C / C++ / MFC

Runish Kumar wrote:

I have a problem for you

• Read Len from whatever you're reading from
• Allocate a buffer of size Len + sizeof Len bytes.
• Copy Len into the first sizeof Len bytes of the buffer
• Read Len bytes into the buffer after the copied value of Len
• Cast the buffer pointer to FRAME* and return it

FRAME* ReadFRAME(FILE* file)
{
   int Len;
   fread((void*)&Len, sizeof(Len), 1, file);
   char* space = (char*)malloc(Len + sizeof(Len));
   FRAME* gotFrame = (FRAME*)space;
   gotFrame->Len = Len;
   fread((void*)gotFrame->Text, 1, Len, file);
   return gotFrame;
}

Redeye92 wrote:

I've tried doing a GDI BitBlt() instead but while that function is fast, the creation of the HDC and HBITMAP and everything else needed isn't, and there's no speed advantage.

m_pbmpMemory->GetHBITMAP(Color::White, &m_hMemBitmap);
m_hMemHDC = m_gr->GetHDC();
SelectObject(m_hMemHDC, m_hMemBitmap);
BitBlt(pDC->m_hDC, rcPaint.left, rcPaint.top, rcPaint.Width(), rcPaint.Height(),
    m_hMemHDC, rcPaint.left, rcPaint.top, SRCCOPY);
m_gr->ReleaseHDC(m_hMemHDC);

Redeye92 wrote:

I just can't see how to keep a hold of the HDC and HBITMAP between calls to OnPaint(),

void MyDlg::CreateMemDC( CDC* pRefDC, int nWidth, int nHeight )
{
  m_dcMem.CreateCompatibleDC( pRefDC );
  m_bitmapMem.CreateCompatibleBitmap( pRefDC, nWidth, nHeight );
  m_dcMem.SelectObject( &m_bitmapMem );
}

void MyDlg::OnInitDlg()
{
  // some code
  CClientDC dc( this );
  CreateMemDC( &dc, 300, 200 ); // or what ever size you needed
  // draw the image to this m_dcMem
}

void MyDlg::OnPaint()
{
  BitBlt( pDC->m_hDC, .... .... ... , m_dcMem.m_hDC, ...... );
}

<br />
        // Get a device context for painting<br />
	CPaintDC dc(this);<br />
	if(!m_pMemDC)<br />
	{<br />
		vUpdateBitmap(&dc);<br />
	}<br />
	// Get the client rect<br />
	CRect rcClientRect;<br />
	GetClientRect(&rcClientRect);<br />
        // Get the actual width of the view we want to draw<br />
	ULONG32 ulViewWidth = ulGetViewWidth();<br />
	// If the window size has changed for any reason, we need to redraw the bitmap<br />
        // Put your if statement here.<br />
	{<br />
		vUpdateBitmap(&dc);<br />
	}<br />
	// Get the invalid rectangle<br />
	CRect rcPaint;<br />
	dc.GetClipBox(rcPaint);<br />
	// Then just copy the bit of the memory bitmap that we need<br />
	dc.BitBlt(rcPaint.left, rcPaint.top, rcPaint.Width(), rcPaint.Height(),<br />
		m_pMemDC, rcPaint.left, rcPaint.top, SRCCOPY);<br />

<br />
<br />
		// Recreate the memory bitmap and graphics objects<br />
		if(pDC)<br />
		{<br />
			if(m_pMemDC)<br />
			{<br />
				delete m_pMemDC;<br />
			}<br />
			m_pMemDC = new CDC;<br />
			// Make a compatible DC<br />
			m_pMemDC->CreateCompatibleDC(pDC);;<br />
			<br />
			// Create a new bitmap<br />
			CBitmap *m_pNewBitmap;<br />
			m_pNewBitmap = new CBitmap;<br />
			// Create the new bitmap<br />
			m_pNewBitmap->CreateCompatibleBitmap(pDC, rcClient.Width(), rcClient.Height());<br />
			m_pNewBitmap->SetBitmapDimension(rcClient.Width(), rcClient.Height());<br />
			// Select the new bitmap into the memory DC<br />
			m_pMemDC->SelectObject(m_pNewBitmap);<br />
			// Delete the old one<br />
			delete m_pbmpMemBitmap;<br />
			// Reset the view pointer<br />
			m_pbmpMemBitmap = m_pNewBitmap;<br />
			if(m_gr)<br />
			{ delete m_gr; }<br />
			m_gr = Graphics::FromHDC(m_pMemDC->m_hDC);<br />
		}<br />