interface/wx/graphics.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        graphics.h
   3 // Purpose:     interface of various wxGraphics* classes
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows licence
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxGraphicsPath
  11
  12     A wxGraphicsPath is a native representation of a geometric path. The
  13     contents are specific an private to the respective renderer. Instances are
  14     reference counted and can therefore be assigned as usual. The only way to
  15     get a valid instance is by using wxGraphicsContext::CreatePath() or
  16     wxGraphicsRenderer::CreatePath().
  17
  18     @library{wxcore}
  19     @category{gdi}
  20 */
  21 class wxGraphicsPath : public wxGraphicsObject
  22 {
  23 public:
  24     /**
  25         Adds an arc of a circle.
  26
  27         The circle is defined by the coordinates of its centre (@a x, @a y) or
  28         @a c and its radius @a r. The arc goes from the starting angle @a
  29         startAngle to @a endAngle either clockwise or counter-clockwise
  30         depending on the value of @a clockwise argument.
  31
  32         The angles are measured in radians but, contrary to the usual
  33         mathematical convention, are always @e clockwise from the horizontal
  34         axis.
  35     */
  36     //@{
  37     virtual void AddArc(wxDouble x, wxDouble y, wxDouble r,
  38                         wxDouble startAngle, wxDouble endAngle,
  39                         bool clockwise);
  40     void AddArc(const wxPoint2DDouble& c, wxDouble r,
  41                 wxDouble startAngle, wxDouble endAngle, bool clockwise);
  42     //@}
  43
  44     /**
  45         Appends a an arc to two tangents connecting (current) to (@a x1,@a y1)
  46         and (@a x1,@a y1) to (@a x2,@a y2), also a straight line from (current)
  47         to (@a x1,@a y1).
  48     */
  49     virtual void AddArcToPoint(wxDouble x1, wxDouble y1, wxDouble x2,
  50                                wxDouble y2, wxDouble r);
  51
  52     /**
  53         Appends a circle around (@a x,@a y) with radius @a r as a new closed
  54         subpath.
  55     */
  56     virtual void AddCircle(wxDouble x, wxDouble y, wxDouble r);
  57
  58     /**
  59         Adds a cubic bezier curve from the current point, using two control
  60         points and an end point.
  61     */
  62     virtual void AddCurveToPoint(wxDouble cx1, wxDouble cy1,
  63                                  wxDouble cx2, wxDouble cy2,
  64                                  wxDouble x, wxDouble y);
  65     /**
  66         Adds a cubic bezier curve from the current point, using two control
  67         points and an end point.
  68     */
  69     void AddCurveToPoint(const wxPoint2DDouble& c1,
  70                          const wxPoint2DDouble& c2,
  71                          const wxPoint2DDouble& e);
  72
  73     /**
  74         Appends an ellipse fitting into the passed in rectangle.
  75     */
  76     virtual void AddEllipse(wxDouble x, wxDouble y, wxDouble w, wxDouble h);
  77
  78     /**
  79         Adds a straight line from the current point to (@a x,@a y).
  80     */
  81     virtual void AddLineToPoint(wxDouble x, wxDouble y);
  82     /**
  83         Adds a straight line from the current point to @a p.
  84     */
  85     void AddLineToPoint(const wxPoint2DDouble& p);
  86
  87     /**
  88         Adds another path.
  89     */
  90     virtual void AddPath(const wxGraphicsPath& path);
  91
  92     /**
  93         Adds a quadratic bezier curve from the current point, using a control
  94         point and an end point.
  95     */
  96     virtual void AddQuadCurveToPoint(wxDouble cx, wxDouble cy,
  97                                      wxDouble x, wxDouble y);
  98
  99     /**
 100         Appends a rectangle as a new closed subpath.
 101     */
 102     virtual void AddRectangle(wxDouble x, wxDouble y, wxDouble w, wxDouble h);
 103
 104     /**
 105         Appends a rounded rectangle as a new closed subpath.
 106     */
 107     virtual void AddRoundedRectangle(wxDouble x, wxDouble y, wxDouble w,
 108                                      wxDouble h, wxDouble radius);
 109
 110     /**
 111         Closes the current sub-path.
 112     */
 113     virtual void CloseSubpath();
 114
 115     /**
 116         @return @true if the point is within the path.
 117     */
 118     bool Contains(const wxPoint2DDouble& c,
 119                   wxPolygonFillMode fillStyle = wxODDEVEN_RULE) const;
 120     /**
 121         @return @true if the point is within the path.
 122     */
 123     virtual bool Contains(wxDouble x, wxDouble y,
 124                           wxPolygonFillMode fillStyle = wxODDEVEN_RULE) const;
 125
 126     /**
 127         Gets the bounding box enclosing all points (possibly including control
 128         points).
 129     */
 130     wxRect2DDouble GetBox() const;
 131     /**
 132         Gets the bounding box enclosing all points (possibly including control
 133         points).
 134     */
 135     virtual void GetBox(wxDouble* x, wxDouble* y,
 136                         wxDouble* w, wxDouble* h) const;
 137
 138     /**
 139         Gets the last point of the current path, (0,0) if not yet set.
 140     */
 141     virtual void GetCurrentPoint(wxDouble* x, wxDouble* y) const;
 142     /**
 143         Gets the last point of the current path, (0,0) if not yet set.
 144     */
 145     wxPoint2DDouble GetCurrentPoint() const;
 146
 147     /**
 148         Returns the native path (CGPathRef for Core Graphics, Path pointer for
 149         GDIPlus and a cairo_path_t pointer for cairo).
 150     */
 151     virtual void* GetNativePath() const;
 152
 153     /**
 154         Begins a new subpath at (@a x,@a y).
 155     */
 156     virtual void MoveToPoint(wxDouble x, wxDouble y);
 157     /**
 158         Begins a new subpath at @a p.
 159     */
 160     void MoveToPoint(const wxPoint2DDouble& p);
 161
 162     /**
 163         Transforms each point of this path by the matrix.
 164     */
 165     virtual void Transform(const wxGraphicsMatrix& matrix);
 166
 167     /**
 168         Gives back the native path returned by GetNativePath() because there
 169         might be some deallocations necessary (e.g. on cairo the native path
 170         returned by GetNativePath() is newly allocated each time).
