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 #include "wx/cocoa/string.h"
  20
  21 #import <AppKit/NSBezierPath.h>
  22 #import <AppKit/NSTextStorage.h>
  23 #import <AppKit/NSLayoutManager.h>
  24 #import <AppKit/NSTextContainer.h>
  25 #import <AppKit/NSGraphicsContext.h>
  26 #import <AppKit/NSAffineTransform.h>
  27 #import <AppKit/NSColor.h>
  28 #import <AppKit/NSTypesetter.h>
  29 #import <AppKit/NSImage.h>
  30
  31 #include <wx/listimpl.cpp>
  32 WX_DEFINE_LIST(wxCocoaDCStack);
  33
  34 IMPLEMENT_ABSTRACT_CLASS(wxDC, wxObject)
  35 WX_NSTextStorage wxDC::sm_cocoaNSTextStorage = nil;
  36 WX_NSLayoutManager wxDC::sm_cocoaNSLayoutManager = nil;
  37 WX_NSTextContainer wxDC::sm_cocoaNSTextContainer = nil;
  38 wxCocoaDCStack wxDC::sm_cocoaDCStack;
  39
  40 inline void CocoaSetPenForNSBezierPath(wxPen &pen, NSBezierPath *bezpath)
  41 {
  42     [pen.GetNSColor() set];
  43     const float *pattern;
  44     [bezpath setLineDash:pattern count:pen.GetCocoaLineDash(&pattern) phase:0.0];
  45     [bezpath setLineWidth:pen.GetWidth()];
  46     switch(pen.GetJoin())
  47     {
  48     case wxJOIN_BEVEL:
  49         [bezpath setLineJoinStyle:NSBevelLineJoinStyle];
  50         break;
  51     case wxJOIN_ROUND:
  52         [bezpath setLineJoinStyle:NSRoundLineJoinStyle];
  53         break;
  54     case wxJOIN_MITER:
  55         [bezpath setLineJoinStyle:NSMiterLineJoinStyle];
  56         break;
  57     }
  58     switch(pen.GetCap())
  59     {
  60     case wxCAP_ROUND:
  61         [bezpath setLineCapStyle:NSRoundLineCapStyle];
  62         break;
  63     case wxCAP_PROJECTING:
  64         [bezpath setLineCapStyle:NSSquareLineCapStyle];
  65         break;
  66     case wxCAP_BUTT:
  67         [bezpath setLineCapStyle:NSButtLineCapStyle];
  68         break;
  69     }
  70 }
  71
  72 void wxDC::CocoaInitializeTextSystem()
  73 {
  74     wxASSERT_MSG(!sm_cocoaNSTextStorage && !sm_cocoaNSLayoutManager && !sm_cocoaNSTextContainer,wxT("Text system already initalized!  BAD PROGRAMMER!"));
  75
  76     sm_cocoaNSTextStorage = [[NSTextStorage alloc] init];
  77
  78     sm_cocoaNSLayoutManager = [[NSLayoutManager alloc] init];
  79     [sm_cocoaNSTextStorage addLayoutManager:sm_cocoaNSLayoutManager];
  80     // NSTextStorage retains NSLayoutManager, but so do we
  81     // [sm_cocoaNSLayoutManager release]; [sm_cocoaNSLayoutManager retain];
  82
  83     // NOTE:  initWithContainerSize is the designated initializer, but the
  84     // Apple CircleView sample gets away with just calling init, which
  85     // is all we really need for our purposes.
