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     /**
 811        Push the current state of the context's transformation matrix on a
 812        stack.
 813
 814        @see wxGraphicsContext::PopState
 815     */
 816     virtual void PushState() = 0;
 817
 818     /**
 819        Pops a stored state from the stack and sets the current transformation
 820        matrix to that state.
 821
 822        @see wxGraphicsContext::PopState
 823     */
 824     virtual void PopState() = 0;
 825
 826
 827     virtual void EnableOffset(bool enable = true);
 828     void DisableOffset();
 829     bool OffsetEnabled();
 830
 831 };
 832
 833 /**
 834     Represents a single gradient stop in a collection of gradient stops as
 835     represented by wxGraphicsGradientStops.
 836
 837     @library{wxcore}
 838     @category{gdi}
 839
 840     @since 2.9.1
 841 */
 842 class wxGraphicsGradientStop
 843 {
 844 public:
 845     /**
 846         Creates a stop with the given colour and position.
 847
 848         @param col The colour of this stop. Note that the alpha component of
 849             the colour is honoured thus allowing the background colours to
 850             partially show through the gradient.
 851         @param pos The stop position, must be in [0, 1] range with 0 being the
 852             beginning and 1 the end of the gradient.
 853     */
 854     wxGraphicsGradientStop(wxColour col = wxTransparentColour, float pos = 0.);
 855
 856     /// Return the stop colour.
 857     const wxColour& GetColour() const;
 858
 859     /**
 860         Change the stop colour.
 861
 862         @param col The new colour.
 863     */
 864     void SetColour(const wxColour& col);
 865
 866     /// Return the stop position.
 867     float GetPosition() const;
 868
 869     /**
 870         Change the stop position.
 871
 872         @param pos The new position, must always be in [0, 1] range.
 873     */
 874     void SetPosition(float pos);
 875 };
 876
 877 /**
 878     Represents a collection of wxGraphicGradientStop values for use with
 879     CreateLinearGradientBrush and CreateRadialGradientBrush.
 880
 881     The stops are maintained in order of position.  If two or more stops are
 882     added with the same position then the one(s) added later come later.
 883     This can be useful for producing discontinuities in the colour gradient.
 884
 885     Notice that this class is write-once, you can't modify the stops once they
 886     had been added.
 887
 888     @library{wxcore}
 889     @category{gdi}
 890
 891     @since 2.9.1
 892 */
 893 class wxGraphicsGradientStops
 894 {
 895 public:
 896     /**
 897         Initializes the gradient stops with the given boundary colours.
 898
 899         Creates a wxGraphicsGradientStops instance with start colour given
 900         by @a startCol and end colour given by @a endCol.
 901     */
 902     wxGraphicsGradientStops(wxColour startCol = wxTransparentColour,
 903                             wxColour endCol = wxTransparentColour);
 904
 905     /**
 906         Add a new stop.
 907     */
 908     //@{
 909     void Add(const wxGraphicsGradientStop& stop);
 910     void Add(wxColour col, float pos);
 911     //@}
 912
 913     /**
 914         Returns the stop at the given index.
 915
 916         @param n The index, must be in [0, GetCount()) range.
 917     */
 918     wxGraphicsGradientStop Item(unsigned n) const;
 919
 920     /**
 921         Returns the number of stops.
 922     */
 923     unsigned GetCount() const;
 924
 925     /**
 926         Set the start colour to @a col
 927     */
 928     void SetStartColour(wxColour col);
 929
 930     /**
 931         Returns the start colour.
 932     */
 933     wxColour GetStartColour() const;
 934
 935     /**
 936         Set the end colour to @a col
 937     */
 938     void SetEndColour(wxColour col);
 939
 940     /**
 941         Returns the end colour.
 942     */
 943     wxColour GetEndColour() const;
 944 };
 945
 946 /**
 947     @class wxGraphicsRenderer
 948
 949     A wxGraphicsRenderer is the instance corresponding to the rendering engine
 950     used. There may be multiple instances on a system, if there are different
 951     rendering engines present, but there is always only one instance per
 952     engine. This instance is pointed back to by all objects created by it
 953     (wxGraphicsContext, wxGraphicsPath etc) and can be retrieved through their
 954     wxGraphicsObject::GetRenderer() method. Therefore you can create an
 955     additional instance of a path etc. by calling
 956     wxGraphicsObject::GetRenderer() and then using the appropriate CreateXXX()
 957     function of that renderer.
