fixing overrelease and out-of-bounds write, fixes #13725

[wxWidgets.git] / src / common / dcgraph.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:        src/common/dcgraph.cpp
// Purpose:     graphics context methods common to all platforms
// Author:      Stefan Csomor
// Modified by:
// Created:
// RCS-ID:      $Id$
// Copyright:   (c) Stefan Csomor
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

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

#if defined(__BORLANDC__)
    #pragma hdrstop
#endif

#if wxUSE_GRAPHICS_CONTEXT

#include "wx/dcgraph.h"

#ifndef WX_PRECOMP
    #include "wx/icon.h"
    #include "wx/dcclient.h"
    #include "wx/dcmemory.h"
#endif

//-----------------------------------------------------------------------------
// constants
//-----------------------------------------------------------------------------

static const double RAD2DEG = 180.0 / M_PI;

//-----------------------------------------------------------------------------
// Local functions
//-----------------------------------------------------------------------------

static inline double DegToRad(double deg)
{
    return (deg * M_PI) / 180.0;
}

static wxCompositionMode TranslateRasterOp(wxRasterOperationMode function)
{
    switch ( function )
    {
        case wxCOPY: // src
            // since we are supporting alpha, _OVER is closer to the intention than _SOURCE
            // since the latter would overwrite even when alpha is not set to opaque
            return wxCOMPOSITION_OVER;

        case wxOR:         // src OR dst
            return wxCOMPOSITION_ADD;

        case wxNO_OP:      // dst
            return wxCOMPOSITION_DEST; // ignore the source

        case wxCLEAR:      // 0
            return wxCOMPOSITION_CLEAR;// clear dst

        case wxXOR:        // src XOR dst
            return wxCOMPOSITION_XOR;

        case wxAND:        // src AND dst
        case wxAND_INVERT: // (NOT src) AND dst
        case wxAND_REVERSE:// src AND (NOT dst)
        case wxEQUIV:      // (NOT src) XOR dst
        case wxINVERT:     // NOT dst
        case wxNAND:       // (NOT src) OR (NOT dst)
        case wxNOR:        // (NOT src) AND (NOT dst)
        case wxOR_INVERT:  // (NOT src) OR dst
        case wxOR_REVERSE: // src OR (NOT dst)
        case wxSET:        // 1
        case wxSRC_INVERT: // NOT src
            break;
    }

    return wxCOMPOSITION_INVALID;
}

//-----------------------------------------------------------------------------
// wxDC bridge class
//-----------------------------------------------------------------------------

IMPLEMENT_DYNAMIC_CLASS(wxGCDC, wxDC)

wxGCDC::wxGCDC(const wxWindowDC& dc) :
  wxDC( new wxGCDCImpl( this, dc ) )
{
}

wxGCDC::wxGCDC( const wxMemoryDC& dc) :
  wxDC( new wxGCDCImpl( this, dc ) )
{
}

#if wxUSE_PRINTING_ARCHITECTURE
wxGCDC::wxGCDC( const wxPrinterDC& dc) :
  wxDC( new wxGCDCImpl( this, dc ) )
{
}
#endif

#if defined(__WXMSW__) && wxUSE_ENH_METAFILE
wxGCDC::wxGCDC(const wxEnhMetaFileDC& dc)
   : wxDC(new wxGCDCImpl(this, dc))
{
}
#endif

wxGCDC::wxGCDC(wxGraphicsContext* context) :
    wxDC( new wxGCDCImpl( this ) )
{
    SetGraphicsContext(context);
}

wxGCDC::wxGCDC() :
  wxDC( new wxGCDCImpl( this ) )
{
}

wxGCDC::~wxGCDC()
{
}

wxGraphicsContext* wxGCDC::GetGraphicsContext() const
{
    if (!m_pimpl) return NULL;
    wxGCDCImpl *gc_impl = (wxGCDCImpl*) m_pimpl;
    return gc_impl->GetGraphicsContext();
}

void wxGCDC::SetGraphicsContext( wxGraphicsContext* ctx )
{
    if (!m_pimpl) return;
    wxGCDCImpl *gc_impl = (wxGCDCImpl*) m_pimpl;
    gc_impl->SetGraphicsContext( ctx );
}

