src/cocoa/dc.mm

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/cocoa/dc.mm
   3 // Purpose:     wxDC
   4 // Author:      David Elliott
   5 // Modified by:
   6 // Created:     2003/04/01
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2003 David Elliott
   9 // Licence:     wxWindows license
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #include "wx/wxprec.h"
  13 #ifndef WX_PRECOMP
  14     #include "wx/log.h"
  15     #include "wx/dc.h"
  16 #endif //WX_PRECOMP
  17
  18 #include "wx/cocoa/autorelease.h"
  19
  20 #import <AppKit/NSBezierPath.h>
  21 #import <AppKit/NSTextStorage.h>
  22 #import <AppKit/NSLayoutManager.h>
  23 #import <AppKit/NSTextContainer.h>
  24 #import <AppKit/NSGraphicsContext.h>
  25 #import <AppKit/NSAffineTransform.h>
  26 #import <AppKit/NSColor.h>
  27 #import <AppKit/NSTypesetter.h>
  28 #import <AppKit/NSImage.h>
  29
  30 #include <wx/listimpl.cpp>
  31 WX_DEFINE_LIST(wxCocoaDCStack);
  32
  33 IMPLEMENT_ABSTRACT_CLASS(wxDC, wxObject)
  34 WX_NSTextStorage wxDC::sm_cocoaNSTextStorage = nil;
  35 WX_NSLayoutManager wxDC::sm_cocoaNSLayoutManager = nil;
  36 WX_NSTextContainer wxDC::sm_cocoaNSTextContainer = nil;
  37 wxCocoaDCStack wxDC::sm_cocoaDCStack;
  38
  39 inline void CocoaSetPenForNSBezierPath(wxPen &pen, NSBezierPath *bezpath)
  40 {
  41     [pen.GetNSColor() set];
  42     const float *pattern;
  43     [bezpath setLineDash:pattern count:pen.GetCocoaLineDash(&pattern) phase:0.0];
  44     [bezpath setLineWidth:pen.GetWidth()];
  45     switch(pen.GetJoin())
  46     {
  47     case wxJOIN_BEVEL:
  48         [bezpath setLineJoinStyle:NSBevelLineJoinStyle];
  49         break;
  50     case wxJOIN_ROUND:
  51         [bezpath setLineJoinStyle:NSRoundLineJoinStyle];
  52         break;
  53     case wxJOIN_MITER:
  54         [bezpath setLineJoinStyle:NSMiterLineJoinStyle];
  55         break;
  56     }
  57     switch(pen.GetCap())
  58     {
  59     case wxCAP_ROUND:
  60         [bezpath setLineCapStyle:NSRoundLineCapStyle];
  61         break;
  62     case wxCAP_PROJECTING:
  63         [bezpath setLineCapStyle:NSSquareLineCapStyle];
  64         break;
  65     case wxCAP_BUTT:
  66         [bezpath setLineCapStyle:NSButtLineCapStyle];
  67         break;
  68     }
  69 }
  70
  71 void wxDC::CocoaInitializeTextSystem()
  72 {
  73     wxASSERT_MSG(!sm_cocoaNSTextStorage && !sm_cocoaNSLayoutManager && !sm_cocoaNSTextContainer,wxT("Text system already initalized!  BAD PROGRAMMER!"));
  74
  75     sm_cocoaNSTextStorage = [[NSTextStorage alloc] init];
  76
  77     sm_cocoaNSLayoutManager = [[NSLayoutManager alloc] init];
  78     [sm_cocoaNSTextStorage addLayoutManager:sm_cocoaNSLayoutManager];
  79     // NSTextStorage retains NSLayoutManager, but so do we
  80     // [sm_cocoaNSLayoutManager release]; [sm_cocoaNSLayoutManager retain];
  81
  82     // NOTE:  initWithContainerSize is the designated initializer, but the
  83     // Apple CircleView sample gets away with just calling init, which
  84     // is all we really need for our purposes.
