VC只用GDI实现位图展现简单特效

展示截图（略大，4.24M）：



Demo下载（需要1积分）：http://download.csdn.net/detail/joneeky/7860555

这些把位图加载到内存DC上的代码需要重复使用，于是定义成宏：

#define READY_CODE								\
CGditestDlg *pMainDlg = (CGditestDlg *)pParam;	\
CDC *pDC = pMainDlg->GetDC();					\
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;					\
}												\
CDC dcMem;										\
dcMem.CreateCompatibleDC(pDC);					\
dcMem.SelectObject(&bmp);						\
BITMAP bm;										\
bmp.GetBitmap(&bm);								\
pMainDlg->Invalidate();							\
EnumChildWindows(pMainDlg->GetSafeHwnd(),		\
EnumChildProc, 0L);

#define CLEAN_CODE			\
dcMem.DeleteDC();			\
bmp.DeleteObject();			\
EnumChildWindows(			\
pMainDlg->GetSafeHwnd(),\
EnumChildProc, 1L);		\

#define PI	3.14

//弧度 = 2π * 角度 / 360
#define RADIAN(degree)	((float)((2 * PI * degree) / 360))

/*从上飞入*/
UINT CGditestDlg::FlyIntoFromTop(LPVOID pParam)
{
READY_CODE
for (int ySrc = bm.bmHeight; ySrc >= 0; ySrc -= 10)
{
pDC->BitBlt(0, 0, bm.bmWidth, bm.bmHeight, &dcMem, 0, ySrc, SRCCOPY);
Sleep(1);
}
CLEAN_CODE
return 0;
}

/*从左飞入*/
UINT CGditestDlg::FlyIntoFromLeft(LPVOID pParam)
{
READY_CODE
for (int xSrc = bm.bmWidth; xSrc >= 0; xSrc -= 10)
{
pDC->BitBlt(0, 0, bm.bmWidth, bm.bmHeight, &dcMem, xSrc, 0, SRCCOPY);
Sleep(1);
}
CLEAN_CODE
return 0;
}

/*从上展开*/
UINT CGditestDlg::UnfoldFromTop(LPVOID pParam)
{
READY_CODE
for (int htDes = 0; htDes <= bm.bmHeight; htDes += 10)
{
pDC->BitBlt(0, 0, bm.bmWidth, htDes, &dcMem, 0, 0, SRCCOPY);
Sleep(1);
}
CLEAN_CODE
return 0;
}

/*从左展开*/
UINT CGditestDlg::UnfoldFromLeft(LPVOID pParam)
{
READY_CODE
for (int wtDes = 0; wtDes <= bm.bmWidth; wtDes += 10)
{
pDC->BitBlt(0, 0, wtDes, bm.bmHeight, &dcMem, 0, 0, SRCCOPY);
Sleep(1);
}
CLEAN_CODE
return 0;
}

百叶窗就是把位图分块同步显示，原理比较简单。

/*水平百叶窗*/
UINT CGditestDlg::HorizontalWindow(LPVOID pParam)
{
READY_CODE
int n = bm.bmHeight / 8;
for (int htDes = 0; htDes <= n; htDes += 1)
{
for (int i = 0; i < 8; i++)
{
pDC->BitBlt(0, n * i, bm.bmWidth, htDes, &dcMem, 0, n * i, SRCCOPY);
}
Sleep(10);
}
CLEAN_CODE
return 0;
}

/*垂直百叶窗*/
UINT CGditestDlg::VerticalWindow(LPVOID pParam)
{
READY_CODE
int n = bm.bmWidth / 8;
for (int wtDes = 0; wtDes <= n; wtDes += 1)
{
for (int i = 0; i < 8; i++)
{
pDC->BitBlt(n * i, 0, wtDes, bm.bmHeight, &dcMem, n * i, 0, SRCCOPY);
}
Sleep(10);
}
CLEAN_CODE
return 0;
}