  86     sm_cocoaNSTextContainer = [[NSTextContainer alloc] init];
  87     [sm_cocoaNSLayoutManager addTextContainer:sm_cocoaNSTextContainer];
  88     // NSLayoutManager retains NSTextContainer, but so do we
  89     // [sm_cocoaNSTextContainer release]; [sm_cocoaNSTextContainer retain];
  90 }
  91
  92 void wxDC::CocoaShutdownTextSystem()
  93 {
  94     [sm_cocoaNSTextContainer release]; sm_cocoaNSTextContainer = nil;
  95     [sm_cocoaNSLayoutManager release]; sm_cocoaNSLayoutManager = nil;
  96     [sm_cocoaNSTextStorage release]; sm_cocoaNSTextStorage = nil;
  97 }
  98
  99 void wxDC::CocoaUnwindStackAndLoseFocus()
 100 {
 101     wxCocoaDCStack::compatibility_iterator ourNode=sm_cocoaDCStack.Find(this);
 102     if(ourNode)
 103     {
 104         wxCocoaDCStack::compatibility_iterator node=sm_cocoaDCStack.GetFirst();
 105         for(;node!=ourNode; node=sm_cocoaDCStack.GetFirst())
 106         {
 107             wxDC *dc = node->GetData();
 108             wxASSERT(dc);
 109             wxASSERT(dc!=this);
 110             if(!dc->CocoaUnlockFocus())
 111             {
 112                 wxFAIL_MSG(wxT("Unable to unlock focus on higher-level DC!"));
 113             }
 114             sm_cocoaDCStack.Erase(node);
 115         }
 116         wxASSERT(node==ourNode);
 117         wxASSERT(ourNode->GetData() == this);
 118         ourNode->GetData()->CocoaUnlockFocus();
 119         sm_cocoaDCStack.Erase(ourNode);
 120     }
 121 }
 122
 123 bool wxDC::CocoaUnwindStackAndTakeFocus()
 124 {
 125     wxCocoaDCStack::compatibility_iterator node=sm_cocoaDCStack.GetFirst();
 126     for(;node;node = sm_cocoaDCStack.GetFirst())
 127     {
 128         wxDC *dc = node->GetData();
 129         wxASSERT(dc);
 130         // If we're on the stack, then it's unwound enough and we have focus
 131         if(dc==this)
 132             return true;
 133         // If unable to unlockFocus (e.g. wxPaintDC) stop here
 134         if(!dc->CocoaUnlockFocus())
 135             break;
 136         sm_cocoaDCStack.Erase(node);
 137     }
 138     return CocoaLockFocus();
 139 }
 140
 141 wxDC::wxDC(void)
 142 {
 143     m_cocoaFlipped = false;
 144     m_cocoaHeight = 0.0;
 145     m_pen = *wxBLACK_PEN;
 146 }
 147
 148 wxDC::~wxDC(void)
 149 {
 150 }
 151
 152 bool wxDC::CocoaLockFocus()
 153 {
 154     return false;
 155 }
 156
 157 bool wxDC::CocoaUnlockFocus()
 158 {
 159     return false;
 160 }
 161
 162 void wxDC::CocoaApplyTransformations()
 163 {
 164     // This transform flips the graphics since wxDC uses top-left origin
 165     if(!m_cocoaFlipped)
 166     {
 167         // The transform is auto released
 168         NSAffineTransform *transform = [NSAffineTransform transform];
 169         /*  x' = 1x + 0y + 0
 170             y' = 0x + -1y + window's height
 171         */
 172         NSAffineTransformStruct matrix = {
 173             1,  0
 174         ,   0, -1
 175         ,   0, m_cocoaHeight
 176         };
 177         [transform setTransformStruct: matrix];
 178         // Apply the transform
 179         [transform concat];
 180     }
 181     // TODO: Apply scaling transformation
 182 }
 183
 184 void wxDC::DoDrawRectangle(wxCoord x, wxCoord y, wxCoord width, wxCoord height)
 185 {
 186     if(!CocoaTakeFocus()) return;
 187     NSBezierPath *bezpath = [NSBezierPath bezierPathWithRect:NSMakeRect(x,y,width,height)];
 188     CocoaSetPenForNSBezierPath(m_pen,bezpath);
 189     [bezpath stroke];
 190     [m_brush.GetNSColor() set];
 191     [bezpath fill];
 192 }
 193
 194 void wxDC::DoDrawLine(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2)
 195 {
 196     if(!CocoaTakeFocus()) return;
 197     NSBezierPath *bezpath = [NSBezierPath bezierPath];