  85     sm_cocoaNSTextContainer = [[NSTextContainer alloc] init];
  86     [sm_cocoaNSLayoutManager addTextContainer:sm_cocoaNSTextContainer];
  87     // NSLayoutManager retains NSTextContainer, but so do we
  88     // [sm_cocoaNSTextContainer release]; [sm_cocoaNSTextContainer retain];
  89 }
  90
  91 void wxDC::CocoaShutdownTextSystem()
  92 {
  93     [sm_cocoaNSTextContainer release]; sm_cocoaNSTextContainer = nil;
  94     [sm_cocoaNSLayoutManager release]; sm_cocoaNSLayoutManager = nil;
  95     [sm_cocoaNSTextStorage release]; sm_cocoaNSTextStorage = nil;
  96 }
  97
  98 void wxDC::CocoaUnwindStackAndLoseFocus()
  99 {
 100     wxCocoaDCStack::Node *ourNode=sm_cocoaDCStack.Find(this);
 101     if(ourNode)
 102     {
 103         wxCocoaDCStack::Node *node=sm_cocoaDCStack.GetFirst();
 104         for(;node!=ourNode; node=sm_cocoaDCStack.GetFirst())
 105         {
 106             wxDC *dc = node->GetData();
 107             wxASSERT(dc);
 108             wxASSERT(dc!=this);
 109             if(!dc->CocoaUnlockFocus())
 110             {
 111                 wxFAIL_MSG(wxT("Unable to unlock focus on higher-level DC!"));
 112             }
 113             sm_cocoaDCStack.DeleteNode(node);
 114         }
 115         wxASSERT(node==ourNode);
 116         wxASSERT(ourNode->GetData() == this);
 117         ourNode->GetData()->CocoaUnlockFocus();
 118         sm_cocoaDCStack.DeleteNode(ourNode);
 119     }
 120 }
 121
 122 bool wxDC::CocoaUnwindStackAndTakeFocus()
 123 {
 124     wxCocoaDCStack::Node *node=sm_cocoaDCStack.GetFirst();
 125     for(;node;node = sm_cocoaDCStack.GetFirst())
 126     {
 127         wxDC *dc = node->GetData();
 128         wxASSERT(dc);
 129         // If we're on the stack, then it's unwound enough and we have focus
 130         if(dc==this)
 131             return true;
 132         // If unable to unlockFocus (e.g. wxPaintDC) stop here
 133         if(!dc->CocoaUnlockFocus())
 134             break;
 135         sm_cocoaDCStack.DeleteNode(node);
 136     }
 137     return CocoaLockFocus();
 138 }
 139
 140 wxDC::wxDC(void)
 141 {
 142     m_cocoaFlipped = false;
 143     m_cocoaHeight = 0.0;
 144     m_pen = *wxBLACK_PEN;
 145 }
 146
 147 wxDC::~wxDC(void)
 148 {
 149 }
 150
 151 bool wxDC::CocoaLockFocus()
 152 {
 153     return false;
 154 }
 155
 156 bool wxDC::CocoaUnlockFocus()
 157 {
 158     return false;
 159 }
 160
 161 void wxDC::CocoaApplyTransformations()
 162 {
 163     // This transform flips the graphics since wxDC uses top-left origin
 164     if(!m_cocoaFlipped)
 165     {
 166         // The transform is auto released
 167         NSAffineTransform *transform = [NSAffineTransform transform];
 168         /*  x' = 1x + 0y + 0
 169             y' = 0x + -1y + window's height
 170         */
 171         NSAffineTransformStruct matrix = {
 172             1,  0
 173         ,   0, -1
 174         ,   0, m_cocoaHeight
 175         };
 176         [transform setTransformStruct: matrix];
 177         // Apply the transform
 178         [transform concat];
 179     }
 180     // TODO: Apply scaling transformation
 181 }
 182
 183 void wxDC::DoDrawRectangle(wxCoord x, wxCoord y, wxCoord width, wxCoord height)
 184 {
 185     if(!CocoaTakeFocus()) return;
 186     NSBezierPath *bezpath = [NSBezierPath bezierPathWithRect:NSMakeRect(x,y,width,height)];
 187     CocoaSetPenForNSBezierPath(m_pen,bezpath);
 188     [bezpath stroke];
 189     [m_brush.GetNSColor() set];
 190     [bezpath fill];
 191 }
 192
 193 void wxDC::DoDrawLine(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2)
 194 {
 195     if(!CocoaTakeFocus()) return;
 196     NSBezierPath *bezpath = [NSBezierPath bezierPath];
 197     [bezpath moveToPoint:NSMakePoint(x1,y1)];
