include/ftglyph.h

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftglyph.h                                                              */
   4 /*                                                                         */
   5 /*    FreeType convenience functions to handle glyphs (specification).     */
   6 /*                                                                         */
   7 /*  Copyright 1996-2003, 2006, 2008, 2009, 2011, 2013, 2014 by             */
   8 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
   9 /*                                                                         */
  10 /*  This file is part of the FreeType project, and may only be used,       */
  11 /*  modified, and distributed under the terms of the FreeType project      */
  12 /*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
  13 /*  this file you indicate that you have read the license and              */
  14 /*  understand and accept it fully.                                        */
  15 /*                                                                         */
  16 /***************************************************************************/
  17
  18
  19   /*************************************************************************/
  20   /*                                                                       */
  21   /* This file contains the definition of several convenience functions    */
  22   /* that can be used by client applications to easily retrieve glyph      */
  23   /* bitmaps and outlines from a given face.                               */
  24   /*                                                                       */
  25   /* These functions should be optional if you are writing a font server   */
  26   /* or text layout engine on top of FreeType.  However, they are pretty   */
  27   /* handy for many other simple uses of the library.                      */
  28   /*                                                                       */
  29   /*************************************************************************/
  30
  31
  32 #ifndef __FTGLYPH_H__
  33 #define __FTGLYPH_H__
  34
  35
  36 #include <ft2build.h>
  37 #include FT_FREETYPE_H
  38
  39 #ifdef FREETYPE_H
  40 #error "freetype.h of FreeType 1 has been loaded!"
  41 #error "Please fix the directory search order for header files"
  42 #error "so that freetype.h of FreeType 2 is found first."
  43 #endif
  44
  45
  46 FT_BEGIN_HEADER
  47
  48
  49   /*************************************************************************/
  50   /*                                                                       */
  51   /* <Section>                                                             */
  52   /*    glyph_management                                                   */
  53   /*                                                                       */
  54   /* <Title>                                                               */
  55   /*    Glyph Management                                                   */
  56   /*                                                                       */
  57   /* <Abstract>                                                            */
  58   /*    Generic interface to manage individual glyph data.                 */
  59   /*                                                                       */
  60   /* <Description>                                                         */
  61   /*    This section contains definitions used to manage glyph data        */
  62   /*    through generic FT_Glyph objects.  Each of them can contain a      */
  63   /*    bitmap, a vector outline, or even images in other formats.         */
  64   /*                                                                       */
  65   /*************************************************************************/
  66
  67
  68   /* forward declaration to a private type */
  69   typedef struct FT_Glyph_Class_  FT_Glyph_Class;
  70
  71
  72   /*************************************************************************/
  73   /*                                                                       */
  74   /* <Type>                                                                */
  75   /*    FT_Glyph                                                           */
  76   /*                                                                       */
  77   /* <Description>                                                         */
  78   /*    Handle to an object used to model generic glyph images.  It is a   */
  79   /*    pointer to the @FT_GlyphRec structure and can contain a glyph      */
  80   /*    bitmap or pointer.                                                 */
  81   /*                                                                       */
  82   /* <Note>                                                                */
  83   /*    Glyph objects are not owned by the library.  You must thus release */
  84   /*    them manually (through @FT_Done_Glyph) _before_ calling            */
  85   /*    @FT_Done_FreeType.                                                 */
  86   /*                                                                       */
  87   typedef struct FT_GlyphRec_*  FT_Glyph;
  88
  89
  90   /*************************************************************************/
  91   /*                                                                       */
  92   /* <Struct>                                                              */
  93   /*    FT_GlyphRec                                                        */
  94   /*                                                                       */
  95   /* <Description>                                                         */
  96   /*    The root glyph structure contains a given glyph image plus its     */