 198     [bezpath moveToPoint:NSMakePoint(x1,y1)];
 199     [bezpath lineToPoint:NSMakePoint(x2,y2)];
 200
 201     CocoaSetPenForNSBezierPath(m_pen,bezpath);
 202     [bezpath stroke];
 203 }
 204
 205 void wxDC::DoGetTextExtent(const wxString& text, wxCoord *x, wxCoord *y, wxCoord *descent, wxCoord *externalLeading, wxFont *theFont) const
 206 {
 207     wxAutoNSAutoreleasePool pool;
 208 // FIXME: Cache this so it can be used for DoDrawText
 209     wxASSERT_MSG(sm_cocoaNSTextStorage && sm_cocoaNSLayoutManager && sm_cocoaNSTextContainer, wxT("Text system has not been initialized.  BAD PROGRAMMER!"));
 210     NSAttributedString *attributedString = [[NSAttributedString alloc]
 211             initWithString:wxNSStringWithWxString(text.c_str())];
 212     [sm_cocoaNSTextStorage setAttributedString:attributedString];
 213     [attributedString release];
 214
 215     NSRange glyphRange = [sm_cocoaNSLayoutManager glyphRangeForTextContainer:sm_cocoaNSTextContainer];
 216     NSRect usedRect = [sm_cocoaNSLayoutManager usedRectForTextContainer:sm_cocoaNSTextContainer];
 217     if(x)
 218         *x=(int)usedRect.size.width;
 219     if(y)
 220         *y=(int)usedRect.size.height;
 221     if(descent)
 222         *descent=0;
 223     if(externalLeading)
 224         *externalLeading=0;
 225 }
 226
 227 void wxDC::DoDrawText(const wxString& text, wxCoord x, wxCoord y)
 228 {
 229     if(!CocoaTakeFocus()) return;
 230     wxASSERT_MSG(sm_cocoaNSTextStorage && sm_cocoaNSLayoutManager && sm_cocoaNSTextContainer, wxT("Text system has not been initialized.  BAD PROGRAMMER!"));
 231     NSAttributedString *attributedString = [[NSAttributedString alloc]
 232             initWithString:wxNSStringWithWxString(text.c_str())];
 233     [sm_cocoaNSTextStorage setAttributedString:attributedString];
 234     [attributedString release];
 235
 236     // Set the color (and later font) attributes
 237     NSColor *fgColor = m_textForegroundColour.GetNSColor();
 238     NSColor *bgColor = m_textBackgroundColour.GetNSColor();
 239     if(!fgColor)
 240         fgColor = [NSColor clearColor];
 241     if(!bgColor)
 242         bgColor = [NSColor clearColor];
 243     NSDictionary *attrDict = [[NSDictionary alloc] initWithObjectsAndKeys:
 244             fgColor, NSForegroundColorAttributeName,
 245             bgColor, NSBackgroundColorAttributeName,
 246             nil];
 247     [sm_cocoaNSTextStorage addAttributes: attrDict range:NSMakeRange(0,[sm_cocoaNSTextStorage length])];
 248     [attrDict release];
 249
 250     NSRange glyphRange = [sm_cocoaNSLayoutManager glyphRangeForTextContainer:sm_cocoaNSTextContainer];
 251     NSRect usedRect = [sm_cocoaNSLayoutManager usedRectForTextContainer:sm_cocoaNSTextContainer];
 252     // NOTE: We'll crash trying to get the location of glyphAtIndex:0 if
 253     // there is no length or we don't start at zero
 254     if(!glyphRange.length)
 255         return;
 256     wxASSERT_MSG(glyphRange.location==0,wxT("glyphRange must begin at zero"));
 257
 258     NSAffineTransform *transform = [NSAffineTransform transform];
 259     [transform translateXBy:x yBy:y];
 260
 261     NSAffineTransform *flipTransform = [NSAffineTransform transform];
 262     /*  x' = 1x + 0y + 0
 263         y' = 0x + -1y + window's height
 264     */
 265     NSAffineTransformStruct matrix = {
 266         1,  0
 267     ,   0, -1
 268     ,   0, usedRect.size.height
 269     };
 270     [flipTransform setTransformStruct: matrix];
 271
 272     NSGraphicsContext *context = [NSGraphicsContext currentContext];
 273     [context saveGraphicsState];
 274     [transform concat];
 275     [flipTransform concat];
 276     #if 0
 277     // Draw+fill a rectangle so we can see where the shit is supposed to be.
