sdk/lib/3rdparty/freetype/src/cff/cf2font.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  cf2font.c                                                              */
   4 /*                                                                         */
   5 /*    Adobe's code for font instances (body).                              */
   6 /*                                                                         */
   7 /*  Copyright 2007-2014 Adobe Systems Incorporated.                        */
   8 /*                                                                         */
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  35 /*                                                                         */
  36 /***************************************************************************/
  37
  38
  39 #include <ft2build.h>
  40 #include FT_INTERNAL_CALC_H
  41
  42 #include "cf2ft.h"
  43
  44 #include "cf2glue.h"
  45 #include "cf2font.h"
  46 #include "cf2error.h"
  47 #include "cf2intrp.h"
  48
  49
  50   /* Compute a stem darkening amount in character space. */
  51   static void
  52   cf2_computeDarkening( CF2_Fixed   emRatio,
  53                         CF2_Fixed   ppem,
  54                         CF2_Fixed   stemWidth,
  55                         CF2_Fixed*  darkenAmount,
  56                         CF2_Fixed   boldenAmount,
  57                         FT_Bool     stemDarkened,
  58                         FT_Int*     darkenParams )
  59   {
  60     /*
  61      * Total darkening amount is computed in 1000 unit character space
  62      * using the modified 5 part curve as Adobe's Avalon rasterizer.
  63      * The darkening amount is smaller for thicker stems.
  64      * It becomes zero when the stem is thicker than 2.333 pixels.
  65      *
  66      * By default, we use
  67      *
  68      *   darkenAmount = 0.4 pixels   if scaledStem <= 0.5 pixels,
  69      *   darkenAmount = 0.275 pixels if 1 <= scaledStem <= 1.667 pixels,
  70      *   darkenAmount = 0 pixel      if scaledStem >= 2.333 pixels,
  71      *
  72      * and piecewise linear in-between:
  73      *
  74      *
  75      *   darkening
  76      *       ^
  77      *       |
  78      *       |      (x1,y1)
  79      *       |--------+
  80      *       |         \
  81      *       |          \
  82      *       |           \          (x3,y3)
  83      *       |            +----------+
  84      *       |        (x2,y2)         \
  85      *       |                         \
  86      *       |                          \
  87      *       |                           +-----------------
  88      *       |                         (x4,y4)
  89      *       +--------------------------------------------->   stem
  90      *                                                       thickness
  91      *
  92      *
  93      * This corresponds to the following values for the
  94      * `darkening-parameters' property:
  95      *
  96      *   (x1, y1) = (500, 400)
  97      *   (x2, y2) = (1000, 275)
  98      *   (x3, y3) = (1667, 275)
  99      *   (x4, y4) = (2333, 0)
 100      *
 101      */
 102
 103     /* Internal calculations are done in units per thousand for */
 104     /* convenience. The x axis is scaled stem width in          */
 105     /* thousandths of a pixel. That is, 1000 is 1 pixel.        */
 106     /* The y axis is darkening amount in thousandths of a pixel.*/
 107     /* In the code, below, dividing by ppem and                 */
 108     /* adjusting for emRatio converts darkenAmount to character */
 109     /* space (font units).                                      */
 110     CF2_Fixed  stemWidthPer1000, scaledStem;
 111     FT_Int     logBase2;
 112
 113
 114     *darkenAmount = 0;
 115
 116     if ( boldenAmount == 0 && !stemDarkened )
 117       return;
 118
 119     /* protect against range problems and divide by zero */
 120     if ( emRatio < cf2_doubleToFixed( .01 ) )
 121       return;
 122
 123     if ( stemDarkened )
 124     {
 125       FT_Int  x1 = darkenParams[0];
 126       FT_Int  y1 = darkenParams[1];
 127       FT_Int  x2 = darkenParams[2];
 128       FT_Int  y2 = darkenParams[3];
 129       FT_Int  x3 = darkenParams[4];
 130       FT_Int  y3 = darkenParams[5];
 131       FT_Int  x4 = darkenParams[6];
 132       FT_Int  y4 = darkenParams[7];