  97   /*    advance width in 16.16 fixed-point format.                         */
  98   /*                                                                       */
  99   /* <Fields>                                                              */
 100   /*    library :: A handle to the FreeType library object.                */
 101   /*                                                                       */
 102   /*    clazz   :: A pointer to the glyph's class.  Private.               */
 103   /*                                                                       */
 104   /*    format  :: The format of the glyph's image.                        */
 105   /*                                                                       */
 106   /*    advance :: A 16.16 vector that gives the glyph's advance width.    */
 107   /*                                                                       */
 108   typedef struct  FT_GlyphRec_
 109   {
 110     FT_Library             library;
 111     const FT_Glyph_Class*  clazz;
 112     FT_Glyph_Format        format;
 113     FT_Vector              advance;
 114
 115   } FT_GlyphRec;
 116
 117
 118   /*************************************************************************/
 119   /*                                                                       */
 120   /* <Type>                                                                */
 121   /*    FT_BitmapGlyph                                                     */
 122   /*                                                                       */
 123   /* <Description>                                                         */
 124   /*    A handle to an object used to model a bitmap glyph image.  This is */
 125   /*    a sub-class of @FT_Glyph, and a pointer to @FT_BitmapGlyphRec.     */
 126   /*                                                                       */
 127   typedef struct FT_BitmapGlyphRec_*  FT_BitmapGlyph;
 128
 129
 130   /*************************************************************************/
 131   /*                                                                       */
 132   /* <Struct>                                                              */
 133   /*    FT_BitmapGlyphRec                                                  */
 134   /*                                                                       */
 135   /* <Description>                                                         */
 136   /*    A structure used for bitmap glyph images.  This really is a        */
 137   /*    `sub-class' of @FT_GlyphRec.                                       */
 138   /*                                                                       */
 139   /* <Fields>                                                              */
 140   /*    root   :: The root @FT_Glyph fields.                               */
 141   /*                                                                       */
 142   /*    left   :: The left-side bearing, i.e., the horizontal distance     */
 143   /*              from the current pen position to the left border of the  */
 144   /*              glyph bitmap.                                            */
 145   /*                                                                       */
 146   /*    top    :: The top-side bearing, i.e., the vertical distance from   */
 147   /*              the current pen position to the top border of the glyph  */
 148   /*              bitmap.  This distance is positive for upwards~y!        */
 149   /*                                                                       */
 150   /*    bitmap :: A descriptor for the bitmap.                             */
 151   /*                                                                       */
 152   /* <Note>                                                                */
 153   /*    You can typecast an @FT_Glyph to @FT_BitmapGlyph if you have       */
 154   /*    `glyph->format == FT_GLYPH_FORMAT_BITMAP'.  This lets you access   */
 155   /*    the bitmap's contents easily.                                      */
 156   /*                                                                       */
 157   /*    The corresponding pixel buffer is always owned by @FT_BitmapGlyph  */
 158   /*    and is thus created and destroyed with it.                         */
 159   /*                                                                       */
 160   typedef struct  FT_BitmapGlyphRec_
 161   {
 162     FT_GlyphRec  root;
 163     FT_Int       left;
 164     FT_Int       top;
 165     FT_Bitmap    bitmap;
 166
 167   } FT_BitmapGlyphRec;
 168
 169
 170   /*************************************************************************/
 171   /*                                                                       */
 172   /* <Type>                                                                */
 173   /*    FT_OutlineGlyph                                                    */
 174   /*                                                                       */
 175   /* <Description>                                                         */
 176   /*    A handle to an object used to model an outline glyph image.  This  */
 177   /*    is a sub-class of @FT_Glyph, and a pointer to @FT_OutlineGlyphRec. */
 178   /*                                                                       */
 179   typedef struct FT_OutlineGlyphRec_*  FT_OutlineGlyph;
 180
 181
 182   /*************************************************************************/
 183   /*                                                                       */
 184   /* <Struct>                                                              */
 185   /*    FT_OutlineGlyphRec                                                 */
 186   /*                                                                       */
