ref: 0ad326236607df0802dc72c4f13b3f35484b7672
dir: /src/cff/cf2blues.c/
/***************************************************************************/
/* */
/* cf2blues.c */
/* */
/* Adobe's code for handling Blue Zones (body). */
/* */
/* Copyright 2009-2014 Adobe Systems Incorporated. */
/* */
/* This software, and all works of authorship, whether in source or */
/* object code form as indicated by the copyright notice(s) included */
/* herein (collectively, the "Work") is made available, and may only be */
/* used, modified, and distributed under the FreeType Project License, */
/* LICENSE.TXT. Additionally, subject to the terms and conditions of the */
/* FreeType Project License, each contributor to the Work hereby grants */
/* to any individual or legal entity exercising permissions granted by */
/* the FreeType Project License and this section (hereafter, "You" or */
/* "Your") a perpetual, worldwide, non-exclusive, no-charge, */
/* royalty-free, irrevocable (except as stated in this section) patent */
/* license to make, have made, use, offer to sell, sell, import, and */
/* otherwise transfer the Work, where such license applies only to those */
/* patent claims licensable by such contributor that are necessarily */
/* infringed by their contribution(s) alone or by combination of their */
/* contribution(s) with the Work to which such contribution(s) was */
/* submitted. If You institute patent litigation against any entity */
/* (including a cross-claim or counterclaim in a lawsuit) alleging that */
/* the Work or a contribution incorporated within the Work constitutes */
/* direct or contributory patent infringement, then any patent licenses */
/* granted to You under this License for that Work shall terminate as of */
/* the date such litigation is filed. */
/* */
/* By using, modifying, or distributing the Work you indicate that you */
/* have read and understood the terms and conditions of the */
/* FreeType Project License as well as those provided in this section, */
/* and you accept them fully. */
/* */
/***************************************************************************/
#include "cf2ft.h"
#include FT_INTERNAL_DEBUG_H
#include "cf2blues.h"
#include "cf2hints.h"
#include "cf2font.h"
/*************************************************************************/
/* */
/* The macro FT_COMPONENT is used in trace mode. It is an implicit */
/* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */
/* messages during execution. */
/* */
#undef FT_COMPONENT
#define FT_COMPONENT trace_cf2blues
/*
* For blue values, the FreeType parser produces an array of integers,
* while the Adobe CFF engine produces an array of fixed.
* Define a macro to convert FreeType to fixed.
*/
#define cf2_blueToFixed( x ) cf2_intToFixed( x )
FT_LOCAL_DEF( void )
cf2_blues_init( CF2_Blues blues,
CF2_Font font )
{
/* pointer to parsed font object */
CFF_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 = 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 = 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( 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( 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( 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 );
}
}
/*
* Check whether `stemHint' is captured by one of the blue zones.
*
* Zero, one or both edges may be valid; only valid edges can be
* captured. For compatibility with CoolType, search top and bottom
* zones in the same pass (see `BlueLock'). If a hint is captured,
* return true and position the edge(s) in one of 3 ways:
*
* 1) If `BlueScale' suppresses overshoot, position the captured edge
* at the flat edge of the zone.
* 2) If overshoot is not suppressed and `BlueShift' requires
* overshoot, position the captured edge a minimum of 1 device pixel
* from the flat edge.
* 3) If overshoot is not suppressed or required, position the captured
* edge at the nearest device pixel.
*
*/
FT_LOCAL_DEF( FT_Bool )
cf2_blues_capture( const CF2_Blues blues,
CF2_Hint bottomHintEdge,
CF2_Hint topHintEdge )
{
/* 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 ( ( blues->zone[i].csBottomEdge - csFuzz ) <=
bottomHintEdge->csCoord &&
bottomHintEdge->csCoord <=
( blues->zone[i].csTopEdge + csFuzz ) )
{
/* bottom edge captured by bottom zone */
if ( blues->suppressOvershoot )
dsNew = blues->zone[i].dsFlatEdge;
else if ( ( 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 = dsNew - bottomHintEdge->dsCoord;
captured = TRUE;
break;
}
}
if ( !blues->zone[i].bottomZone && cf2_hint_isTop( topHintEdge ) )
{
if ( ( blues->zone[i].csBottomEdge - csFuzz ) <=
topHintEdge->csCoord &&
topHintEdge->csCoord <=
( blues->zone[i].csTopEdge + csFuzz ) )
{
/* top edge captured by top zone */
if ( blues->suppressOvershoot )
dsNew = blues->zone[i].dsFlatEdge;
else if ( ( 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 = dsNew - topHintEdge->dsCoord;
captured = TRUE;
break;
}
}
}
if ( captured )
{
/* move both edges and flag them `locked' */
if ( cf2_hint_isValid( bottomHintEdge ) )
{
bottomHintEdge->dsCoord += dsMove;
cf2_hint_lock( bottomHintEdge );
}
if ( cf2_hint_isValid( topHintEdge ) )
{
topHintEdge->dsCoord += dsMove;
cf2_hint_lock( topHintEdge );
}
}
return captured;
}
/* END */