 133
 134
 135       /* convert from true character space to 1000 unit character space; */
 136       /* add synthetic emboldening effect                                */
 137
 138       /* `stemWidthPer1000' will not overflow for a legitimate font      */
 139
 140       stemWidthPer1000 = FT_MulFix( stemWidth + boldenAmount, emRatio );
 141
 142       /* `scaledStem' can easily overflow, so we must clamp its maximum  */
 143       /* value; the test doesn't need to be precise, but must be         */
 144       /* conservative.  The clamp value (default 2333) where             */
 145       /* `darkenAmount' is zero is well below the overflow value of      */
 146       /* 32767.                                                          */
 147       /*                                                                 */
 148       /* FT_MSB computes the integer part of the base 2 logarithm.  The  */
 149       /* number of bits for the product is 1 or 2 more than the sum of   */
 150       /* logarithms; remembering that the 16 lowest bits of the fraction */
 151       /* are dropped this is correct to within a factor of almost 4.     */
 152       /* For example, 0x80.0000 * 0x80.0000 = 0x4000.0000 is 23+23 and   */
 153       /* is flagged as possible overflow because 0xFF.FFFF * 0xFF.FFFF = */
 154       /* 0xFFFF.FE00 is also 23+23.                                      */
 155
 156       logBase2 = FT_MSB( (FT_UInt32)stemWidthPer1000 ) +
 157                    FT_MSB( (FT_UInt32)ppem );
 158
 159       if ( logBase2 >= 46 )
 160         /* possible overflow */
 161         scaledStem = cf2_intToFixed( x4 );
 162       else
 163         scaledStem = FT_MulFix( stemWidthPer1000, ppem );
 164
 165       /* now apply the darkening parameters */
 166
 167       if ( scaledStem < cf2_intToFixed( x1 ) )
 168         *darkenAmount = FT_DivFix( cf2_intToFixed( y1 ), ppem );
 169
 170       else if ( scaledStem < cf2_intToFixed( x2 ) )
 171       {
 172         FT_Int  xdelta = x2 - x1;
 173         FT_Int  ydelta = y2 - y1;
 174         FT_Int  x      = stemWidthPer1000 -
 175                            FT_DivFix( cf2_intToFixed( x1 ), ppem );
 176
 177
 178         if ( !xdelta )
 179           goto Try_x3;
 180
 181         *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
 182                           FT_DivFix( cf2_intToFixed( y1 ), ppem );
 183       }
 184
 185       else if ( scaledStem < cf2_intToFixed( x3 ) )
 186       {
 187       Try_x3:
 188         {
 189           FT_Int  xdelta = x3 - x2;
 190           FT_Int  ydelta = y3 - y2;
 191           FT_Int  x      = stemWidthPer1000 -
 192                              FT_DivFix( cf2_intToFixed( x2 ), ppem );
 193
 194
 195           if ( !xdelta )
 196             goto Try_x4;
 197
 198           *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
 199                             FT_DivFix( cf2_intToFixed( y2 ), ppem );
 200         }
 201       }
 202
 203       else if ( scaledStem < cf2_intToFixed( x4 ) )
 204       {
 205       Try_x4:
 206         {
 207           FT_Int  xdelta = x4 - x3;
 208           FT_Int  ydelta = y4 - y3;
 209           FT_Int  x      = stemWidthPer1000 -
 210                              FT_DivFix( cf2_intToFixed( x3 ), ppem );
 211
 212
 213           if ( !xdelta )
 214             goto Use_y4;
 215
 216           *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
 217                             FT_DivFix( cf2_intToFixed( y3 ), ppem );
 218         }
 219       }
 220
 221       else
 222       {
 223       Use_y4:
 224         *darkenAmount = FT_DivFix( cf2_intToFixed( y4 ), ppem );
 225       }
 226
 227       /* use half the amount on each side and convert back to true */
 228       /* character space                                           */
 229       *darkenAmount = FT_DivFix( *darkenAmount, 2 * emRatio );
 230     }
 231
 232     /* add synthetic emboldening effect in character space */
 233     *darkenAmount += boldenAmount / 2;
 234   }
 235
 236
 237   /* set up values for the current FontDict and matrix; */
 238   /* called for each glyph to be rendered               */
 239
 240   /* caller's transform is adjusted for subpixel positioning */
 241   static void
 242   cf2_font_setup( CF2_Font           font,
