bitmapviewer.cpp

从CWnd派生自定义类 CustomControl

// BitmapViewer.cpp : implementation file
//

#include "stdafx.h"
#include "CustomControlDemo.h"
#include "BitmapViewer.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CBitmapViewer

CBitmapViewer::CBitmapViewer()
{
    RegisterWindowClass();
}

CBitmapViewer::~CBitmapViewer()
{
}

// Register the window class if it has not already been registered.
BOOL CBitmapViewer::RegisterWindowClass()
{
    WNDCLASS wndcls;
    HINSTANCE hInst = AfxGetInstanceHandle();

    if (!(::GetClassInfo(hInst, BITMAPVIEWER_CLASSNAME, &wndcls)))
    {
        // otherwise we need to register a new class
        wndcls.style            = CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
        wndcls.lpfnWndProc      = ::DefWindowProc;
        wndcls.cbClsExtra       = wndcls.cbWndExtra = 0;
        wndcls.hInstance        = hInst;
        wndcls.hIcon            = NULL;
        wndcls.hCursor          = AfxGetApp()->LoadStandardCursor(IDC_ARROW);
        wndcls.hbrBackground    = (HBRUSH) (COLOR_3DFACE + 1);
        wndcls.lpszMenuName     = NULL;
        wndcls.lpszClassName    = BITMAPVIEWER_CLASSNAME;

        if (!AfxRegisterClass(&wndcls))
        {
            AfxThrowResourceException();
            return FALSE;
        }
    }

    return TRUE;
}


BEGIN_MESSAGE_MAP(CBitmapViewer, CWnd)
	//{{AFX_MSG_MAP(CBitmapViewer)
	ON_WM_PAINT()
	ON_WM_ERASEBKGND()
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()


/////////////////////////////////////////////////////////////////////////////
// CBitmapViewer message handlers

void CBitmapViewer::OnPaint() 
{
    // Draw the bitmap - if we have one.
    if (m_Bitmap.GetSafeHandle() != NULL)
    {
	    CPaintDC dc(this); // device context for painting

        // Create memory DC
        CDC MemDC;
        if (!MemDC.CreateCompatibleDC(&dc))
            return;

        // Get Size of Display area
        CRect rect;
        GetClientRect(rect);

        // Get size of bitmap
        BITMAP bm;
        m_Bitmap.GetBitmap(&bm);
        
        // Draw the bitmap
        CBitmap* pOldBitmap = (CBitmap*) MemDC.SelectObject(&m_Bitmap);
        dc.StretchBlt(0, 0, rect.Width(), rect.Height(), 
                      &MemDC, 
                      0, 0, bm.bmWidth, bm.bmHeight, 
                      SRCCOPY);
        MemDC.SelectObject(pOldBitmap);      
    }
	
	// Do not call CWnd::OnPaint() for painting messages
}

BOOL CBitmapViewer::OnEraseBkgnd(CDC* pDC) 
{
    // If we have an image then don't perform any erasing, since the OnPaint
    // function will simply draw over the background
    if (m_Bitmap.GetSafeHandle() != NULL)
        return TRUE;
	
    // Obviously we don't have a bitmap - let the base class deal with it.
	return CWnd::OnEraseBkgnd(pDC);
}

void CBitmapViewer::PreSubclassWindow() 
{
	// TODO: Add your specialized code here and/or call the base class
	// In our case this is not needed - yet - so just drop through to
    // the base class
	CWnd::PreSubclassWindow();
}

/////////////////////////////////////////////////////////////////////////////
// CBitmapViewer methods

BOOL CBitmapViewer::Create(CWnd* pParentWnd, const RECT& rect, UINT nID, DWORD dwStyle /*=WS_VISIBLE*/)
{
	return CWnd::Create(BITMAPVIEWER_CLASSNAME, _T(""), dwStyle, rect, pParentWnd, nID);
}

BOOL CBitmapViewer::SetBitmap(UINT nIDResource)
{
    return m_Bitmap.LoadBitmap(nIDResource);
}