 171     */
 172     virtual void UnGetNativePath(void* p) const;
 173 };
 174
 175
 176
 177 /**
 178     @class wxGraphicsObject
 179
 180     This class is the superclass of native graphics objects like pens etc. It
 181     allows reference counting. Not instantiated by user code.
 182
 183     @library{wxcore}
 184     @category{gdi}
 185
 186     @see wxGraphicsBrush, wxGraphicsPen, wxGraphicsMatrix, wxGraphicsPath
 187 */
 188 class wxGraphicsObject : public wxObject
 189 {
 190 public:
 191     /**
 192         Returns the renderer that was used to create this instance, or @NULL
 193         if it has not been initialized yet.
 194     */
 195     wxGraphicsRenderer* GetRenderer() const;
 196
 197     /**
 198         @return @false if this object is valid, otherwise returns @true.
 199     */
 200     bool IsNull() const;
 201 };
 202
 203 /**
 204     Anti-aliasing modes used by wxGraphicsContext::SetAntialiasMode().
 205 */
 206 enum wxAntialiasMode
 207 {
 208     /** No anti-aliasing */
 209     wxANTIALIAS_NONE,
 210
 211     /** The default anti-aliasing */
 212     wxANTIALIAS_DEFAULT,
 213 };
 214
 215 /**
 216     Interpolation quality used by wxGraphicsContext::SetInterpolationQuality().
 217  */
 218 enum wxInterpolationQuality
 219 {
 220     /** default interpolation, based on type of context, in general medium quality */
 221     wxINTERPOLATION_DEFAULT,
 222     /** no interpolation */
 223     wxINTERPOLATION_NONE,
 224     /** fast interpolation, suited for interactivity */
 225     wxINTERPOLATION_FAST,
 226     /** better quality */
 227     wxINTERPOLATION_GOOD,
 228     /** best quality, not suited for interactivity */
 229     wxINTERPOLATION_BEST
 230 };
 231
 232 /**
 233     Compositing is done using Porter-Duff compositions
 234     (see http://keithp.com/~keithp/porterduff/p253-porter.pdf) with
 235     wxGraphicsContext::SetCompositionMode().
 236
 237     The description give a short equation on how the values of a resulting
 238     pixel are calculated.
 239     @e R = Result, @e S = Source, @e D = Destination, colors premultiplied with alpha
 240     @e Ra, @e Sa, @e Da their alpha components
 241 */
 242 enum wxCompositionMode
 243 {
 244     /**
 245         Indicates invalid or unsupported composition mode.
 246
 247         This value can't be passed to wxGraphicsContext::SetCompositionMode().
 248
 249         @since 2.9.2
 250      */
 251     wxCOMPOSITION_INVALID = -1,
 252     wxCOMPOSITION_CLEAR, /**< @e R = 0 */
 253     wxCOMPOSITION_SOURCE, /**< @e R = S */
 254     wxCOMPOSITION_OVER, /**< @e R = @e S + @e D*(1 - @e Sa) */
 255     wxCOMPOSITION_IN, /**< @e R = @e S*@e Da */
 256     wxCOMPOSITION_OUT, /**< @e R = @e S*(1 - @e Da) */
 257     wxCOMPOSITION_ATOP, /**< @e R = @e S*@e Da + @e D*(1 - @e Sa) */
 258
 259     wxCOMPOSITION_DEST, /**< @e R = @e D, essentially a noop */
 260     wxCOMPOSITION_DEST_OVER, /**< @e R = @e S*(1 - @e Da) + @e D */
 261     wxCOMPOSITION_DEST_IN, /**< @e R = @e D*@e Sa */
 262     wxCOMPOSITION_DEST_OUT, /**< @e R = @e D*(1 - @e Sa) */
 263     wxCOMPOSITION_DEST_ATOP, /**< @e R = @e S*(1 - @e Da) + @e D*@e Sa */
 264     wxCOMPOSITION_XOR, /**< @e R = @e S*(1 - @e Da) + @e D*(1 - @e Sa) */
 265     wxCOMPOSITION_ADD  /**< @e R = @e S + @e D */
 266 };
 267
 268 /**
 269     Represents a bitmap.
 270
 271     The objects of this class are not created directly but only via
 272     wxGraphicsContext or wxGraphicsRenderer CreateBitmap(),
 273     CreateBitmapFromImage() or CreateSubBitmap() methods. They can subsequently
 274     be used with wxGraphicsContext::DrawBitmap(). The only other operation is
 275     testing for the bitmap validity which can be performed using IsNull()
 276     method inherited from the base class.
 277  */
 278 class wxGraphicsBitmap : public wxGraphicsObject
 279 {
 280 public:
 281     /**
 282         Default constructor creates an invalid bitmap.
 283      */
 284     wxGraphicsBitmap() {}
 285
 286     /**
 287         Return the contents of this bitmap as wxImage.
 288
 289         Using this method is more efficient than converting wxGraphicsBitmap to
 290         wxBitmap first and then to wxImage and can be useful if, for example,
 291         you want to save wxGraphicsBitmap as a disk file in a format not
 292         directly supported by wxBitmap.
 293
 294         Invalid image is returned if the bitmap is invalid.
 295
 296         @since 2.9.3
 297      */
 298     wxImage ConvertToImage() const;
 299 };
 300
 301 /**
 302     @class wxGraphicsContext
 303
 304     A wxGraphicsContext instance is the object that is drawn upon. It is
 305     created by a renderer using wxGraphicsRenderer::CreateContext(). This can
 306     be either directly using a renderer instance, or indirectly using the
 307     static convenience Create() functions of wxGraphicsContext that always
 308     delegate the task to the default renderer.