 243                   const CF2_Matrix*  transform )
 244   {
 245     /* pointer to parsed font object */
 246     CFF_Decoder*  decoder = font->decoder;
 247
 248     FT_Bool  needExtraSetup = FALSE;
 249
 250     CFF_VStoreRec*  vstore;
 251     FT_Bool         hasVariations = FALSE;
 252
 253     /* character space units */
 254     CF2_Fixed  boldenX = font->syntheticEmboldeningAmountX;
 255     CF2_Fixed  boldenY = font->syntheticEmboldeningAmountY;
 256
 257     CFF_SubFont  subFont;
 258     CF2_Fixed    ppem;
 259
 260     CF2_UInt   lenNormalizedV = 0;
 261     FT_Fixed*  normalizedV    = NULL;
 262
 263
 264     /* clear previous error */
 265     font->error = FT_Err_Ok;
 266
 267     /* if a CID fontDict has changed, we need to recompute some cached */
 268     /* data                                                            */
 269     subFont = cf2_getSubfont( decoder );
 270     if ( font->lastSubfont != subFont )
 271     {
 272       font->lastSubfont = subFont;
 273       needExtraSetup    = TRUE;
 274     }
 275
 276     /* check for variation vectors */
 277     vstore        = cf2_getVStore( decoder );
 278     hasVariations = ( vstore->dataCount != 0 );
 279
 280     if ( hasVariations )
 281     {
 282 #ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
 283       /* check whether Private DICT in this subfont needs to be reparsed */
 284       font->error = cf2_getNormalizedVector( decoder,
 285                                              &lenNormalizedV,
 286                                              &normalizedV );
 287       if ( font->error )
 288         return;
 289
 290       if ( cff_blend_check_vector( &subFont->blend,
 291                                    subFont->private_dict.vsindex,
 292                                    lenNormalizedV,
 293                                    normalizedV ) )
 294       {
 295         /* blend has changed, reparse */
 296         cff_load_private_dict( decoder->cff,
 297                                subFont,
 298                                lenNormalizedV,
 299                                normalizedV );
 300         needExtraSetup = TRUE;
 301       }
 302 #endif
 303
 304       /* copy from subfont */
 305       font->blend.font = subFont->blend.font;
 306
 307       /* clear state of charstring blend */
 308       font->blend.usedBV = FALSE;
 309
 310       /* initialize value for charstring */
 311       font->vsindex = subFont->private_dict.vsindex;
 312
 313       /* store vector inputs for blends in charstring */
 314       font->lenNDV = lenNormalizedV;
 315       font->NDV    = normalizedV;
 316     }
 317
 318     /* if ppem has changed, we need to recompute some cached data         */
 319     /* note: because of CID font matrix concatenation, ppem and transform */
 320     /*       do not necessarily track.                                    */
 321     ppem = cf2_getPpemY( decoder );
 322     if ( font->ppem != ppem )
 323     {
 324       font->ppem     = ppem;
 325       needExtraSetup = TRUE;
 326     }
 327
 328     /* copy hinted flag on each call */
 329     font->hinted = (FT_Bool)( font->renderingFlags & CF2_FlagsHinted );
 330
 331     /* determine if transform has changed;       */
 332     /* include Fontmatrix but ignore translation */
 333     if ( ft_memcmp( transform,
 334                     &font->currentTransform,
 335                     4 * sizeof ( CF2_Fixed ) ) != 0 )
 336     {
 337       /* save `key' information for `cache of one' matrix data; */
 338       /* save client transform, without the translation         */
 339       font->currentTransform    = *transform;
 340       font->currentTransform.tx =
 341       font->currentTransform.ty = cf2_intToFixed( 0 );
 342
 343       /* TODO: FreeType transform is simple scalar; for now, use identity */
 344       /*       for outer                                                  */
 345       font->innerTransform   = *transform;
 346       font->outerTransform.a =
 347       font->outerTransform.d = cf2_intToFixed( 1 );
 348       font->outerTransform.b =
 349       font->outerTransform.c = cf2_intToFixed( 0 );
 350
 351       needExtraSetup = TRUE;
 352     }
 353
 354     /*
 355      * font->darkened is set to true if there is a stem darkening request or
 356      * the font is synthetic emboldened.
