ref: 7f569f4574e035aeb3bc4457ac8d01d8cede9cf6
dir: /src/cff/cf2font.c/
/***************************************************************************/
/* */
/* cf2font.c */
/* */
/* Adobe's code for font instances (body). */
/* */
/* Copyright 2007-2014 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 <ft2build.h>
#include FT_INTERNAL_CALC_H
#include "cf2ft.h"
#include "cf2glue.h"
#include "cf2font.h"
#include "cf2error.h"
#include "cf2intrp.h"
/* Compute a stem darkening amount in character space. */
static void
cf2_computeDarkening( CF2_Fixed emRatio,
CF2_Fixed ppem,
CF2_Fixed stemWidth,
CF2_Fixed* darkenAmount,
CF2_Fixed boldenAmount,
FT_Bool stemDarkened,
FT_Int* darkenParams )
{
/*
* Total darkening amount is computed in 1000 unit character space
* using the modified 5 part curve as Adobe's Avalon rasterizer.
* The darkening amount is smaller for thicker stems.
* It becomes zero when the stem is thicker than 2.333 pixels.
*
* By default, we use
*
* darkenAmount = 0.4 pixels if scaledStem <= 0.5 pixels,
* darkenAmount = 0.275 pixels if 1 <= scaledStem <= 1.667 pixels,
* darkenAmount = 0 pixel if scaledStem >= 2.333 pixels,
*
* and piecewise linear in-between:
*
*
* darkening
* ^
* |
* | (x1,y1)
* |--------+
* | \
* | \
* | \ (x3,y3)
* | +----------+
* | (x2,y2) \
* | \
* | \
* | +-----------------
* | (x4,y4)
* +---------------------------------------------> stem
* thickness
*
*
* This corresponds to the following values for the
* `darkening-parameters' property:
*
* (x1, y1) = (500, 400)
* (x2, y2) = (1000, 275)
* (x3, y3) = (1667, 275)
* (x4, y4) = (2333, 0)
*
*/
/* Internal calculations are done in units per thousand for */
/* convenience. The x axis is scaled stem width in */
/* thousandths of a pixel. That is, 1000 is 1 pixel. */
/* The y axis is darkening amount in thousandths of a pixel.*/
/* In the code, below, dividing by ppem and */
/* adjusting for emRatio converts darkenAmount to character */
/* space (font units). */
CF2_Fixed stemWidthPer1000, scaledStem;
FT_Int logBase2;
*darkenAmount = 0;
if ( boldenAmount == 0 && !stemDarkened )
return;
/* protect against range problems and divide by zero */
if ( emRatio < cf2_floatToFixed( .01 ) )
return;
if ( stemDarkened )
{
FT_Int x1 = darkenParams[0];
FT_Int y1 = darkenParams[1];
FT_Int x2 = darkenParams[2];
FT_Int y2 = darkenParams[3];
FT_Int x3 = darkenParams[4];
FT_Int y3 = darkenParams[5];
FT_Int x4 = darkenParams[6];
FT_Int y4 = darkenParams[7];
/* convert from true character space to 1000 unit character space; */
/* add synthetic emboldening effect */
/* `stemWidthPer1000' will not overflow for a legitimate font */
stemWidthPer1000 = FT_MulFix( stemWidth + boldenAmount, emRatio );
/* `scaledStem' can easily overflow, so we must clamp its maximum */
/* value; the test doesn't need to be precise, but must be */
/* conservative. The clamp value (default 2333) where */
/* `darkenAmount' is zero is well below the overflow value of */
/* 32767. */
/* */
/* FT_MSB computes the integer part of the base 2 logarithm. The */
/* number of bits for the product is 1 or 2 more than the sum of */
/* logarithms; remembering that the 16 lowest bits of the fraction */
/* are dropped this is correct to within a factor of almost 4. */
/* For example, 0x80.0000 * 0x80.0000 = 0x4000.0000 is 23+23 and */
/* is flagged as possible overflow because 0xFF.FFFF * 0xFF.FFFF = */
/* 0xFFFF.FE00 is also 23+23. */
logBase2 = FT_MSB( (FT_UInt32)stemWidthPer1000 ) +
FT_MSB( (FT_UInt32)ppem );
if ( logBase2 >= 46 )