 278     wxLogTrace(wxTRACE_COCOA,wxT("(%f,%f) (%fx%f)"),usedRect.origin.x,usedRect.origin.y,usedRect.size.width,usedRect.size.height);
 279     NSBezierPath *bezpath = [NSBezierPath bezierPathWithRect:NSMakeRect(0,0,usedRect.size.width,usedRect.size.height)];
 280     [[NSColor blackColor] set];
 281     [bezpath stroke];
 282     [[NSColor blueColor] set];
 283     [bezpath fill];
 284     #endif
 285
 286     NSPoint layoutLocation = [sm_cocoaNSLayoutManager locationForGlyphAtIndex:0];
 287     layoutLocation.x = 0.0;
 288     layoutLocation.y *= -1.0;
 289     layoutLocation.y += [[sm_cocoaNSLayoutManager typesetter] baselineOffsetInLayoutManager:sm_cocoaNSLayoutManager glyphIndex:0];
 290     if(m_backgroundMode==wxSOLID)
 291         [sm_cocoaNSLayoutManager drawBackgroundForGlyphRange:glyphRange  atPoint:NSZeroPoint];
 292     [sm_cocoaNSLayoutManager drawGlyphsForGlyphRange:glyphRange  atPoint:layoutLocation];
 293
 294     [context restoreGraphicsState];
 295 }
 296
 297 // wxDCBase functions
 298 int wxDCBase::DeviceToLogicalX(int x) const
 299 {
 300     return x;
 301 }
 302
 303 int wxDCBase::DeviceToLogicalY(int y) const
 304 {
 305     return y;
 306 }
 307
 308 int wxDCBase::DeviceToLogicalXRel(int x) const
 309 {
 310     return x;
 311 }
 312
 313 int wxDCBase::DeviceToLogicalYRel(int y) const
 314 {
 315     return y;
 316 }
 317
 318 int wxDCBase::LogicalToDeviceX(int x) const
 319 {
 320     return x;
 321 }
 322
 323 int wxDCBase::LogicalToDeviceY(int y) const
 324 {
 325     return y;
 326 }
 327
 328 int wxDCBase::LogicalToDeviceXRel(int x) const
 329 {
 330     return x;
 331 }
 332
 333 int wxDCBase::LogicalToDeviceYRel(int y) const
 334 {
 335     return y;
 336 }
 337
 338 ///////////////////////////////////////////////////////////////////////////
 339 // cut here, the rest is stubs
 340 ///////////////////////////////////////////////////////////////////////////
 341
 342 //-----------------------------------------------------------------------------
 343 // constants
 344 //-----------------------------------------------------------------------------
 345
 346 #define mm2inches               0.0393700787402
 347 #define inches2mm               25.4
 348 #define mm2twips                56.6929133859
 349 #define twips2mm                0.0176388888889
 350 #define mm2pt                   2.83464566929
 351 #define pt2mm                   0.352777777778
 352
 353 //-----------------------------------------------------------------------------
 354 // wxDC
 355 //-----------------------------------------------------------------------------
 356
 357 void wxDC::DoDrawIcon( const wxIcon &WXUNUSED(icon), int WXUNUSED(x), int WXUNUSED(y) )
 358 {
 359 };
 360
 361 void wxDC::DoDrawPoint( int x, int y )
 362 {
 363 };
 364
 365 void wxDC::DoDrawPolygon( int, wxPoint *, int, int, int)
 366 {
 367 };
 368
 369 void wxDC::DoDrawLines( int, wxPoint *, int, int )
 370 {
 371 }
 372
 373 int wxDC::GetDepth() const
 374 {
 375     return 0;
 376 }
 377
 378 wxSize wxDC::GetPPI() const
 379 {
 380     return wxSize(0,0);
 381 }
 382
 383 bool wxDC::CanGetTextExtent() const
 384 {
 385     return false;
 386 }
 387
 388 wxCoord wxDC::GetCharHeight() const
 389 {
 390     return 0;