IMPLEMENT_ABSTRACT_CLASS(wxGCDCImpl, wxDCImpl)

wxGCDCImpl::wxGCDCImpl( wxDC *owner ) :
   wxDCImpl( owner )
{
    Init(wxGraphicsContext::Create());
}

void wxGCDCImpl::SetGraphicsContext( wxGraphicsContext* ctx )
{
    delete m_graphicContext;
    m_graphicContext = ctx;
    if ( m_graphicContext )
    {
        m_matrixOriginal = m_graphicContext->GetTransform();
        m_ok = true;
        // apply the stored transformations to the passed in context
        ComputeScaleAndOrigin();
        m_graphicContext->SetFont( m_font , m_textForegroundColour );
        m_graphicContext->SetPen( m_pen );
        m_graphicContext->SetBrush( m_brush);
    }
}

wxGCDCImpl::wxGCDCImpl( wxDC *owner, const wxWindowDC& dc ) :
   wxDCImpl( owner )
{
    Init(wxGraphicsContext::Create(dc));
    m_window = dc.GetWindow();
}

wxGCDCImpl::wxGCDCImpl( wxDC *owner, const wxMemoryDC& dc ) :
   wxDCImpl( owner )
{
    Init(wxGraphicsContext::Create(dc));
}

#if wxUSE_PRINTING_ARCHITECTURE
wxGCDCImpl::wxGCDCImpl( wxDC *owner, const wxPrinterDC& dc ) :
   wxDCImpl( owner )
{
    Init(wxGraphicsContext::Create(dc));
}
#endif

#if defined(__WXMSW__) && wxUSE_ENH_METAFILE
wxGCDCImpl::wxGCDCImpl(wxDC *owner, const wxEnhMetaFileDC& dc)
   : wxDCImpl(owner)
{
    Init(wxGraphicsContext::Create(dc));
}
#endif

wxGCDCImpl::wxGCDCImpl(wxDC* owner, int)
   : wxDCImpl(owner)
{
    // derived class will set a context
    Init(NULL);
}

void wxGCDCImpl::Init(wxGraphicsContext* ctx)
{
    m_ok = false;
    m_colour = true;
    m_mm_to_pix_x = mm2pt;
    m_mm_to_pix_y = mm2pt;

    m_pen = *wxBLACK_PEN;
    m_font = *wxNORMAL_FONT;
    m_brush = *wxWHITE_BRUSH;

    m_graphicContext = NULL;
    if (ctx)
        SetGraphicsContext(ctx);

    m_logicalFunctionSupported = true;
}

wxGCDCImpl::~wxGCDCImpl()
{
    delete m_graphicContext;
}

void wxGCDCImpl::DoDrawBitmap( const wxBitmap &bmp, wxCoord x, wxCoord y,
                               bool useMask )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawBitmap - invalid DC") );
    wxCHECK_RET( bmp.IsOk(), wxT("wxGCDC(cg)::DoDrawBitmap - invalid bitmap") );

    int w = bmp.GetWidth();
    int h = bmp.GetHeight();
    if ( bmp.GetDepth() == 1 )
    {
        m_graphicContext->SetPen(*wxTRANSPARENT_PEN);
        m_graphicContext->SetBrush( wxBrush( m_textBackgroundColour , wxSOLID ) );
        m_graphicContext->DrawRectangle( x, y, w, h );
        m_graphicContext->SetBrush( wxBrush( m_textForegroundColour , wxSOLID ) );
        m_graphicContext->DrawBitmap( bmp, x, y, w, h );
        m_graphicContext->SetBrush( m_graphicContext->CreateBrush(m_brush));
        m_graphicContext->SetPen( m_graphicContext->CreatePen(m_pen));
    }
    else // not a monochrome bitmap, handle it normally
    {
        // make a copy in case we need to remove its mask, if we don't modify
        // it the copy is cheap as bitmaps are reference-counted
        wxBitmap bmpCopy(bmp);
        if ( !useMask && bmp.GetMask() )
            bmpCopy.SetMask(NULL);

        m_graphicContext->DrawBitmap( bmpCopy, x, y, w, h );
    }
}

void wxGCDCImpl::DoDrawIcon( const wxIcon &icon, wxCoord x, wxCoord y )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawIcon - invalid DC") );
    wxCHECK_RET( icon.IsOk(), wxT("wxGCDC(cg)::DoDrawIcon - invalid icon") );

    wxCoord w = icon.GetWidth();
    wxCoord h = icon.GetHeight();

    m_graphicContext->DrawIcon( icon , x, y, w, h );
}

bool wxGCDCImpl::StartDoc( const wxString& WXUNUSED(message) )
{
    return true;
}

void wxGCDCImpl::EndDoc()
{
}

void wxGCDCImpl::StartPage()
{
}

void wxGCDCImpl::EndPage()
{
}

void wxGCDCImpl::Flush()
{
    m_graphicContext->Flush();
}

void wxGCDCImpl::DoSetClippingRegion( wxCoord x, wxCoord y, wxCoord w, wxCoord h )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoSetClippingRegion - invalid DC") );

    m_graphicContext->Clip( x, y, w, h );

