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 wxGraphicsBitmap from a native bitmap handle.
 974
 975         @a bitmap meaning is platform-dependent. Currently it's a GDI+ @c
 976         Bitmap pointer under MSW, @c CGImage pointer under OS X or a @c
 977         cairo_surface_t pointer when using Cairo under any platform.
 978      */
 979     virtual wxGraphicsBitmap CreateBitmapFromNativeBitmap( void* bitmap ) = 0;
 980
 981     /**
 982         Creates a wxGraphicsContext from a wxWindow.
 983     */
 984     virtual wxGraphicsContext* CreateContext(wxWindow* window) = 0;
 985
 986     /**
 987         Creates a wxGraphicsContext from a wxWindowDC
 988     */
 989     virtual wxGraphicsContext* CreateContext(const wxWindowDC& windowDC) = 0 ;
 990
 991     /**
 992         Creates a wxGraphicsContext from a wxMemoryDC
 993     */
 994     virtual wxGraphicsContext* CreateContext(const wxMemoryDC& memoryDC) = 0 ;
 995
 996     /**
 997         Creates a wxGraphicsContext from a wxPrinterDC
 998     */
 999     virtual wxGraphicsContext* CreateContext(const wxPrinterDC& printerDC) = 0 ;
1000
1001     /**
1002         Creates a wxGraphicsContext from a wxEnhMetaFileDC.
1003
1004         This function, as wxEnhMetaFileDC class itself, is only available only
1005         under MSW.
1006     */
1007     virtual wxGraphicsContext* CreateContext(const wxEnhMetaFileDC& metaFileDC) = 0;
1008
1009     /**
1010         Creates a wxGraphicsContext associated with a wxImage.
1011
1012         This function is used by wxContext::CreateFromImage() and is not
1013         normally called directly.
1014
1015         @since 2.9.3
1016      */
1017     wxGraphicsContext* CreateContextFromImage(wxImage& image);
1018
1019     /**
1020         Creates a native brush from a wxBrush.
1021     */
1022     virtual wxGraphicsBrush CreateBrush(const wxBrush& brush) = 0;
1023
1024     /**
1025         Creates a wxGraphicsContext from a native context. This native context
1026         must be a CGContextRef for Core Graphics, a Graphics pointer for
1027         GDIPlus, or a cairo_t pointer for cairo.
1028     */
1029     virtual wxGraphicsContext* CreateContextFromNativeContext(void* context) = 0;
1030
1031     /**
1032         Creates a wxGraphicsContext from a native window.
1033     */
1034     virtual wxGraphicsContext* CreateContextFromNativeWindow(void* window) = 0;
1035
1036     /**
1037         Creates a wxGraphicsContext that can be used for measuring texts only.
1038         No drawing commands are allowed.
1039     */
1040     virtual wxGraphicsContext * CreateMeasuringContext() = 0;
1041
1042     /**
1043         Creates a native graphics font from a wxFont and a text colour.
1044     */
1045     virtual wxGraphicsFont CreateFont(const wxFont& font,
1046                                       const wxColour& col = *wxBLACK) = 0;
1047
1048     /**
1049         Creates a graphics font with the given characteristics.
1050
1051         If possible, the CreateFont() overload taking wxFont should be used
1052         instead. The main advantage of this overload is that it can be used
1053         without X server connection under Unix when using Cairo.
1054
1055         @param sizeInPixels
1056             Height of the font in user space units, i.e. normally pixels.
1057             Notice that this is different from the overload taking wxFont as
1058             wxFont size is specified in points.
1059         @param facename
1060             The name of the font. The same font name might not be available
1061             under all platforms so the font name can also be empty to use the
1062             default platform font.
1063         @param flags
1064             Combination of wxFontFlag enum elements. Currently only
1065             @c wxFONTFLAG_ITALIC and @c wxFONTFLAG_BOLD are supported. By
1066             default the normal font version is used.