 391 }
 392
 393 wxCoord wxDC::GetCharWidth() const
 394 {
 395     return 0;
 396 }
 397
 398 bool wxDC::CanDrawBitmap() const
 399 {
 400     return true;
 401 }
 402
 403 bool wxDC::DoGetPixel(wxCoord x, wxCoord y, wxColour *col) const
 404 {
 405     return false;
 406 }
 407
 408 void wxDC::DoDrawArc(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2, wxCoord xc, wxCoord yc)
 409 {
 410 }
 411
 412 void wxDC::SetPen(const wxPen& pen)
 413 {
 414     m_pen = pen;
 415 }
 416
 417 void wxDC::SetBrush(const wxBrush& brush)
 418 {
 419     m_brush = brush;
 420 }
 421
 422 void wxDC::DoSetClippingRegionAsRegion(const wxRegion& region)
 423 {
 424 }
 425
 426 void wxDC::DoSetClippingRegion(wxCoord x, wxCoord y, wxCoord width, wxCoord height)
 427 {
 428 }
 429
 430 void wxDC::DestroyClippingRegion()
 431 {
 432 }
 433
 434 void wxDC::DoDrawRoundedRectangle(wxCoord x, wxCoord y, wxCoord width, wxCoord height, double radius)
 435 {
 436 }
 437
 438 void wxDC::DoDrawRotatedText(const wxString& text, wxCoord x, wxCoord y, double angle)
 439 {
 440 }
 441
 442 void wxDC::DoDrawEllipticArc(wxCoord x, wxCoord y, wxCoord w, wxCoord h, double sa, double ea)
 443 {
 444 }
 445
 446 void wxDC::DoDrawEllipse(wxCoord x, wxCoord y, wxCoord width, wxCoord height)
 447 {
 448 }
 449
 450 void wxDC::DoDrawBitmap(const wxBitmap &bmp, wxCoord x, wxCoord y, bool useMask)
 451 {
 452     if(!CocoaTakeFocus()) return;
 453     if(!bmp.Ok())
 454         return;
 455
 456 #if 0
 457     // Draw a rect so we can see where it's supposed to be
 458     wxLogTrace(wxTRACE_COCOA,wxT("image at (%d,%d) size %dx%d"),x,y,bmp.GetWidth(),bmp.GetHeight());
 459     NSBezierPath *bezpath = [NSBezierPath bezierPathWithRect:NSMakeRect(x,y,bmp.GetWidth(),bmp.GetHeight())];
 460     [[NSColor blackColor] set];
 461     [bezpath stroke];
 462     [[NSColor blueColor] set];
 463     [bezpath fill];
 464 #endif // 0
 465
 466     NSAffineTransform *transform = [NSAffineTransform transform];
 467     [transform translateXBy:x yBy:y];
 468
 469     NSAffineTransform *flipTransform = [NSAffineTransform transform];
 470     /*  x' = 1x + 0y + 0
 471         y' = 0x + -1y + window's height
 472     */
 473     NSAffineTransformStruct matrix = {
 474         1,  0
 475     ,   0, -1
 476     ,   0, bmp.GetHeight()
 477     };
 478     [flipTransform setTransformStruct: matrix];
 479
 480     NSGraphicsContext *context = [NSGraphicsContext currentContext];
 481     [context saveGraphicsState];
 482     [transform concat];
 483     [flipTransform concat];
 484
 485     NSImage *nsimage = [bmp.GetNSImage(useMask) retain];
 486
 487     [nsimage drawAtPoint: NSMakePoint(0,0)
 488         fromRect: NSMakeRect(0.0,0.0,bmp.GetWidth(),bmp.GetHeight())
 489         operation: NSCompositeSourceOver
 490         fraction: 1.0];
 491
 492     [nsimage release];
 493     [context restoreGraphicsState];
 494 }
 495
 496 bool wxDC::DoFloodFill(wxCoord x, wxCoord y, const wxColour& col, int style)
 497 {
 498     return false;
 499 }
 500
 501 void wxDC::DoCrossHair(wxCoord x, wxCoord y)
 502 {
 503 }
 504
 505
 506 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)
 507 {
 508     if(!CocoaTakeFocus()) return false;
 509     if(!source) return false;
