( sourcex >= 0 && sourcex < bm.bmWidth && sourcey >= 0
& sourcey < bm.bmHeight )
destDC.SetPixel(x,y,sourceDC.GetPixel(sourcex,sourcey));
/ Restore DCs
:SelectObject( sourceDC.m_hDC, hbmOldSource );
:SelectObject( destDC.m_hDC, hbmOldDest );
eturn hbmResult;
函数三: GetRotatedBitmap()使用DIB
// GetRotatedBitmap - Create a new bitmap with rotated image
// Returns - Returns new bitmap with rotated image
// hDIB - Device-independent bitmap to rotate
// radians - Angle of rotation in radians
// clrBack - Color of pixels in the resulting bitmap that do
// not get covered by source pixels
HANDLE GetRotatedBitmap( HANDLE hDIB, float radians, COLORREF clrBack)
{
// Get source bitmap info
BITMAPINFO &bmInfo = *(LPBITMAPINFO)hDIB ;
int bpp = bmInfo.bmiHeader.biBitCount; // Bits per pixel
int nColors = bmInfo.bmiHeader.biClrUsed ? bmInfo.bmiHeader.biClrUsed
:
1 << bpp;
int nWidth = bmInfo.bmiHeader.biWidth;
int nHeight = bmInfo.bmiHeader.biHeight;
int nRowBytes = ((((nWidth * bpp) + 31) & ~31) / 8);
BI_BITFIELDS
DWORD &compression = bmInfo.bmiHeader.biCompression;
if( nHeight < 0 || (compression!=BI_RGB &&
compression!=BI_BITFIELDS))
return NULL;
LPVOID lpDIBBits;
if( bmInfo.bmiHeader.biBitCount > 8 )
lpDIBBits = (LPVOID)((LPDWORD)(bmInfo.bmiColors +
bmInfo.bmiHeader.biClrUsed) +
((compression == BI_BITFIELDS) ? 3 : 0));
else
lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
// Compute the cosine and sine only once
float cosine = (float)cos(radians);
float sine = (float)sin(radians);
// Compute dimensions of the resulting bitmap
// First get the coordinates of the 3 corners other than origin
int x1 = (int)(-nHeight * sine);
int y1 = (int)(nHeight * cosine);
int x2 = (int)(nWidth * cosine - nHeight * sine);
int y2 = (int)(nHeight * cosine + nWidth * sine);
int x3 = (int)(nWidth * cosine);
int y3 = (int)(nWidth * sine);
int minx = min(0,min(x1, min(x2,x3)));
int miny = min(0,min(y1, min(y2,y3)));
int maxx = max(x1, max(x2,x3));
int maxy = max(y1, max(y2,y3));
int w = maxx - minx;
int h = maxy - miny;
// Create a DIB to hold the result
int nResultRowBytes = ((((w * bpp) + 31) & ~31) / 8);
long len = nResultRowBytes * h;
int nHeaderSize = ((LPBYTE)lpDIBBits-(LPBYTE)hDIB) ;
HANDLE hDIBResult = GlobalAlloc(GMEM_FIXED,len+nHeaderSize);
// Initialize the header information
memcpy( (void*)hDIBResult, (void*)hDIB, nHeaderSize);
BITMAPINFO &bmInfoResult = *(LPBITMAPINFO)hDIBResult ;
bmInfoResult.bmiHeader.biWidth = w;
bmInfoResult.bmiHeader.biHeight = h;
bmInfoResult.bmiHeader.biSizeImage = len;
LPVOID lpDIBBitsResult = (LPVOID)((LPBYTE)hDIBResult + nHeaderSize);
// Get the back color value (index)
ZeroMemory( lpDIBBitsResult, len );
DWORD dwBackColor;
switch(bpp)
{
case 1: //Monochrome
if( clrBack == RGB(255,255,255) )
memset( lpDIBBitsResult, 0xff, len );
break;
case 4:
case 8: //Search the color table
int i;
for(i = 0; i < nColors; i++ )
{
if( bmInfo.bmiColors[i].rgbBlue == GetBValue(clrBack)
&& bmInfo.bmiColors[i].rgbGreen == GetGValue(clrBack)
&& bmInfo.bmiColors[i].rgbRed == GetRValue(clrBack) )
{
if(bpp==4) i = i | i<<4;
memset( lpDIBBitsResult, i, len );
break;
}
}
// If not match found the color remains black