 309
 310     @code
 311     void MyCanvas::OnPaint(wxPaintEvent &event)
 312     {
 313         // Create paint DC
 314         wxPaintDC dc(this);
 315
 316         // Create graphics context from it
 317         wxGraphicsContext *gc = wxGraphicsContext::Create( dc );
 318
 319         if (gc)
 320         {
 321             // make a path that contains a circle and some lines
 322             gc->SetPen( *wxRED_PEN );
 323             wxGraphicsPath path = gc->CreatePath();
 324             path.AddCircle( 50.0, 50.0, 50.0 );
 325             path.MoveToPoint(0.0, 50.0);
 326             path.AddLineToPoint(100.0, 50.0);
 327             path.MoveToPoint(50.0, 0.0);
 328             path.AddLineToPoint(50.0, 100.0 );
 329             path.CloseSubpath();
 330             path.AddRectangle(25.0, 25.0, 50.0, 50.0);
 331
 332             gc->StrokePath(path);
 333
 334             delete gc;
 335         }
 336     }
 337     @endcode
 338
 339     @library{wxcore}
 340     @category{gdi,dc}
 341
 342     @see wxGraphicsRenderer::CreateContext(), wxGCDC, wxDC
 343 */
 344 class wxGraphicsContext : public wxGraphicsObject
 345 {
 346 public:
 347     /**
 348         Creates a wxGraphicsContext from a wxWindow.
 349
 350         @see wxGraphicsRenderer::CreateContext()
 351     */
 352     static wxGraphicsContext* Create(wxWindow* window);
 353
 354     /**
 355         Creates a wxGraphicsContext from a wxWindowDC
 356
 357         @see wxGraphicsRenderer::CreateContext()
 358     */
 359     static wxGraphicsContext* Create(const wxWindowDC& windowDC);
 360
 361     /**
 362         Creates a wxGraphicsContext from a wxMemoryDC
 363
 364         @see wxGraphicsRenderer::CreateContext()
 365     */
 366     static wxGraphicsContext* Create(const wxMemoryDC& memoryDC);
 367
 368     /**
 369         Creates a wxGraphicsContext from a wxPrinterDC. Under GTK+, this will
 370         only work when using the GtkPrint printing backend which is available
 371         since GTK+ 2.10.
 372
 373         @see wxGraphicsRenderer::CreateContext(), @ref overview_unixprinting
 374     */
 375     static wxGraphicsContext* Create(const wxPrinterDC& printerDC);
 376
 377     /**
 378         Creates a wxGraphicsContext from a wxEnhMetaFileDC.
 379
 380         This function, as wxEnhMetaFileDC class itself, is only available only
 381         under MSW.
 382
 383         @see wxGraphicsRenderer::CreateContext()
 384     */
 385     static wxGraphicsContext* Create(const wxEnhMetaFileDC& metaFileDC);
 386
 387     /**
 388         Creates a wxGraphicsContext associated with a wxImage.
 389
 390         The image specifies the size of the context as well as whether alpha is
 391         supported (if wxImage::HasAlpha()) or not and the initial contents of
 392         the context. The @a image object must have a life time greater than
 393         that of the new context as the context copies its contents back to the
 394         image when it is destroyed.
 395
 396         @since 2.9.3
 397      */
 398     static wxGraphicsContext* Create(wxImage& image);
 399
 400     /**
 401         Clips drawings to the specified region.
 402     */
 403     virtual void Clip(const wxRegion& region) = 0;
 404
 405     /**
 406         Clips drawings to the specified rectangle.
 407     */
 408     virtual void Clip(wxDouble x, wxDouble y, wxDouble w, wxDouble h) = 0;
 409
 410     /**
 411         Concatenates the passed in transform with the current transform of this
 412         context.
 413     */
 414     virtual void ConcatTransform(const wxGraphicsMatrix& matrix) = 0;
 415
 416     /**
 417         Creates wxGraphicsBitmap from an existing wxBitmap.
 418
 419         Returns an invalid wxNullGraphicsBitmap on failure.
 420      */
 421     virtual wxGraphicsBitmap CreateBitmap( const wxBitmap &bitmap ) = 0;
 422
 423     /**
 424         Creates wxGraphicsBitmap from an existing wxImage.
 425
 426         This method is more efficient than converting wxImage to wxBitmap first
 427         and then calling CreateBitmap() but otherwise has the same effect.
 428
 429         Returns an invalid wxNullGraphicsBitmap on failure.
 430
 431         @since 2.9.3
 432      */
 433     virtual wxGraphicsBitmap CreateBitmapFromImage(const wxImage& image);
 434
 435     /**
 436         Extracts a sub-bitmap from an existing bitmap.
 437
 438         Currently this function is implemented in the native MSW and OS X
 439         versions but not when using Cairo.
 440      */
 441     virtual wxGraphicsBitmap CreateSubBitmap(const wxGraphicsBitmap& bitmap,
 442                                              wxDouble x, wxDouble y,
 443                                              wxDouble w, wxDouble h) = 0;
 444
 445     /**
 446         Creates a native brush from a wxBrush.
 447     */
 448     virtual wxGraphicsBrush CreateBrush(const wxBrush& brush) const;
 449
 450     /**
 451         Creates a native graphics font from a wxFont and a text colour.
 452     */
 453     virtual wxGraphicsFont CreateFont(const wxFont& font,
 454                                       const wxColour& col = *wxBLACK) const;
 455
 456     /**
 457         Creates a font object with the specified attributes.
 458
 459         The use of overload taking wxFont is preferred, see
 460         wxGraphicsRenderer::CreateFont() for more details.
