Thread: Windows CE & Bitmap & ( DCscroll or scrollWindow ? )

Hello,

In my Research project, i'm trying to draw a bitmap and scrolling it with the mouse.

I don't have problem to print a bitmap on a screen.

But my problem is to scroll it, I tried the ScrollDC function and ScrollWindow, but nothing happen !


I would like to know how to scroll a bitmap that are printed on the screen ? ( I'm trying to avoid the function "BitBlt" because I can see the refresh )


My first test was :

detecting the new position of the mouse with "onMouseMove" and calling invalidate function.

And in the function OnPaint() I added the scrollDC function, but I found that the screen is erased by calling the function invalidate. So my first test failed.


My second test was :
on the function "onMouseMove", I called the function ScrollWindow(2,2,NULL,NULL);

but nothing happen


My third test was :
on the function "onMouseMove", I called the function :
dc.ScrollDC(5,5,clientRectScroll,clientRectclip,NU LL,NULL);

( clientrectscroll and clientrectclip are at the screen size )


but nothing happen!

I really don't understand why!


Last informations : I'm printing the bitmap in the derived class of CWnd.


I don't know if someone can help me, but i'm lost :'(

hello thx for the help!

Finally I chosse to use a buffer as you said.

But now I got sometime this exception :

Unhandled exception at 0x0004bf14 in BITMAPLOADER.exe: 0xC0000005: Violation d'accès lors de la lecture de l'emplacement 0x00000004 :

Code:

 
BOOL CGdiObject::DeleteObject()
{
	if (m_hObject == NULL)             <========= HERE
		return FALSE;
	return ::DeleteObject(Detach());
}

Do you know where does it come from ?


My blitter function :

Code:

 
void Blitter::BlitTo (CDC& pDC){
	//
	CDC dcMemory;
	//
	CBitmap   *spBitMap= CBitmap::FromHandle(_bmp->_hBitmap);

	// create a new dc :
	dcMemory.CreateCompatibleDC(&pDC);
	// add the bitmap :
	dcMemory.SelectObject(spBitMap);
	//
	// update the screen with this :
	pDC.BitBlt(_xDst, _yDst, _width-_xSrc, _height-_ySrc,&dcMemory,_xSrc, _ySrc, _mode);

	spBitMap->DeleteObject();
	dcMemory.DeleteDC();


	//delete spBitMap;



}

The creation of my buffer :

Code:

 
int CChildView::OnCreate(LPCREATESTRUCT lpCreateStruct) {
	CDC *dc = GetDC();   // this is the screen DC
	m_MemDC.CreateCompatibleDC(dc);
	m_Bitmap.CreateCompatibleBitmap(dc,WINDOW_W,WINDOW_H);
	m_MemDC.SelectObject(m_Bitmap);
	ReleaseDC(dc);

	return 0;
}

my paint function called with RedrawWindow() :

Code:

 
void CChildView::OnPaint() {
	CPaintDC dc(this); 
	dc.BitBlt(0,0,WINDOW_W,WINDOW_H,&m_MemDC,0,0,SRCCOPY);
	DeleteDC(dc);

}