how to avoid window swing when it zoom out from center point

[onlywjh]

hi everyone. i want to create a window which can zoom out from the center,but the window swung when i use MoveWindow/SetWindowPos to reposition and resize the window. it was just like the situation below. 1:____[--]____ (original place) 2:___[--]_____ (rePosition) the right side of the window has gone astern 3:___[----]___ (reSize) 4:__[----]____ (rePosition) 5:__[------]__ (reSize) 6:_[------]___ (rePosition) 7:_[--------]_ (final place) does anyone has the solution about that? code as below.

//draw window background with gdi+ and UpdateLayerdWindow
void CWindowAnimateDlg::DrawBackground()
{
CDC* dc=this->GetWindowDC();
HDC hdcMemory=CreateCompatibleDC(dc->GetSafeHdc());

CRect rct;
GetWindowRect(&rct);
//{
	BITMAPINFO bmih;
	ZeroMemory( &bmih, sizeof( BITMAPINFO ) );
	bmih.bmiHeader.biSize                  = sizeof (BITMAPINFOHEADER) ;
	bmih.bmiHeader.biWidth                = rct.Width() ;
	bmih.bmiHeader.biHeight                = rct.Height() ;
	bmih.bmiHeader.biPlanes                = 1 ;
	bmih.bmiHeader.biBitCount              = 32;        
	bmih.bmiHeader.biCompression          = BI\_RGB ;
	bmih.bmiHeader.biSizeImage            = 0 ;
	bmih.bmiHeader.biXPelsPerMeter        = 0 ;
	bmih.bmiHeader.biYPelsPerMeter        = 0 ;
	bmih.bmiHeader.biClrUsed              = 0 ;
	bmih.bmiHeader.biClrImportant          = 0 ;

//}

HBITMAP hBitMap;
hBitMap = CreateDIBSection (NULL,   &bmih, 0, NULL, NULL, 0) ;

HBITMAP oldBitmap=(HBITMAP)SelectObject(hdcMemory,hBitMap);

//GDI+
Graphics gpc(hdcMemory);
gpc.SetCompositingMode(CompositingModeSourceCopy);

DWORD dwExStyle=GetWindowLong(m\_hWnd,GWL\_EXSTYLE);
SetWindowLongA(m\_hWnd,GWL\_EXSTYLE,dwExStyle|WS\_EX\_LAYERED);

HDC hdcScreen=::GetDC(m\_hWnd);
CDC cdc;
cdc.Attach(hdcScreen);
CDC cdc2;
cdc2.Attach(hdcMemory);

if(m\_bkImage)
{
	gpc.DrawImage(
		m\_bkImage,
		Rect(0,0,rct.Width(),rct.Height()),
		0,0,m\_bkImage->GetWidth(),m\_bkImage->GetHeight(),
		UnitPixel
		);
}

POINT ptWinPos={rct.left,rct.top};
POINT ptSrc={0,0};
SIZE sizeWindow={rct.Width(),rct.Height()};
BLENDFUNCTION blend;
blend.BlendOp=0; 
blend.BlendFlags=0; 
blend.AlphaFormat=AC\_SRC\_ALPHA; 
blend.SourceConstantAlpha=255;

UpdateLayeredWindow( &cdc,&ptWinPos,
                    &sizeWindow,&cdc2,&ptSrc,0,&blend,ULW\_ALPHA);

::SelectObject(hdcMemory,oldBitmap);
ReleaseDC(dc);
gpc.ReleaseHDC(hdcMemory)

[_Superman_]

AnimateWindow[^]

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Polymorphism in C

[onlywjh]

thanks for your reply. but, AnimateWindow does not help i think. i want to move the window from one Rect to another Rect smoothly.

[onlywjh]

and, why SetWindowPos make the window 'resize' and 'reposition' seperetely? does anybody know? thank you.

[Rozis]

I guess it is because reposition and size lead both to a repaint of the window. You could use validaterect() or validatewindowrgn() (these are GDI-functions, look for GDI+ equivalents) after reposition so windows believes there's no need to repaint. Then repainting only occurs after size showing the reposition also. Hope this will work...

[onlywjh]

anyone has other ideas?

[onlywjh]

it seems did not work with the solution below .