 461
 462         @since 2.9.3
 463      */
 464     virtual wxGraphicsFont CreateFont(double sizeInPixels,
 465                                       const wxString& facename,
 466                                       int flags = wxFONTFLAG_DEFAULT,
 467                                       const wxColour& col = *wxBLACK) const;
 468
 469     /**
 470         Creates a wxGraphicsContext from a native context. This native context
 471         must be a CGContextRef for Core Graphics, a Graphics pointer for
 472         GDIPlus, or a cairo_t pointer for cairo.
 473
 474         @see wxGraphicsRenderer::CreateContextFromNativeContext()
 475     */
 476     static wxGraphicsContext* CreateFromNative(void* context);
 477
 478     /**
 479         Creates a wxGraphicsContext from a native window.
 480
 481         @see wxGraphicsRenderer::CreateContextFromNativeWindow()
 482     */
 483     static wxGraphicsContext* CreateFromNativeWindow(void* window);
 484
 485     /**
 486         Creates a native brush with a linear gradient.
 487
 488         The brush starts at (@a x1, @a y1) and ends at (@a x2, @a y2). Either
 489         just the start and end gradient colours (@a c1 and @a c2) or full set
 490         of gradient @a stops can be specified.
 491
 492         The version taking wxGraphicsGradientStops is new in wxWidgets 2.9.1.
 493     */
 494     //@{
 495     wxGraphicsBrush
 496     CreateLinearGradientBrush(wxDouble x1, wxDouble y1,
 497                               wxDouble x2, wxDouble y2,
 498                               const wxColour& c1, const wxColour& c2) const;
 499
 500     wxGraphicsBrush
 501     CreateLinearGradientBrush(wxDouble x1, wxDouble y1,
 502                               wxDouble x2, wxDouble y2,
 503                               const wxGraphicsGradientStops& stops) const;
 504     //@}
 505
 506     /**
 507         Creates a native affine transformation matrix from the passed in
 508         values. The default parameters result in an identity matrix.
 509     */
 510     virtual wxGraphicsMatrix CreateMatrix(wxDouble a = 1.0, wxDouble b = 0.0,
 511                                           wxDouble c = 0.0, wxDouble d = 1.0,
 512                                           wxDouble tx = 0.0,
 513                                           wxDouble ty = 0.0) const;
 514
 515     /**
 516         Creates a native graphics path which is initially empty.
 517     */
 518     wxGraphicsPath CreatePath() const;
 519
 520     /**
 521         Creates a native pen from a wxPen.
 522     */
 523     virtual wxGraphicsPen CreatePen(const wxPen& pen) const;
 524
 525     /**
 526         Creates a native brush with a radial gradient.
 527
 528         The brush originates at (@a xo, @a yc) and ends on a circle around
 529         (@a xc, @a yc) with the given @a radius.
 530
 531         The gradient may be specified either by its start and end colours @a
 532         oColor and @a cColor or by a full set of gradient @a stops.
 533
 534         The version taking wxGraphicsGradientStops is new in wxWidgets 2.9.1.
 535     */
 536     //@{
 537     virtual wxGraphicsBrush
 538     CreateRadialGradientBrush(wxDouble xo, wxDouble yo,
 539                               wxDouble xc, wxDouble yc,
 540                               wxDouble radius,
 541                               const wxColour& oColor,
 542                               const wxColour& cColor) const;
 543
 544     virtual wxGraphicsBrush
 545     CreateRadialGradientBrush(wxDouble xo, wxDouble yo,
 546                               wxDouble xc, wxDouble yc,
 547                               wxDouble radius,
 548                               const wxGraphicsGradientStops& stops) = 0;
 549     //@}
 550
 551     /**
 552         Draws the bitmap. In case of a mono bitmap, this is treated as a mask
 553         and the current brushed is used for filling.
 554     */
 555     //@{
 556     virtual void DrawBitmap(const wxGraphicsBitmap& bmp,
 557                             wxDouble x, wxDouble y,
 558                             wxDouble w, wxDouble h ) = 0;
 559     virtual void DrawBitmap(const wxBitmap& bmp,
 560                             wxDouble x, wxDouble y,
 561                             wxDouble w, wxDouble h) = 0;
 562     //@}
 563
 564     /**
 565         Draws an ellipse.
 566     */
 567     virtual void DrawEllipse(wxDouble x, wxDouble y, wxDouble w, wxDouble h);
 568
 569     /**
 570         Draws the icon.
 571     */
 572     virtual void DrawIcon(const wxIcon& icon, wxDouble x, wxDouble y,
 573                           wxDouble w, wxDouble h) = 0;
 574
 575     /**
 576         Draws a polygon.
 577     */
 578     virtual void DrawLines(size_t n, const wxPoint2DDouble* points,
 579                            wxPolygonFillMode fillStyle = wxODDEVEN_RULE);
 580
 581     /**
 582         Draws the path by first filling and then stroking.
 583     */
 584     virtual void DrawPath(const wxGraphicsPath& path,
 585                           wxPolygonFillMode fillStyle = wxODDEVEN_RULE);
 586
 587     /**
 588         Draws a rectangle.
 589     */
 590     virtual void DrawRectangle(wxDouble x, wxDouble y, wxDouble w, wxDouble h);
 591
 592     /**
 593         Draws a rounded rectangle.
 594     */
 595     virtual void DrawRoundedRectangle(wxDouble x, wxDouble y, wxDouble w,
 596                                       wxDouble h, wxDouble radius);
 597
 598     /**
 599         Draws text at the defined position.
 600     */
 601     void DrawText(const wxString& str, wxDouble x, wxDouble y);
 602     /**
 603         Draws text at the defined position.
 604
 605         @param str
 606             The text to draw.
 607         @param x
 608             The x coordinate position to draw the text at.
 609         @param y
 610             The y coordinate position to draw the text at.
 611         @param angle
 612             The angle relative to the (default) horizontal direction to draw
 613             the string.