 187   /* <Description>                                                         */
 188   /*    A structure used for outline (vectorial) glyph images.  This       */
 189   /*    really is a `sub-class' of @FT_GlyphRec.                           */
 190   /*                                                                       */
 191   /* <Fields>                                                              */
 192   /*    root    :: The root @FT_Glyph fields.                              */
 193   /*                                                                       */
 194   /*    outline :: A descriptor for the outline.                           */
 195   /*                                                                       */
 196   /* <Note>                                                                */
 197   /*    You can typecast an @FT_Glyph to @FT_OutlineGlyph if you have      */
 198   /*    `glyph->format == FT_GLYPH_FORMAT_OUTLINE'.  This lets you access  */
 199   /*    the outline's content easily.                                      */
 200   /*                                                                       */
 201   /*    As the outline is extracted from a glyph slot, its coordinates are */
 202   /*    expressed normally in 26.6 pixels, unless the flag                 */
 203   /*    @FT_LOAD_NO_SCALE was used in @FT_Load_Glyph() or @FT_Load_Char(). */
 204   /*                                                                       */
 205   /*    The outline's tables are always owned by the object and are        */
 206   /*    destroyed with it.                                                 */
 207   /*                                                                       */
 208   typedef struct  FT_OutlineGlyphRec_
 209   {
 210     FT_GlyphRec  root;
 211     FT_Outline   outline;
 212
 213   } FT_OutlineGlyphRec;
 214
 215
 216   /*************************************************************************/
 217   /*                                                                       */
 218   /* <Function>                                                            */
 219   /*    FT_Get_Glyph                                                       */
 220   /*                                                                       */
 221   /* <Description>                                                         */
 222   /*    A function used to extract a glyph image from a slot.  Note that   */
 223   /*    the created @FT_Glyph object must be released with @FT_Done_Glyph. */
 224   /*                                                                       */
 225   /* <Input>                                                               */
 226   /*    slot   :: A handle to the source glyph slot.                       */
 227   /*                                                                       */
 228   /* <Output>                                                              */
 229   /*    aglyph :: A handle to the glyph object.                            */
 230   /*                                                                       */
 231   /* <Return>                                                              */
 232   /*    FreeType error code.  0~means success.                             */
 233   /*                                                                       */
 234   FT_EXPORT( FT_Error )
 235   FT_Get_Glyph( FT_GlyphSlot  slot,
 236                 FT_Glyph     *aglyph );
 237
 238
 239   /*************************************************************************/
 240   /*                                                                       */
 241   /* <Function>                                                            */
 242   /*    FT_Glyph_Copy                                                      */
 243   /*                                                                       */
 244   /* <Description>                                                         */
 245   /*    A function used to copy a glyph image.  Note that the created      */
 246   /*    @FT_Glyph object must be released with @FT_Done_Glyph.             */
 247   /*                                                                       */
 248   /* <Input>                                                               */
 249   /*    source :: A handle to the source glyph object.                     */
 250   /*                                                                       */
 251   /* <Output>                                                              */
 252   /*    target :: A handle to the target glyph object.  0~in case of       */
 253   /*              error.                                                   */
 254   /*                                                                       */
 255   /* <Return>                                                              */
 256   /*    FreeType error code.  0~means success.                             */
 257   /*                                                                       */
 258   FT_EXPORT( FT_Error )
 259   FT_Glyph_Copy( FT_Glyph   source,
 260                  FT_Glyph  *target );
 261
 262
 263   /*************************************************************************/
 264   /*                                                                       */
 265   /* <Function>                                                            */
 266   /*    FT_Glyph_Transform                                                 */
 267   /*                                                                       */
 268   /* <Description>                                                         */
 269   /*    Transform a glyph image if its format is scalable.                 */
 270   /*                                                                       */
 271   /* <InOut>                                                               */