 198     [bezpath lineToPoint:NSMakePoint(x2,y2)];
 199
 200     CocoaSetPenForNSBezierPath(m_pen,bezpath);
 201     [bezpath stroke];
 202 }
 203
 204 void wxDC::DoGetTextExtent(const wxString& text, wxCoord *x, wxCoord *y, wxCoord *descent, wxCoord *externalLeading, wxFont *theFont) const
 205 {
 206     wxAutoNSAutoreleasePool pool;
 207 // FIXME: Cache this so it can be used for DoDrawText
 208     wxASSERT_MSG(sm_cocoaNSTextStorage && sm_cocoaNSLayoutManager && sm_cocoaNSTextContainer, wxT("Text system has not been initialized.  BAD PROGRAMMER!"));
 209     NSAttributedString *attributedString = [[NSAttributedString alloc]
 210             initWithString:[NSString stringWithCString:text.c_str()]];
 211     [sm_cocoaNSTextStorage setAttributedString:attributedString];
 212     [attributedString release];
 213
 214     NSRange glyphRange = [sm_cocoaNSLayoutManager glyphRangeForTextContainer:sm_cocoaNSTextContainer];
 215     NSRect usedRect = [sm_cocoaNSLayoutManager usedRectForTextContainer:sm_cocoaNSTextContainer];
 216     if(x)
 217         *x=(int)usedRect.size.width;
 218     if(y)
 219         *y=(int)usedRect.size.height;
 220     if(descent)
 221         *descent=0;
 222     if(externalLeading)
 223         *externalLeading=0;
 224 }
 225
 226 void wxDC::DoDrawText(const wxString& text, wxCoord x, wxCoord y)
 227 {
 228     if(!CocoaTakeFocus()) return;
 229     wxASSERT_MSG(sm_cocoaNSTextStorage && sm_cocoaNSLayoutManager && sm_cocoaNSTextContainer, wxT("Text system has not been initialized.  BAD PROGRAMMER!"));
 230     NSAttributedString *attributedString = [[NSAttributedString alloc]
 231             initWithString:[NSString stringWithCString:text.c_str()]];
 232     [sm_cocoaNSTextStorage setAttributedString:attributedString];
 233     [attributedString release];
 234
 235     // Set the color (and later font) attributes
 236     NSColor *fgColor = m_textForegroundColour.GetNSColor();
 237     NSColor *bgColor = m_textBackgroundColour.GetNSColor();
 238     if(!fgColor)
 239         fgColor = [NSColor clearColor];
 240     if(!bgColor)
 241         bgColor = [NSColor clearColor];
 242     NSDictionary *attrDict = [[NSDictionary alloc] initWithObjectsAndKeys:
 243             fgColor, NSForegroundColorAttributeName,
 244             bgColor, NSBackgroundColorAttributeName,
 245             nil];
 246     [sm_cocoaNSTextStorage addAttributes: attrDict range:NSMakeRange(0,[sm_cocoaNSTextStorage length])];
 247     [attrDict release];
 248
 249     NSRange glyphRange = [sm_cocoaNSLayoutManager glyphRangeForTextContainer:sm_cocoaNSTextContainer];
 250     NSRect usedRect = [sm_cocoaNSLayoutManager usedRectForTextContainer:sm_cocoaNSTextContainer];
 251     // NOTE: We'll crash trying to get the location of glyphAtIndex:0 if
 252     // there is no length or we don't start at zero
 253     if(!glyphRange.length)
 254         return;
 255     wxASSERT_MSG(glyphRange.location==0,wxT("glyphRange must begin at zero"));
 256
 257     NSAffineTransform *transform = [NSAffineTransform transform];
 258     [transform translateXBy:x yBy:y];
 259
 260     NSAffineTransform *flipTransform = [NSAffineTransform transform];
 261     /*  x' = 1x + 0y + 0
 262         y' = 0x + -1y + window's height
 263     */
 264     NSAffineTransformStruct matrix = {
 265         1,  0
 266     ,   0, -1
 267     ,   0, usedRect.size.height
 268     };
 269     [flipTransform setTransformStruct: matrix];
 270
 271     NSGraphicsContext *context = [NSGraphicsContext currentContext];
 272     [context saveGraphicsState];
 273     [transform concat];
 274     [flipTransform concat];
 275     #if 0
 276     // Draw+fill a rectangle so we can see where the shit is supposed to be.