 614     */
 615     void DrawText(const wxString& str, wxDouble x, wxDouble y, wxDouble angle);
 616     /**
 617         Draws text at the defined position.
 618
 619         @param str
 620             The text to draw.
 621         @param x
 622             The x coordinate position to draw the text at.
 623         @param y
 624             The y coordinate position to draw the text at.
 625         @param backgroundBrush
 626             Brush to fill the text with.
 627     */
 628     void DrawText(const wxString& str, wxDouble x, wxDouble y,
 629                   const wxGraphicsBrush& backgroundBrush);
 630     /**
 631         Draws text at the defined position.
 632
 633         @param str
 634             The text to draw.
 635         @param x
 636             The x coordinate position to draw the text at.
 637         @param y
 638             The y coordinate position to draw the text at.
 639         @param angle
 640             The angle relative to the (default) horizontal direction to draw
 641             the string.
 642         @param backgroundBrush
 643             Brush to fill the text with.
 644     */
 645     void DrawText(const wxString& str, wxDouble x, wxDouble y,
 646                   wxDouble angle, const wxGraphicsBrush& backgroundBrush);
 647
 648     /**
 649         Fills the path with the current brush.
 650     */
 651     virtual void FillPath(const wxGraphicsPath& path,
 652                           wxPolygonFillMode fillStyle = wxODDEVEN_RULE) = 0;
 653
 654     /**
 655         Returns the native context (CGContextRef for Core Graphics, Graphics
 656         pointer for GDIPlus and cairo_t pointer for cairo).
 657     */
 658     virtual void* GetNativeContext() = 0;
 659
 660     /**
 661         Fills the @a widths array with the widths from the beginning of
 662         @a text to the corresponding character of @a text.
 663     */
 664     virtual void GetPartialTextExtents(const wxString& text,
 665                                        wxArrayDouble& widths) const = 0;
 666
 667     /**
 668         Gets the dimensions of the string using the currently selected font.
 669
 670         @param text
 671             The text string to measure.
 672         @param width
 673             Variable to store the total calculated width of the text.
 674         @param height
 675             Variable to store the total calculated height of the text.
 676         @param descent
 677             Variable to store the dimension from the baseline of the font to
 678             the bottom of the descender.
 679         @param externalLeading
 680             Any extra vertical space added to the font by the font designer
 681             (usually is zero).
 682     */
 683     virtual void GetTextExtent(const wxString& text, wxDouble* width,
 684                                wxDouble* height, wxDouble* descent,
 685                                wxDouble* externalLeading) const = 0;
 686
 687     /**
 688         Gets the current transformation matrix of this context.
 689     */
 690     virtual wxGraphicsMatrix GetTransform() const = 0;
 691
 692     /**
 693         Resets the clipping to original shape.
 694     */
 695     virtual void ResetClip() = 0;
 696
 697     /**
 698         Rotates the current transformation matrix (in radians).
 699     */
 700     virtual void Rotate(wxDouble angle) = 0;
 701
 702     /**
 703         Scales the current transformation matrix.
 704     */
 705     virtual void Scale(wxDouble xScale, wxDouble yScale) = 0;
 706
 707     /**
 708         Sets the brush for filling paths.
 709     */
 710     void SetBrush(const wxBrush& brush);
 711     /**
 712         Sets the brush for filling paths.
 713     */
 714     virtual void SetBrush(const wxGraphicsBrush& brush);
 715
 716     /**
 717         Sets the font for drawing text.
 718     */
 719     void SetFont(const wxFont& font, const wxColour& colour);
 720     /**
 721         Sets the font for drawing text.
 722     */
 723     virtual void SetFont(const wxGraphicsFont& font);
 724
 725     /**
 726         Sets the pen used for stroking.
 727     */
 728     void SetPen(const wxPen& pen);
 729     /**
 730         Sets the pen used for stroking.
 731     */
 732     virtual void SetPen(const wxGraphicsPen& pen);
 733
 734     /**
 735         Sets the current transformation matrix of this context
 736     */
 737     virtual void SetTransform(const wxGraphicsMatrix& matrix) = 0;
 738
 739     /**
 740         Strokes a single line.
 741     */
 742     virtual void StrokeLine(wxDouble x1, wxDouble y1, wxDouble x2, wxDouble y2);
 743
 744     /**
 745         Stroke disconnected lines from begin to end points, fastest method
 746         available for this purpose.
 747     */
 748     virtual void StrokeLines(size_t n, const wxPoint2DDouble* beginPoints,
 749                              const wxPoint2DDouble* endPoints);
 750     /**
 751         Stroke lines connecting all the points.
 752
 753         Unlike the other overload of this function, this method draws a single
 754         polyline and not a number of disconnected lines.
 755     */
 756     virtual void StrokeLines(size_t n, const wxPoint2DDouble* points);
 757
 758     /**
 759         Strokes along a path with the current pen.
 760     */
 761     virtual void StrokePath(const wxGraphicsPath& path) = 0;
 762
 763     /**
 764         Translates the current transformation matrix.
 765     */
 766     virtual void Translate(wxDouble dx, wxDouble dy) = 0;
 767
 768     /**
 769         Redirects all rendering is done into a fully transparent temporary context
 770     */
 771     virtual void BeginLayer(wxDouble opacity) = 0;
 772
 773     /**
 774         Composites back the drawings into the context with the opacity given at
 775         the BeginLayer call
 776     */
 777     virtual void EndLayer() = 0;
 778
 779     /**
 780         Sets the antialiasing mode, returns true if it supported
 781     */
 782     virtual bool SetAntialiasMode(wxAntialiasMode antialias) = 0;
 783
 784     /**
 785         Returns the current shape antialiasing mode
 786     */
 787     virtual wxAntialiasMode GetAntialiasMode() const ;
 788
 789     /**
 790         Sets the interpolation quality, returns true if it supported
 791      */
 792     virtual bool SetInterpolationQuality(wxInterpolationQuality interpolation) = 0;
 793
 794     /**
 795         Returns the current interpolation quality
 796      */
 797     virtual wxInterpolationQuality GetInterpolationQuality() const;
 798
 799     /**
 800         Sets the compositing operator, returns true if it supported
 801     */
 802     virtual bool SetCompositionMode(wxCompositionMode op) = 0;
 803
 804     /**
 805         Returns the current compositing operator
 806     */
 807     virtual wxCompositionMode GetCompositionMode() const;
 808
 809
 810     virtual void EnableOffset(bool enable = true);
 811     void DisableOffset();
 812     bool OffsetEnabled();
 813
 814 };
 815
 816 /**
 817     Represents a single gradient stop in a collection of gradient stops as
 818     represented by wxGraphicsGradientStops.
