psblues.h File Reference

#include "psglue.h"

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Classes
struct	CF2_HintRec_
struct	CF2_BlueRec_
struct	CF2_BluesRec_

Macros
#define	CF2_MIN_COUNTER   cf2_doubleToFixed( 0.5 )

Typedefs
typedef struct CF2_BlueRec_	CF2_BlueRec
typedef struct CF2_BluesRec_	CF2_BluesRec
typedef struct CF2_BluesRec_ *	CF2_Blues

Enumerations
enum	{   CF2_GhostBottom = 0x1, CF2_GhostTop = 0x2, CF2_PairBottom = 0x4, CF2_PairTop = 0x8,   CF2_Locked = 0x10, CF2_Synthetic = 0x20 }
enum	{ CF2_ICF_Top = cf2_intToFixed( 880 ), CF2_ICF_Bottom = cf2_intToFixed( -120 ) }
enum	{ CF2_MAX_BLUES = 7, CF2_MAX_OTHERBLUES = 5 }

Functions
	cf2_blues_init (CF2_Blues blues, CF2_Font font)
	cf2_blues_capture (const CF2_Blues blues, CF2_Hint bottomHintEdge, CF2_Hint topHintEdge)

Macro Definition Documentation

CF2_MIN_COUNTER

#define CF2_MIN_COUNTER   cf2_doubleToFixed( 0.5 )

Definition at line 114 of file psblues.h.

Typedef Documentation

CF2_BlueRec

typedef struct CF2_BlueRec_ CF2_BlueRec

CF2_Blues

typedef struct CF2_BluesRec_ * CF2_Blues

CF2_BluesRec

typedef struct CF2_BluesRec_ CF2_BluesRec

Enumeration Type Documentation

anonymous enum

anonymous enum

Enumerator
CF2_GhostBottom
CF2_GhostTop
CF2_PairBottom
CF2_PairTop
CF2_Locked
CF2_Synthetic

Definition at line 85 of file psblues.h.

  {
    CF2_GhostBottom = 0x1,  /* a single bottom edge           */
    CF2_GhostTop    = 0x2,  /* a single top edge              */
    CF2_PairBottom  = 0x4,  /* the bottom edge of a stem hint */
    CF2_PairTop     = 0x8,  /* the top edge of a stem hint    */
    CF2_Locked      = 0x10, /* this edge has been aligned     */
                            /* by a blue zone                 */
    CF2_Synthetic   = 0x20  /* this edge was synthesized      */
  };

anonymous enum

anonymous enum

Enumerator
CF2_ICF_Top
CF2_ICF_Bottom

Definition at line 103 of file psblues.h.

  {
    CF2_ICF_Top    = cf2_intToFixed(  880 ),
    CF2_ICF_Bottom = cf2_intToFixed( -120 )
  };

anonymous enum

anonymous enum

Enumerator
CF2_MAX_BLUES
CF2_MAX_OTHERBLUES

Definition at line 142 of file psblues.h.

  {
    CF2_MAX_BLUES      = 7,
    CF2_MAX_OTHERBLUES = 5
  };

Function Documentation

cf2_blues_capture()

cf2_blues_capture	(	const CF2_Blues	blues,
		CF2_Hint	bottomHintEdge,
		CF2_Hint	topHintEdge
	)

Definition at line 465 of file psblues.c.

  {
    /* TODO: validate? */
    CF2_Fixed  csFuzz = blues->blueFuzz;

    /* new position of captured edge */
    CF2_Fixed  dsNew;

    /* amount that hint is moved when positioned */
    CF2_Fixed  dsMove = 0;

    FT_Bool   captured = FALSE;
    CF2_UInt  i;


    /* assert edge flags are consistent */
    FT_ASSERT( !cf2_hint_isTop( bottomHintEdge ) &&
               !cf2_hint_isBottom( topHintEdge ) );