 272   /*    glyph  :: A handle to the target glyph object.                     */
 273   /*                                                                       */
 274   /* <Input>                                                               */
 275   /*    matrix :: A pointer to a 2x2 matrix to apply.                      */
 276   /*                                                                       */
 277   /*    delta  :: A pointer to a 2d vector to apply.  Coordinates are      */
 278   /*              expressed in 1/64th of a pixel.                          */
 279   /*                                                                       */
 280   /* <Return>                                                              */
 281   /*    FreeType error code (if not 0, the glyph format is not scalable).  */
 282   /*                                                                       */
 283   /* <Note>                                                                */
 284   /*    The 2x2 transformation matrix is also applied to the glyph's       */
 285   /*    advance vector.                                                    */
 286   /*                                                                       */
 287   FT_EXPORT( FT_Error )
 288   FT_Glyph_Transform( FT_Glyph    glyph,
 289                       FT_Matrix*  matrix,
 290                       FT_Vector*  delta );
 291
 292
 293   /*************************************************************************/
 294   /*                                                                       */
 295   /* <Enum>                                                                */
 296   /*    FT_Glyph_BBox_Mode                                                 */
 297   /*                                                                       */
 298   /* <Description>                                                         */
 299   /*    The mode how the values of @FT_Glyph_Get_CBox are returned.        */
 300   /*                                                                       */
 301   /* <Values>                                                              */
 302   /*    FT_GLYPH_BBOX_UNSCALED ::                                          */
 303   /*      Return unscaled font units.                                      */
 304   /*                                                                       */
 305   /*    FT_GLYPH_BBOX_SUBPIXELS ::                                         */
 306   /*      Return unfitted 26.6 coordinates.                                */
 307   /*                                                                       */
 308   /*    FT_GLYPH_BBOX_GRIDFIT ::                                           */
 309   /*      Return grid-fitted 26.6 coordinates.                             */
 310   /*                                                                       */
 311   /*    FT_GLYPH_BBOX_TRUNCATE ::                                          */
 312   /*      Return coordinates in integer pixels.                            */
 313   /*                                                                       */
 314   /*    FT_GLYPH_BBOX_PIXELS ::                                            */
 315   /*      Return grid-fitted pixel coordinates.                            */
 316   /*                                                                       */
 317   typedef enum  FT_Glyph_BBox_Mode_
 318   {
 319     FT_GLYPH_BBOX_UNSCALED  = 0,
 320     FT_GLYPH_BBOX_SUBPIXELS = 0,
 321     FT_GLYPH_BBOX_GRIDFIT   = 1,
 322     FT_GLYPH_BBOX_TRUNCATE  = 2,
 323     FT_GLYPH_BBOX_PIXELS    = 3
 324
 325   } FT_Glyph_BBox_Mode;
 326
 327
 328   /* these constants are deprecated; use the corresponding */
 329   /* `FT_Glyph_BBox_Mode' values instead                   */
 330 #define ft_glyph_bbox_unscaled   FT_GLYPH_BBOX_UNSCALED
 331 #define ft_glyph_bbox_subpixels  FT_GLYPH_BBOX_SUBPIXELS
 332 #define ft_glyph_bbox_gridfit    FT_GLYPH_BBOX_GRIDFIT
 333 #define ft_glyph_bbox_truncate   FT_GLYPH_BBOX_TRUNCATE
 334 #define ft_glyph_bbox_pixels     FT_GLYPH_BBOX_PIXELS
 335
 336
 337   /*************************************************************************/
 338   /*                                                                       */
 339   /* <Function>                                                            */
 340   /*    FT_Glyph_Get_CBox                                                  */
 341   /*                                                                       */
 342   /* <Description>                                                         */
 343   /*    Return a glyph's `control box'.  The control box encloses all the  */
 344   /*    outline's points, including Bézier control points.  Though it      */
 345   /*    coincides with the exact bounding box for most glyphs, it can be   */
 346   /*    slightly larger in some situations (like when rotating an outline  */
 347   /*    that contains Bézier outside arcs).                                */
 348   /*                                                                       */
 349   /*    Computing the control box is very fast, while getting the bounding */
 350   /*    box can take much more time as it needs to walk over all segments  */
 351   /*    and arcs in the outline.  To get the latter, you can use the       */
 352   /*    `ftbbox' component, which is dedicated to this single task.        */
 353   /*                                                                       */
 354   /* <Input>                                                               */
 355   /*    glyph :: A handle to the source glyph object.                      */
 356   /*                                                                       */
 357   /*    mode  :: The mode that indicates how to interpret the returned     */
 358   /*             bounding box values.                                      */