    wxDCImpl::DoSetClippingRegion(x, y, w, h);
}

void wxGCDCImpl::DoSetDeviceClippingRegion( const wxRegion &region )
{
    // region is in device coordinates
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoSetDeviceClippingRegion - invalid DC") );

    if (region.Empty())
    {
        //DestroyClippingRegion();
        return;
    }

    wxRegion logRegion( region );
    wxCoord x, y, w, h;

    logRegion.Offset( DeviceToLogicalX(0), DeviceToLogicalY(0) );
    logRegion.GetBox( x, y, w, h );

    m_graphicContext->Clip( logRegion );
    if ( m_clipping )
    {
        m_clipX1 = wxMax( m_clipX1, x );
        m_clipY1 = wxMax( m_clipY1, y );
        m_clipX2 = wxMin( m_clipX2, (x + w) );
        m_clipY2 = wxMin( m_clipY2, (y + h) );
    }
    else
    {
        m_clipping = true;

        m_clipX1 = x;
        m_clipY1 = y;
        m_clipX2 = x + w;
        m_clipY2 = y + h;
    }
}

void wxGCDCImpl::DestroyClippingRegion()
{
    m_graphicContext->ResetClip();
    // currently the clip eg of a window extends to the area between the scrollbars
    // so we must explicitly make sure it only covers the area we want it to draw
    int width, height ;
    GetOwner()->GetSize( &width , &height ) ;
    m_graphicContext->Clip( DeviceToLogicalX(0) , DeviceToLogicalY(0) , DeviceToLogicalXRel(width), DeviceToLogicalYRel(height) );

    m_graphicContext->SetPen( m_pen );
    m_graphicContext->SetBrush( m_brush );

    m_clipping = false;
}

void wxGCDCImpl::DoGetSizeMM( int* width, int* height ) const
{
    int w = 0, h = 0;

    GetOwner()->GetSize( &w, &h );
    if (width)
        *width = long( double(w) / (m_scaleX * m_mm_to_pix_x) );
    if (height)
        *height = long( double(h) / (m_scaleY * m_mm_to_pix_y) );
}

void wxGCDCImpl::SetTextForeground( const wxColour &col )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::SetTextForeground - invalid DC") );

    // don't set m_textForegroundColour to an invalid colour as we'd crash
    // later then (we use m_textForegroundColour.GetColor() without checking
    // in a few places)
    if ( col.IsOk() )
    {
        m_textForegroundColour = col;
        m_graphicContext->SetFont( m_font, m_textForegroundColour );
    }
}

void wxGCDCImpl::SetTextBackground( const wxColour &col )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::SetTextBackground - invalid DC") );

    m_textBackgroundColour = col;
}

wxSize wxGCDCImpl::GetPPI() const
{
    return wxSize(72, 72);
}

int wxGCDCImpl::GetDepth() const
{
    return 32;
}

void wxGCDCImpl::ComputeScaleAndOrigin()
{
    wxDCImpl::ComputeScaleAndOrigin();

    if ( m_graphicContext )
    {
        m_matrixCurrent = m_graphicContext->CreateMatrix();

        // the logical origin sets the origin to have new coordinates
        m_matrixCurrent.Translate( m_deviceOriginX - m_logicalOriginX * m_signX * m_scaleX,
                                   m_deviceOriginY-m_logicalOriginY * m_signY * m_scaleY);

        m_matrixCurrent.Scale( m_scaleX * m_signX, m_scaleY * m_signY );

        m_graphicContext->SetTransform( m_matrixOriginal );
        m_graphicContext->ConcatTransform( m_matrixCurrent );
    }
}

void* wxGCDCImpl::GetHandle() const
{
    void* cgctx = NULL;
    wxGraphicsContext* gc = GetGraphicsContext();
    if (gc) {
        cgctx = gc->GetNativeContext();
    }
    return cgctx;
}

void wxGCDCImpl::SetPalette( const wxPalette& WXUNUSED(palette) )
{

}

void wxGCDCImpl::SetBackgroundMode( int mode )
{
    m_backgroundMode = mode;
}

void wxGCDCImpl::SetFont( const wxFont &font )
{
    m_font = font;
    if ( m_graphicContext )
    {
        m_graphicContext->SetFont(font, m_textForegroundColour);
    }
}

void wxGCDCImpl::SetPen( const wxPen &pen )
{
    m_pen = pen;
    if ( m_graphicContext )
    {
        m_graphicContext->SetPen( m_pen );
    }
}

void wxGCDCImpl::SetBrush( const wxBrush &brush )
{
    m_brush = brush;
    if ( m_graphicContext )
    {
        m_graphicContext->SetBrush( m_brush );
    }
}