    /* TODO: search once without blue fuzz for compatibility with coretype? */
    for ( i = 0; i < blues->count; i++ )
    {
      if ( blues->zone[i].bottomZone           &&
           cf2_hint_isBottom( bottomHintEdge ) )
      {
        if ( SUB_INT32( blues->zone[i].csBottomEdge, csFuzz ) <=
               bottomHintEdge->csCoord                           &&
             bottomHintEdge->csCoord <=
               ADD_INT32( blues->zone[i].csTopEdge, csFuzz )     )
        {
          /* bottom edge captured by bottom zone */

          if ( blues->suppressOvershoot )
            dsNew = blues->zone[i].dsFlatEdge;

          else if ( SUB_INT32( blues->zone[i].csTopEdge,
                               bottomHintEdge->csCoord ) >=
                      blues->blueShift )
          {
            /* guarantee minimum of 1 pixel overshoot */
            dsNew = FT_MIN(
                      cf2_fixedRound( bottomHintEdge->dsCoord ),
                      blues->zone[i].dsFlatEdge - cf2_intToFixed( 1 ) );
          }

          else
          {
            /* simply round captured edge */
            dsNew = cf2_fixedRound( bottomHintEdge->dsCoord );
          }

          dsMove   = SUB_INT32( dsNew, bottomHintEdge->dsCoord );
          captured = TRUE;

          break;
        }
      }

      if ( !blues->zone[i].bottomZone && cf2_hint_isTop( topHintEdge ) )
      {
        if ( SUB_INT32( blues->zone[i].csBottomEdge, csFuzz ) <=
               topHintEdge->csCoord                              &&
             topHintEdge->csCoord <=
               ADD_INT32( blues->zone[i].csTopEdge, csFuzz )     )
        {
          /* top edge captured by top zone */

          if ( blues->suppressOvershoot )
            dsNew = blues->zone[i].dsFlatEdge;

          else if ( SUB_INT32( topHintEdge->csCoord,
                               blues->zone[i].csBottomEdge ) >=
                      blues->blueShift )
          {
            /* guarantee minimum of 1 pixel overshoot */
            dsNew = FT_MAX(
                      cf2_fixedRound( topHintEdge->dsCoord ),
                      blues->zone[i].dsFlatEdge + cf2_intToFixed( 1 ) );
          }

          else
          {
            /* simply round captured edge */
            dsNew = cf2_fixedRound( topHintEdge->dsCoord );
          }

          dsMove   = SUB_INT32( dsNew, topHintEdge->dsCoord );
          captured = TRUE;

          break;
        }
      }
    }

    if ( captured )
    {
      /* move both edges and flag them `locked' */
      if ( cf2_hint_isValid( bottomHintEdge ) )
      {
        bottomHintEdge->dsCoord = ADD_INT32( bottomHintEdge->dsCoord,
                                             dsMove );
        cf2_hint_lock( bottomHintEdge );
      }

      if ( cf2_hint_isValid( topHintEdge ) )
      {
        topHintEdge->dsCoord = ADD_INT32( topHintEdge->dsCoord, dsMove );
        cf2_hint_lock( topHintEdge );
      }
    }

    return captured;
  }

Referenced by cf2_hintmap_build().

cf2_blues_init()

cf2_blues_init	(	CF2_Blues	blues,
		CF2_Font	font
	)

Definition at line 66 of file psblues.c.

  {
    /* pointer to parsed font object */
    PS_Decoder*  decoder = font->decoder;

    CF2_Fixed  zoneHeight;
    CF2_Fixed  maxZoneHeight = 0;
    CF2_Fixed  csUnitsPerPixel;

    size_t  numBlueValues;
    size_t  numOtherBlues;
    size_t  numFamilyBlues;
    size_t  numFamilyOtherBlues;

    FT_Pos*  blueValues;
    FT_Pos*  otherBlues;
    FT_Pos*  familyBlues;
    FT_Pos*  familyOtherBlues;

    size_t     i;
    CF2_Fixed  emBoxBottom, emBoxTop;