 359   /*                                                                       */
 360   /* <Output>                                                              */
 361   /*    acbox :: The glyph coordinate bounding box.  Coordinates are       */
 362   /*             expressed in 1/64th of pixels if it is grid-fitted.       */
 363   /*                                                                       */
 364   /* <Note>                                                                */
 365   /*    Coordinates are relative to the glyph origin, using the y~upwards  */
 366   /*    convention.                                                        */
 367   /*                                                                       */
 368   /*    If the glyph has been loaded with @FT_LOAD_NO_SCALE, `bbox_mode'   */
 369   /*    must be set to @FT_GLYPH_BBOX_UNSCALED to get unscaled font        */
 370   /*    units in 26.6 pixel format.  The value @FT_GLYPH_BBOX_SUBPIXELS    */
 371   /*    is another name for this constant.                                 */
 372   /*                                                                       */
 373   /*    If the font is tricky and the glyph has been loaded with           */
 374   /*    @FT_LOAD_NO_SCALE, the resulting CBox is meaningless.  To get      */
 375   /*    reasonable values for the CBox it is necessary to load the glyph   */
 376   /*    at a large ppem value (so that the hinting instructions can        */
 377   /*    properly shift and scale the subglyphs), then extracting the CBox, */
 378   /*    which can be eventually converted back to font units.              */
 379   /*                                                                       */
 380   /*    Note that the maximum coordinates are exclusive, which means that  */
 381   /*    one can compute the width and height of the glyph image (be it in  */
 382   /*    integer or 26.6 pixels) as:                                        */
 383   /*                                                                       */
 384   /*    {                                                                  */
 385   /*      width  = bbox.xMax - bbox.xMin;                                  */
 386   /*      height = bbox.yMax - bbox.yMin;                                  */
 387   /*    }                                                                  */
 388   /*                                                                       */
 389   /*    Note also that for 26.6 coordinates, if `bbox_mode' is set to      */
 390   /*    @FT_GLYPH_BBOX_GRIDFIT, the coordinates will also be grid-fitted,  */
 391   /*    which corresponds to:                                              */
 392   /*                                                                       */
 393   /*    {                                                                  */
 394   /*      bbox.xMin = FLOOR(bbox.xMin);                                    */
 395   /*      bbox.yMin = FLOOR(bbox.yMin);                                    */
 396   /*      bbox.xMax = CEILING(bbox.xMax);                                  */
 397   /*      bbox.yMax = CEILING(bbox.yMax);                                  */
 398   /*    }                                                                  */
 399   /*                                                                       */
 400   /*    To get the bbox in pixel coordinates, set `bbox_mode' to           */
 401   /*    @FT_GLYPH_BBOX_TRUNCATE.                                           */
 402   /*                                                                       */
 403   /*    To get the bbox in grid-fitted pixel coordinates, set `bbox_mode'  */
 404   /*    to @FT_GLYPH_BBOX_PIXELS.                                          */
 405   /*                                                                       */
 406   FT_EXPORT( void )
 407   FT_Glyph_Get_CBox( FT_Glyph  glyph,
 408                      FT_UInt   bbox_mode,
 409                      FT_BBox  *acbox );
 410
 411
 412   /*************************************************************************/
 413   /*                                                                       */
 414   /* <Function>                                                            */
 415   /*    FT_Glyph_To_Bitmap                                                 */
 416   /*                                                                       */
 417   /* <Description>                                                         */
 418   /*    Convert a given glyph object to a bitmap glyph object.             */
 419   /*                                                                       */
 420   /* <InOut>                                                               */
 421   /*    the_glyph   :: A pointer to a handle to the target glyph.          */
 422   /*                                                                       */
 423   /* <Input>                                                               */
 424   /*    render_mode :: An enumeration that describes how the data is       */
 425   /*                   rendered.                                           */
 426   /*                                                                       */
 427   /*    origin      :: A pointer to a vector used to translate the glyph   */
 428   /*                   image before rendering.  Can be~0 (if no            */
 429   /*                   translation).  The origin is expressed in           */
 430   /*                   26.6 pixels.                                        */
 431   /*                                                                       */
 432   /*    destroy     :: A boolean that indicates that the original glyph    */
 433   /*                   image should be destroyed by this function.  It is  */