 819
 820     @library{wxcore}
 821     @category{gdi}
 822
 823     @since 2.9.1
 824 */
 825 class wxGraphicsGradientStop
 826 {
 827 public:
 828     /**
 829         Creates a stop with the given colour and position.
 830
 831         @param col The colour of this stop. Note that the alpha component of
 832             the colour is honoured thus allowing the background colours to
 833             partially show through the gradient.
 834         @param pos The stop position, must be in [0, 1] range with 0 being the
 835             beginning and 1 the end of the gradient.
 836     */
 837     wxGraphicsGradientStop(wxColour col = wxTransparentColour, float pos = 0.);
 838
 839     /// Return the stop colour.
 840     const wxColour& GetColour() const;
 841
 842     /**
 843         Change the stop colour.
 844
 845         @param col The new colour.
 846     */
 847     void SetColour(const wxColour& col);
 848
 849     /// Return the stop position.
 850     float GetPosition() const;
 851
 852     /**
 853         Change the stop position.
 854
 855         @param pos The new position, must always be in [0, 1] range.
 856     */
 857     void SetPosition(float pos);
 858 };
 859
 860 /**
 861     Represents a collection of wxGraphicGradientStop values for use with
 862     CreateLinearGradientBrush and CreateRadialGradientBrush.
 863
 864     The stops are maintained in order of position.  If two or more stops are
 865     added with the same position then the one(s) added later come later.
 866     This can be useful for producing discontinuities in the colour gradient.
 867
 868     Notice that this class is write-once, you can't modify the stops once they
 869     had been added.
 870
 871     @library{wxcore}
 872     @category{gdi}
 873
 874     @since 2.9.1
 875 */
 876 class wxGraphicsGradientStops
 877 {
 878 public:
 879     /**
 880         Initializes the gradient stops with the given boundary colours.
 881
 882         Creates a wxGraphicsGradientStops instance with start colour given
 883         by @a startCol and end colour given by @a endCol.
 884     */
 885     wxGraphicsGradientStops(wxColour startCol = wxTransparentColour,
 886                             wxColour endCol = wxTransparentColour);
 887
 888     /**
 889         Add a new stop.
 890     */
 891     //@{
 892     void Add(const wxGraphicsGradientStop& stop);
 893     void Add(wxColour col, float pos);
 894     //@}
 895
 896     /**
 897         Returns the stop at the given index.
 898
 899         @param n The index, must be in [0, GetCount()) range.
 900     */
 901     wxGraphicsGradientStop Item(unsigned n) const;
 902
 903     /**
 904         Returns the number of stops.
 905     */
 906     unsigned GetCount() const;
 907
 908     /**
 909         Set the start colour to @a col
 910     */
 911     void SetStartColour(wxColour col);
 912
 913     /**
 914         Returns the start colour.
 915     */
 916     wxColour GetStartColour() const;
 917
 918     /**
 919         Set the end colour to @a col
 920     */
 921     void SetEndColour(wxColour col);
 922
 923     /**
 924         Returns the end colour.
 925     */
 926     wxColour GetEndColour() const;
 927 };
 928
 929 /**
 930     @class wxGraphicsRenderer
 931
 932     A wxGraphicsRenderer is the instance corresponding to the rendering engine
 933     used. There may be multiple instances on a system, if there are different
 934     rendering engines present, but there is always only one instance per
 935     engine. This instance is pointed back to by all objects created by it
 936     (wxGraphicsContext, wxGraphicsPath etc) and can be retrieved through their
 937     wxGraphicsObject::GetRenderer() method. Therefore you can create an
 938     additional instance of a path etc. by calling
 939     wxGraphicsObject::GetRenderer() and then using the appropriate CreateXXX()
 940     function of that renderer.
 941
 942     @code
 943     wxGraphicsPath *path = // from somewhere
 944     wxGraphicsBrush *brush = path->GetRenderer()->CreateBrush( *wxBLACK_BRUSH );
 945     @endcode
 946
 947     @library{wxcore}
 948     @category{gdi}
 949 */
 950 class wxGraphicsRenderer : public wxObject
 951 {
 952 public:
 953     /**
 954         Creates wxGraphicsBitmap from an existing wxBitmap.
 955
 956         Returns an invalid wxNullGraphicsBitmap on failure.
 957      */
 958     virtual wxGraphicsBitmap CreateBitmap( const wxBitmap &bitmap ) = 0;
 959
 960     /**
 961         Creates wxGraphicsBitmap from an existing wxImage.
 962
 963         This method is more efficient than converting wxImage to wxBitmap first
 964         and then calling CreateBitmap() but otherwise has the same effect.
 965
 966         Returns an invalid wxNullGraphicsBitmap on failure.
 967
 968         @since 2.9.3
 969      */
 970     virtual wxGraphicsBitmap CreateBitmapFromImage(const wxImage& image) = 0;
 971
 972     /**
 973        Creates a wxImage from a wxGraphicsBitmap.
 974
 975        This method is used by the more convenient wxGraphicsBitmap::ConvertToImage.
 976     */
 977     virtual wxImage CreateImageFromBitmap(const wxGraphicsBitmap& bmp) = 0;
 978
 979     /**
 980         Creates wxGraphicsBitmap from a native bitmap handle.
 981
 982         @a bitmap meaning is platform-dependent. Currently it's a GDI+ @c
 983         Bitmap pointer under MSW, @c CGImage pointer under OS X or a @c
 984         cairo_surface_t pointer when using Cairo under any platform.
