with only a little modification could be generic

[wxWidgets.git] / src / msw / dcmemory.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:        dcmemory.cpp
// Purpose:     wxMemoryDC class
// Author:      Julian Smart
// Modified by:
// Created:     01/02/97
// RCS-ID:      $Id$
// Copyright:   (c) Julian Smart and Markus Holzem
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ============================================================================
// declarations
// ============================================================================

// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------

#ifdef __GNUG__
    #pragma implementation "dcmemory.h"
#endif

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"

#ifdef __BORLANDC__
    #pragma hdrstop
#endif

#ifndef WX_PRECOMP
    #include "wx/utils.h"
    #include "wx/log.h"
#endif

#include "wx/msw/private.h"

#include "wx/dcmemory.h"

// ----------------------------------------------------------------------------
// wxWin macros
// ----------------------------------------------------------------------------

#if !USE_SHARED_LIBRARY
    IMPLEMENT_DYNAMIC_CLASS(wxMemoryDC, wxDC)
#endif

// ============================================================================
// implementation
// ============================================================================

// ----------------------------------------------------------------------------
// wxMemoryDC
// ----------------------------------------------------------------------------

wxMemoryDC::wxMemoryDC()
{
    m_hDC = (WXHDC) ::CreateCompatibleDC((HDC) NULL);
    m_ok = (m_hDC != 0);
    m_bOwnsDC = TRUE;

    SetBrush(*wxWHITE_BRUSH);
    SetPen(*wxBLACK_PEN);

    // the background mode is only used for text background and is set in
    // DrawText() to OPAQUE as required, otherwise always TRANSPARENT
    ::SetBkMode( GetHdc(), TRANSPARENT );
}

wxMemoryDC::wxMemoryDC(wxDC *old_dc)
{
    old_dc->BeginDrawing();

    m_hDC = (WXHDC) ::CreateCompatibleDC(GetHdcOf(*old_dc));
    m_ok = (m_hDC != 0);

    old_dc->EndDrawing();

    SetBrush(*wxWHITE_BRUSH);
    SetPen(*wxBLACK_PEN);

    // the background mode is only used for text background and is set in
    // DrawText() to OPAQUE as required, otherwise always TRANSPARENT
    ::SetBkMode( GetHdc(), TRANSPARENT );
}

wxMemoryDC::~wxMemoryDC()
{
}

void wxMemoryDC::SelectObject(const wxBitmap& bitmap)
{
    // select old bitmap out of the device context
    if ( m_oldBitmap )
    {
        ::SelectObject(GetHdc(), (HBITMAP) m_oldBitmap);
        if ( m_selectedBitmap.Ok() )
        {
            m_selectedBitmap.SetSelectedInto(NULL);
            m_selectedBitmap = wxNullBitmap;
        }
    }

    // check for whether the bitmap is already selected into a device context
    wxCHECK_RET( !bitmap.GetSelectedInto() ||
                 (bitmap.GetSelectedInto() == this),
                 wxT("Bitmap is selected in another wxMemoryDC, delete the "
                     "first wxMemoryDC or use SelectObject(NULL)") );

    m_selectedBitmap = bitmap;
    WXHBITMAP hBmp = m_selectedBitmap.GetHBITMAP();
    if ( !hBmp )
        return;

    m_selectedBitmap.SetSelectedInto(this);
    hBmp = (WXHBITMAP)::SelectObject(GetHdc(), (HBITMAP)hBmp);

    if ( !hBmp )
    {
        wxLogLastError("SelectObject(memDC, bitmap)");

        wxFAIL_MSG(wxT("Couldn't select a bitmap into wxMemoryDC"));
    }
    else if ( !m_oldBitmap )
    {
        m_oldBitmap = hBmp;
    }
}

void wxMemoryDC::DoGetSize(int *width, int *height) const
{
    if ( m_selectedBitmap.Ok() )
    {
        *width = m_selectedBitmap.GetWidth();
        *height = m_selectedBitmap.GetHeight();
    }
    else
    {
        *width = 0;
        *height = 0;
    }
}