#if 0
    CF2_Int  unitsPerEm = font->unitsPerEm;


    if ( unitsPerEm == 0 )
      unitsPerEm = 1000;
#endif

    FT_ZERO( blues );
    blues->scale = font->innerTransform.d;

    cf2_getBlueMetrics( decoder,
                        &blues->blueScale,
                        &blues->blueShift,
                        &blues->blueFuzz );

    cf2_getBlueValues( decoder, &numBlueValues, &blueValues );
    cf2_getOtherBlues( decoder, &numOtherBlues, &otherBlues );
    cf2_getFamilyBlues( decoder, &numFamilyBlues, &familyBlues );
    cf2_getFamilyOtherBlues( decoder, &numFamilyOtherBlues, &familyOtherBlues );

    /*
     * synthetic em box hint heuristic
     *
     * Apply this when ideographic dictionary (LanguageGroup 1) has no
     * real alignment zones.  Adobe tools generate dummy zones at -250 and
     * 1100 for a 1000 unit em.  Fonts with ICF-based alignment zones
     * should not enable the heuristic.  When the heuristic is enabled,
     * the font's blue zones are ignored.
     *
     */

    /* get em box from OS/2 typoAscender/Descender                      */
    /* TODO: FreeType does not parse these metrics.  Skip them for now. */
#if 0
    FCM_getHorizontalLineMetrics( &e,
                                  font->font,
                                  &ascender,
                                  &descender,
                                  &linegap );
    if ( ascender - descender == unitsPerEm )
    {
      emBoxBottom = cf2_intToFixed( descender );
      emBoxTop    = cf2_intToFixed( ascender );
    }
    else
#endif
    {
      emBoxBottom = CF2_ICF_Bottom;
      emBoxTop    = CF2_ICF_Top;
    }

    if ( cf2_getLanguageGroup( decoder ) == 1                   &&
         ( numBlueValues == 0                                 ||
           ( numBlueValues == 4                             &&
             cf2_blueToFixed( blueValues[0] ) < emBoxBottom &&
             cf2_blueToFixed( blueValues[1] ) < emBoxBottom &&
             cf2_blueToFixed( blueValues[2] ) > emBoxTop    &&
             cf2_blueToFixed( blueValues[3] ) > emBoxTop    ) ) )
    {
      /*
       * Construct hint edges suitable for synthetic ghost hints at top
       * and bottom of em box.  +-CF2_MIN_COUNTER allows for unhinted
       * features above or below the last hinted edge.  This also gives a
       * net 1 pixel boost to the height of ideographic glyphs.
       *
       * Note: Adjust synthetic hints outward by epsilon (0x.0001) to
       *       avoid interference.  E.g., some fonts have real hints at
       *       880 and -120.
       */

      blues->emBoxBottomEdge.csCoord = emBoxBottom - CF2_FIXED_EPSILON;
      blues->emBoxBottomEdge.dsCoord = cf2_fixedRound(
                                         FT_MulFix(
                                           blues->emBoxBottomEdge.csCoord,
                                           blues->scale ) ) -
                                       CF2_MIN_COUNTER;
      blues->emBoxBottomEdge.scale   = blues->scale;
      blues->emBoxBottomEdge.flags   = CF2_GhostBottom |
                                       CF2_Locked |
                                       CF2_Synthetic;

      blues->emBoxTopEdge.csCoord = emBoxTop + CF2_FIXED_EPSILON +
                                    2 * font->darkenY;
      blues->emBoxTopEdge.dsCoord = cf2_fixedRound(
                                      FT_MulFix(
                                        blues->emBoxTopEdge.csCoord,
                                        blues->scale ) ) +
                                    CF2_MIN_COUNTER;
      blues->emBoxTopEdge.scale   = blues->scale;
      blues->emBoxTopEdge.flags   = CF2_GhostTop |
                                    CF2_Locked |
                                    CF2_Synthetic;

      blues->doEmBoxHints = TRUE;    /* enable the heuristic */

      return;
    }

    /* copy `BlueValues' and `OtherBlues' to a combined array of top and */
    /* bottom zones                                                      */
    for ( i = 0; i < numBlueValues; i += 2 )
    {
      blues->zone[blues->count].csBottomEdge =
        cf2_blueToFixed( blueValues[i] );
      blues->zone[blues->count].csTopEdge =
        cf2_blueToFixed( blueValues[i + 1] );

      zoneHeight = SUB_INT32( blues->zone[blues->count].csTopEdge,
                              blues->zone[blues->count].csBottomEdge );

      if ( zoneHeight < 0 )
      {
        FT_TRACE4(( "cf2_blues_init: ignoring negative zone height\n" ));
        continue;   /* reject this zone */
      }

      if ( zoneHeight > maxZoneHeight )
      {
        /* take maximum before darkening adjustment      */
        /* so overshoot suppression point doesn't change */
        maxZoneHeight = zoneHeight;
      }