 985      */
 986     virtual wxGraphicsBitmap CreateBitmapFromNativeBitmap( void* bitmap ) = 0;
 987
 988     /**
 989         Creates a wxGraphicsContext from a wxWindow.
 990     */
 991     virtual wxGraphicsContext* CreateContext(wxWindow* window) = 0;
 992
 993     /**
 994         Creates a wxGraphicsContext from a wxWindowDC
 995     */
 996     virtual wxGraphicsContext* CreateContext(const wxWindowDC& windowDC) = 0 ;
 997
 998     /**
 999         Creates a wxGraphicsContext from a wxMemoryDC
1000     */
1001     virtual wxGraphicsContext* CreateContext(const wxMemoryDC& memoryDC) = 0 ;
1002
1003     /**
1004         Creates a wxGraphicsContext from a wxPrinterDC
1005     */
1006     virtual wxGraphicsContext* CreateContext(const wxPrinterDC& printerDC) = 0 ;
1007
1008     /**
1009         Creates a wxGraphicsContext from a wxEnhMetaFileDC.
1010
1011         This function, as wxEnhMetaFileDC class itself, is only available only
1012         under MSW.
1013     */
1014     virtual wxGraphicsContext* CreateContext(const wxEnhMetaFileDC& metaFileDC) = 0;
1015
1016     /**
1017         Creates a wxGraphicsContext associated with a wxImage.
1018
1019         This function is used by wxContext::CreateFromImage() and is not
1020         normally called directly.
1021
1022         @since 2.9.3
1023      */
1024     wxGraphicsContext* CreateContextFromImage(wxImage& image);
1025
1026     /**
1027         Creates a native brush from a wxBrush.
1028     */
1029     virtual wxGraphicsBrush CreateBrush(const wxBrush& brush) = 0;
1030
1031     /**
1032         Creates a wxGraphicsContext from a native context. This native context
1033         must be a CGContextRef for Core Graphics, a Graphics pointer for
1034         GDIPlus, or a cairo_t pointer for cairo.
1035     */
1036     virtual wxGraphicsContext* CreateContextFromNativeContext(void* context) = 0;
1037
1038     /**
1039         Creates a wxGraphicsContext from a native window.
1040     */
1041     virtual wxGraphicsContext* CreateContextFromNativeWindow(void* window) = 0;
1042
1043     /**
1044         Creates a wxGraphicsContext that can be used for measuring texts only.
1045         No drawing commands are allowed.
1046     */
1047     virtual wxGraphicsContext * CreateMeasuringContext() = 0;
1048
1049     /**
1050         Creates a native graphics font from a wxFont and a text colour.
1051     */
1052     virtual wxGraphicsFont CreateFont(const wxFont& font,
1053                                       const wxColour& col = *wxBLACK) = 0;
1054
1055     /**
1056         Creates a graphics font with the given characteristics.
1057
1058         If possible, the CreateFont() overload taking wxFont should be used
1059         instead. The main advantage of this overload is that it can be used
1060         without X server connection under Unix when using Cairo.
1061
1062         @param sizeInPixels
1063             Height of the font in user space units, i.e. normally pixels.
1064             Notice that this is different from the overload taking wxFont as
1065             wxFont size is specified in points.
1066         @param facename
1067             The name of the font. The same font name might not be available
1068             under all platforms so the font name can also be empty to use the
1069             default platform font.
1070         @param flags
1071             Combination of wxFontFlag enum elements. Currently only
1072             @c wxFONTFLAG_ITALIC and @c wxFONTFLAG_BOLD are supported. By
1073             default the normal font version is used.
1074         @param col
1075             The font colour, black by default.
1076
1077         @since 2.9.3
1078      */
1079     virtual wxGraphicsFont CreateFont(double sizeInPixels,
1080                                       const wxString& facename,
1081                                       int flags = wxFONTFLAG_DEFAULT,
1082                                       const wxColour& col = *wxBLACK) = 0;
1083
1084
1085     /**
1086         Creates a native brush with a linear gradient.
1087
1088         Stops support is new since wxWidgets 2.9.1, previously only the start
1089         and end colours could be specified.
1090     */
1091     virtual wxGraphicsBrush CreateLinearGradientBrush(wxDouble x1,
1092                                                       wxDouble y1,
1093                                                       wxDouble x2,
1094                                                       wxDouble y2,
1095                                                       const wxGraphicsGradientStops& stops) = 0;
1096
1097     /**
1098         Creates a native affine transformation matrix from the passed in
1099         values. The defaults result in an identity matrix.
1100     */
1101     virtual wxGraphicsMatrix CreateMatrix(wxDouble a = 1.0, wxDouble b = 0.0,
1102                                           wxDouble c = 0.0, wxDouble d = 1.0,
1103                                           wxDouble tx = 0.0,
1104                                           wxDouble ty = 0.0) = 0;
1105
1106     /**
1107         Creates a native graphics path which is initially empty.
1108     */
1109     virtual wxGraphicsPath CreatePath() = 0;
1110
1111     /**
1112         Creates a native pen from a wxPen.
1113     */
1114     virtual wxGraphicsPen CreatePen(const wxPen& pen) = 0;
1115
1116     /**
1117         Creates a native brush with a radial gradient.
1118
1119         Stops support is new since wxWidgets 2.9.1, previously only the start
1120         and end colours could be specified.
1121     */
1122     virtual wxGraphicsBrush CreateRadialGradientBrush(wxDouble xo, wxDouble yo,
1123                                                       wxDouble xc, wxDouble yc,
1124                                                       wxDouble radius,
1125                                                       const wxGraphicsGradientStops& stops) = 0;
1126
1127     /**
1128         Extracts a sub-bitmap from an existing bitmap.
1129
1130         Currently this function is implemented in the native MSW and OS X
1131         versions but not when using Cairo.
