)x, (int)y, (int)w, (int)h, &dcMem, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY);
Sleep(10);
}
CLEAN_CODE
return 0;
}
旋转变大比较复杂，在上网找到可以完成位图按任意弧度旋转的代码改了一下，使其可以指定显示的大小：
最后一个参数的颜色值，指定图像旋转后空出来的位置填充的颜色
HBITMAP GetRotatedBitmap(HBITMAP hBitmap, float radians, int width, int height, COLORREF clrBack)
{
// Create a memory DC compatible with the display
CDC sourceDC, destDC;
sourceDC.CreateCompatibleDC( NULL );
destDC.CreateCompatibleDC( NULL );
// Get logical coordinates
BITMAP bm, bmOld;
::GetObject( hBitmap, sizeof( bm ), &bm );
bmOld = bm;
bm.bmWidth = width;
bm.bmHeight = height;
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)(bm.bmHeight * sine);
int y1 = (int)(bm.bmHeight * cosine);
int x2 = (int)(bm.bmWidth * cosine + bm.bmHeight * sine);
int y2 = (int)(bm.bmHeight * cosine - bm.bmWidth * sine);
int x3 = (int)(bm.bmWidth * cosine);
int y3 = (int)(-bm.bmWidth * sine);
int minx = min(0,min(x1, min(x2,x3)));
int miny = min(0,min(y1, min(y2,y3)));
int maxx = max(0,max(x1, max(x2,x3)));
int maxy = max(0,max(y1, max(y2,y3)));
int w = maxx - minx;
int h = maxy - miny;
// Create a bitmap to hold the result
HBITMAP hbmResult = ::CreateCompatibleBitmap(CClientDC(NULL), w, h);
HBITMAP hbmOldSource = (HBITMAP)::SelectObject( sourceDC.m_hDC, hBitmap );
HBITMAP hbmOldDest = (HBITMAP)::SelectObject( destDC.m_hDC, hbmResult );
// Draw the background color before we change mapping mode
HBRUSH hbrBack = CreateSolidBrush( clrBack );
HBRUSH hbrOld = (HBRUSH)::SelectObject( destDC.m_hDC, hbrBack );
destDC.PatBlt( 0, 0, w, h, PATCOPY );
::DeleteObject( ::SelectObject( destDC.m_hDC, hbrOld ) );
// We will use world transform to rotate the bitmap
SetGraphicsMode(destDC.m_hDC, GM_ADVANCED);
XFORM xform;
xform.eM11 = cosine;
xform.eM12 = -sine;
xform.eM21 = sine;
xform.eM22 = cosine;
xform.eDx = (float)-minx;
xform.eDy = (float)-miny;
SetWorldTransform( destDC.m_hDC, &xform );
// Now do the actual rotating - a pixel at a time
// destDC.BitBlt(0,0,bm.bmWidth, bm.bmHeight, &sourceDC, 0, 0, SRCCOPY );
destDC.SetStretchBltMode(HALFTONE);
destDC.StretchBlt(0, 0, bm.bmWidth, bm.bmHeight, &sourceDC, 0, 0, bmOld.bmWidth, bmOld.bmHeight, SRCCOPY);
// Restore DCs
::SelectObject( sourceDC.m_hDC, hbmOldSource );
::SelectObject( destDC.m_hDC, hbmOldDest );
return hbmResult;
}
只要是要控制当位图变到最大时旋转角度是0度，也就是说当变到最大时就不能再大了，但是如果角度不是0度也还是要转到0度去。
还有就是我使用了双缓冲，怎么还闪烁得这么厉害我也不清楚了。
/*旋转变大*/
UINT CGditestDlg::LargerWithSpin(LPVOID pParam)
{
// READY_CODE
CGditestDlg *pMainDlg = (CGditestDlg *)pParam;
CDC *pDC = pMainDlg->GetDC();
pMainDlg->Invalidate();
EnumChildWindows(pMainDlg->GetSafeHwnd(), EnumChildProc, 0L);
pDC->SetStretchBltMode(HALFTONE);
CBitmap bmp;
if (1 == pMainDlg->m_counter)
{
bmp.LoadBitmap(IDB_BITMAP1);
pMainDlg->m_counter = 2;
}
else if (2 == pMainDlg->m_counter)
{
bmp.LoadBitmap(IDB_BITMAP2);
pMainDlg->m_counter = 3;
}
else
{
bmp.LoadBitmap(IDB_BITMAP3);
pMainDlg->m_counter = 1;
}
HBITMAP hBmp;
CDC dcMem;
CBitmap *pbmpRotated;
BITMAP bm;
int degree = 0;
float width, height;
float base = 0;
long oldWidth, ol