 277     wxLogDebug(wxT("(%f,%f) (%fx%f)"),usedRect.origin.x,usedRect.origin.y,usedRect.size.width,usedRect.size.height);
 278     NSBezierPath *bezpath = [NSBezierPath bezierPathWithRect:NSMakeRect(0,0,usedRect.size.width,usedRect.size.height)];
 279     [[NSColor blackColor] set];
 280     [bezpath stroke];
 281     [[NSColor blueColor] set];
 282     [bezpath fill];
 283     #endif
 284
 285     NSPoint layoutLocation = [sm_cocoaNSLayoutManager locationForGlyphAtIndex:0];
 286     layoutLocation.x = 0.0;
 287     layoutLocation.y *= -1.0;
 288     layoutLocation.y += [[sm_cocoaNSLayoutManager typesetter] baselineOffsetInLayoutManager:sm_cocoaNSLayoutManager glyphIndex:0];
 289     if(m_backgroundMode==wxSOLID)
 290         [sm_cocoaNSLayoutManager drawBackgroundForGlyphRange:glyphRange  atPoint:NSZeroPoint];
 291     [sm_cocoaNSLayoutManager drawGlyphsForGlyphRange:glyphRange  atPoint:layoutLocation];
 292
 293     [context restoreGraphicsState];
 294 }
 295
 296 // wxDCBase functions
 297 int wxDCBase::DeviceToLogicalX(int x) const
 298 {
 299     return x;
 300 }
 301
 302 int wxDCBase::DeviceToLogicalY(int y) const
 303 {
 304     return y;
 305 }
 306
 307 int wxDCBase::DeviceToLogicalXRel(int x) const
 308 {
 309     return x;
 310 }
 311
 312 int wxDCBase::DeviceToLogicalYRel(int y) const
 313 {
 314     return y;
 315 }
 316
 317 int wxDCBase::LogicalToDeviceX(int x) const
 318 {
 319     return x;
 320 }
 321
 322 int wxDCBase::LogicalToDeviceY(int y) const
 323 {
 324     return y;
 325 }
 326
 327 int wxDCBase::LogicalToDeviceXRel(int x) const
 328 {
 329     return x;
 330 }
 331
 332 int wxDCBase::LogicalToDeviceYRel(int y) const
 333 {
 334     return y;
 335 }
 336
 337 ///////////////////////////////////////////////////////////////////////////
 338 // cut here, the rest is stubs
 339 ///////////////////////////////////////////////////////////////////////////
 340
 341 //-----------------------------------------------------------------------------
 342 // constants
 343 //-----------------------------------------------------------------------------
 344
 345 #define mm2inches               0.0393700787402
 346 #define inches2mm               25.4
 347 #define mm2twips                56.6929133859
 348 #define twips2mm                0.0176388888889
 349 #define mm2pt                   2.83464566929
 350 #define pt2mm                   0.352777777778
 351
 352 //-----------------------------------------------------------------------------
 353 // wxDC
 354 //-----------------------------------------------------------------------------
 355
 356 void wxDC::DoDrawIcon( const wxIcon &WXUNUSED(icon), int WXUNUSED(x), int WXUNUSED(y) )
 357 {
 358 };
 359
 360 void wxDC::DoDrawPoint( int x, int y )
 361 {
 362 };
 363
 364 void wxDC::DoDrawPolygon( int, wxPoint *, int, int, int)
 365 {
 366 };
 367
 368 void wxDC::DoDrawLines( int, wxPoint *, int, int )
 369 {
 370 }
 371
 372 int wxDC::GetDepth() const
 373 {
 374     return 0;
 375 }
 376
 377 wxSize wxDC::GetPPI() const
 378 {
 379     return wxSize(0,0);
 380 }
 381
 382 bool wxDC::CanGetTextExtent() const
 383 {
 384     return false;
 385 }
 386
 387 wxCoord wxDC::GetCharHeight() const
 388 {
 389     return 0;
 390 }
 391
 392 wxCoord wxDC::GetCharWidth() const