/* possible overflow */
scaledStem = cf2_intToFixed( x4 );
else
scaledStem = FT_MulFix( stemWidthPer1000, ppem );
/* now apply the darkening parameters */
if ( scaledStem < cf2_intToFixed( x1 ) )
*darkenAmount = FT_DivFix( cf2_intToFixed( y1 ), ppem );
else if ( scaledStem < cf2_intToFixed( x2 ) )
{
FT_Int xdelta = x2 - x1;
FT_Int ydelta = y2 - y1;
FT_Int x = stemWidthPer1000 -
FT_DivFix( cf2_intToFixed( x1 ), ppem );
if ( !xdelta )
goto Try_x3;
*darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
FT_DivFix( cf2_intToFixed( y1 ), ppem );
}
else if ( scaledStem < cf2_intToFixed( x3 ) )
{
Try_x3:
{
FT_Int xdelta = x3 - x2;
FT_Int ydelta = y3 - y2;
FT_Int x = stemWidthPer1000 -
FT_DivFix( cf2_intToFixed( x2 ), ppem );
if ( !xdelta )
goto Try_x4;
*darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
FT_DivFix( cf2_intToFixed( y2 ), ppem );
}
}
else if ( scaledStem < cf2_intToFixed( x4 ) )
{
Try_x4:
{
FT_Int xdelta = x4 - x3;
FT_Int ydelta = y4 - y3;
FT_Int x = stemWidthPer1000 -
FT_DivFix( cf2_intToFixed( x3 ), ppem );
if ( !xdelta )
goto Use_y4;
*darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
FT_DivFix( cf2_intToFixed( y3 ), ppem );
}
}
else
{
Use_y4:
*darkenAmount = FT_DivFix( cf2_intToFixed( y4 ), ppem );
}
/* use half the amount on each side and convert back to true */
/* character space */
*darkenAmount = FT_DivFix( *darkenAmount, 2 * emRatio );
}
/* add synthetic emboldening effect in character space */
*darkenAmount += boldenAmount / 2;
}
/* set up values for the current FontDict and matrix */
/* caller's transform is adjusted for subpixel positioning */
static void
cf2_font_setup( CF2_Font font,
const CF2_Matrix* transform )
{
/* pointer to parsed font object */
CFF_Decoder* decoder = font->decoder;
FT_Bool needExtraSetup = FALSE;
/* character space units */
CF2_Fixed boldenX = font->syntheticEmboldeningAmountX;
CF2_Fixed boldenY = font->syntheticEmboldeningAmountY;
CFF_SubFont subFont;
CF2_Fixed ppem;
/* clear previous error */
font->error = FT_Err_Ok;
/* if a CID fontDict has changed, we need to recompute some cached */
/* data */
subFont = cf2_getSubfont( decoder );
if ( font->lastSubfont != subFont )
{
font->lastSubfont = subFont;
needExtraSetup = TRUE;
}
/* if ppem has changed, we need to recompute some cached data */
/* note: because of CID font matrix concatenation, ppem and transform */
/* do not necessarily track. */
ppem = cf2_getPpemY( decoder );
if ( font->ppem != ppem )
{
font->ppem = ppem;
needExtraSetup = TRUE;
}
/* copy hinted flag on each call */
font->hinted = (FT_Bool)( font->renderingFlags & CF2_FlagsHinted );
/* determine if transform has changed; */
/* include Fontmatrix but ignore translation */
if ( ft_memcmp( transform,
&font->currentTransform,
4 * sizeof ( CF2_Fixed ) ) != 0 )
{
/* save `key' information for `cache of one' matrix data; */
/* save client transform, without the translation */
font->currentTransform = *transform;
font->currentTransform.tx =
font->currentTransform.ty = cf2_intToFixed( 0 );
/* TODO: FreeType transform is simple scalar; for now, use identity */
/* for outer */
font->innerTransform = *transform;
font->outerTransform.a =
font->outerTransform.d = cf2_intToFixed( 1 );
font->outerTransform.b =
font->outerTransform.c = cf2_intToFixed( 0 );
needExtraSetup = TRUE;
}
/*
* font->darkened is set to true if there is a stem darkening request or
* the font is synthetic emboldened.
* font->darkened controls whether to adjust blue zones, winding order,
* and hinting.