 958
 959     @code
 960     wxGraphicsPath *path = // from somewhere
 961     wxGraphicsBrush *brush = path->GetRenderer()->CreateBrush( *wxBLACK_BRUSH );
 962     @endcode
 963
 964     @library{wxcore}
 965     @category{gdi}
 966 */
 967 class wxGraphicsRenderer : public wxObject
 968 {
 969 public:
 970     /**
 971         Creates wxGraphicsBitmap from an existing wxBitmap.
 972
 973         Returns an invalid wxNullGraphicsBitmap on failure.
 974      */
 975     virtual wxGraphicsBitmap CreateBitmap( const wxBitmap &bitmap ) = 0;
 976
 977     /**
 978         Creates wxGraphicsBitmap from an existing wxImage.
 979
 980         This method is more efficient than converting wxImage to wxBitmap first
 981         and then calling CreateBitmap() but otherwise has the same effect.
 982
 983         Returns an invalid wxNullGraphicsBitmap on failure.
 984
 985         @since 2.9.3
 986      */
 987     virtual wxGraphicsBitmap CreateBitmapFromImage(const wxImage& image) = 0;
 988
 989     /**
 990        Creates a wxImage from a wxGraphicsBitmap.
 991
 992        This method is used by the more convenient wxGraphicsBitmap::ConvertToImage.
 993     */
 994     virtual wxImage CreateImageFromBitmap(const wxGraphicsBitmap& bmp) = 0;
 995
 996     /**
 997         Creates wxGraphicsBitmap from a native bitmap handle.
 998
 999         @a bitmap meaning is platform-dependent. Currently it's a GDI+ @c
1000         Bitmap pointer under MSW, @c CGImage pointer under OS X or a @c
1001         cairo_surface_t pointer when using Cairo under any platform.
1002      */
1003     virtual wxGraphicsBitmap CreateBitmapFromNativeBitmap( void* bitmap ) = 0;
1004
1005     /**
1006         Creates a wxGraphicsContext from a wxWindow.
1007     */
1008     virtual wxGraphicsContext* CreateContext(wxWindow* window) = 0;
1009
1010     /**
1011         Creates a wxGraphicsContext from a wxWindowDC
1012     */
1013     virtual wxGraphicsContext* CreateContext(const wxWindowDC& windowDC) = 0 ;
1014
1015     /**
1016         Creates a wxGraphicsContext from a wxMemoryDC
1017     */
1018     virtual wxGraphicsContext* CreateContext(const wxMemoryDC& memoryDC) = 0 ;
1019
1020     /**
1021         Creates a wxGraphicsContext from a wxPrinterDC
1022     */
1023     virtual wxGraphicsContext* CreateContext(const wxPrinterDC& printerDC) = 0 ;
1024
1025     /**
1026         Creates a wxGraphicsContext from a wxEnhMetaFileDC.
1027
1028         This function, as wxEnhMetaFileDC class itself, is only available only
1029         under MSW.
1030     */
1031     virtual wxGraphicsContext* CreateContext(const wxEnhMetaFileDC& metaFileDC) = 0;
1032
1033     /**
1034         Creates a wxGraphicsContext associated with a wxImage.
1035
1036         This function is used by wxContext::CreateFromImage() and is not
1037         normally called directly.
1038
1039         @since 2.9.3
1040      */
1041     wxGraphicsContext* CreateContextFromImage(wxImage& image);
1042
1043     /**
1044         Creates a native brush from a wxBrush.
1045     */
1046     virtual wxGraphicsBrush CreateBrush(const wxBrush& brush) = 0;
1047
1048     /**
1049         Creates a wxGraphicsContext from a native context. This native context
1050         must be a CGContextRef for Core Graphics, a Graphics pointer for
1051         GDIPlus, or a cairo_t pointer for cairo.
1052     */
1053     virtual wxGraphicsContext* CreateContextFromNativeContext(void* context) = 0;
1054
1055     /**
1056         Creates a wxGraphicsContext from a native window.
1057     */
1058     virtual wxGraphicsContext* CreateContextFromNativeWindow(void* window) = 0;
1059
1060     /**
1061         Creates a wxGraphicsContext that can be used for measuring texts only.
1062         No drawing commands are allowed.
1063     */
1064     virtual wxGraphicsContext * CreateMeasuringContext() = 0;
1065
1066     /**
1067         Creates a native graphics font from a wxFont and a text colour.
1068     */
1069     virtual wxGraphicsFont CreateFont(const wxFont& font,
1070                                       const wxColour& col = *wxBLACK) = 0;
1071
1072     /**
1073         Creates a graphics font with the given characteristics.
1074
1075         If possible, the CreateFont() overload taking wxFont should be used
1076         instead. The main advantage of this overload is that it can be used
1077         without X server connection under Unix when using Cairo.