1067         @param col
1068             The font colour, black by default.
1069
1070         @since 2.9.3
1071      */
1072     virtual wxGraphicsFont CreateFont(double sizeInPixels,
1073                                       const wxString& facename,
1074                                       int flags = wxFONTFLAG_DEFAULT,
1075                                       const wxColour& col = *wxBLACK) = 0;
1076
1077
1078     /**
1079         Creates a native brush with a linear gradient.
1080
1081         Stops support is new since wxWidgets 2.9.1, previously only the start
1082         and end colours could be specified.
1083     */
1084     virtual wxGraphicsBrush CreateLinearGradientBrush(wxDouble x1,
1085                                                       wxDouble y1,
1086                                                       wxDouble x2,
1087                                                       wxDouble y2,
1088                                                       const wxGraphicsGradientStops& stops) = 0;
1089
1090     /**
1091         Creates a native affine transformation matrix from the passed in
1092         values. The defaults result in an identity matrix.
1093     */
1094     virtual wxGraphicsMatrix CreateMatrix(wxDouble a = 1.0, wxDouble b = 0.0,
1095                                           wxDouble c = 0.0, wxDouble d = 1.0,
1096                                           wxDouble tx = 0.0,
1097                                           wxDouble ty = 0.0) = 0;
1098
1099     /**
1100         Creates a native graphics path which is initially empty.
1101     */
1102     virtual wxGraphicsPath CreatePath() = 0;
1103
1104     /**
1105         Creates a native pen from a wxPen.
1106     */
1107     virtual wxGraphicsPen CreatePen(const wxPen& pen) = 0;
1108
1109     /**
1110         Creates a native brush with a radial gradient.
1111
1112         Stops support is new since wxWidgets 2.9.1, previously only the start
1113         and end colours could be specified.
1114     */
1115     virtual wxGraphicsBrush CreateRadialGradientBrush(wxDouble xo, wxDouble yo,
1116                                                       wxDouble xc, wxDouble yc,
1117                                                       wxDouble radius,
1118                                                       const wxGraphicsGradientStops& stops) = 0;
1119
1120     /**
1121         Extracts a sub-bitmap from an existing bitmap.
1122
1123         Currently this function is implemented in the native MSW and OS X
1124         versions but not when using Cairo.
1125      */
1126     virtual wxGraphicsBitmap CreateSubBitmap(const wxGraphicsBitmap& bitmap,
1127                                              wxDouble x, wxDouble y,
1128                                              wxDouble w, wxDouble h) = 0;
1129
1130     /**
1131         Returns the default renderer on this platform. On OS X this is the Core
1132         Graphics (a.k.a. Quartz 2D) renderer, on MSW the GDIPlus renderer, and
1133         on GTK we currently default to the cairo renderer.
1134     */
1135     static wxGraphicsRenderer* GetDefaultRenderer();
1136     static wxGraphicsRenderer* GetCairoRenderer();
1137
1138 };
1139
1140
1141
1142 /**
1143     @class wxGraphicsBrush
1144
1145     A wxGraphicsBrush is a native representation of a brush. The contents are
1146     specific and private to the respective renderer. Instances are ref counted
1147     and can therefore be assigned as usual. The only way to get a valid
1148     instance is via wxGraphicsContext::CreateBrush() or
1149     wxGraphicsRenderer::CreateBrush().
1150
1151     @library{wxcore}
1152     @category{gdi}
1153 */
1154 class wxGraphicsBrush : public wxGraphicsObject
1155 {
1156 public:
1157
1158 };
1159
1160
1161
1162 /**
1163     @class wxGraphicsFont
1164
1165     A wxGraphicsFont is a native representation of a font. The contents are
1166     specific and private to the respective renderer. Instances are ref counted
1167     and can therefore be assigned as usual. The only way to get a valid
1168     instance is via wxGraphicsContext::CreateFont() or
1169     wxGraphicsRenderer::CreateFont().
1170
1171     @library{wxcore}
1172     @category{gdi}
1173 */
1174 class wxGraphicsFont : public wxGraphicsObject
1175 {
1176 public:
1177
1178 };
1179
1180
1181
1182 /**
1183     @class wxGraphicsPen
1184
1185     A wxGraphicsPen is a native representation of a pen. The contents are
1186     specific and private to the respective renderer. Instances are ref counted
1187     and can therefore be assigned as usual. The only way to get a valid
1188     instance is via wxGraphicsContext::CreatePen() or
1189     wxGraphicsRenderer::CreatePen().