void wxGCDCImpl::SetBackground( const wxBrush &brush )
{
    m_backgroundBrush = brush;
    if (!m_backgroundBrush.IsOk())
        return;
}

void wxGCDCImpl::SetLogicalFunction( wxRasterOperationMode function )
{
    m_logicalFunction = function;

    wxCompositionMode mode = TranslateRasterOp( function );
    m_logicalFunctionSupported = mode != wxCOMPOSITION_INVALID;
    if (m_logicalFunctionSupported)
        m_logicalFunctionSupported = m_graphicContext->SetCompositionMode(mode);

    if ( function == wxXOR )
        m_graphicContext->SetAntialiasMode(wxANTIALIAS_NONE);
    else
        m_graphicContext->SetAntialiasMode(wxANTIALIAS_DEFAULT);
}

bool wxGCDCImpl::DoFloodFill(wxCoord WXUNUSED(x), wxCoord WXUNUSED(y),
                             const wxColour& WXUNUSED(col),
                             wxFloodFillStyle WXUNUSED(style))
{
    return false;
}

bool wxGCDCImpl::DoGetPixel( wxCoord WXUNUSED(x), wxCoord WXUNUSED(y), wxColour *WXUNUSED(col) ) const
{
    //  wxCHECK_MSG( 0 , false, wxT("wxGCDC(cg)::DoGetPixel - not implemented") );
    return false;
}

void wxGCDCImpl::DoDrawLine( wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2 )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawLine - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    m_graphicContext->StrokeLine(x1,y1,x2,y2);

    CalcBoundingBox(x1, y1);
    CalcBoundingBox(x2, y2);
}

void wxGCDCImpl::DoCrossHair( wxCoord x, wxCoord y )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoCrossHair - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    int w = 0, h = 0;

    GetOwner()->GetSize( &w, &h );

    m_graphicContext->StrokeLine(0,y,w,y);
    m_graphicContext->StrokeLine(x,0,x,h);

    CalcBoundingBox(0, 0);
    CalcBoundingBox(0+w, 0+h);
}

void wxGCDCImpl::DoDrawArc( wxCoord x1, wxCoord y1,
                        wxCoord x2, wxCoord y2,
                        wxCoord xc, wxCoord yc )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawArc - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    double dx = x1 - xc;
    double dy = y1 - yc;
    double radius = sqrt((double)(dx * dx + dy * dy));
    wxCoord rad = (wxCoord)radius;
    double sa, ea;
    if (x1 == x2 && y1 == y2)
    {
        sa = 0.0;
        ea = 360.0;
    }
    else if (radius == 0.0)
    {
        sa = ea = 0.0;
    }
    else
    {
        sa = (x1 - xc == 0) ?
     (y1 - yc < 0) ? 90.0 : -90.0 :
             -atan2(double(y1 - yc), double(x1 - xc)) * RAD2DEG;
        ea = (x2 - xc == 0) ?
     (y2 - yc < 0) ? 90.0 : -90.0 :
             -atan2(double(y2 - yc), double(x2 - xc)) * RAD2DEG;
    }

    bool fill = m_brush.GetStyle() != wxTRANSPARENT;

    wxGraphicsPath path = m_graphicContext->CreatePath();
    if ( fill && ((x1!=x2)||(y1!=y2)) )
        path.MoveToPoint( xc, yc );
    // since these angles (ea,sa) are measured counter-clockwise, we invert them to
    // get clockwise angles
    path.AddArc( xc, yc , rad , DegToRad(-sa) , DegToRad(-ea), false );
    if ( fill && ((x1!=x2)||(y1!=y2)) )
        path.AddLineToPoint( xc, yc );
    m_graphicContext->DrawPath(path);
}

void wxGCDCImpl::DoDrawEllipticArc( wxCoord x, wxCoord y, wxCoord w, wxCoord h,
                                double sa, double ea )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawEllipticArc - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    m_graphicContext->PushState();
    m_graphicContext->Translate(x+w/2.0,y+h/2.0);
    wxDouble factor = ((wxDouble) w) / h;
    m_graphicContext->Scale( factor , 1.0);

    // since these angles (ea,sa) are measured counter-clockwise, we invert them to
    // get clockwise angles
    if ( m_brush.GetStyle() != wxTRANSPARENT )
    {
        wxGraphicsPath path = m_graphicContext->CreatePath();
        path.MoveToPoint( 0, 0 );
        path.AddArc( 0, 0, h/2.0 , DegToRad(-sa) , DegToRad(-ea), sa > ea );
        path.AddLineToPoint( 0, 0 );
        m_graphicContext->FillPath( path );

        path = m_graphicContext->CreatePath();
        path.AddArc( 0, 0, h/2.0 , DegToRad(-sa) , DegToRad(-ea), sa > ea );
        m_graphicContext->StrokePath( path );
    }
    else
    {
        wxGraphicsPath path = m_graphicContext->CreatePath();
        path.AddArc( 0, 0, h/2.0 , DegToRad(-sa) , DegToRad(-ea), sa > ea );
        m_graphicContext->DrawPath( path );
    }

    m_graphicContext->PopState();
}

void wxGCDCImpl::DoDrawPoint( wxCoord x, wxCoord y )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawPoint - invalid DC") );