1078
1079         @param sizeInPixels
1080             Height of the font in user space units, i.e. normally pixels.
1081             Notice that this is different from the overload taking wxFont as
1082             wxFont size is specified in points.
1083         @param facename
1084             The name of the font. The same font name might not be available
1085             under all platforms so the font name can also be empty to use the
1086             default platform font.
1087         @param flags
1088             Combination of wxFontFlag enum elements. Currently only
1089             @c wxFONTFLAG_ITALIC and @c wxFONTFLAG_BOLD are supported. By
1090             default the normal font version is used.
1091         @param col
1092             The font colour, black by default.
1093
1094         @since 2.9.3
1095      */
1096     virtual wxGraphicsFont CreateFont(double sizeInPixels,
1097                                       const wxString& facename,
1098                                       int flags = wxFONTFLAG_DEFAULT,
1099                                       const wxColour& col = *wxBLACK) = 0;
1100
1101
1102     /**
1103         Creates a native brush with a linear gradient.
1104
1105         Stops support is new since wxWidgets 2.9.1, previously only the start
1106         and end colours could be specified.
1107     */
1108     virtual wxGraphicsBrush CreateLinearGradientBrush(wxDouble x1,
1109                                                       wxDouble y1,
1110                                                       wxDouble x2,
1111                                                       wxDouble y2,
1112                                                       const wxGraphicsGradientStops& stops) = 0;
1113
1114     /**
1115         Creates a native affine transformation matrix from the passed in
1116         values. The defaults result in an identity matrix.
1117     */
1118     virtual wxGraphicsMatrix CreateMatrix(wxDouble a = 1.0, wxDouble b = 0.0,
1119                                           wxDouble c = 0.0, wxDouble d = 1.0,
1120                                           wxDouble tx = 0.0,
1121                                           wxDouble ty = 0.0) = 0;
1122
1123     /**
1124         Creates a native graphics path which is initially empty.
1125     */
1126     virtual wxGraphicsPath CreatePath() = 0;
1127
1128     /**
1129         Creates a native pen from a wxPen.
1130     */
1131     virtual wxGraphicsPen CreatePen(const wxPen& pen) = 0;
1132
1133     /**
1134         Creates a native brush with a radial gradient.
1135
1136         Stops support is new since wxWidgets 2.9.1, previously only the start
1137         and end colours could be specified.
1138     */
1139     virtual wxGraphicsBrush CreateRadialGradientBrush(wxDouble xo, wxDouble yo,
1140                                                       wxDouble xc, wxDouble yc,
1141                                                       wxDouble radius,
1142                                                       const wxGraphicsGradientStops& stops) = 0;
1143
1144     /**
1145         Extracts a sub-bitmap from an existing bitmap.
1146
1147         Currently this function is implemented in the native MSW and OS X
1148         versions but not when using Cairo.
1149      */
1150     virtual wxGraphicsBitmap CreateSubBitmap(const wxGraphicsBitmap& bitmap,
1151                                              wxDouble x, wxDouble y,
1152                                              wxDouble w, wxDouble h) = 0;
1153
1154     /**
1155         Returns the default renderer on this platform. On OS X this is the Core
1156         Graphics (a.k.a. Quartz 2D) renderer, on MSW the GDIPlus renderer, and
1157         on GTK we currently default to the cairo renderer.
1158     */
1159     static wxGraphicsRenderer* GetDefaultRenderer();
1160     static wxGraphicsRenderer* GetCairoRenderer();
1161
1162 };
1163
1164
1165
1166 /**
1167     @class wxGraphicsBrush
1168
1169     A wxGraphicsBrush is a native representation of a brush. The contents are
1170     specific and private to the respective renderer. Instances are ref counted
1171     and can therefore be assigned as usual. The only way to get a valid
1172     instance is via wxGraphicsContext::CreateBrush() or
1173     wxGraphicsRenderer::CreateBrush().
1174
1175     @library{wxcore}
1176     @category{gdi}
1177 */
1178 class wxGraphicsBrush : public wxGraphicsObject
1179 {
1180 public:
1181
1182 };
1183
1184
1185
1186 /**
1187     @class wxGraphicsFont
1188
1189     A wxGraphicsFont is a native representation of a font. The contents are
1190     specific and private to the respective renderer. Instances are ref counted
1191     and can therefore be assigned as usual. The only way to get a valid
1192     instance is via wxGraphicsContext::CreateFont() or
1193     wxGraphicsRenderer::CreateFont().