 357      * font->darkened controls whether to adjust blue zones, winding order,
 358      * and hinting.
 359      *
 360      */
 361     if ( font->stemDarkened != ( font->renderingFlags & CF2_FlagsDarkened ) )
 362     {
 363       font->stemDarkened =
 364         (FT_Bool)( font->renderingFlags & CF2_FlagsDarkened );
 365
 366       /* blue zones depend on darkened flag */
 367       needExtraSetup = TRUE;
 368     }
 369
 370     /* recompute variables that are dependent on transform or FontDict or */
 371     /* darken flag                                                        */
 372     if ( needExtraSetup )
 373     {
 374       /* StdVW is found in the private dictionary;                       */
 375       /* recompute darkening amounts whenever private dictionary or      */
 376       /* transform change                                                */
 377       /* Note: a rendering flag turns darkening on or off, so we want to */
 378       /*       store the `on' amounts;                                   */
 379       /*       darkening amount is computed in character space           */
 380       /* TODO: testing size-dependent darkening here;                    */
 381       /*       what to do for rotations?                                 */
 382
 383       CF2_Fixed  emRatio;
 384       CF2_Fixed  stdHW;
 385       CF2_Int    unitsPerEm = font->unitsPerEm;
 386
 387
 388       if ( unitsPerEm == 0 )
 389         unitsPerEm = 1000;
 390
 391       ppem = FT_MAX( cf2_intToFixed( 4 ),
 392                      font->ppem ); /* use minimum ppem of 4 */
 393
 394 #if 0
 395       /* since vstem is measured in the x-direction, we use the `a' member */
 396       /* of the fontMatrix                                                 */
 397       emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->a );
 398 #endif
 399
 400       /* Freetype does not preserve the fontMatrix when parsing; use */
 401       /* unitsPerEm instead.                                         */
 402       /* TODO: check precision of this                               */
 403       emRatio     = cf2_intToFixed( 1000 ) / unitsPerEm;
 404       font->stdVW = cf2_getStdVW( decoder );
 405
 406       if ( font->stdVW <= 0 )
 407         font->stdVW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
 408
 409       if ( boldenX > 0 )
 410       {
 411         /* Ensure that boldenX is at least 1 pixel for synthetic bold font */
 412         /* (similar to what Avalon does)                                   */
 413         boldenX = FT_MAX( boldenX,
 414                           FT_DivFix( cf2_intToFixed( unitsPerEm ), ppem ) );
 415
 416         /* Synthetic emboldening adds at least 1 pixel to darkenX, while */
 417         /* stem darkening adds at most half pixel.  Since the purpose of */
 418         /* stem darkening (readability at small sizes) is met with       */
 419         /* synthetic emboldening, no need to add stem darkening for a    */
 420         /* synthetic bold font.                                          */
 421         cf2_computeDarkening( emRatio,
 422                               ppem,
 423                               font->stdVW,
 424                               &font->darkenX,
 425                               boldenX,
 426                               FALSE,
 427                               font->darkenParams );
 428       }
 429       else
 430         cf2_computeDarkening( emRatio,
 431                               ppem,
 432                               font->stdVW,
 433                               &font->darkenX,
 434                               0,
 435                               font->stemDarkened,
 436                               font->darkenParams );
 437
 438 #if 0
 439       /* since hstem is measured in the y-direction, we use the `d' member */
 440       /* of the fontMatrix                                                 */
 441       /* TODO: use the same units per em as above; check this              */
 442       emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->d );