1190
1191     @library{wxcore}
1192     @category{gdi}
1193 */
1194 class wxGraphicsPen : public wxGraphicsObject
1195 {
1196 public:
1197
1198 };
1199
1200
1201
1202 /**
1203     @class wxGraphicsMatrix
1204
1205     A wxGraphicsMatrix is a native representation of an affine matrix. The
1206     contents are specific and private to the respective renderer. Instances are
1207     ref counted and can therefore be assigned as usual. The only way to get a
1208     valid instance is via wxGraphicsContext::CreateMatrix() or
1209     wxGraphicsRenderer::CreateMatrix().
1210
1211     @library{wxcore}
1212     @category{gdi}
1213 */
1214 class wxGraphicsMatrix : public wxGraphicsObject
1215 {
1216 public:
1217     /**
1218         Concatenates the matrix passed with the current matrix.
1219     */
1220     virtual void Concat(const wxGraphicsMatrix* t);
1221     /**
1222         Concatenates the matrix passed with the current matrix.
1223     */
1224     void Concat(const wxGraphicsMatrix& t);
1225
1226     /**
1227         Returns the component values of the matrix via the argument pointers.
1228     */
1229     virtual void Get(wxDouble* a = NULL, wxDouble* b = NULL,
1230                      wxDouble* c = NULL, wxDouble* d = NULL,
1231                      wxDouble* tx = NULL, wxDouble* ty = NULL) const;
1232
1233     /**
1234         Returns the native representation of the matrix. For CoreGraphics this
1235         is a CFAffineMatrix pointer, for GDIPlus a Matrix Pointer, and for
1236         Cairo a cairo_matrix_t pointer.
1237     */
1238     virtual void* GetNativeMatrix() const;
1239
1240     /**
1241         Inverts the matrix.
1242     */
1243     virtual void Invert();
1244
1245     /**
1246         Returns @true if the elements of the transformation matrix are equal.
1247     */
1248     virtual bool IsEqual(const wxGraphicsMatrix* t) const;
1249     /**
1250         Returns @true if the elements of the transformation matrix are equal.
1251     */
1252     bool IsEqual(const wxGraphicsMatrix& t) const;
1253
1254     /**
1255         Return @true if this is the identity matrix.
1256     */
1257     virtual bool IsIdentity() const;
1258
1259     /**
1260         Rotates this matrix (in radians).
1261     */
1262     virtual void Rotate(wxDouble angle);
1263
1264     /**
1265         Scales this matrix.
1266     */
1267     virtual void Scale(wxDouble xScale, wxDouble yScale);
1268
1269     /**
1270         Sets the matrix to the respective values (default values are the
1271         identity matrix).
1272     */
1273     virtual void Set(wxDouble a = 1.0, wxDouble b = 0.0, wxDouble c = 0.0,
1274                      wxDouble d = 1.0, wxDouble tx = 0.0, wxDouble ty = 0.0);
1275
1276     /**
1277         Applies this matrix to a distance (ie. performs all transforms except
1278         translations).
1279     */
1280     virtual void TransformDistance(wxDouble* dx, wxDouble* dy) const;
1281
1282     /**
1283         Applies this matrix to a point.
1284     */
1285     virtual void TransformPoint(wxDouble* x, wxDouble* y) const;
1286
1287     /**
1288         Translates this matrix.
1289     */
1290     virtual void Translate(wxDouble dx, wxDouble dy);
1291 };
1292
1293
1294 const wxGraphicsPen     wxNullGraphicsPen;
1295 const wxGraphicsBrush   wxNullGraphicsBrush;
1296 const wxGraphicsFont    wxNullGraphicsFont;
1297 const wxGraphicsBitmap  wxNullGraphicsBitmap;
1298 const wxGraphicsMatrix  wxNullGraphicsMatrix;
1299 const wxGraphicsPath    wxNullGraphicsPath;