    DoDrawLine( x , y , x + 1 , y + 1 );
}

void wxGCDCImpl::DoDrawLines(int n, wxPoint points[],
                         wxCoord xoffset, wxCoord yoffset)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawLines - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    wxPoint2DDouble* pointsD = new wxPoint2DDouble[n];
    for( int i = 0; i < n; ++i)
    {
        pointsD[i].m_x = points[i].x + xoffset;
        pointsD[i].m_y = points[i].y + yoffset;
    }

    m_graphicContext->StrokeLines( n , pointsD);
    delete[] pointsD;
}

#if wxUSE_SPLINES
void wxGCDCImpl::DoDrawSpline(const wxPointList *points)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawSpline - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    wxGraphicsPath path = m_graphicContext->CreatePath();

    wxPointList::compatibility_iterator node = points->GetFirst();
    if ( !node )
        // empty list
        return;

    wxPoint *p = node->GetData();

    wxCoord x1 = p->x;
    wxCoord y1 = p->y;

    node = node->GetNext();
    p = node->GetData();

    wxCoord x2 = p->x;
    wxCoord y2 = p->y;
    wxCoord cx1 = ( x1 + x2 ) / 2;
    wxCoord cy1 = ( y1 + y2 ) / 2;

    path.MoveToPoint( x1 , y1 );
    path.AddLineToPoint( cx1 , cy1 );
#if !wxUSE_STD_CONTAINERS

    while ((node = node->GetNext()) != NULL)
#else

    while ((node = node->GetNext()))
#endif // !wxUSE_STD_CONTAINERS

    {
        p = node->GetData();
        x1 = x2;
        y1 = y2;
        x2 = p->x;
        y2 = p->y;
        wxCoord cx4 = (x1 + x2) / 2;
        wxCoord cy4 = (y1 + y2) / 2;

        path.AddQuadCurveToPoint(x1 , y1 ,cx4 , cy4 );

        cx1 = cx4;
        cy1 = cy4;
    }

    path.AddLineToPoint( x2 , y2 );

    m_graphicContext->StrokePath( path );
}
#endif // wxUSE_SPLINES

void wxGCDCImpl::DoDrawPolygon( int n, wxPoint points[],
                                wxCoord xoffset, wxCoord yoffset,
                                wxPolygonFillMode fillStyle )
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawPolygon - invalid DC") );

    if ( n <= 0 || (m_brush.GetStyle() == wxTRANSPARENT && m_pen.GetStyle() == wxTRANSPARENT ) )
        return;
    if ( !m_logicalFunctionSupported )
        return;

    bool closeIt = false;
    if (points[n-1] != points[0])
        closeIt = true;

    wxPoint2DDouble* pointsD = new wxPoint2DDouble[n+(closeIt?1:0)];
    for( int i = 0; i < n; ++i)
    {
        pointsD[i].m_x = points[i].x + xoffset;
        pointsD[i].m_y = points[i].y + yoffset;
    }
    if ( closeIt )
        pointsD[n] = pointsD[0];

    m_graphicContext->DrawLines( n+(closeIt?1:0) , pointsD, fillStyle);
    delete[] pointsD;
}

void wxGCDCImpl::DoDrawPolyPolygon(int n,
                               int count[],
                               wxPoint points[],
                               wxCoord xoffset,
                               wxCoord yoffset,
                               wxPolygonFillMode fillStyle)
{
    wxASSERT(n > 1);
    wxGraphicsPath path = m_graphicContext->CreatePath();

    int i = 0;
    for ( int j = 0; j < n; ++j)
    {
        wxPoint start = points[i];
        path.MoveToPoint( start.x+ xoffset, start.y+ yoffset);
        ++i;
        int l = count[j];
        for ( int k = 1; k < l; ++k)
        {
            path.AddLineToPoint( points[i].x+ xoffset, points[i].y+ yoffset);
            ++i;
        }
        // close the polygon
        if ( start != points[i-1])
            path.AddLineToPoint( start.x+ xoffset, start.y+ yoffset);
    }
    m_graphicContext->DrawPath( path , fillStyle);
}