1194
1195     @library{wxcore}
1196     @category{gdi}
1197 */
1198 class wxGraphicsFont : public wxGraphicsObject
1199 {
1200 public:
1201
1202 };
1203
1204
1205
1206 /**
1207     @class wxGraphicsPen
1208
1209     A wxGraphicsPen is a native representation of a pen. The contents are
1210     specific and private to the respective renderer. Instances are ref counted
1211     and can therefore be assigned as usual. The only way to get a valid
1212     instance is via wxGraphicsContext::CreatePen() or
1213     wxGraphicsRenderer::CreatePen().
1214
1215     @library{wxcore}
1216     @category{gdi}
1217 */
1218 class wxGraphicsPen : public wxGraphicsObject
1219 {
1220 public:
1221
1222 };
1223
1224
1225
1226 /**
1227     @class wxGraphicsMatrix
1228
1229     A wxGraphicsMatrix is a native representation of an affine matrix. The
1230     contents are specific and private to the respective renderer. Instances are
1231     ref counted and can therefore be assigned as usual. The only way to get a
1232     valid instance is via wxGraphicsContext::CreateMatrix() or
1233     wxGraphicsRenderer::CreateMatrix().
1234
1235     @library{wxcore}
1236     @category{gdi}
1237 */
1238 class wxGraphicsMatrix : public wxGraphicsObject
1239 {
1240 public:
1241     /**
1242         Concatenates the matrix passed with the current matrix.
1243     */
1244     virtual void Concat(const wxGraphicsMatrix* t);
1245     /**
1246         Concatenates the matrix passed with the current matrix.
1247     */
1248     void Concat(const wxGraphicsMatrix& t);
1249
1250     /**
1251         Returns the component values of the matrix via the argument pointers.
1252     */
1253     virtual void Get(wxDouble* a = NULL, wxDouble* b = NULL,
1254                      wxDouble* c = NULL, wxDouble* d = NULL,
1255                      wxDouble* tx = NULL, wxDouble* ty = NULL) const;
1256
1257     /**
1258         Returns the native representation of the matrix. For CoreGraphics this
1259         is a CFAffineMatrix pointer, for GDIPlus a Matrix Pointer, and for
1260         Cairo a cairo_matrix_t pointer.
1261     */
1262     virtual void* GetNativeMatrix() const;
1263
1264     /**
1265         Inverts the matrix.
1266     */
1267     virtual void Invert();
1268
1269     /**
1270         Returns @true if the elements of the transformation matrix are equal.
1271     */
1272     virtual bool IsEqual(const wxGraphicsMatrix* t) const;
1273     /**
1274         Returns @true if the elements of the transformation matrix are equal.
1275     */
1276     bool IsEqual(const wxGraphicsMatrix& t) const;
1277
1278     /**
1279         Return @true if this is the identity matrix.
1280     */
1281     virtual bool IsIdentity() const;
1282
1283     /**
1284         Rotates this matrix (in radians).
1285     */
1286     virtual void Rotate(wxDouble angle);
1287
1288     /**
1289         Scales this matrix.
1290     */
1291     virtual void Scale(wxDouble xScale, wxDouble yScale);
1292
1293     /**
1294         Sets the matrix to the respective values (default values are the
1295         identity matrix).
1296     */
1297     virtual void Set(wxDouble a = 1.0, wxDouble b = 0.0, wxDouble c = 0.0,
1298                      wxDouble d = 1.0, wxDouble tx = 0.0, wxDouble ty = 0.0);
1299
1300     /**
1301         Applies this matrix to a distance (ie. performs all transforms except
1302         translations).
1303     */
1304     virtual void TransformDistance(wxDouble* dx, wxDouble* dy) const;
1305
1306     /**
1307         Applies this matrix to a point.
1308     */
1309     virtual void TransformPoint(wxDouble* x, wxDouble* y) const;
1310
1311     /**
1312         Translates this matrix.
1313     */
1314     virtual void Translate(wxDouble dx, wxDouble dy);
1315 };
1316
1317
1318 const wxGraphicsPen     wxNullGraphicsPen;
1319 const wxGraphicsBrush   wxNullGraphicsBrush;
1320 const wxGraphicsFont    wxNullGraphicsFont;
1321 const wxGraphicsBitmap  wxNullGraphicsBitmap;
1322 const wxGraphicsMatrix  wxNullGraphicsMatrix;
1323 const wxGraphicsPath    wxNullGraphicsPath;