      /* adjust both edges of top zone upward by twice darkening amount */
      if ( i != 0 )
      {
        blues->zone[blues->count].csTopEdge    += 2 * font->darkenY;
        blues->zone[blues->count].csBottomEdge += 2 * font->darkenY;
      }

      /* first `BlueValue' is bottom zone; others are top */
      if ( i == 0 )
      {
        blues->zone[blues->count].bottomZone =
          TRUE;
        blues->zone[blues->count].csFlatEdge =
          blues->zone[blues->count].csTopEdge;
      }
      else
      {
        blues->zone[blues->count].bottomZone =
          FALSE;
        blues->zone[blues->count].csFlatEdge =
          blues->zone[blues->count].csBottomEdge;
      }

      blues->count += 1;
    }

    for ( i = 0; i < numOtherBlues; i += 2 )
    {
      blues->zone[blues->count].csBottomEdge =
        cf2_blueToFixed( otherBlues[i] );
      blues->zone[blues->count].csTopEdge =
        cf2_blueToFixed( otherBlues[i + 1] );

      zoneHeight = SUB_INT32( blues->zone[blues->count].csTopEdge,
                              blues->zone[blues->count].csBottomEdge );

      if ( zoneHeight < 0 )
      {
        FT_TRACE4(( "cf2_blues_init: ignoring negative zone height\n" ));
        continue;   /* reject this zone */
      }

      if ( zoneHeight > maxZoneHeight )
      {
        /* take maximum before darkening adjustment      */
        /* so overshoot suppression point doesn't change */
        maxZoneHeight = zoneHeight;
      }

      /* Note: bottom zones are not adjusted for darkening amount */

      /* all OtherBlues are bottom zone */
      blues->zone[blues->count].bottomZone =
        TRUE;
      blues->zone[blues->count].csFlatEdge =
        blues->zone[blues->count].csTopEdge;

      blues->count += 1;
    }

    /* Adjust for FamilyBlues */

    /* Search for the nearest flat edge in `FamilyBlues' or                */
    /* `FamilyOtherBlues'.  According to the Black Book, any matching edge */
    /* must be within one device pixel                                     */

    csUnitsPerPixel = FT_DivFix( cf2_intToFixed( 1 ), blues->scale );

    /* loop on all zones in this font */
    for ( i = 0; i < blues->count; i++ )
    {
      size_t     j;
      CF2_Fixed  minDiff;
      CF2_Fixed  flatFamilyEdge, diff;
      /* value for this font */
      CF2_Fixed  flatEdge = blues->zone[i].csFlatEdge;


      if ( blues->zone[i].bottomZone )
      {
        /* In a bottom zone, the top edge is the flat edge.             */
        /* Search `FamilyOtherBlues' for bottom zones; look for closest */
        /* Family edge that is within the one pixel threshold.          */

        minDiff = CF2_FIXED_MAX;

        for ( j = 0; j < numFamilyOtherBlues; j += 2 )
        {
          /* top edge */
          flatFamilyEdge = cf2_blueToFixed( familyOtherBlues[j + 1] );

          diff = cf2_fixedAbs( SUB_INT32( flatEdge, flatFamilyEdge ) );

          if ( diff < minDiff && diff < csUnitsPerPixel )
          {
            blues->zone[i].csFlatEdge = flatFamilyEdge;
            minDiff                   = diff;

            if ( diff == 0 )
              break;
          }
        }

        /* check the first member of FamilyBlues, which is a bottom zone */
        if ( numFamilyBlues >= 2 )
        {
          /* top edge */
          flatFamilyEdge = cf2_blueToFixed( familyBlues[1] );

          diff = cf2_fixedAbs( SUB_INT32( flatEdge, flatFamilyEdge ) );