*
*/
if ( font->stemDarkened != ( font->renderingFlags & CF2_FlagsDarkened ) )
{
font->stemDarkened =
(FT_Bool)( font->renderingFlags & CF2_FlagsDarkened );
/* blue zones depend on darkened flag */
needExtraSetup = TRUE;
}
/* recompute variables that are dependent on transform or FontDict or */
/* darken flag */
if ( needExtraSetup )
{
/* StdVW is found in the private dictionary; */
/* recompute darkening amounts whenever private dictionary or */
/* transform change */
/* Note: a rendering flag turns darkening on or off, so we want to */
/* store the `on' amounts; */
/* darkening amount is computed in character space */
/* TODO: testing size-dependent darkening here; */
/* what to do for rotations? */
CF2_Fixed emRatio;
CF2_Fixed stdHW;
CF2_Int unitsPerEm = font->unitsPerEm;
if ( unitsPerEm == 0 )
unitsPerEm = 1000;
ppem = FT_MAX( cf2_intToFixed( 4 ),
font->ppem ); /* use minimum ppem of 4 */
#if 0
/* since vstem is measured in the x-direction, we use the `a' member */
/* of the fontMatrix */
emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->a );
#endif
/* Freetype does not preserve the fontMatrix when parsing; use */
/* unitsPerEm instead. */
/* TODO: check precision of this */
emRatio = cf2_intToFixed( 1000 ) / unitsPerEm;
font->stdVW = cf2_getStdVW( decoder );
if ( font->stdVW <= 0 )
font->stdVW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
if ( boldenX > 0 )
{
/* Ensure that boldenX is at least 1 pixel for synthetic bold font */
/* (similar to what Avalon does) */
boldenX = FT_MAX( boldenX,
FT_DivFix( cf2_intToFixed( unitsPerEm ), ppem ) );
/* Synthetic emboldening adds at least 1 pixel to darkenX, while */
/* stem darkening adds at most half pixel. Since the purpose of */
/* stem darkening (readability at small sizes) is met with */
/* synthetic emboldening, no need to add stem darkening for a */
/* synthetic bold font. */
cf2_computeDarkening( emRatio,
ppem,
font->stdVW,
&font->darkenX,
boldenX,
FALSE,
font->darkenParams );
}
else
cf2_computeDarkening( emRatio,
ppem,
font->stdVW,
&font->darkenX,
0,
font->stemDarkened,
font->darkenParams );
#if 0
/* since hstem is measured in the y-direction, we use the `d' member */
/* of the fontMatrix */
/* TODO: use the same units per em as above; check this */
emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->d );
#endif
/* set the default stem width, because it must be the same for all */
/* family members; */
/* choose a constant for StdHW that depends on font contrast */
stdHW = cf2_getStdHW( decoder );
if ( stdHW > 0 && font->stdVW > 2 * stdHW )
font->stdHW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
else
{
/* low contrast font gets less hstem darkening */
font->stdHW = FT_DivFix( cf2_intToFixed( 110 ), emRatio );
}
cf2_computeDarkening( emRatio,
ppem,
font->stdHW,
&font->darkenY,
boldenY,
font->stemDarkened,
font->darkenParams );
if ( font->darkenX != 0 || font->darkenY != 0 )
font->darkened = TRUE;
else
font->darkened = FALSE;
font->reverseWinding = FALSE; /* initial expectation is CCW */
/* compute blue zones for this instance */
cf2_blues_init( &font->blues, font );
}
}
/* equivalent to AdobeGetOutline */
FT_LOCAL_DEF( FT_Error )
cf2_getGlyphOutline( CF2_Font font,
CF2_Buffer charstring,
const CF2_Matrix* transform,
CF2_F16Dot16* glyphWidth )
{
FT_Error lastError = FT_Err_Ok;
FT_Vector translation;
#if 0
FT_Vector advancePoint;
#endif
CF2_Fixed advWidth = 0;
FT_Bool needWinding;
/* Note: use both integer and fraction for outlines. This allows bbox */
/* to come out directly. */
translation.x = transform->tx;
translation.y = transform->ty;
/* set up values based on transform */
cf2_font_setup( font, transform );
if ( font->error )
goto exit; /* setup encountered an error */
/* reset darken direction */
font->reverseWinding = FALSE;
/* winding order only affects darkening */
needWinding = font->darkened;
while ( 1 )
{
/* reset output buffer */
cf2_outline_reset( &font->outline );
/* build the outline, passing the full translation */
cf2_interpT2CharString( font,
charstring,
(CF2_OutlineCallbacks)&font->outline,
&translation,
FALSE,
0,
0,
&advWidth );
if ( font->error )
goto exit;
if ( !needWinding )
break;
/* check winding order */
if ( font->outline.root.windingMomentum >= 0 ) /* CFF is CCW */
break;
/* invert darkening and render again */
/* TODO: this should be a parameter to getOutline-computeOffset */
font->reverseWinding = TRUE;
needWinding = FALSE; /* exit after next iteration */
}
/* finish storing client outline */
cf2_outline_close( &font->outline );
exit:
/* FreeType just wants the advance width; there is no translation */
*glyphWidth = advWidth;
/* free resources and collect errors from objects we've used */
cf2_setError( &font->error, lastError );
return font->error;
}
/* END */