 434   /*                   never destroyed in case of error.                   */
 435   /*                                                                       */
 436   /* <Return>                                                              */
 437   /*    FreeType error code.  0~means success.                             */
 438   /*                                                                       */
 439   /* <Note>                                                                */
 440   /*    This function does nothing if the glyph format isn't scalable.     */
 441   /*                                                                       */
 442   /*    The glyph image is translated with the `origin' vector before      */
 443   /*    rendering.                                                         */
 444   /*                                                                       */
 445   /*    The first parameter is a pointer to an @FT_Glyph handle, that will */
 446   /*    be _replaced_ by this function (with newly allocated data).        */
 447   /*    Typically, you would use (omitting error handling):                */
 448   /*                                                                       */
 449   /*                                                                       */
 450   /*      {                                                                */
 451   /*        FT_Glyph        glyph;                                         */
 452   /*        FT_BitmapGlyph  glyph_bitmap;                                  */
 453   /*                                                                       */
 454   /*                                                                       */
 455   /*        // load glyph                                                  */
 456   /*        error = FT_Load_Char( face, glyph_index, FT_LOAD_DEFAUT );     */
 457   /*                                                                       */
 458   /*        // extract glyph image                                         */
 459   /*        error = FT_Get_Glyph( face->glyph, &glyph );                   */
 460   /*                                                                       */
 461   /*        // convert to a bitmap (default render mode + destroying old)  */
 462   /*        if ( glyph->format != FT_GLYPH_FORMAT_BITMAP )                 */
 463   /*        {                                                              */
 464   /*          error = FT_Glyph_To_Bitmap( &glyph, FT_RENDER_MODE_NORMAL,   */
 465   /*                                      0, 1 );                          */
 466   /*          if ( error ) // `glyph' unchanged                            */
 467   /*            ...                                                        */
 468   /*        }                                                              */
 469   /*                                                                       */
 470   /*        // access bitmap content by typecasting                        */
 471   /*        glyph_bitmap = (FT_BitmapGlyph)glyph;                          */
 472   /*                                                                       */
 473   /*        // do funny stuff with it, like blitting/drawing               */
 474   /*        ...                                                            */
 475   /*                                                                       */
 476   /*        // discard glyph image (bitmap or not)                         */
 477   /*        FT_Done_Glyph( glyph );                                        */
 478   /*      }                                                                */
 479   /*                                                                       */
 480   /*                                                                       */
 481   /*    Here another example, again without error handling:                */
 482   /*                                                                       */
 483   /*                                                                       */
 484   /*      {                                                                */
 485   /*        FT_Glyph  glyphs[MAX_GLYPHS]                                   */
 486   /*                                                                       */
 487   /*                                                                       */
 488   /*        ...                                                            */
 489   /*                                                                       */
 490   /*        for ( idx = 0; i < MAX_GLYPHS; i++ )                           */
 491   /*          error = FT_Load_Glyph( face, idx, FT_LOAD_DEFAULT ) ||       */
 492   /*                  FT_Get_Glyph ( face->glyph, &glyph[idx] );           */
 493   /*                                                                       */
 494   /*        ...                                                            */
 495   /*                                                                       */
 496   /*        for ( idx = 0; i < MAX_GLYPHS; i++ )                           */
 497   /*        {                                                              */
 498   /*          FT_Glyph  bitmap = glyphs[idx];                              */
 499   /*                                                                       */
 500   /*                                                                       */
 501   /*          ...                                                          */
 502   /*                                                                       */
 503   /*          // after this call, `bitmap' no longer points into           */
 504   /*          // the `glyphs' array (and the old value isn't destroyed)    */