          if ( diff < minDiff && diff < csUnitsPerPixel )
            blues->zone[i].csFlatEdge = flatFamilyEdge;
        }
      }
      else
      {
        /* In a top zone, the bottom edge is the flat edge.                */
        /* Search `FamilyBlues' for top zones; skip first zone, which is a */
        /* bottom zone; look for closest Family edge that is within the    */
        /* one pixel threshold                                             */

        minDiff = CF2_FIXED_MAX;

        for ( j = 2; j < numFamilyBlues; j += 2 )
        {
          /* bottom edge */
          flatFamilyEdge = cf2_blueToFixed( familyBlues[j] );

          /* adjust edges of top zone upward by twice darkening amount */
          flatFamilyEdge += 2 * font->darkenY;      /* bottom edge */

          diff = cf2_fixedAbs( SUB_INT32( flatEdge, flatFamilyEdge ) );

          if ( diff < minDiff && diff < csUnitsPerPixel )
          {
            blues->zone[i].csFlatEdge = flatFamilyEdge;
            minDiff                   = diff;

            if ( diff == 0 )
              break;
          }
        }
      }
    }

    /* TODO: enforce separation of zones, including BlueFuzz */

    /* Adjust BlueScale; similar to AdjustBlueScale() in coretype */
    /* `bcsetup.c'.                                               */

    if ( maxZoneHeight > 0 )
    {
      if ( blues->blueScale > FT_DivFix( cf2_intToFixed( 1 ),
                                         maxZoneHeight ) )
      {
        /* clamp at maximum scale */
        blues->blueScale = FT_DivFix( cf2_intToFixed( 1 ),
                                      maxZoneHeight );
      }

      /*
       * TODO: Revisit the bug fix for 613448.  The minimum scale
       *       requirement catches a number of library fonts.  For
       *       example, with default BlueScale (.039625) and 0.4 minimum,
       *       the test below catches any font with maxZoneHeight < 10.1.
       *       There are library fonts ranging from 2 to 10 that get
       *       caught, including e.g., Eurostile LT Std Medium with
       *       maxZoneHeight of 6.
       *
       */
#if 0
      if ( blueScale < .4 / maxZoneHeight )
      {
        tetraphilia_assert( 0 );
        /* clamp at minimum scale, per bug 0613448 fix */
        blueScale = .4 / maxZoneHeight;
      }
#endif

    }

    /*
     * Suppress overshoot and boost blue zones at small sizes.  Boost
     * amount varies linearly from 0.5 pixel near 0 to 0 pixel at
     * blueScale cutoff.
     * Note: This boost amount is different from the coretype heuristic.
     *
     */

    if ( blues->scale < blues->blueScale )
    {
      blues->suppressOvershoot = TRUE;

      /* Change rounding threshold for `dsFlatEdge'.                    */
      /* Note: constant changed from 0.5 to 0.6 to avoid a problem with */
      /*       10ppem Arial                                             */

      blues->boost = cf2_doubleToFixed( .6 ) -
                       FT_MulDiv( cf2_doubleToFixed ( .6 ),
                                  blues->scale,
                                  blues->blueScale );
      if ( blues->boost > 0x7FFF )
      {
        /* boost must remain less than 0.5, or baseline could go negative */
        blues->boost = 0x7FFF;
      }
    }

    /* boost and darkening have similar effects; don't do both */
    if ( font->stemDarkened )
      blues->boost = 0;

    /* set device space alignment for each zone;    */
    /* apply boost amount before rounding flat edge */

    for ( i = 0; i < blues->count; i++ )
    {
      if ( blues->zone[i].bottomZone )
        blues->zone[i].dsFlatEdge = cf2_fixedRound(
                                      FT_MulFix(
                                        blues->zone[i].csFlatEdge,
                                        blues->scale ) -
                                      blues->boost );
      else
        blues->zone[i].dsFlatEdge = cf2_fixedRound(
                                      FT_MulFix(
                                        blues->zone[i].csFlatEdge,
                                        blues->scale ) +
                                      blues->boost );
    }
  }

Referenced by cf2_font_setup().