void wxGCDCImpl::DoDrawRectangle(wxCoord x, wxCoord y, wxCoord w, wxCoord h)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawRectangle - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    // CMB: draw nothing if transformed w or h is 0
    if (w == 0 || h == 0)
        return;

    if ( m_graphicContext->ShouldOffset() )
    {
        // if we are offsetting the entire rectangle is moved 0.5, so the
        // border line gets off by 1
        w -= 1;
        h -= 1;
    }
    m_graphicContext->DrawRectangle(x,y,w,h);
}

void wxGCDCImpl::DoDrawRoundedRectangle(wxCoord x, wxCoord y,
                                    wxCoord w, wxCoord h,
                                    double radius)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawRoundedRectangle - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    if (radius < 0.0)
        radius = - radius * ((w < h) ? w : h);

    // CMB: draw nothing if transformed w or h is 0
    if (w == 0 || h == 0)
        return;

    if ( m_graphicContext->ShouldOffset() )
    {
        // if we are offsetting the entire rectangle is moved 0.5, so the
        // border line gets off by 1
        w -= 1;
        h -= 1;
    }
    m_graphicContext->DrawRoundedRectangle( x,y,w,h,radius);
}

void wxGCDCImpl::DoDrawEllipse(wxCoord x, wxCoord y, wxCoord w, wxCoord h)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawEllipse - invalid DC") );

    if ( !m_logicalFunctionSupported )
        return;

    if ( m_graphicContext->ShouldOffset() )
    {
        // if we are offsetting the entire rectangle is moved 0.5, so the
        // border line gets off by 1
        w -= 1;
        h -= 1;
    }
    m_graphicContext->DrawEllipse(x,y,w,h);
}

bool wxGCDCImpl::CanDrawBitmap() const
{
    return true;
}

bool wxGCDCImpl::DoBlit(
    wxCoord xdest, wxCoord ydest, wxCoord width, wxCoord height,
    wxDC *source, wxCoord xsrc, wxCoord ysrc,
    wxRasterOperationMode logical_func , bool useMask,
    wxCoord xsrcMask, wxCoord ysrcMask )
{
    return DoStretchBlit( xdest, ydest, width, height,
        source, xsrc, ysrc, width, height, logical_func, useMask,
        xsrcMask,ysrcMask );
}

bool wxGCDCImpl::DoStretchBlit(
    wxCoord xdest, wxCoord ydest, wxCoord dstWidth, wxCoord dstHeight,
    wxDC *source, wxCoord xsrc, wxCoord ysrc, wxCoord srcWidth, wxCoord srcHeight,
    wxRasterOperationMode logical_func , bool useMask,
    wxCoord xsrcMask, wxCoord ysrcMask )
{
    wxCHECK_MSG( IsOk(), false, wxT("wxGCDC(cg)::DoStretchBlit - invalid DC") );
    wxCHECK_MSG( source->IsOk(), false, wxT("wxGCDC(cg)::DoStretchBlit - invalid source DC") );

    if ( logical_func == wxNO_OP )
        return true;

    wxCompositionMode mode = TranslateRasterOp(logical_func);
    if ( mode == wxCOMPOSITION_INVALID )
    {
        wxFAIL_MSG( wxT("Blitting is not supported with this logical operation.") );
        return false;
    }

    wxRect subrect(source->LogicalToDeviceX(xsrc),
                   source->LogicalToDeviceY(ysrc),
                   source->LogicalToDeviceXRel(srcWidth),
                   source->LogicalToDeviceYRel(srcHeight));
    const wxRect subrectOrig = subrect;
    // clip the subrect down to the size of the source DC
    wxRect clip;
    source->GetSize(&clip.width, &clip.height);
    subrect.Intersect(clip);
    if (subrect.width == 0)
        return true;

    bool retval = true;

    wxCompositionMode formerMode = m_graphicContext->GetCompositionMode();
    if (m_graphicContext->SetCompositionMode(mode))
    {
        wxAntialiasMode formerAa = m_graphicContext->GetAntialiasMode();
        if (mode == wxCOMPOSITION_XOR)
        {
            m_graphicContext->SetAntialiasMode(wxANTIALIAS_NONE);
        }

        if (xsrcMask == -1 && ysrcMask == -1)
        {
            xsrcMask = xsrc;
            ysrcMask = ysrc;
        }

        wxBitmap blit = source->GetAsBitmap( &subrect );

        if ( blit.IsOk() )
        {
            if ( !useMask && blit.GetMask() )
                blit.SetMask(NULL);