 443 #endif
 444
 445       /* set the default stem width, because it must be the same for all */
 446       /* family members;                                                 */
 447       /* choose a constant for StdHW that depends on font contrast       */
 448       stdHW = cf2_getStdHW( decoder );
 449
 450       if ( stdHW > 0 && font->stdVW > MUL_INT32( 2, stdHW ) )
 451         font->stdHW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
 452       else
 453       {
 454         /* low contrast font gets less hstem darkening */
 455         font->stdHW = FT_DivFix( cf2_intToFixed( 110 ), emRatio );
 456       }
 457
 458       cf2_computeDarkening( emRatio,
 459                             ppem,
 460                             font->stdHW,
 461                             &font->darkenY,
 462                             boldenY,
 463                             font->stemDarkened,
 464                             font->darkenParams );
 465
 466       if ( font->darkenX != 0 || font->darkenY != 0 )
 467         font->darkened = TRUE;
 468       else
 469         font->darkened = FALSE;
 470
 471       font->reverseWinding = FALSE; /* initial expectation is CCW */
 472
 473       /* compute blue zones for this instance */
 474       cf2_blues_init( &font->blues, font );
 475
 476     } /* needExtraSetup */
 477   }
 478
 479
 480   /* equivalent to AdobeGetOutline */
 481   FT_LOCAL_DEF( FT_Error )
 482   cf2_getGlyphOutline( CF2_Font           font,
 483                        CF2_Buffer         charstring,
 484                        const CF2_Matrix*  transform,
 485                        CF2_F16Dot16*      glyphWidth )
 486   {
 487     FT_Error  lastError = FT_Err_Ok;
 488
 489     FT_Vector  translation;
 490
 491 #if 0
 492     FT_Vector  advancePoint;
 493 #endif
 494
 495     CF2_Fixed  advWidth = 0;
 496     FT_Bool    needWinding;
 497
 498
 499     /* Note: use both integer and fraction for outlines.  This allows bbox */
 500     /*       to come out directly.                                         */
 501
 502     translation.x = transform->tx;
 503     translation.y = transform->ty;
 504
 505     /* set up values based on transform */
 506     cf2_font_setup( font, transform );
 507     if ( font->error )
 508       goto exit;                      /* setup encountered an error */
 509
 510     /* reset darken direction */
 511     font->reverseWinding = FALSE;
 512
 513     /* winding order only affects darkening */
 514     needWinding = font->darkened;
 515
 516     while ( 1 )
 517     {
 518       /* reset output buffer */
 519       cf2_outline_reset( &font->outline );
 520
 521       /* build the outline, passing the full translation */
 522       cf2_interpT2CharString( font,
 523                               charstring,
 524                               (CF2_OutlineCallbacks)&font->outline,
 525                               &translation,
 526                               FALSE,
 527                               0,
 528                               0,
 529                               &advWidth );
 530
 531       if ( font->error )
 532         goto exit;
 533
 534       if ( !needWinding )
 535         break;
 536
 537       /* check winding order */
 538       if ( font->outline.root.windingMomentum >= 0 ) /* CFF is CCW */
 539         break;
 540
 541       /* invert darkening and render again                            */
 542       /* TODO: this should be a parameter to getOutline-computeOffset */
 543       font->reverseWinding = TRUE;
 544
 545       needWinding = FALSE;    /* exit after next iteration */
 546     }
 547
 548     /* finish storing client outline */
 549     cf2_outline_close( &font->outline );
 550
 551   exit:
 552     /* FreeType just wants the advance width; there is no translation */
 553     *glyphWidth = advWidth;
 554
 555     /* free resources and collect errors from objects we've used */
 556     cf2_setError( &font->error, lastError );
 557
 558     return font->error;
 559   }
 560
 561
 562 /* END */