内存是如何泄漏的？
下面是一个钟表程序的一部分，模拟秒针旋转所以要旋转位图。在ontimer里有内存泄露，ontimer每秒执行一次，能看到内存明显增长。可能是旋转位图引起的，请各位大虾看看如何改正。thanks。
//几个成员变量：
CDC m_dcSecPointer;//the second pointer
CPoint m_ClockCenter;//the clock pointer center
CDC m_dcBKGround;//the back ground
//ontimer函数，里面调用了RotateBitmap（）函数
void CClockDlg::OnTimer(UINT nIDEvent)
{
CTime time=CTime::GetCurrentTime();
int nSec=time.GetSecond();
float fAngle;
CPoint pointS;
HDC dcS;
int nWS=SEC_WIDTH;
int nHS=SEC_HEIGHT;
switch(nIDEvent)
{
case MAIN_TIMER:
fAngle=nSec*6*pi/180;
pointS.y=-SEC_HEIGHT*cos(fAngle)/2;
pointS.x=SEC_HEIGHT*sin(fAngle)/2;
pointS=pointS+m_ClockCenter;
dcS=RotateBitmap(m_dcSecPointer,nWS,nHS,pointS,fAngle);
GetDC()-> StretchBlt(0,0,m_ClockCenter.x*2,2*m_ClockCenter.y,&m_dcBKGround,0,0,m_ClockCenter.x*2,2*m_ClockCenter.y,SRCCOPY);
TransparentBlt(GetDC()-> m_hDC,pointS.x,pointS.y,nWS,nHS,dcS,0,0,nWS,nHS,RGB(0,0,0));
DeleteDC(dcS);
break;
}
CDialog::OnTimer(nIDEvent);
}
//旋转位图的函数
HDC CClockDlg::RotateBitmap(
HDC dcSrc,//source bitmap
int &SrcWidth,
//[in]width of source bitmap
//[out]width of the rotated bitmap
int &SrcHeight,
//[in]height of source bitmap
//[out]height of the rotated bitmap
CPoint &cpCenter,
//[in]the rotated bitmap 's center wanted be shown
//[out]the rotated bitmap 's left top corner
double dAngle//angle of rotation and y axis
)
{//return value:rotated bitmap is temporarily stored here
double x1,x2,x3,y1,y2,y3;
double maxWidth,maxHeight,minWidth,minHeight;
double srcX,srcY;
double sinA,cosA;
double DstWidth,DstHeight;
HDC TmpDcDst;//temp dc for rotate
HBITMAP newBitmap;
sinA = sin(dAngle);
cosA = cos(dAngle);
x1 = -SrcHeight * sinA;
y1 = SrcHeight * cosA;
x2 = SrcWidth * cosA - SrcHeight * sinA;
y2 = SrcHeight * cosA + SrcWidth * sinA;
x3 = SrcWidth * cosA;
y3 = SrcWidth * sinA;
minWidth = x3> (x1> x2?x2:x1)?(x1> x2?x2:x1):x3;
minWidth = minWidth> 0?0:minWidth;
minHeight = y3> (y1> y2?y2:y1)?(y1> y2?y2:y1):y3;
minHeight = minHeight> 0?0:minHeight;
maxWidth = x3> (x1> x2?x1:x2)?x3:(x1> x2?x1:x2);
maxWidth = maxWidth> 0?maxWidth:0;
maxHeight = y3> (y1> y2?y1:y2)?y3:(y1> y2?y1:y2);
maxHeight = maxHeight> 0?maxHeight:0;
DstWidth = maxWidth - minWidth;
DstHeight = maxHeight - minHeight;
//prepare a temp empty bitmap for drawing
TmpDcDst = CreateCompatibleDC(dcSrc);
newBitmap = CreateCompatibleBitmap(dcSrc,(int)DstWidth,(int)DstHeight);
SelectObject(TmpDcDst,newBitmap);
//copy to the temp bitmap from source bitmap
for( int I = 0 ;I <DstHeight;I++){
for(int J = 0 ;J <DstWidth;J++){
srcX = (J + minWidth) * cosA + (I + minHeight) * sinA;
srcY = (I + minHeight) * cosA - (J + minWidth) * sinA;
if( (srcX > = 0) && (srcX <= SrcWidth) &&(srcY > = 0) && (srcY <= SrcHeight))
{
BitBlt(TmpDcDst, J, I, 1, 1, dcSrc,(int)srcX, (int)srcY, SRCINVERT);
}
}
}
DeleteObject(newBitmap);
//return values
SrcWidth=DstWidth;
SrcHeight=DstHeight;
cpCenter.x=cpCenter.x-DstWidth/2;
cpCenter.y=cpCenter.y-DstHeight/2;
return TmpDcDst;
}
[解决办法]
而且你的程序中到处都有 GetDC()-> XXX 这种语句，也很容易导致泄漏。
我没记错的话，GetDC()之后都是要ReleaseDC()的。