break;
case 16:
// Windows95 supports 5 bits each for all colors or 5 bits for red
& blue
// and 6 bits for green - Check the color mask for RGB555 or RGB565
if( *((DWORD*)bmInfo.bmiColors) == 0x7c00 )
{
// Bitmap is RGB555
dwBackColor = ((GetRValue(clrBack)>>3) << 10) +
((GetRValue(clrBack)>>3) << 5) +
(GetBValue(clrBack)>>3) ;
}
else
{
// Bitmap is RGB565
dwBackColor = ((GetRValue(clrBack)>>3) << 11) +
((GetRValue(clrBack)>>2) << 5) +
(GetBValue(clrBack)>>3) ;
}
break;
case 24:
case 32:
dwBackColor = (((DWORD)GetRValue(clrBack)) << 16) |
(((DWORD)GetGValue(clrBack)) << 8) |
(((DWORD)GetBValue(clrBack)));
break;
}
// Now do the actual rotating - a pixel at a time
// Computing the destination point for each source point
// will leave a few pixels that do not get covered
// So we use a reverse transform - e.i. compute the source point
// for each destination point
for( int y = 0; y < h; y++ )
{
for( int x = 0; x < w; x++ )
{
int sourcex = (int)((x+minx)*cosine + (y+miny)*sine);
int sourcey = (int)((y+miny)*cosine - (x+minx)*sine);
if( sourcex >= 0 && sourcex < nWidth && sourcey
>= 0
&& sourcey < nHeight )
{
// Set the destination pixel
switch(bpp)
{
BYTE mask;
case 1: //Monochrome
mask = *((LPBYTE)lpDIBBits + nRowBytes*sourcey +
sourcex/8) & (0x80 >> sourcex%8);
//Adjust mask for destination bitmap
mask = mask ? (0x80 >> x%8) : 0;
*((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) +
(x/8)) &= ~(0x80 >> x%8);
*((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) +
(x/8)) |= mask;
break;
case 4:
mask = *((LPBYTE)lpDIBBits + nRowBytes*sourcey +
sourcex/2) & ((sourcex&1) ? 0x0f : 0xf0);
//Adjust mask for destination bitmap
if( (sourcex&1) != (x&1) )
mask = (mask&0xf0) ? (mask>>4) : (mask<<4);
*((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) +
(x/2)) &= ~((x&1) ? 0x0f : 0xf0);
*((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) +
(x/2)) |= mask;
break;
case 8:
BYTE pixel ;
pixel = *((LPBYTE)lpDIBBits + nRowBytes*sourcey +
sourcex);
*((LPBYTE)lpDIBBitsResult + nResultRowBytes*(y) +
(x)) = pixel;
break;
case 16:
DWORD dwPixel;
dwPixel = *((LPWORD)((LPBYTE)lpDIBBits +
nRowBytes*sourcey + sourcex*2));
*((LPWORD)((LPBYTE)lpDIBBitsResult +
nResultRowBytes*y + x*2)) = (WORD)dwPixel;
break;
case 24:
dwPixel = *((LPDWORD)((LPBYTE)lpDIBBits +
nRowBytes*sourcey + sourcex*3)) & 0xffffff;
*((LPDWORD)((LPBYTE)lpDIBBitsResult +
nResultRowBytes*y + x*3)) |= dwPixel;
break;
case 32:
dwPixel = *((LPDWORD)((LPBYTE)lpDIBBits +
nRowBytes*sourcey + sourcex*4));
*((LPDWORD)((LPBYTE)lpDIBBitsResult +
nResultRowBytes*y + x*4)) = dwPixel;
}
}
else
{
// Draw the background "color."
tppabs="http://www.codeguru.com/bitmap/color." The
background color
// has already been drawn for 8 bits per pixel and less
switch(bpp)
{
case 16:
*((LPWORD)((LPBYTE)lpDIBBitsResult +
nResultRowBytes*y + x*2)) =
(WORD)dwBackColor;
break;
case 24:
*((LPDWORD)((LPBYTE)lpDIBBitsResult +
nResultRowBytes*y + x*3)) |= dwBackColor;
break;
case 32:
*((LPDWORD)((LPBYTE)lpDIBBitsResult +
nResultRowBytes*y + x*4)) = dwBackColor;
break;
}
}
}
}
return hDIBResult;
}
http://www.ittide.com/document/article/graphic/13.html