 510     return source->CocoaDoBlitOnFocusedDC(xdest,ydest,width,height,
 511         xsrc, ysrc, rop, useMask, xsrcMask, ysrcMask);
 512 }
 513
 514 bool wxDC::CocoaDoBlitOnFocusedDC(wxCoord xdest, wxCoord ydest,
 515     wxCoord width, wxCoord height, wxCoord xsrc, wxCoord ysrc,
 516     int logicalFunc, bool useMask, wxCoord xsrcMask, wxCoord ysrcMask)
 517 {
 518     return false;
 519 }
 520
 521 void wxDC::DoGetSize( int* width, int* height ) const
 522 {
 523   *width = m_maxX-m_minX;
 524   *height = m_maxY-m_minY;
 525 };
 526
 527 void wxDC::DoGetSizeMM( int* width, int* height ) const
 528 {
 529   int w = 0;
 530   int h = 0;
 531   GetSize( &w, &h );
 532 };
 533
 534 void wxDC::SetTextForeground( const wxColour &col )
 535 {
 536   if (!Ok()) return;
 537   m_textForegroundColour = col;
 538 };
 539
 540 void wxDC::SetTextBackground( const wxColour &col )
 541 {
 542   if (!Ok()) return;
 543   m_textBackgroundColour = col;
 544 };
 545
 546 void wxDC::Clear()
 547 {
 548 }
 549
 550 void wxDC::SetBackground(const wxBrush& brush)
 551 {
 552     m_backgroundBrush = brush;
 553 }
 554
 555 void wxDC::SetPalette(const wxPalette&)
 556 {
 557 }
 558
 559 void wxDC::SetLogicalFunction(int)
 560 {
 561 }
 562
 563
 564 void wxDC::SetMapMode( int mode )
 565 {
 566   switch (mode)
 567   {
 568     case wxMM_TWIPS:
 569       break;
 570     case wxMM_POINTS:
 571       break;
 572     case wxMM_METRIC:
 573       break;
 574     case wxMM_LOMETRIC:
 575       break;
 576     default:
 577     case wxMM_TEXT:
 578       SetLogicalScale( 1.0, 1.0 );
 579       break;
 580   };
 581   if (mode != wxMM_TEXT)
 582   {
 583   };
 584 };
 585
 586 void wxDC::SetUserScale( double x, double y )
 587 {
 588   // allow negative ? -> no
 589   m_userScaleX = x;
 590   m_userScaleY = y;
 591   ComputeScaleAndOrigin();
 592 };
 593
 594 void wxDC::SetLogicalScale( double x, double y )
 595 {
 596   // allow negative ?
 597   m_logicalScaleX = x;
 598   m_logicalScaleY = y;
 599   ComputeScaleAndOrigin();
 600 };
 601
 602 void wxDC::SetLogicalOrigin( wxCoord x, wxCoord y )
 603 {
 604   m_logicalOriginX = x * m_signX;   // is this still correct ?
 605   m_logicalOriginY = y * m_signY;
 606   ComputeScaleAndOrigin();
 607 };
 608
 609 void wxDC::SetDeviceOrigin( wxCoord x, wxCoord y )
 610 {
 611   ComputeScaleAndOrigin();
 612 };
 613
 614 void wxDC::SetAxisOrientation( bool xLeftRight, bool yBottomUp )
 615 {
 616   m_signX = (xLeftRight ?  1 : -1);
 617   m_signY = (yBottomUp  ? -1 :  1);
 618   ComputeScaleAndOrigin();
 619 };
 620
 621 void wxDC::ComputeScaleAndOrigin(void)
 622 {
 623   // CMB: copy scale to see if it changes
 624   double origScaleX = m_scaleX;
 625   double origScaleY = m_scaleY;
 626
 627   m_scaleX = m_logicalScaleX * m_userScaleX;
 628   m_scaleY = m_logicalScaleY * m_userScaleY;
 629
 630   // CMB: if scale has changed call SetPen to recalulate the line width
 631   if (m_scaleX != origScaleX || m_scaleY != origScaleY)
 632   {
 633     // this is a bit artificial, but we need to force wxDC to think
 634     // the pen has changed
 635     wxPen* pen = & GetPen();
 636     wxPen tempPen;
 637     m_pen = tempPen;
 638     SetPen(* pen);
 639   }
 640 };
 641