            double x = xdest;
            double y = ydest;
            double w = dstWidth;
            double h = dstHeight;
            // adjust dest rect if source rect is clipped
            if (subrect.width != subrectOrig.width || subrect.height != subrectOrig.height)
            {
                x += (subrect.x - subrectOrig.x) / double(subrectOrig.width) * dstWidth;
                y += (subrect.y - subrectOrig.y) / double(subrectOrig.height) * dstHeight;
                w *= double(subrect.width) / subrectOrig.width;
                h *= double(subrect.height) / subrectOrig.height;
            }
            m_graphicContext->DrawBitmap(blit, x, y, w, h);
        }
        else
        {
            wxFAIL_MSG( wxT("Cannot Blit. Unable to get contents of DC as bitmap.") );
            retval = false;
        }

        if (mode == wxCOMPOSITION_XOR)
        {
            m_graphicContext->SetAntialiasMode(formerAa);
        }
    }
    // reset composition
    m_graphicContext->SetCompositionMode(formerMode);

    return retval;
}

void wxGCDCImpl::DoDrawRotatedText(const wxString& str, wxCoord x, wxCoord y,
                               double angle)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawRotatedText - invalid DC") );

    if ( str.empty() )
        return;
    if ( !m_logicalFunctionSupported )
        return;

    if ( m_backgroundMode == wxTRANSPARENT )
        m_graphicContext->DrawText( str, x ,y , DegToRad(angle ));
    else
        m_graphicContext->DrawText( str, x ,y , DegToRad(angle ), m_graphicContext->CreateBrush( wxBrush(m_textBackgroundColour,wxSOLID) ) );
}

void wxGCDCImpl::DoDrawText(const wxString& str, wxCoord x, wxCoord y)
{
    // For compatibility with other ports (notably wxGTK) and because it's
    // genuinely useful, we allow passing multiline strings to DrawText().
    // However there is no native OSX function to draw them directly so we
    // instead reuse the generic DrawLabel() method to render them. Of course,
    // DrawLabel() itself will call back to us but with single line strings
    // only so there won't be any infinite recursion here.
    if ( str.find('\n') != wxString::npos )
    {
        GetOwner()->DrawLabel(str, wxRect(x, y, 0, 0));
        return;
    }

    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoDrawText - invalid DC") );

    if ( str.empty() )
        return;

    if ( !m_logicalFunctionSupported )
        return;

    if ( m_backgroundMode == wxTRANSPARENT )
        m_graphicContext->DrawText( str, x ,y);
    else
        m_graphicContext->DrawText( str, x ,y , m_graphicContext->CreateBrush( wxBrush(m_textBackgroundColour,wxSOLID) ) );
}

bool wxGCDCImpl::CanGetTextExtent() const
{
    wxCHECK_MSG( IsOk(), false, wxT("wxGCDC(cg)::CanGetTextExtent - invalid DC") );

    return true;
}

void wxGCDCImpl::DoGetTextExtent( const wxString &str, wxCoord *width, wxCoord *height,
                              wxCoord *descent, wxCoord *externalLeading ,
                              const wxFont *theFont ) const
{
    wxCHECK_RET( m_graphicContext, wxT("wxGCDC(cg)::DoGetTextExtent - invalid DC") );

    if ( theFont )
    {
        m_graphicContext->SetFont( *theFont, m_textForegroundColour );
    }

    wxDouble h , d , e , w;

    m_graphicContext->GetTextExtent( str, &w, &h, &d, &e );

    if ( height )
        *height = (wxCoord)(h+0.5);
    if ( descent )
        *descent = (wxCoord)(d+0.5);
    if ( externalLeading )
        *externalLeading = (wxCoord)(e+0.5);
    if ( width )
        *width = (wxCoord)(w+0.5);

    if ( theFont )
    {
        m_graphicContext->SetFont( m_font, m_textForegroundColour );
    }
}

bool wxGCDCImpl::DoGetPartialTextExtents(const wxString& text, wxArrayInt& widths) const
{
    wxCHECK_MSG( m_graphicContext, false, wxT("wxGCDC(cg)::DoGetPartialTextExtents - invalid DC") );
    widths.Clear();
    widths.Add(0,text.Length());
    if ( text.IsEmpty() )
        return true;

    wxArrayDouble widthsD;

    m_graphicContext->GetPartialTextExtents( text, widthsD );
    for ( size_t i = 0; i < widths.GetCount(); ++i )
        widths[i] = (wxCoord)(widthsD[i] + 0.5);

    return true;
}

wxCoord wxGCDCImpl::GetCharWidth(void) const
{
    wxCoord width;
    DoGetTextExtent( wxT("g") , &width , NULL , NULL , NULL , NULL );

    return width;
}

wxCoord wxGCDCImpl::GetCharHeight(void) const
{
    wxCoord height;
    DoGetTextExtent( wxT("g") , NULL , &height , NULL , NULL , NULL );