 505   /*          FT_Glyph_To_Bitmap( &bitmap, FT_RENDER_MODE_MONO, 0, 0 );    */
 506   /*                                                                       */
 507   /*          ...                                                          */
 508   /*                                                                       */
 509   /*          FT_Done_Glyph( bitmap );                                     */
 510   /*        }                                                              */
 511   /*                                                                       */
 512   /*        ...                                                            */
 513   /*                                                                       */
 514   /*        for ( idx = 0; i < MAX_GLYPHS; i++ )                           */
 515   /*          FT_Done_Glyph( glyphs[idx] );                                */
 516   /*      }                                                                */
 517   /*                                                                       */
 518   FT_EXPORT( FT_Error )
 519   FT_Glyph_To_Bitmap( FT_Glyph*       the_glyph,
 520                       FT_Render_Mode  render_mode,
 521                       FT_Vector*      origin,
 522                       FT_Bool         destroy );
 523
 524
 525   /*************************************************************************/
 526   /*                                                                       */
 527   /* <Function>                                                            */
 528   /*    FT_Done_Glyph                                                      */
 529   /*                                                                       */
 530   /* <Description>                                                         */
 531   /*    Destroy a given glyph.                                             */
 532   /*                                                                       */
 533   /* <Input>                                                               */
 534   /*    glyph :: A handle to the target glyph object.                      */
 535   /*                                                                       */
 536   FT_EXPORT( void )
 537   FT_Done_Glyph( FT_Glyph  glyph );
 538
 539   /* */
 540
 541
 542   /* other helpful functions */
 543
 544   /*************************************************************************/
 545   /*                                                                       */
 546   /* <Section>                                                             */
 547   /*    computations                                                       */
 548   /*                                                                       */
 549   /*************************************************************************/
 550
 551
 552   /*************************************************************************/
 553   /*                                                                       */
 554   /* <Function>                                                            */
 555   /*    FT_Matrix_Multiply                                                 */
 556   /*                                                                       */
 557   /* <Description>                                                         */
 558   /*    Perform the matrix operation `b = a*b'.                            */
 559   /*                                                                       */
 560   /* <Input>                                                               */
 561   /*    a :: A pointer to matrix `a'.                                      */
 562   /*                                                                       */
 563   /* <InOut>                                                               */
 564   /*    b :: A pointer to matrix `b'.                                      */
 565   /*                                                                       */
 566   /* <Note>                                                                */
 567   /*    The result is undefined if either `a' or `b' is zero.              */
 568   /*                                                                       */
 569   FT_EXPORT( void )
 570   FT_Matrix_Multiply( const FT_Matrix*  a,
 571                       FT_Matrix*        b );
 572
 573
 574   /*************************************************************************/
 575   /*                                                                       */
 576   /* <Function>                                                            */
 577   /*    FT_Matrix_Invert                                                   */
 578   /*                                                                       */
 579   /* <Description>                                                         */
 580   /*    Invert a 2x2 matrix.  Return an error if it can't be inverted.     */
 581   /*                                                                       */
 582   /* <InOut>                                                               */
 583   /*    matrix :: A pointer to the target matrix.  Remains untouched in    */
 584   /*              case of error.                                           */
 585   /*                                                                       */
 586   /* <Return>                                                              */
 587   /*    FreeType error code.  0~means success.                             */
 588   /*                                                                       */
 589   FT_EXPORT( FT_Error )
 590   FT_Matrix_Invert( FT_Matrix*  matrix );
 591
 592   /* */
 593
 594
 595 FT_END_HEADER
 596
 597 #endif /* __FTGLYPH_H__ */
 598
 599
 600 /* END */
 601
 602
 603 /* Local Variables: */
 604 /* coding: utf-8    */
 605 /* End:             */