1132      */
1133     virtual wxGraphicsBitmap CreateSubBitmap(const wxGraphicsBitmap& bitmap,
1134                                              wxDouble x, wxDouble y,
1135                                              wxDouble w, wxDouble h) = 0;
1136
1137     /**
1138         Returns the default renderer on this platform. On OS X this is the Core
1139         Graphics (a.k.a. Quartz 2D) renderer, on MSW the GDIPlus renderer, and
1140         on GTK we currently default to the cairo renderer.
1141     */
1142     static wxGraphicsRenderer* GetDefaultRenderer();
1143     static wxGraphicsRenderer* GetCairoRenderer();
1144
1145 };
1146
1147
1148
1149 /**
1150     @class wxGraphicsBrush
1151
1152     A wxGraphicsBrush is a native representation of a brush. The contents are
1153     specific and private to the respective renderer. Instances are ref counted
1154     and can therefore be assigned as usual. The only way to get a valid
1155     instance is via wxGraphicsContext::CreateBrush() or
1156     wxGraphicsRenderer::CreateBrush().
1157
1158     @library{wxcore}
1159     @category{gdi}
1160 */
1161 class wxGraphicsBrush : public wxGraphicsObject
1162 {
1163 public:
1164
1165 };
1166
1167
1168
1169 /**
1170     @class wxGraphicsFont
1171
1172     A wxGraphicsFont is a native representation of a font. The contents are
1173     specific and private to the respective renderer. Instances are ref counted
1174     and can therefore be assigned as usual. The only way to get a valid
1175     instance is via wxGraphicsContext::CreateFont() or
1176     wxGraphicsRenderer::CreateFont().
1177
1178     @library{wxcore}
1179     @category{gdi}
1180 */
1181 class wxGraphicsFont : public wxGraphicsObject
1182 {
1183 public:
1184
1185 };
1186
1187
1188
1189 /**
1190     @class wxGraphicsPen
1191
1192     A wxGraphicsPen is a native representation of a pen. The contents are
1193     specific and private to the respective renderer. Instances are ref counted
1194     and can therefore be assigned as usual. The only way to get a valid
1195     instance is via wxGraphicsContext::CreatePen() or
1196     wxGraphicsRenderer::CreatePen().
1197
1198     @library{wxcore}
1199     @category{gdi}
1200 */
1201 class wxGraphicsPen : public wxGraphicsObject
1202 {
1203 public:
1204
1205 };
1206
1207
1208
1209 /**
1210     @class wxGraphicsMatrix
1211
1212     A wxGraphicsMatrix is a native representation of an affine matrix. The
1213     contents are specific and private to the respective renderer. Instances are
1214     ref counted and can therefore be assigned as usual. The only way to get a
1215     valid instance is via wxGraphicsContext::CreateMatrix() or
1216     wxGraphicsRenderer::CreateMatrix().
1217
1218     @library{wxcore}
1219     @category{gdi}
1220 */
1221 class wxGraphicsMatrix : public wxGraphicsObject
1222 {
1223 public:
1224     /**
1225         Concatenates the matrix passed with the current matrix.
1226     */
1227     virtual void Concat(const wxGraphicsMatrix* t);
1228     /**
1229         Concatenates the matrix passed with the current matrix.
1230     */
1231     void Concat(const wxGraphicsMatrix& t);
1232
1233     /**
1234         Returns the component values of the matrix via the argument pointers.
1235     */
1236     virtual void Get(wxDouble* a = NULL, wxDouble* b = NULL,
1237                      wxDouble* c = NULL, wxDouble* d = NULL,
1238                      wxDouble* tx = NULL, wxDouble* ty = NULL) const;
1239
1240     /**
1241         Returns the native representation of the matrix. For CoreGraphics this
1242         is a CFAffineMatrix pointer, for GDIPlus a Matrix Pointer, and for
1243         Cairo a cairo_matrix_t pointer.
1244     */
1245     virtual void* GetNativeMatrix() const;
1246
1247     /**
1248         Inverts the matrix.
1249     */
1250     virtual void Invert();
1251
1252     /**
1253         Returns @true if the elements of the transformation matrix are equal.
1254     */
1255     virtual bool IsEqual(const wxGraphicsMatrix* t) const;
1256     /**
1257         Returns @true if the elements of the transformation matrix are equal.
1258     */
1259     bool IsEqual(const wxGraphicsMatrix& t) const;
1260
1261     /**
1262         Return @true if this is the identity matrix.
1263     */
1264     virtual bool IsIdentity() const;
1265
1266     /**
1267         Rotates this matrix (in radians).
1268     */
1269     virtual void Rotate(wxDouble angle);
1270
1271     /**
1272         Scales this matrix.
1273     */
1274     virtual void Scale(wxDouble xScale, wxDouble yScale);
1275
1276     /**
1277         Sets the matrix to the respective values (default values are the
1278         identity matrix).
1279     */
1280     virtual void Set(wxDouble a = 1.0, wxDouble b = 0.0, wxDouble c = 0.0,
1281                      wxDouble d = 1.0, wxDouble tx = 0.0, wxDouble ty = 0.0);
1282
1283     /**
1284         Applies this matrix to a distance (ie. performs all transforms except
1285         translations).
1286     */
1287     virtual void TransformDistance(wxDouble* dx, wxDouble* dy) const;
1288
1289     /**
1290         Applies this matrix to a point.
1291     */
1292     virtual void TransformPoint(wxDouble* x, wxDouble* y) const;
1293
1294     /**
1295         Translates this matrix.
1296     */
1297     virtual void Translate(wxDouble dx, wxDouble dy);
1298 };
1299
1300
1301 const wxGraphicsPen     wxNullGraphicsPen;
1302 const wxGraphicsBrush   wxNullGraphicsBrush;
1303 const wxGraphicsFont    wxNullGraphicsFont;
1304 const wxGraphicsBitmap  wxNullGraphicsBitmap;
1305 const wxGraphicsMatrix  wxNullGraphicsMatrix;
1306 const wxGraphicsPath    wxNullGraphicsPath;