    return height;
}

void wxGCDCImpl::Clear(void)
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::Clear - invalid DC") );
    // TODO better implementation / incorporate size info into wxGCDC or context
    m_graphicContext->SetBrush( m_backgroundBrush );
    wxPen p = *wxTRANSPARENT_PEN;
    m_graphicContext->SetPen( p );
    wxCompositionMode formerMode = m_graphicContext->GetCompositionMode();
    m_graphicContext->SetCompositionMode(wxCOMPOSITION_SOURCE);
    // maximum positive coordinate Cairo can handle is 2^23 - 1
    DoDrawRectangle(
        DeviceToLogicalX(0), DeviceToLogicalY(0),
        DeviceToLogicalXRel(0x007fffff), DeviceToLogicalYRel(0x007fffff));
    m_graphicContext->SetCompositionMode(formerMode);
    m_graphicContext->SetPen( m_pen );
    m_graphicContext->SetBrush( m_brush );
}

void wxGCDCImpl::DoGetSize(int *width, int *height) const
{
    wxCHECK_RET( IsOk(), wxT("wxGCDC(cg)::DoGetSize - invalid DC") );
    wxDouble w,h;
    m_graphicContext->GetSize( &w, &h );
    if ( height )
        *height = (int) (h+0.5);
    if ( width )
        *width = (int) (w+0.5);
}

void wxGCDCImpl::DoGradientFillLinear(const wxRect& rect,
                                  const wxColour& initialColour,
                                  const wxColour& destColour,
                                  wxDirection nDirection )
{
    wxPoint start;
    wxPoint end;
    switch( nDirection)
    {
    case wxWEST :
        start = rect.GetRightBottom();
        start.x++;
        end = rect.GetLeftBottom();
        break;
    case wxEAST :
        start = rect.GetLeftBottom();
        end = rect.GetRightBottom();
        end.x++;
        break;
    case wxNORTH :
        start = rect.GetLeftBottom();
        start.y++;
        end = rect.GetLeftTop();
        break;
    case wxSOUTH :
        start = rect.GetLeftTop();
        end = rect.GetLeftBottom();
        end.y++;
        break;
    default :
        break;
    }

    if (rect.width == 0 || rect.height == 0)
        return;

    m_graphicContext->SetBrush( m_graphicContext->CreateLinearGradientBrush(
        start.x,start.y,end.x,end.y, initialColour, destColour));
    m_graphicContext->SetPen(*wxTRANSPARENT_PEN);
    m_graphicContext->DrawRectangle(rect.x,rect.y,rect.width,rect.height);
    m_graphicContext->SetPen(m_pen);
    m_graphicContext->SetBrush(m_brush);
}

void wxGCDCImpl::DoGradientFillConcentric(const wxRect& rect,
                                      const wxColour& initialColour,
                                      const wxColour& destColour,
                                      const wxPoint& circleCenter)
{
    //Radius
    wxInt32 cx = rect.GetWidth() / 2;
    wxInt32 cy = rect.GetHeight() / 2;
    wxInt32 nRadius;
    if (cx < cy)
        nRadius = cx;
    else
        nRadius = cy;

    // make sure the background is filled (todo move into specific platform implementation ?)
    m_graphicContext->SetPen(*wxTRANSPARENT_PEN);
    m_graphicContext->SetBrush( wxBrush( destColour) );
    m_graphicContext->DrawRectangle(rect.x,rect.y,rect.width,rect.height);

    m_graphicContext->SetBrush( m_graphicContext->CreateRadialGradientBrush(
        rect.x+circleCenter.x,rect.y+circleCenter.y,
        rect.x+circleCenter.x,rect.y+circleCenter.y,
        nRadius,initialColour,destColour));

    m_graphicContext->DrawRectangle(rect.x,rect.y,rect.width,rect.height);
    m_graphicContext->SetPen(m_pen);
    m_graphicContext->SetBrush(m_brush);
}

void wxGCDCImpl::DoDrawCheckMark(wxCoord x, wxCoord y,
                             wxCoord width, wxCoord height)
{
    wxDCImpl::DoDrawCheckMark(x,y,width,height);
}

#ifdef __WXMSW__
wxRect wxGCDCImpl::MSWApplyGDIPlusTransform(const wxRect& r) const
{
    wxGraphicsContext* const gc = GetGraphicsContext();
    wxCHECK_MSG( gc, r, wxT("Invalid wxGCDC") );

    double x = 0,
           y = 0;
    gc->GetTransform().TransformPoint(&x, &y);

    wxRect rect(r);
    rect.Offset(x, y);

    return rect;
}
#endif // __WXMSW__

#endif // wxUSE_GRAPHICS_CONTEXT