 393 {
 394     return 0;
 395 }
 396
 397 bool wxDC::CanDrawBitmap() const
 398 {
 399     return true;
 400 }
 401
 402 bool wxDC::DoGetPixel(wxCoord x, wxCoord y, wxColour *col) const
 403 {
 404     return false;
 405 }
 406
 407 void wxDC::DoDrawArc(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2, wxCoord xc, wxCoord yc)
 408 {
 409 }
 410
 411 void wxDC::SetPen(const wxPen& pen)
 412 {
 413     m_pen = pen;
 414 }
 415
 416 void wxDC::SetBrush(const wxBrush& brush)
 417 {
 418     m_brush = brush;
 419 }
 420
 421 void wxDC::DoSetClippingRegionAsRegion(const wxRegion& region)
 422 {
 423 }
 424
 425 void wxDC::DoSetClippingRegion(wxCoord x, wxCoord y, wxCoord width, wxCoord height)
 426 {
 427 }
 428
 429 void wxDC::DestroyClippingRegion()
 430 {
 431 }
 432
 433 void wxDC::DoDrawRoundedRectangle(wxCoord x, wxCoord y, wxCoord width, wxCoord height, double radius)
 434 {
 435 }
 436
 437 void wxDC::DoDrawRotatedText(const wxString& text, wxCoord x, wxCoord y, double angle)
 438 {
 439 }
 440
 441 void wxDC::DoDrawEllipticArc(wxCoord x, wxCoord y, wxCoord w, wxCoord h, double sa, double ea)
 442 {
 443 }
 444
 445 void wxDC::DoDrawEllipse(wxCoord x, wxCoord y, wxCoord width, wxCoord height)
 446 {
 447 }
 448
 449 void wxDC::DoDrawBitmap(const wxBitmap &bmp, wxCoord x, wxCoord y, bool useMask)
 450 {
 451     if(!CocoaTakeFocus()) return;
 452     if(!bmp.Ok())
 453         return;
 454
 455 #if 0
 456     // Draw a rect so we can see where it's supposed to be
 457     wxLogDebug(wxT("image at (%d,%d) size %dx%d"),x,y,bmp.GetWidth(),bmp.GetHeight());
 458     NSBezierPath *bezpath = [NSBezierPath bezierPathWithRect:NSMakeRect(x,y,bmp.GetWidth(),bmp.GetHeight())];
 459     [[NSColor blackColor] set];
 460     [bezpath stroke];
 461     [[NSColor blueColor] set];
 462     [bezpath fill];
 463 #endif // 0
 464
 465     NSAffineTransform *transform = [NSAffineTransform transform];
 466     [transform translateXBy:x yBy:y];
 467
 468     NSAffineTransform *flipTransform = [NSAffineTransform transform];
 469     /*  x' = 1x + 0y + 0
 470         y' = 0x + -1y + window's height
 471     */
 472     NSAffineTransformStruct matrix = {
 473         1,  0
 474     ,   0, -1
 475     ,   0, bmp.GetHeight()
 476     };
 477     [flipTransform setTransformStruct: matrix];
 478
 479     NSGraphicsContext *context = [NSGraphicsContext currentContext];
 480     [context saveGraphicsState];
 481     [transform concat];
 482     [flipTransform concat];
 483
 484     NSImage *nsimage = [bmp.GetNSImage(useMask) retain];
 485
 486     [nsimage drawAtPoint: NSMakePoint(0,0)
 487         fromRect: NSMakeRect(0.0,0.0,bmp.GetWidth(),bmp.GetHeight())
 488         operation: NSCompositeSourceOver
 489         fraction: 1.0];
 490
 491     [nsimage release];
 492     [context restoreGraphicsState];
 493 }
 494
 495 bool wxDC::DoFloodFill(wxCoord x, wxCoord y, const wxColour& col, int style)
 496 {
 497     return false;
 498 }
 499
 500 void wxDC::DoCrossHair(wxCoord x, wxCoord y)
 501 {
 502 }
 503
 504
 505 bool wxDC::DoBlit(wxCoord xdest, wxCoord ydest, wxCoord width, wxCoord height, wxDC *source, wxCoord xsrc, wxCoord ysrc, int rop, bool useMask , wxCoord xsrcMask, wxCoord ysrcMask)
 506 {
 507     if(!CocoaTakeFocus()) return false;