拉直其实和百叶窗相差不了多少，也是分块同步显示，但是每一块是慢慢变大的。

/*往下拉直*/
UINT CGditestDlg::StraightenToBottom(LPVOID pParam)
{
READY_CODE
int n = bm.bmHeight / 8;
for (int htDes = 0; htDes <= n; htDes += 1)
{
for (int i = 0; i < 8; i++)
{
pDC->BitBlt(0, htDes * i, bm.bmWidth, htDes, &dcMem, 0, n * i, SRCCOPY);
}
Sleep(10);
}
CLEAN_CODE
return 0;
}

/*往右拉直*/
UINT CGditestDlg::StraightenToRight(LPVOID pParam)
{
READY_CODE
int n = bm.bmWidth / 8;
for (int wtDes = 0; wtDes <= n; wtDes += 1)
{
for (int i = 0; i < 8; i++)
{
pDC->BitBlt(wtDes * i, 0, wtDes, bm.bmHeight, &dcMem, n * i, 0, SRCCOPY);
}
Sleep(10);
}
CLEAN_CODE
return 0;
}

由小变大主要是要保存图像比例和算位图从在哪个坐标显示，图像大小发生变化，坐标随之变化。可以先确定图像的宽，然后 长=宽*(高/2)；x坐标=位图实际的宽/2-当前的宽/2，y坐标=位图实际的高/2-当前的高/2。

/*由小变大*/
UINT CGditestDlg::SmallToLarge(LPVOID pParam)
{
READY_CODE
float x, y, w, h;
float base = 0;
pDC->SetStretchBltMode(HALFTONE);
while ((int)(base += 10) <= bm.bmWidth)
{
w = base;
h = base * ((float)bm.bmHeight / (float)bm.bmWidth);
x = (float)bm.bmWidth / 2 - w / 2;
y = (float)bm.bmHeight / 2 - h / 2;
pDC->StretchBlt((int)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, oldHeight;
float x, y;
int lastX = 0, lastY = 0, lastWidth = 0, lastHeight = 0;
dcMem.CreateCompatibleDC(pDC);
bmp.GetBitmap(&bm);
oldWidth = bm.bmWidth;
oldHeight = bm.bmHeight;
CRect rcWnd;
pMainDlg->GetWindowRect(&rcWnd);
CBitmap bmpBkgd;
CDC dcBkgd;
dcBkgd.CreateCompatibleDC(pDC);
bmpBkgd.CreateCompatibleBitmap(pDC, rcWnd.Width() + 200, rcWnd.Height() + 200);
dcBkgd.SelectObject(&bmpBkgd);
dcBkgd.FillSolidRect(0, 0, rcWnd.Width() + 200, rcWnd.Height() + 200, RGB(255, 174 ,201));
while (1)
{
if (base <= oldWidth)
{
base += 15;
}
if (base > oldWidth && degree == 0)
{
break;
}
width = base;
height = base * ((float)oldHeight / (float)oldWidth);
hBmp = GetRotatedBitmap((HBITMAP)bmp.GetSafeHandle(), RADIAN(degree), (int)width, (int)height, RGB(255, 174 ,201));
pbmpRotated = CBitmap::FromHandle(hBmp);
dcMem.SelectObject(pbmpRotated);
pbmpRotated->GetBitmap(&bm);
x = (float)oldWidth / 2 - (float)bm.bmWidth / 2;
y = (float)oldHeight / 2 - (float)bm.bmHeight / 2;
pDC->BitBlt(lastX, lastY, lastWidth, lastHeight, &dcBkgd, 0, 0, SRCCOPY);
pDC->BitBlt((int)x, (int)y, bm.bmWidth, bm.bmHeight, &dcMem, 0, 0, SRCCOPY);
lastX = (int)x;
lastY = (int)y;
lastWidth = bm.bmWidth;
lastHeight = bm.bmHeight;
pbmpRotated->DeleteObject();
degree = (degree += 15) > 360 ? 0 : degree;
Sleep(1);
}
dcMem.DeleteDC();
dcBkgd.DeleteDC();
bmpBkgd.DeleteObject();
EnumChildWindows(pMainDlg->GetSafeHwnd(), EnumChildProc, 1L);

//	CLEAN_CODE
return 0;
}