 508     if(!source) return false;
 509     return source->CocoaDoBlitOnFocusedDC(xdest,ydest,width,height,
 510         xsrc, ysrc, rop, useMask, xsrcMask, ysrcMask);
 511 }
 512
 513 bool wxDC::CocoaDoBlitOnFocusedDC(wxCoord xdest, wxCoord ydest,
 514     wxCoord width, wxCoord height, wxCoord xsrc, wxCoord ysrc,
 515     int logicalFunc, bool useMask, wxCoord xsrcMask, wxCoord ysrcMask)
 516 {
 517     return false;
 518 }
 519
 520 void wxDC::DoGetSize( int* width, int* height ) const
 521 {
 522   *width = m_maxX-m_minX;
 523   *height = m_maxY-m_minY;
 524 };
 525
 526 void wxDC::DoGetSizeMM( int* width, int* height ) const
 527 {
 528   int w = 0;
 529   int h = 0;
 530   GetSize( &w, &h );
 531 };
 532
 533 void wxDC::SetTextForeground( const wxColour &col )
 534 {
 535   if (!Ok()) return;
 536   m_textForegroundColour = col;
 537 };
 538
 539 void wxDC::SetTextBackground( const wxColour &col )
 540 {
 541   if (!Ok()) return;
 542   m_textBackgroundColour = col;
 543 };
 544
 545 void wxDC::Clear()
 546 {
 547 }
 548
 549 void wxDC::SetBackground(const wxBrush& brush)
 550 {
 551     m_backgroundBrush = brush;
 552 }
 553
 554 void wxDC::SetPalette(const wxPalette&)
 555 {
 556 }
 557
 558 void wxDC::SetLogicalFunction(int)
 559 {
 560 }
 561
 562
 563 void wxDC::SetMapMode( int mode )
 564 {
 565   switch (mode)
 566   {
 567     case wxMM_TWIPS:
 568       break;
 569     case wxMM_POINTS:
 570       break;
 571     case wxMM_METRIC:
 572       break;
 573     case wxMM_LOMETRIC:
 574       break;
 575     default:
 576     case wxMM_TEXT:
 577       SetLogicalScale( 1.0, 1.0 );
 578       break;
 579   };
 580   if (mode != wxMM_TEXT)
 581   {
 582   };
 583 };
 584
 585 void wxDC::SetUserScale( double x, double y )
 586 {
 587   // allow negative ? -> no
 588   m_userScaleX = x;
 589   m_userScaleY = y;
 590   ComputeScaleAndOrigin();
 591 };
 592
 593 void wxDC::SetLogicalScale( double x, double y )
 594 {
 595   // allow negative ?
 596   m_logicalScaleX = x;
 597   m_logicalScaleY = y;
 598   ComputeScaleAndOrigin();
 599 };
 600
 601 void wxDC::SetLogicalOrigin( wxCoord x, wxCoord y )
 602 {
 603   m_logicalOriginX = x * m_signX;   // is this still correct ?
 604   m_logicalOriginY = y * m_signY;
 605   ComputeScaleAndOrigin();
 606 };
 607
 608 void wxDC::SetDeviceOrigin( wxCoord x, wxCoord y )
 609 {
 610   ComputeScaleAndOrigin();
 611 };
 612
 613 void wxDC::SetAxisOrientation( bool xLeftRight, bool yBottomUp )
 614 {
 615   m_signX = (xLeftRight ?  1 : -1);
 616   m_signY = (yBottomUp  ? -1 :  1);
 617   ComputeScaleAndOrigin();
 618 };
 619
 620 void wxDC::ComputeScaleAndOrigin(void)
 621 {
 622   // CMB: copy scale to see if it changes
 623   double origScaleX = m_scaleX;
 624   double origScaleY = m_scaleY;
 625
 626   m_scaleX = m_logicalScaleX * m_userScaleX;
 627   m_scaleY = m_logicalScaleY * m_userScaleY;
 628
 629   // CMB: if scale has changed call SetPen to recalulate the line width
 630   if (m_scaleX != origScaleX || m_scaleY != origScaleY)
 631   {
 632     // this is a bit artificial, but we need to force wxDC to think
 633     // the pen has changed
 634     wxPen* pen = & GetPen();
 635     wxPen tempPen;
 636     m_pen = tempPen;
 637     SetPen(* pen);
 638   }
 639 };
 640